1973 Isuzu Bellett: Refresh

As you all know, I absolutely adore driving my Bellett like a complete hoon. She’s not fast, pulling 0-100 km/h in about 13 seconds, but she’s one of the most hilariously fun cars I’ve ever owned. But, she’s still more than 45 years old, which means things break. As of late, the carburetors were begging for a clean (which makes sense because I stupidly don’t run a fuel filter) and the brakes were feeling atrocious – pulling hard to the right with a spongy pedal. On top of the that, the springs in the driver seat bottom had given way, giving me a terrible backache if I drove the car for too long. So, I knew it was time for a refresh, but I was putting it off and putting it off because I had other projects I was in the middle of.

What finally made me decide to start the overall refresh was the picture above. After searching on and off for a few years, that set of carbs and manifold showed up on Yahoo Auctions and I jumped on it. Finding a pair of Mikuni Solex 40 PHH carbs isn’t all that rare in and of itself, but finding them attached to a manifold for the G180SS engine is super rare. Once I finally got the carbs back to the US, I pulled the Bellett into the garage and got to work.

Not wanting to have a massive clutch fan obscuring the sweet, sweet noise of those Mikuni carbs, I took the opportunity to change over to an electric cooling fan as well. Which meant it was time to clean up some wiring in the engine bay. First, I built a panel that would hold two relays wired up to two 10A circuit breakers (instead of fuses) to run the e-fan and electric fuel pump. This panel would mount just below the battery and tuck nicely out of the way.

A lick of paint and she looks good installed!

Next up it was time to address the electric fan. I built these two x-brackets to hold the electric fan in place using the radiator mounting bolts.

I’ll show a picture of it installed a little later, but I don’t want to spoil the carbies just yet! While we’re on the topic of electronics, there was one more little problem I wanted to deal with. The alternator was woefully underpowered and would struggle to keep up with the fogs, headlights and high-beams on all at once. Throw in an electric fan and I was afraid I’d overtax it. Fortunately, since I’m in the middle of a Miata engine swap on the 117 Coupe, I had a spare alternator hanging around that was about a 15A upgrade. It didn’t mount up super easy peasy though. First, I had to figure out the wiring, which after a bit research led me to making this guide:

The space between the mounts was about 6mm too small for the alternator to slide onto the Bellett mount. So, after a lot of measuring, I found that the distance from the inside of the front mount to the center of the belt was the same between the two alternators, which meant all I had to do was chop about 6mm off the back mount. It had plenty of meat on it and I had a milling machine at my disposal, so chop chop and it fit perfectly! Just like the e-fan though, I’ll point that out after I get to the carbies.

Which I guess I should go ahead and show! Before cleaning anything up, I went ahead and slid them on to the engine just to make sure I could indeed make these work. Everything seemed to line up pretty well, so off they came and I stripped them completely.

While stripped, I cleaned up the body and manifold to make them look brand new. Then, a full rebuild kit went into the carb and on it went! Only, it didn’t. The manifold fought me tooth and nail the entire time. There must have been some subtle differences between the engine this manifold was designed for and my engine. It was still clearly for an Isuzu G-series counterflow head engine, but some of the tabs were off just enough to make it a bear to install. After some shaving here, grinding there, swearing over there, it finally slipped on and bolted down.

Even with just one carb clean, it looked absolutely brilliant! I set about rebuilding and cleaning up the remaining carb and tossed it on as well. Then, I had to do a few supporting mods to make sure the engine could keep up with the carbs. First, was a fuel filter. I ordered an SA22C RX7 fuel filter and clamp sized specifically for it, then made a little bracket and bolted it in place.

Next up was the ignition. I wanted to upgrade to a point-less type ignition, but you can’t exactly order an Isuzu Bellett conversion. Fortunately, after popping the distributor cap off and taking a look at the points, I could see they were actually a set of Nissan points.

After some hunting, I came across the Hot Spark 3HIT4U1, specifically for Japanese made Hitachi 4-cylinder distributors. After a bit of measuring, it was a perfect fit. I don’t have a picture of it installed, but check out their website linked above for more info.

With the ignition and fuel sorted, it was time to start buttoning up the engine bay!

Good god they look amazing! Other things to note in those two pictures are the 117 Coupe alternator installed just below the carbs and the electric fan tucked up against the radiator. Also, a little harder to see is a completely new ground cable that ties into the chassis at three different points along with the engine. With the carbs installed, it was time to give the old girl a start.

Yeah, that’s amazing! The throttle response is out of this World and the engine seems so much more lively than it ever did on the SUs. And keep in mind, in that video I have done zero tuning on the carbs. However, I can’t run it too long because the exhaust fumes would kill me and there’s still a lot of problems to take care of before I can move the car outside. First up, is the brakes.

After taking the front calipers off and taking a look at the caliper pistons, one major problem was immediately evident. They were so rusted and pitted, it was a miracle they even built pressure at all. Again, it’s not like I can just order new pistons, so it was time to get creative. First up, measure.

Even in those measuring pictures you can see how pitted they were, and I used the cleanest piston I had to get accurate measurements. After a ton of searching on the internet, I discovered there was nothing out there even remotely close that could work. So, I was left with essentially two options. Make new pistons or swap to different calipers. While mulling it over (and even holding an S30 caliper up to see if I could make it work), I looked over at the lathe and got to brainstorming.

I didn’t need the right height, I could fix that on the lathe, all I really needed was the right diameter. And, as it turns out, 350Z base model, single piston calipers use the same diameter. I ordered four seal kits and brake pistons for the 350Z (two pistons per caliper on the Bellett). They were obviously about two times too tall, but that can be fixed with carbide bits. On my first test, I destroyed the piston, which was expected, but I wasn’t smart enough to order spares. I then promptly ordered spares. My next trial was a total success, as seen in the picture above. The piston on the left is the 350Z piston, the piston on the right is the stock piston, the piston in the middle is my modified 350Z piston. The next attempt after that destroyed another piston. I was having difficulty because even though all the pistons I ordered were from the same manufacturer and for the same car, it turns out they were made of different materials. Some cut super easy, some were a right pain. Finally, after about eight pistons in total, I came up with four that would work.

I decided to get the rotors turned as well, which required pulling the hubs off. I’m not sure what wheel bearing grease I used when I built the car, but it was the wrong type of grease. The grease had turned black and wasn’t doing its duties as grease. Time for new wheel bearings too. With those ordered and installed, I put the whole brake system back together and started the arduous process of bleeding.

Unfortunately, it just wouldn’t build pressure. You’d give the pedal a few pumps and it’d firm right up, but wait 10 seconds and the pedal would go right to the floor again. I thought I was just crap at bleeding and went through two full bottles of brake fluid trying to get it to bleed, but it just wouldn’t. I figured it had to be a bunk master cylinder, so, out it came. Interestingly, when I built the car about 10 years ago, you could still get new master cylinders, and this was a new Isuzu part. But after dismantling it, I could see it was leaking pretty profusely.

A brand new master cylinder kicking it in under ten years is just… frustrating. Not wanting to go through the rigamarole of trying to get another new one from Isuzu Japan and get it shipped here, if they even still had any, I decided to start the hunt for something could work. After a couple trials and errors, I settled on a proper racing brake master cylinder from Tilton.

Unfortunately, this isn’t a dual master cylinder, so the entire brake system is now on a single circuit. Which means if I get a leak, the entire system loses pressure. That’s why they call it an “emergency” brake, right? The upside is that it was almost a direct bolt-in upgrade. I had to enlarge the mounting holes on the Tilton master by 1.5mm and I had to remake a few of the nasty Bellett hardlines, but that was it. I even was able to reuse the Bellett push-rod. Also, I bumped up in master cylinder bore diameter from the 3/4” of the stock master to 7/8” on the Tilton. This should give a firmer pedal that I can really lean into.

And boy did it deliver! After a single round of bleeding the pedal was the most affirming and brilliant brake pedal I’ve ever felt in this car! Before we could go for serious test drives though, there were still a few more things to tackle. First, the seat.

I ordered this OMP Silverstone seat slightly used off eBay and ordered an OMP seat rail off Amazon. Interestingly, the factory Bellett seat mounting holes were so close to the OMP seat, that all I had to was enlarge the Bellett holes by about 3 mm and the seat bolted right up. It’s super weird that I’m having better luck with bolt-ons for a car from the 70s than I ever had on cars from the 80s and 90s!

It is super comfortable! I would prefer for it to drop down about another half-inch and slide back another 2 inches or so, but that would require a fairly large amount of cutting on the Bellett. So, we’ll drive it like this for a while and see how I like it.

Some of the more astute viewers may notice in those seat pictures that I’m missing a shift lever. Let me tell you a story about how I’m an idiot sometimes. While working on the car, I noticed that there was an alarmingly large puddle of trans fluid forming underneath it. After climbing around I could see that it was coming from where the speedo cable goes into the trans. Not too surprising, the speedo has been having trouble for a while now and a shot cable was on my list of suspects. After some research, I think I’ll change over to a GPS box that spins an electric motor with a short cable to turn the original speedo, eliminating the need for a new cable. I pulled the old cable out, and dumbly didn’t realize that it was below the fill line of the transmission. A ton of fluid came out, dropping the transmission fill level to about half. Okay, that’s a problem for future David, first, let’s make a plug for the speedo hole.

God, I love having a lathe in the shop. I popped my new plug in, tightened it down and set about refilling the transmission with fluid. Except, I couldn’t get the fill plug out. Throughout the years it had been stripped, broken and beat to hell, and I remember the last time I filled the transmission that I hoped I never had to fill it again. It was so stripped I could not crack it loose, and with the transmission tunnel in the way, there was no space to get vice grips or anything on it. So, I started looking for other potential places to fill from. I tried dropping the drive shaft and filling from there, but that was a no go. Then I noticed just above the fill spot there was a small bolt holding a plug in place. “Sweet, it’ll overfill, but I’ll just be careful” I thought. I undid the bolt, slid the plug out and promptly discovered that it wasn’t a plug at all, but rather a pin for the shift linkage. Hmmm, that meant there was only one direction to go from here:

Yup, transmission out. Fortunately, the shift linkage was all on top and easy to access once out of the car. With the pin back in place, I ripped that crappy fill plug out.

It was properly gone. I measured it up and ordered a new one, so now I won’t have this problem again hopefully. While I was messing about with the shift linkage, I decided to address the sloppy shifter. Upon closer inspection, it was clearly sloppy because the original bushing had exploded into a million tiny pieces. Welp, time to spin that lathe up again.

Transmission got thrown back in, shifter with new bushing thrown in, and the whole car buttoned up. It was time for a proper test drive. My God it’s a different animal. After some idle tuning and playing with ignition timing, I’ve got it set pretty close. The jetting on the carbs feels pretty close too and the plugs look good, but I need to get a proper tune done on a dyno to make sure I’m not leaning out anywhere. The brake feel absolutely amazing, they’re the best feeling brakes of any car I’ve ever owned. Thank you Tilton! The seat is ultra comfy with fantastic support. The fan kicks on when it’s supposed to and keeps engine temps perfectly in check. It’s just an absolutely wonderful car to drive now!

Here’s the “Too Long, Didn’t Read” list of all the changes that went down:

New Mikni Solex 40 PHH carbs and manifold
New electronic ignition
New fuel filter (from SA22C)
Upgraded alternator (taken from 117 Coupe)
Electric fan (with thermo switch in bottom radiator hose)
New breaker and relay panel for e-fan and fuel pump
Tilton brake master cylinder
Modified 350Z brake pistons to fit Bellett calipers
Turned brake rotors
New wheel bearings
New OMP Silverstone seat
New shift bushing

Thank for reading!

4 thoughts on “1973 Isuzu Bellett: Refresh”

  1. I just remembered you had this website when I was re-watching one of your videos on Youtube!

    Love to see this car…it’s definitely one of my favorites of all the ones you’ve owned (the others being the Minica and the Honda Life you had for awhile back in Japan!)

    I bet it’s a blast to drive now…I worry for you with that single-circuit brake system in the event of an emergency, but you only have so much to work with!

    Looking forward to more updates! 😀

    1. Thank you! It’s definitely my favorite in terms of driving it like a complete hoon, haha.
      I was a little worried about the single circuit braking system as well, but even the stock dual circuit wasn’t set up much better. The front was one circuit and the rear a separate circuit. If I lost the rear, no worries, but if I lost the front, it’s the same situation as losing the whole thing and only having the e-brake. At the end of the day though, it’s not my daily driver, so it gets a pretty thorough check of things before i take it out every time anyways.
      I do miss that little Honda Life 360, every time I see one when I’m in Japan, I find myself wanting another one.
      Thanks for watching and commenting on my Youtube videos too!
      I’m currently working through making another series of videos from when my buddy and I took a road trip through Japan this last September. I just need to get up to his place and get all the footage he took too so I can really get into the editing!

        1. Ooh, a left hand drive one to boot, that is a rare find!
          Unfortunately, I’ve got a few too many projects going on at the moment, towing back another one might not go over so well, haha.

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