Too Many Parts

2011-09-06T17:04:00.000-07:00

*Miata Engines in Other Cars -*
For those who don't automatically swap a V-8 into whatever rear wheel drive vehicle they have access to, the Miata drivetrain is a very sensible choice. While the Zetec and Ecotec have many merits, I think there is great value to the fact that the Miata engine and transmission were factory engineered to work together. Does this really make a difference? Probably not too much. But, to me, it feels "right" and it certainly makes things much easier, in my opinion. With the Miata, you buy your drivetrain "ready made" and simply need to install it. To my knowledge, Miata drivetrains have been transplanted into Locost / Caterham / Lotus Seven-style race cars, Datsun Roadsters, MGs of various vintages a Triumph Spitfire and an Austin Healy Sprite. I've put together here a list of the swaps that I have found on the Internet. In the world of print, Grass Roots Motorsports began a series, in June 2007, on doing this transplant into an early-year MGB. They don't seem to have it in their on-line archives; I may scan the story at some point. But, until then... If you know of any such well-documented swaps, please drop me a line & I will post them here. By the way, click on the photos to visit the sites referenced.
	This guy, Bob, has a fabulous website documenting his complete-home-fabbed up-grading of an Austin Healy Sprite. Not only has he swapped in a Miata drivetrain, but he's replaced just about everything else in the car. It runs now & sounds great.
	Not much to see here other than a couple overview shots of the engine bay and some project specs. Here is another photo of a very tidy swap into some other MGA.
	This guy doesn a fine job of documenting the key elements of his Caterham build with photographs and text. His link to the documentation of the work is at the bottom of the intro page. He went with EFI, not carbs, and did some custom work on the transmission (for mounting) and cooling system (for flow). I found a video of his first start here.
	Wade is the first person I know of who has swapped a Miata drivetrain into a Datsun Roadster. His car is a '66, like mine. He did his swap as part of a frame-off restoration. Also, he used a 6-speed transmission, which seems to be narrower than the 5-speed. The photos tell the story.
	Although it doesn't have as many photos as the others, this swap chronicle is very informative. The Spitfire is a tiny, tiny car so it is valuable to see how he got around the problems that the swap posed.
	This site documents the insertion of a Miata 1.8L into a 1973 MGB. While not a methodical how-to, there are good photos of the modified engine and transmission mounts necessary, as well as the alterations to the radiator that they did. To move through the pages, enter the numbers 2-10 between the "miatab" and the "." in the web address.
	I don't know if this counts as a swap, but it's a MG replica kit car that uses the Miata 1.6L engine. There's really no useful technical information on the pages, nor interesting photos of the engine and drivetrain.
	This site is only photos of swapping a Miata engine into a pre-1959 Nash Metropolitan. You get an idea of the transmission tunnel and engine bay mods, though.
	Like the kit car above, this insertion of a Miata engine into an old Morris Minor is more than just a "swap". This fellow built an entire frame to allow himself to use all Miata running gear along with the drivetrain. It looks like quite a project. The website is still being updated occasionally.

2011-09-06T16:56:00.001-07:00

Throttle Installation -

	A clean, simple throttle stop that holds the throttle lever in the same position as stock. I could not use the stock stop, however, because it interfered with the coil bracket. Ultimately I will probably modify or reposition the coil bracket, the throttle lever strikes it when the engine lugs and under extreme acceleration.
	The throttle cable was originally the cruise control cable from a late-model Honda. I believe it was a 4th generation Accord. It is, magically, the correct length, has the correct ends and has the clamp bolts at the throttle body end in the right place. All I had to do to modify it is trim about an inch of sheath off the throttle lever end of the cable.
	I don't love the bracket I made for the throttle lever end of the cable. It is the one piece on the car that was designed with a hammer instead of a ruler. But, it works and looks okay if you squint at it. The clamp is stock Roadster.
	Here's a view of how I made the depressed channel in the top of the bracket to hold the cable in place properly.

2011-09-06T16:55:00.000-07:00

Gas Tank and Filter Installation -

	I affixed all the mounting nuts for the Honda fuel pump and the ring for the fuel level sender with JB weld. Not sexy, but it gets the job done. Lots of #6 sheet metal screws and a thick layer of fuel-resistant Hylomar gasketing material and the tank is back together.
	The breather tube fitting is a 90-degree elbow: 3/8" hose to 1/4" MNPT.
	The old fuel line outlet is easy to cap. I forget the specs of the fitting, but it's the same as the union fitting along the passenger frame rail, so you can always carry that to the store with you to test fitment.
	I cut strips of a strange plastic felt from a nearby discount fabric store to make the isolating belts for above and below the tank. They should result in the same thickness as the stock felt-like strips.
	Here is a view of the new tank through the access port in the trunk. I would have loved to place the pump farther back, so that it would come out through this hole, but the sump basin was as far back as it would go. I'll never get the fuel level sender out now without dropping the tank. But, at least I can access all the lines and leads from here.
	The fuel outlet on the Honda pump is a 12mm banjo fitting leading to a bizarre steel and rubber hose that is useless in this application. I got a similar hose off a '93 Acura that had a longer steel portion that I cut off before the rubber hose and joined to my 5/16 steel lines with aftermarket 8mm EFI hose.
	The fuel return on the Honda pump is tiny -- 6mm (1/4"). I split the difference by using a 7mm diameter EFI hose between the 6mm fitting and the 8mm line.
	The fuel filter solution is from a 1993 Nissan Altima. It's easy to grab from the salvage yard (for the bracket) as it is mounted on the firewall in the Nissan. I mounted mine in the passenger wheel well. I may end up making a shield/enclosure for it. We'll see.

2011-09-06T16:53:00.000-07:00

Fuel Pump Installation -

	I made a few paper templates to figure the smallest area I could cut out and still fit the pump, sump and fuel level sender. I ended up with this rectangle. I drilled out the corners, then cut the panel out with a sabre saw (it did not blow up). Then I drilled out the welds holding on the sender mounting ring and the breather tube.
	The Honda tank is not a simple box, like the Roadster's, so I cut into it with a cold chisel (it did not blow up) to get at the catch can and the complex pump mounting ring (not shown), which I did not use in the end, although most do. If you buy the correct tank, you will not see this catch can, but what follows is how I modified. First I cut off the mounting tabs so that it would sit flat on the bottom of the tank.
	Then, after many fitment tests, I mounted it to one of the baffles with a very large sheet metal screw. A wide fender washer distributes the squeeze of the screw on the plastic wall of the catch can.
	Between the catch can and the baffle is a piece of 1" x 3/4" aluminum channel; it serves as a spacer.
	As mentioned above, the stock Honda pump assembly held the pump too high above the tank bottom for my tastes, so I modified it by cutting the base of the bracket away. Click on the thumb to see before and after.
	With the bracket modified, I could now adjust the height of the pump, and made it so it kisses the bottom of the catch can. The pump is very firmly held by the hose clamp. After this photograph, I replaced the orange rubber with a short section of radiator hose and turned the hose clamp to face down to improve ease of installation.
	If you modify the pump to sit lower as I have, be sure to use in-tank EFI fuel hose for your new, slightly longer hose between the pump and the outlet tubing. Regular EFI hose WILL FAIL, sometimes quite quickly. The hose made by Gates, as a 5/16" side, in 12" lengths. It is Gates #42195185 or #27093 (Napa #H209).

2011-09-06T16:51:00.000-07:00

Fuel System Introduction -

When swapping any EFI engine into a Datsun Roadster, or any other car, you have to add a high-pressure fuel pump. The easy way is to mount an external pump, although many report these to be annoyingly loud. I went with the in-tank solution of an OEM Honda pump. This pump works because will fit in the Roadster's relatively shallow tank. Most pump assemblies, such as that from the Miata itself, are quite tall.

The installation of the Honda pump has been well-documented by others, such as here. The specific source for this pump, according to my notes, Hondas and Acuras from the second half of the '90s. When I first went to the junk yard, I was in a hurry and (a) did not consult my notes and (b) did not check the pump, or even think very much, before buying the tank.

You have to buy the whole tank to get the catch can, so the pump will not be starved during cornering and such. So, since I didn't want to buy another tank, I made due with the wrong catch can and simply used it with the proper pump, which I bought later on. This earlier catch can seems to be bigger than the later one and doesn't fit so well; I had to mount it backwards.

I found that, in my opinion, the Honda pump assembly is *too* shallow. With the stock mounting ring, the base of the pump hangs over an inch above the bottom of the tank. The stock Roadster fuel level sender registers "empty" at about 1/4" from the bottom of the tank. So, I removed the ring, but the pump was still high, so I modified its mounting bracket in a manner that is a little kludgy, but should work fine.

I went with a no-weld solution because (a) I don't weld and (b) I didn't feel like taking it to a place willing to weld a gas tank only to have them screw it up somehow. There are way too many bits and pieces to get in the right place for me to risk the odds. Again, the end result is not as polished or pretty as I would like, but it is functional, and will be hidden away. It does have the small benefit of being easily disassembled should I need to.

2011-09-06T16:44:00.000-07:00

Cooling System Hoses -

	My engine came with a broken water outlet in the front. I replaced it with an early Miata (i.e. 1.6 liter) outlet, which opens up, not towards the left. To that I mounted a 1st generation Honda thermo housing. The Honda housing needed to have its mount holes bored out slightly. The hose is a portion of lower radiator hose from a 4th gen Honda. Perfect fit, including the jog to one side!
	Down below, I had to create a reducer from the Miata's 31mm (ish) hose to the Honda's 28mm hose. Another 1st generation Honda thermo housing and the thermo housing from a Mazda 323 did the trick. Any front drive Mazda or Kia with the B6 or BP engine will have the same housing.
	The front portion of the lower radiator hose comes from a 5th generation Honda (lower). The rear portion of the hose comes from '93 Protege. Both are cut to fit. The clearance with the frame is much better than it looks from above.
	With the cooling system all buttoned up, I poured 4 quarts of distilled water in and waited for a leak. Boy did I get one: water pouring out of the pump housing. Seems the seals in these modern pumps die quickly without water, so the year the engine sat in my yard in Southern California pretty much killed them. Don't let this happen to you! Change your water pump and timing belt at the last possible moment before installation.
	The stock Miata heater line inlet and outlet both jut out towards the driver's side completely parallel to the firewall. To mate with the Roadster heater, I cut the turn off the Miata return tube (not visible here, but shown a few steps below) and assembled an S-shaped hose for the inlet.
	Here is is the S-hose created from the two ends of Goodyear hose #63039. These two bits of hose join the Miata hot water outlet at the back of the block to the Roadster heater inlet pipe, via a Honda heater valve. A custom mounting plate for the control cable is visible as well.
	I'm using the heater valve from an Acura. Just about all Hondas and Acuras from the 90s seem to use this same small valve, with 11/16" fittings. On the Roadster, the cable pushes to open and pulls to close, so I will be installing this valve backwards relative to its stock flow orientation. I've also rotated the lever by 90 degrees.
	I had to modify the valve slightly: I removed the lever and removed the nub that clocked it to a specific face of the square peg. Feel free not to cut as deeply as I clumsily did. I then re-mounted the lever turned 90 degrees from stock, as shown above.
	This plate mounts to the Honda heater valve and holds the control cable in place using a clamp I pulled off an MGB in the salvage yard. Or was it an Opel GT? Anyways, any old car will have a handy screw-down cable clamp.
	This is how the plate looks when mounted to the Honda heater valve.
	Here is a PDF template for the cable clamp plate. If your clamp differs, change the hole and slot at the top accordingly. You'll still find the template handy for locating the offset Honda valve locating pins and screw holes.
	Here is how I cut down the Miata return tube, simply removing the bend (already gone in this photo) and the stock mounting bracket. I made a new bracket and attached it to the tube with JB weld. The tube is 11/16" but a 5/8" heater hose fits on it well enough. Tight is better than loose.
	New bracket for the coolant return tube. Maybe this isn't the best way to do this -- I probably should have made one that clamped. But, this bracket mimics the stock solution, although I substitute JB weld for a real weld.
	Modified coolant return tube completed. The hose is Goodyear #63049, cut down slightly on both ends.
	Here is a close-up of how the bracket mounts to the cut-down Miata coolant return tube.
	I had to cut a hole in the backing plate for the new heater return hose to pass through. The hose doesn't acutally touch the edges, but I want to avoid chaffing. I'll keep an eye on it, and will edge the cut in some sort of rubber trim if there is any rubbing.
	It's hard to see the heater lines all buttoned up, since there's so much going on in that space. I installed a new control cable (from Home Depot, for a lawn mower throttle) and ran it through the firewall in the stock position with a new grommet. No way I'd be able to attach it later. PLEASE NOTE In the stock Miata, water is always flowing through the heater. Thus, for the rear of the engine block to cool properly and for the fan to ever turn off after the engine has gotten to temperature, the shut off valve that I detail below CANNOT BE CLOSED. Since it is winter, I don't care. But, I do need to re-plumb the heater valve so that it bypasses into the return line when shut, rather than simply blocking the flow of water.

2011-09-06T16:43:00.000-07:00

Cooling System Introduction -
The cooling system for this transplant is assembled mostly from a selection of OEM or aftermarket Honda parts. The radiator is one of those cheap types that you see all over eBay. The fan assembly is from a 5th generation Civic. The heater control valve can be found in just about any Honda or Acura from the 90s. Even two of the three thermostat housings used come from a 1st generation Civic. I actually first installed this radiator and electric fan while still driving the stock engine. It was a slightly tight fit, but I was pleased with the efficiency and quiet of the combo. The greater space created by the Miata engine, which sits farther back, allowed me to clean up my mounting system and create a pretty slick set-up. PLEASE NOTE In the stock Miata, water is always flowing through the heater. Thus, for the rear of the engine block to cool properly and for the fan to ever turn off after the engine has gotten to temperature, the shut off valve that I detail below CANNOT BE CLOSED. Since it is winter, I don't care. But, I do need to re-plumb the heater valve so that it bypasses into the return line when shut, rather than simply blocking the flow of water.
	This shot shows the radiator and side deflectors installed with the stock Roadster engine. Note the angled cut of the far deflector. The radiator is tipped to keep the bottom away from the tie rod ends and the top away from the water pump nose. With the Miata engine, there is no need to tip the radiator -- plenty of room.
	The aftermarket Honda Del Sol radiator sits in two rubber bushings held by a pair of custom brackets. The brackets mount to existing threaded holes on the cross member; they are cut from 2" x 1/8" steel. The rubber bushings are from the upper radiator mounts of a late-model Daewoo. Plenty of these cars in one of my usual yards, for some reason.
	Here is a closeup of one of the lower radiator brackets. I used these same brackets to mount this radiator when I had the stock Roadster engine in place. The only difference is that I had to use much slimmer bushings (really just rubber grommets) and tip the radiator forward at the top to clear the Datsun water pump pulley.
	Here is a PDF template of my driver's side lower radiator bracket. Although I simply flipped this template over to create the passenger's side bracket, I did find that I had to tweak the bends slightly to account for differences between the two sides of the crossmember. Test fitment with pieces of cardboard or something before cutting the final pieces.
	Here is the upper radiator mounting bracket, with a Daewoo bushing already installed.
	The template for the upper radiator mounting bracket.
	The upper radiator bracket installed. This is not the most comprehensive view, but suffice it to say that the radiator fits very well and square, with a great deal of clearance all around and no cutting of anything (except hoses). It is well-placed relative to the stock air scoop below. I may yet make deflectors for the sides, though, as the Honda radiator does not fill the space.

2011-09-06T16:32:00.000-07:00

Alternator, Harness, Fusebox -

	The alternator is a Nippon-Denso unit #8172. This is the smallest OEM automotive alternator available. It was stock on 3-cylinder cars, such as the Diahatsu Charade and Chevy / Suzuki Sprint / Swift. No other alternator will fit between block and framerail.
	Even so, I had to clock the rear housing 90-degrees so that the power terminal would face up. In stock form, it would point to the left in this photograph, which makes it bang right into the frame. Clocking required disassembling the entire alternator. A lot of work.
	This bracket is so short that I felt comfortable using 1/4" steel to make it. I left the upper ridges from the drill-based slotting because I thought they looked kinda cool.
	Here is a picture of the alternator installed. The belt is a Goodyear #4040342, as it is 34.25" in circumferance. The pulley comes from a Subaru Justy, which gives the 4-rib pattern that matches the Miata. Take the nut from the Justy and it will all fit together real well.
	Here is an image of the ECU mounted along the driver's side kick panel. I simply drilled three holes and used really big sheet metal screws. (The only modifications to the Datsun itself in the entire build.) This placement allows me to use the Miata ECU harness as my entire engine harness; the wires reach from here all the way to the MAF sensor in the far front of the engine bay.
	The Miata has a nice relay rack mounted on the driver's side fender. I didn't want to see it, though, so I modified it to mount in the Datsun's factory mono radio speaker holes high up in the passenger footwell. First I cut the mounting tabs off of the rack itself, and drilled a 3/16" hole at each end.
	Then, I cut and folded a simple bracket to join the rack to the pre-existing holes in the footwell. I used 22-gauge steel because I had an odd-shaped piece laying around. It's a little flimsy; 18- or 16-gauge might be better. When sitting in the car, you really have to tip yourself flat against the transmission tunnel to see this thing.
	This little bracket, made from 1"x1" aluminum angle stock, mounts the Miata's main fuse box to the lower mount hole for the coil bracket on the Datsun. I threaded the two holes you see at 1/4-20 since holding a nut under there would be a real hassle. Note the notch for a bulge in the back of the fusebox.
	The main fuse box looks rather nice and tidy tucked away in the corner, I think. Never mind all the stray wires; I'll tidy them up as soon as I know that the thing runs.
	Early on in the swap preparation, I pulled the room fusebox from a '96 Miata. I liked its compactness. Unfortunately, this was before I learned to cut all leads as long as possible when pulling parts. So, when it came time to install it, I was left with 1/2" to 2" of wire to use. It's been a year and a half, and I never saw another '96/97 box to pull, so I'm working with it.
	To give myself the greatest flexibility, and to do the best I could with what little wire I had to attach to, I put female crimp spades on every wire coming out of the fusebox. I wish I had more wire so at least these could be proper pigtails. In the future I will probably do something cleaner with this.
	Since I have a '94 engine, it's OBD-I, so my diagnostic options are limited. I have a small Radio Shack LED under the dash that used to be my "fan is on" light & now runs to the "check engine" light lead on the ECU.
	These two switches, to the left of the steering column, under the dash, allow me to diagnose: one grounds the "TEN" (test engine) lead from the ECU, which causes the check engine light to blink stored codes. The other activates the brake switch lead to the ECU, which is used to clear stored trouble codes. [In the end, I linked the brake switch lead to the ECU to the brake light pressure switch (as part of the engine harness).]
	Here is a view of the final, wrapped engine harness before installation. I included the oil pressure lead, the brake leads and the (gauge) coolant temperature lead in this harness, as well as ECU-related power leads. There is a separate harness for the general power leads, not shown. Click on the image to see the pig tails labelled.

2011-09-06T16:30:00.000-07:00

Electrical Introduction -
As I've mentioned elsewhere, I fully intended to install the electrical, cooling and fuel systems necessary for my swap into the car while still running the stock drivetrain. It seemed like a way to approach a large project incrementally -- in terms of time and expense -- while minimizing the time the car was off the road. Ultimately, I was sucessful with the cooling system, got part of the way with the electrical and did nothing about the fuel before pulling the engine. My "part way" move with the electrical system was to take the main fusebox and main power leads (battery, alternator and starter) and mount them into the Datsun. This was pretty easy, just a short afternoon's work. The bonus to doing this was that the Miata has the battery in the back, so my otherwise stock Roadster had a rear-mount battery solution. Unfortunately, I pulled all sorts of "unnecessary" leads out of the guts of the main Miata fuse box, only to discover that they were not only necessary, but also documented solely in the $100 factory manual. After it was clear that I not only had no idea where things went, and had lost some of the OEM patch wires, I bought second, intact fuse box and started over with it. Even with a complete box, figuring out what wires went where (e.g. directly to relays, to the in-cabin fuse box, directly to sensors/actuators, to the ECU, etc.) took a fair amount of time, patience and flipping through 15 or so pages of half-assed Mitchell program Miata wiring diagrams. So far, I have created my own wiring diagrams for the ECU (stripped of unnecessary wires, mostly having to do with smog and safety devices) and the power circuit. I still need to finish the diagram that shows how the new Miata wires (including a retrofitted Miata cabin fusebox) mesh with the Roadster's non-powertrain-related wiring (lights, gauges and eventual audio). This, is really only a matter of redrawing how things connect with the new fuse box and making note of some other aspects of my non-stock harness, which I created about 2 years ago.
	This is my power harness diagram, based on the stock Miata fuseboxes, but stripped of any leads unnecessary to running the engine in the Datsun (stripped of smog devices, power assist devices and A/C). [UPDATED 8/18/08: final alternator hookup and gauges added]
	Here is the ECU harness diagram based on a '94 Miata harness with 5-speed, with all smog devices removed. So far, I've gotten the check engine light to give me some error codes, about the missing smog equipment, but it starts and runs fine. [UPDATED 8/18/08: Tachometer added]

2011-09-06T16:21:00.000-07:00

Tranmission Clutch and Driveshaft -

	Here are the elements I used to link the stock Roadster clutch master to the Miata clutch slave. Clockwise from left: Miata slave; custom bent 10" length of 3/16" steel brake tube with 10mm x 1 inverted flare fittings; stock Miata clutch line upper bracket; stock Miata rubber clutch line; stock Miata clutch line lower bracket (modified). I also modified the very tail end Roadster hard line, as described below.
	I cut the flare off the end of the stock Roadster steel clutch line and removed the stock fitting (shown above), replacing it with an inverted flare fitting with 10mm x 1 metric threads (shown below). Then I made a new double flare to replace the one I cut off. Metric double flare fittings work on the same sizes of tubing as SAE flare fittings. Very convenient for this sort of puzzle.
	Here is a view of everything in place. The black Miata bracket bolts to the block; the gold Miata bracket bolts to the stock Roadster clutch bracket on the frame rail.
	Here is the driveshaft, as grafted (Miata nose, Datsun tail) by Laszlo (Les) at Driveshaft Masters. He's a real nice guy who seems to have an interest world of his own set up in Harbor City, CA. The driveshaft was done in a day and fits great. We'll see how it spins....
	Filling the transmission with oil is no fun, albeit no less fun than on a stock Miata. I don't recall how not fun it was with the stock Datsun. I'm thinking very. If you don't have one of these handy pumps, you're torturing yourself even more than you need to.
	Here is the car moving under its own power for the first time in more than a year. Just a little back-and-forth to make sure the clutch and transmission were working properly. Aside from the exhaust "leak" and filterless intake, it was spooky quiet under power. I could get used to that.

2011-09-06T16:19:00.000-07:00

Transmission Mounting -

	Here is my transmission mounting bracket. The bracket is a 3/8" thick piece of steel drilled to take two industrial vibration isolators. I ordered the isolators from a place called DrillSpot.com. I placed the order at around 10 p.m. one night, and got them 6 p.m. the next day, on standard shipping from halfway across the county. I was impressed!
	The bracket mounts to two existing 10mm threaded holes on the tail housing. This combination puts the transmission output shaft at the same height as stock (if I measured correctly). Note that both this mounting plate and the gear shift mounting cover have to be removed for the transmission to easily slip in between the x-member and the transmission tunnel brace.
	Here is the PDF template for the bracket. You could totally make it out of aluminum, if you want. If I were to make it again, I would certainly do so. Drilling 3/4" holes in 3/8" steel takes a while, at 1/16" increments, even with a decent drill press.
	The two outer holes in the bracket, with the bushings, take two very long 5/16" grade 8 bolts that go through holes in the top and bottom bracing plates of the x-member. Drilling these holes was not fun, but is completely doable without removing the body. Here are the holes seen from above, through the shifter hole in the cabin.
	I needed 18" of clearance to fit my drill, and I availed myself of my 2-ton hoist to achieve it. Basically, I hoisted the car until the tailpipe (which is cut on an angle) kissed the ground. I trust my hoist, but laying under there still scared the crap out of me.
	The drill was mounted to a right-angle jig (the black posts in the picture), which was itself mounted to a positioning plate that I made. The positioning plate is then mounted to the stock transmission mount support. This ensures that the holes I drill will be straight up-and-down and follow the centerline of the car -- at least as much as the stock transmission did.
	Two six-inch-long 3/8" bolts hold the transmission mounting plate down to the x-member. For reasons both aesthetic and practical, the bolts go up from below, so I added a cotter pin so they couldn't fall out completely if the nut loosens up. The really big washer comes with the isolator and serves to hold everything in place even if the rubber fails.
	Here is a view of the transmission bolted into place. It's hard to get a decent shot under there.
	This is a close-up of the same. I'm hoping that the 1/8" below the two silver bolt heads will be enough. I think it should be. If not, I'll remove the thick lock washers and use liquid thread locker.
	That's it. The shifter comes out of the stock hole in the transmission tunnel centered front-to-back and side-to-side. The threaded end needs to be turned down and re-threaded to 5/16" - 18tpi for any standard early-Roadster shift knobs to fit. There are plenty of aftermarket knobs for the Miata, though, if you want.

2011-09-06T16:18:00.000-07:00

Transmission Cuts -

	The Miata has a long rail running down the center of it, to which the transmission bolts through these two big holes. But, on the Roadster, this mounting pad wants to exist in the middle of the X-member. So, it has to go. Even though it's aluminum, this was a whole lot of hacksawing.
	You'll notice I did not saw where I drew my line. When I looked on the other side of the transmission, I noticed that my line would have me cutting into the sloping back face of the transmission. So, I followed the face, instead.
	When I test fit after the previous cut, I found I still had clearance issues, so I pulled the tail housing and found I could cut much farther in without compromising it. This is the cut that followed. You'll see that I cut completely flush with the angled rib. The cut piece is sitting in place just to the right of the clamped 2x4.
	The front passenger-side leg of the x-member goes through where this PPF mounting point is. So, it had to go. This cut goes to the same depth, in the horizontal plane of the transmission, as the previous cuts.
	A little bit of rib had to go to clear the transmission tunnel.
	At the moment, I'm pretty sure that this cut to the top rib of the transmission is not necessary. I did it to clear the Roadster tunnel brace when I was planning a mount that made the transmission sit much higher. The mount documented below allows plenty of clearance.

2011-09-06T16:16:00.000-07:00

Transmission Introduction -

I chose to go with a 5-speed transmission for my swap. Wade, the trail-blazer on the Miata-into-Roadster swap, used the 6-speed. His route has two major advantages. (1) The stock Roadster differential has the same gearing as the differential on the 6-speed Miata. (2) The 6-speed apparently has a much narrower tail section than the 5-speed. Point (2) is open to debate. The first-generation (NA) Miata 5-speeds may be narrow, too. It just so happens that folks who sold me my transmission shipped me a second-generation (NB) 5-speed. It bolts up more or less correctly, but it sure is bulky in the back. I had to cut a lot out to fit over the X-member.

I also went with a different way of mounting the transmission to the frame. Wade drilled two holes in the X-member, with the body off, then sandwiched the X-member with bushings from a Volvo 122. I drilled two holes in the X-member, with the body on, then bolted a custom mount to them. The end result is a little cleaner looking and, if I've measured correctly, places the center of the Miata output shaft at the same height as the stock Roadster output shaft. Apparently Wade had to adjust his pinion angle to accommodate the greater output-shaft height that his bushings produced.

The sole disadvantage to my approach is that the transmission is mounted too close to the X-member to fit a mechanical speedometer drive and cable. In fact, even the rather small electronic drive only fits with some shaving. If the transmission is mounted higher, like Wade did, you can use the mechanical drive if your Miata transmisison comes with one -- the Datsun Roadster speedo drive screws right in. If you have a later Miata transmission with an electronic sender, you can pull the mechanical drive out of an early RX-7 (along with the worm gear off the output shaft of the RX-7) and that will work, too.

My transmisison sits so low that even the electronic drive barely fits. I may end up using that stock sender, slightly modified to fit, or an aftermarket inductive vehicle speed sensor, like the one Dakota Digital manufactures, which is widely available for about $50. For the time being, I've simply memorized the speeds for each gear at 3,500 RPM and let that and the surrounding traffic be my guide.

2011-09-06T15:50:00.000-07:00

Intake

	The air intake setup I'm using consists, from the manifold outwards, of a 3" to 2.5" reducer, a 45-degree, 3" diameter elbow, the MAF, some 3" acordion intake tube, and a knock-off HKS "mushroom" air filter. The components were inexpensive, the fit is clean and I get cold air in with little change of water entering the system.
	This bracket holds the MAF in place. Since it slips directly into the hard elbow, there was no way to clamp the MAF to the tubing. Even though the MAF is hard mounted to the body, there seems to be enough flex in the rubber sleeve at the throttle body that engine movement does not cause a problem.
	I crafted an idle bypass from a random 18mm elbow of hose and a nipple kit by the same people who made the other intake tubing.
	I used the acordian tubing to reach the air filter because the narrow spaces between the 3" rings fit in the 2-3/4" gap between the radiator and the side panel. If I hadn't set the goal to avoid modifying the vehicle, I would have clearanced the side panel and used hard tubing of some sort through here. The filter just barely fits under the hood here.
	An overview of the completed engine bay.

2011-09-06T15:49:00.001-07:00

Gauges

	The stock Roadster oil pressure sender (right) supposedly has the same thread (1/8" BSPT) as the stock Miata oil pressure sender. As I screwed the Miata sender in, I'm convinced the threads were crossing, but it's firmly in there and does not seem to leak, so I'm not touching it.
	I've jury-rigged the Miata tachometer into the Datsun. The engine idles pretty smoothly at 750 RPM, now. The air intake, with no filter, is really loud, as the video to the left demonstrates. The temperature holds steady at 180F. The thermostat and cooling fan are working.

2011-09-06T15:41:00.000-07:00

The Engine in Place

	Over-all shot of the engine finally bolted-in, hopefully for the last time, in the re-painted engine bay.
	From the front here, you can see the mounts in the lower left and right corners.
	This view gives you a sense of how low the engine sits. I couldn't put it any lower without the oil filter being blocked from removal by the frame rail.
	The final installation of the driver's side plates and mount. Sorry for the bad focus.
	The final installation of the passenger's side plates and mount.

2011-09-06T15:39:00.000-07:00

More about Mounts

	Here are the four plates necessary to mount the Miata 1.8L engine to the Roadster frame, using the stock mounting points on both. They put the motor at a height that (a) is nearly as low as possible while still allowing the oil filter to be (relatively) easy to remove and (b) puts the drivetrain level with the transmission output shaft at the stock height.
	Here is a detail shot of the driver's side plate, with the Roadster mount attached. All the bolts for mounting to the block are 10mm, but the lengths vary as the depths of the mounting holes are curiously irregular.
	To ensure clearance of the ribs in the block's casting, I had to use allen-head bolts to attach the mounts to the plates. The mounting points on the driver's side of the BP block form a nice rectangle. But, on the passenger's side, they form a wonky trapedzoid. Also, they are set back 10mm on the passenger's side, relative to the driver's side.
	Here is a shot of the driver's side frame pad extension in place. I bet most of the paint will be scraped off before the motor is bolted down. I would suggest powder coating all of these plates, but it was easier just to rattle-can them. These two are held in place with two 5/16" grade 8 bolts each. They should be able to take the forces of the slight cantilever.
	Two fine-thread, grade-8 5/16" bolts hold each pad plate in place. I backed the threaded front hole on each frame pad with a grade 8 nut and lock washer for good measure. In theory, each of these bolts should be able to take over 8,000 lbs. of tension before the heads pop off. I still don't love the cantilever, but I'm a sucker for ease and simplicity.
	Here is the PDF template for the plate that allows you to bolt the stock Roadster engine mount to the driver's side of the 1.8L Mazda BP engine. It is cut from 3" x 1/4" cold-rolled steel.
	Here is the PDF template for the plate that allows you to bolt the stock Roadster engine mount to the passenger's side of the 1.8L Mazda BP engine. It is cut from 3" x 1/4" cold-rolled steel.
	Here is the PDF template for the plate that allows you to bolt the Roadster mount attached to the Mazda 1.8L BP block to the stock driver's side pad on the Roadster frame. It is cut from 3" x 1/4" cold-rolled steel.
	Here is the PDF template for the plate that allows you to bolt the Roadster mount attached to the Mazda 1.8L BP block to the stock passenger's side pad on the Roadster frame. It is cut from 3" x 1/4" cold-rolled steel.

2011-09-06T15:38:00.000-07:00

The Cuts and The Mounts

	In the end, this was the only "necessary" cut off of the engine, and even it is specific to my particular plan for mounting the engine. It is a small nubbin of iron that sticks off of the lower mounting point for the alternator.
	I also cut some of the tabs for the heat shielding off of the exhaust manifold to clear the steering column and frame rail. At some point, I'm going to replace this ratty thing with a nice aftermarket manifold. But, for now my money is going elsewhere.
	Not a great deal of clearance here! I guess I'm going to have to buy an angle grinder (finally an excuse) and grind the manifold for something more like a 1/4" gap.
	A short portion of the stock Miata downpipe holds the O2 sensor. Before I take the car to the exhaust shop, I'll cut this a little shorter and they should be able to form a nice curve under the footwell and right into the cut-off end of my 2-1/4" exhaust system that I was using with the stock 1600 engine.
	Here is a test fit of my mount solution, on the driver's side. It uses two 1/4" x 3" steel plates to join the stock Roadster mount to the stock BP mounting holes and the stock Roadster frame pad. The cantilevered plate deflects about 1mm under the engine's weight. We'll see what it does under the torque of a running engine.
	Same deal, on the passenger side. I really like this solution because it self-centers the engine and requires so little in the way of fabrication. We'll see how it holds up. I will probably end up welding new pads to the frame at some point, if I love the new engine. I like that, for now, this is completely reversible.

2011-09-06T15:34:00.000-07:00

Engine - Introduction
The 1.8 liter BP block powered Miatas from 1994 through 2001. I've found that engine resellers generally consider the 1994-97 engines to be "the same". Likewise, the 1999 (there was no 1998) through 2001 are also lumped together. I don't know much about the latter group, except that they are much more complicated mechanically and electronically. Also, the head or at least the valve cover is supposed to be noticeably taller, so it might not fit under the hoods of certain classic sports cars. Besides which the earlier engines are much less expensive and are well-served by aftermarket goodies, which can often be had at lower prices themselves, now. It is important to note that these 1994-1997 engines are very much not the same. Most importantly, the 1994 cars and some, but not all, of the 1995 cars are OBD-I. The later 1995 cars, along with the 1996 and 1997 cars, are OBD-II. The 1996-97 cars change further with the addition of a crank sensor and some other sensor changes. Here is a good overview of the changes to the engine over its history. If you are like me, and buy your parts here and there from various cars as they come available, the lack of interchange can pose a real problem. At the very least, it makes the process take a lot more time. My engine arrived shortly after my birthday. Although I had ordered a 1996-97, I got a 1994. This peeved me, as I really wanted OBD-II. Also, the engine was from an automatic, and not a manual, so the compression is lower and I would have to buy a flywheel. Like most engine resellers the one I used insisted that all Miata BP long blocks are the same. Also, did I mentioned that the engine was damaged when it arrived? And I was up-charged $300 shipping? Don't order your engine from these people. The biggest problem with getting an earlier engine is that I had already bought an ECU and several harnesses for a 1996-97 car. Since 1.8 liter Miatas are not very frequently intact when they appear in the So-Cal salvage yards, it had taken me about 6 months to get these parts. Worse, I had passed by '94 ECUs along the way. Frustrating when you have little patience and less money, but after a few more months of looking and a couple bad eBay purchases, I got what I needed from the salvage division of Flyin' Miata. A great resource. I will say it here, and say it again in the Electrical section, you should really buy a whole Miata or a front clip or whatever it takes to provide yourself with an engine, transmission, harnesses and ECU that all fit together. It takes a whole lot more time, and more money, to pull together all the bits and pieces, and the variation among those bits and pieces is surprising and enough to make things not work. Nevertheless, here are two sources for rebuilt Miata engines that I came across: -"Precision Rebuilt Engines" has rebuilt 1.8L Miata engines, long block, for $1520. They are located in Houston, Texas. -"Best Rebuilt Engines" allows you to specify which 1.8L engine you are getting (e.g. the 3/95-11/97 with sensor on oil pump) from $2544
	The engine arrived on this pickup and we hoisted it out with my 2-ton hoist and some 1000-pound rated climbing rope from an army surplus store. That rope is handy stuff.
	Quick and dirty stands cut from 3/4" plywood I had found in the alley behind my house in the morning before my engine arrived. Later I added 2x4s along the bottom edge because that thin tongue in the back had to take a lot of weight once I bolted the transmission on. Very solid stand, though, at a decent height, for working, for free.
	The test fit looks really good. But, this is just the engine. Everything changed once I bolted on the transmission and tried to center and level the drivetrain. Thus began the era of hacksawing bits and pieces off. It's most serious for the transmission, but what follows is what I cut off the engine.

2011-09-06T14:18:00.000-07:00

Introduction
	In May of 2005, my wife and I bought a 1966 Datsun Roadster from a guy down in Huntington Beach. We were looking for an inexpensive, but snazzy, little convertible to use as the "getaway car" for our wedding.
	The SPL311 fit the bill, and I liked the idea of mixing the fun of a British or Italian roadster with the sensibility and user-friendliness of a Japanese car. Plus, we didn't have to pay extra for the rare snow-leopard dash cover.
	The car ran when we got it, but I ended up repairing or replacing just about everything but the engine internals and the front suspension. We also sent it out to get repainted. I drove to the paint place with the car like this, then removed the brake lights in their parking lot.
	The paint job was about $2000 at California West Coast paint, on Venice Boulevard, near Redondo Boulevard. The quality of the paint is so-so, but I was impressed at the attention they gave to the prep. Either way, it looked great in our wedding photos. (by November 2007, this paint was a mess)
Soon, I began thinking about replacing the stock 40-year-old drivetrain a modern EFI engine and 5-speed transmission. After a long period of debate, I decided to go with a 1.8 liter Mazda Miata engine and its associated transmission. It's a well-liked drivetrain with a lot of aftermarket support. The other contender was a Ford Zetec engine mated with a Ford T-9 transmission (the latter found in the US on the XR4Ti ). It's a great engine with a lot of aftermarket support, but a mediocre transmission. And I was not enthusiastic about the parts sourcing necessary to joing the transverse engine to the longitudinal transmission. What follows, then, is the accumulated documentation of my transplant of a 1994 Miata drivetrain into a 1966 Datsun Roadster. I pulled the original engine in July of 2007. I got the engine running in July of 2008. I drove the car around the block in August of 2008 (although it did shut off at the first stop sign). On January 15, 2009, I finished tidying up the swap and declared it complete. The official, if somewhat dull and truncated test drive video: