1978 Isuzu 117 Coupe: The Swap Begins

When we last left off, I had just gotten the new Mazda Miata 1.8 twin-cam engine – read up here for more info on how we got to that point.

First things first, I laid the Miata transmission side by side with the 117 Coupe transmission and the Miata transmission was a bit longer, meaning the engine would need to sit a little further forward than the stock 117 Coupe engine. This actually tuned out to be a very good thing for reasons that will become apparent later.

I measured up the engines next, or rather the lengths of the oil pans, since they are a pretty good indication of overall engine length. Here are the measurements:

117 Coupe pan: 545 mm

117 Coupe transmission: 755 mm

Miata Pan: 460 mm

Miata transmission: 820 mm

117 Coupe total length: 1,300 mm

Miata total length: 1,280 mm

As you can see there’s just 20 mm of overall length difference between the two!  Awesome, this plays well into my overall ethos, which is to get this swap done with zero modifications to the 117 Coupe. So, the next step was to just lift the transmission into place for an initial test fit. For now, all I did was line the shifter up, jack the transmission roughly into place and pop a jack stand under it to see how it sat.

So far so good! The first major problem in this mad experiment soon showed itself. The 117 Coupe uses a ball-nut type steering setup, which necessitates the use of a center sump oil pan. The sump rests in between the crossmember and the steering linkage. The Miata engine uses a rear sump oil pan, which normally wouldn’t be too much of a problem to modify, except the Miata oil pan is aluminum and structural, meaning it also bolts to the transmission.

You can see here that the Miata oil pan is resting on top of the steering linkage, so the entire pan needed to be modified extensively. It was time to call upon my favorite fabricator, Dashbuilt Performance.

All I did was give him a printout of those dimensions with a general idea of what I wanted to achieve and he got work!

The results are stunning!  I actually had to send it back for a revision and the pictures above show the revised pan, but that was because my measurements were off.  That adage of measure twice cut once should be modified to measure 50 times and still have to cut twice. However, the new pan now lined up perfectly, so I slapped it on the motor and lowered the engine into place. After some fiddling and fighting with it, I got the transmission bolted up so I could start locating things properly.

Of course, it doesn’t always go super smoothly. The Cam Angle Sensor located on the back of the cylinder head is just too large and was butting up against the firewall.

In order to keep the transmission optimally located as well as keeping the pan from running into the steering linkage, that sensor will have to be removed. This means I can no longer run the factory ECU, which isn’t necessarily a bad thing. I was planning on running a set of ITBs in the future, which would necessitate the use of a standalone ECU, so this is just moving that idea forward a bit.

Once I was happy with the engine position, the first step was building a transmission mount. Using the factory body mount locations, I built the above piece to run from left to right and hold a factory Miata engine rubber mount. The bottom half of the Miata engine mount bolts onto the piece I made above and the top half bolts onto a piece that connects to the transmission using the factory bolt holes for the piece that connects the Miata trans to the diff in the Miata.

With the transmission located right where I wanted it, it was time to work on engine mounts. I reused the factory 117 Coupe engine mounts to assure that the entire drivetrain is rubber isolated. Then I built adapters that go from the factory engine mounts to the block.

Now, all the mounts are going to come back out and get reinforcing braces welded to them where it counts to make sure everything is plenty strong. However, for the time being, the engine and transmission are in!

With the engine in its final location, I could start work on the next major hurdle I had to overcome. The 117 Coupe uses a cable operated pull clutch while the Miata uses a hydraulic operated push clutch. I tossed around a lot of different ideas of how to overcome this issue, which was compounded by the fact that I refuse to cut the firewall to mount a clutch master cylinder. Ultimately, I decided to build this contraption.

This piece mounts in the front driver side area of the engine bay and uses a lever to operate a BMW 325is clutch master cylinder with the stock cable. The reason it’s shaped so… elaborately, is because it mounts through bolts and holes that were already on the body (for the crossmember, condenser and headlight). I haven’t tested it fully yet because there’s no clutch or flywheel on the engine right now, but I’m quite happy with it!

The Miata slave cylinder uses a 3/4 in. bore size and the BMW master cylinder also uses a 3/4 in. bore size, so we get a 1:1 movement ratio out of that. Through various reading, it seems that the Miata uses anywhere between 15 and 20mm of travel at the slave cylinder, which means we want to aim for 17mm of travel at the master cylinder. The 117 Coupe factory clutch cable has about 30mm of travel. So, the cable is placed 90 mm from the pivot and the master cylinder is placed 50mm from the pivot. Since these draw two different arcs, it means that for about 30mm of travel at the cable, the master cylinder travels 17mm. Of course, I made this whole thing with a sawzall, drill press and an angle grinder (save for the two round pivots I machined on the lathe), so there’s going to be a little inaccuracy, but it should be close enough.

That brings us up to speed. The garage is quite full at the moment, so it may be a while before I get back into the 117 Coupe. In the meantime, keep an eye out for upgrades to the Bellett!

1992 Isuzu Gemini Irmscher R: On the Road!

With the engine in, it was time to start hooking everything up and getting it ready. I started with the clutch and shifter linkage.  While the shifter linkage went on with ease, the clutch linkage was giving me a hard time. Even fully adjusted to the end stop, I wasn’t able to disengage the clutch.  My theory is that when I had the clutch resurfaced, they ground away a bit too much, moving the pressure plate further away from the throwout bearing and making it impossible to push the pedal far enough.  So, I turned up a quick spacer to sit on the end of the cable, giving me about 20mm of extra pull.  This seemed to fix the problem!

Next up, I got the spark plug wires installed, although I had to consult the internet to find out what order they hooked up to the coils on (turns out it’s 2 – 3 – 1 – 4).  With the wiring starting to fall into place, I got the call from Spencer at Dashbuilt Performance saying that my oil lines were finished.  He ended up welding AN fittings to the end of the factory pipes and then made up new braided lines to run between the fittings.  With those in my possession, I could really press on to the first start!

With oil in the engine, all that was left was to finish hooking up the wiring, toss the intercooler and intake piping on and then turn the key!

As you can see, even though the exhaust wasn’t hooked up, it fired right up and purred like a kitten.  Knowing that the engine was solid, it was time to start finishing it up and getting it ready for the first drive.  The intake piping and wiring was all finalized, the axles were put back in, the suspension and brakes reinstalled, the exhaust hooked up and the wheels thrown back on.

I dropped her off the stands and went for the first test drive up and down the driveway!

It was smooth as smooth can be and everything felt tight and perfect!  There was a small oil leak that took a bit of effort to get to, but with it sorted and the undercovers thrown back on, it was surprisingly solid.  I started venturing further and further, putting more kilometers on and getting the engine break-in going on in earnest.  I even drove it up to Dallas and back to visit some friends, which put about 600 km on the engine, and it ran flawlessly the whole way!  With the engine sorted, I started to turn to taking care of a few other things that were bothering me on the car.  Starting with the stereo.  It was held in with double sided tape, so I mounted it properly and tossed an old Zyklus boost gauge I had floating around in.

But, it turned out that the gauge had a busted membrane or something and made a terrible rattle on boost and the radio was shot as well.  So, I ripped the stereo out, tossed in a new Kenwood unit, threw in four new Kenwood 4-inch speakers, and bolted in a new Lamco boost gauge.

And of course now that it was running and driving well, I couldn’t help but get the Bellett out for a group picture!

With the engine fully broken in it was time to go through the rigamarole of getting it registered.  If you want more info on that, check out my Honda Beat, I go into much more detail there.  With plates on it I’ve put just about 3,600 km on the new engine and I’m absolutely loving driving it around!

Honda Beat and Mitsubishi 360 in a Magazine!

A couple of months back a good buddy of mine, Toya san, in Japan sent me a message asking if I knew anyone else that had a Kei car in Texas. So, I immediately contacted my buddy Cameron and asked if he knew anyone. He had a close friend, Nate, who had an Alto Works. We were kind of hoping to collect up a few more people, but unfortunately, it seems these tiny Kei cars aren’t very ubiquitous in Texas, the land of the truck.

At any rate, with Nate’s Suzuki Alto Works, Cameron’s Suzuki Cappuccino along with my Honda Beat and Mitsubishi 360, that was four Kei cars, which was still a pretty decent collection! So, fast forward a couple of weeks and my buddy and one epic photographer were on a plane. They stopped by JCCS in California first and then made their way down to Dallas. We had an awesome little meetup, starting at Mitsuwa before heading to historic downtown Plano.

After an excellent afternoon with some amazing food at Ye Ole Butchershop, Toya san and I set off for Hico to see the Mitsubishi. It was pretty late by the time we arrived, so we just filled up on some Hard Eight Barbeque and turned in for the night. The next morning we got the old Mitsubishi 360 out for some more pictures!

After gallivanting around downtown with my 360cc smoke machine, we came back up to the house for a few more pictures in and around the garage.

Then, with the tight schedule they had, they set back off for Dallas with a plane flight out. Now I work with Toya san pretty regularly, so he kept me apprised of any developments and asked me some follow up questions for the story. Finally, after months of hard work from him and his editors, the magazine hit the shelves!

I turned out better than I could have imagined! If you’re in Japan, go buy a copy at your local bookstore, it’s worth it!

1992 Isuzu Gemini Irmscher R: The Engine is In!

Work and life often get in the way of our progress on cars, but whenever I could steal a chance, I’d get out to the garage and work on bolting more and more stuff to the engine. Keep in mind, originally, this engine was meant to come out the bottom of the car with drivetrain, subframe, suspension, turbo, intake, etc. all attached. Since I’m going in through the top, I’ve got a hard road ahead.

Still, I wanted to get as much bolted to the engine/drivetrain as possible because access in the engine bay is extremely limited. So, all sensors, wiring, vacuum hoses, turbo, intake, downpipe, CAS, coils, etc. got bolted up. The only thing remaining to be attached is the intercooler and the vacuum hose to the cansiter. Now, some of the stuff will need to be dismantled a little to allow me to hook up the clutch cable and shifter cables, but for the most part, it’s good to go!

So, into the air she goes! Before I could slot it in however, I had to attach a final transmission brace and front engine mount bolt. I couldn’t install those while it was sitting on the ground because they kept running into my wooden blocks that were keeping the whole thing upright. It took us about an hour of fiddling, kicking and shoving to get it slotted in. One of the hardest parts was getting the output shaft for the rear drive slotted into the driveshaft while clearing the front A/C condenser. In the process, we smashed up my Intake Air Temperature sensor.

Fortunately, those are still available and a new one is on order! With some more kicking and pushing and swearing, the engine finally dropped into place and we started doing up motor mounts! There are three mounts that hold it in place, one on each side, one up front and one in the back mounted to the transfer case. I got all but the transfer case mount installed and the engine sitting in place on it’s own weight. The transfer case mount is going to be an entirely different battle though!

After the t-case mount, I’ve gotta hook up the wiring for the alternator and starter, then install the A/C compressor and power steering pump, pop on some new belts, throw in new plugs and wires, install the clutch and shifter cables, throw on the intercooler, and… oh… I’ve got to fix the oil cooler lines. One was broken from the previous owner. Fortunately, those are at Dashbuilt Performance getting AN fittings welded on!

More to come as I make more progress!