jmortensen

FWIW I have an early driveshaft with new U-joints, which I bought and then decided to go the V8 route. $50 shipped if you're interested.

On a 70 you can shim between the trans mount and the body to change the driveshaft angle. I would look into that and verify that the driveshaft angles are parallel. There are threads on hybridz.org on how to use laser pointers to measure the driveshaft angles more precisely, but a simple angle gauge also works. I have this one from Harbor Freight, but there are others: Digital Angle Finder / Angle Gauge BTW, that image that Diseazd posted is wrong. You don't want the driveshaft perfectly in line as this prevents the bearings in the U-joints from moving. If they don't spin then you end up running on the same part of the bearing over and over and it fails. There should be an angle and it should be parallel. There was another issue with the early cars, and that was the diff placement. Early cars had the diff forward and the halfshafts angled back to the wheels. After mid-71 they moved the diff back so that the halfshafts went straight out to the wheels. If you don't have the diff moved back, that's another possible solution.

Four Pinion Open Diff - Z31Performance

Yes, the STi spline counts are different.

If you did the 3.54, you would have stock 280Z gearing. Which sucks (IMO). If you did the 3.90 with the wide ratio, that would make 1st gear ridiculously low. Best combo is a close ratio 80-83 280ZX trans with 3.90 or 4.11. The R200 is a popular swap for those making more power. 3.90s were really hard to find in the R180s. I think that there are some Subarus that have that ratio now, so it's becoming easier to find. The 280ZX 5 speeds came with 3.90s, so if you wanted that ratio, the R200 swap was a very easy way to get it. In fact, the 280ZX drivetrain swap (engine/trans/diff) is a pretty easy way to liven up an earlier Z. Really though, if this is a street car, it probably doesn't matter that much one way or the other. If you're racing or just nitpicky, the 2-3 gap in the wide ratio 280 5 speed is a problem.

If you can print a steel gun, I'd be surprised if you couldn't print an aluminum head. First 3D-Printed Metal Gun! That Addresses Politicians' Detectability Worries, Right? - Hit & Run : Reason.com

FWIW you can disconnect the sway bar(s) and brake lines and pull the struts down out of the fenders and use your spring compressors right there and not have to take the entire strut assy out of the car.

Notice the droop limiters? I almost missed them.

One of my first jobs was busting tires, almost 20 years ago now, thankfully. We did starter fluid and pulled the valve stem core out and put the flame right to the valve stem. Worked good. Didn't need to do it very often, since putting ridiculously skinny tires on fat wheels wasn't cool at the time.

On the 240s the heater control valve, listed as water **** in the manual there fails pretty commonly. I've replaced a couple of them. Sometimes you can pull it off and clean it and fix it that way.

So you had this safety wired and you still lost the bolts? That's a pretty rare failure to begin with, but much weirder if they were really safety wired in to start. I wouldn't bother rebuilding the diff. Just get another one. As to the ring gear bolts, I've always reused them with no issues, but they're cheap enough that one could definitely justify the expense.

DIY laser tool. Differential Laser Alignment Tool - Powertrain - HybridZ

Wind tunnel testing of Z's with common aftermarket parts: Windtunnel Test Data - Windtunnel Test Results and Analysis - HybridZ Windtunnel Testing the Datsun S-30 Z - Windtunnel Test Results and Analysis - HybridZ

Check HybridZ to find out. There are lots of people who have done that conversion, there is a kit from John's Cars with motor and trans mounts, etc.

R32 Skyline diff has 4.38 with LSD.

Poly bushings in the TC rod can be a bad thing. If you run the poly in the front and a rubber bush in the rear, that helps, or you can drill a bunch of holes in the bushing to make it more flexible. More here: scary tension rod failure - Brakes, Wheels, Suspension and Chassis - HybridZ

Yep. That race had me on the edge of my seat the whole way through.

I've got the 60 gal unit from HF: 60 Gallon Air Compressor - 2 Stage, 5 HP, 165 PSI and I think I had the regulator turned down to 40. I also thinned the paint with acetone. It's been a couple years, can't remember exactly but I can tell you I found all the details of what to do online. Thanks for the compliment. That quarter came out the cleanest and it looks the best, but the rest of it looks presentable too.

I tried the roller method and it looked like it was going to be VERY time consuming so I went down to harbor freight, got the cheapest HVLP spray gun I could and sprayed my car. It came out pretty nicely. Mine is a race car so I didn't really care that much and it could have been done better, but it is better than the previous pro job that I spent thousands on for sure. I used Rustoleum so that if I have to make a quick repair later I can use spray cans.

Much to Blue and bblackmore's dismay, seems to be working fine now.

It would appear that they are using different chemicals now, so I stand corrected. If the bottle says tolulene or xylene though, it's not really doing much of anything.

I have no doubt that the last few degrees of timing could be worth 20 hp. That's why for others building motors I'd suggest cutting back just a little on the compression to enable running the correct amount of timing. If your motor just needs a few tenths more to keep from pinging that's great, but a more reputable brand of tolulene or xylene isn't going to be fundamentally different in its ability to prevent pinging. So long as they're selling tolulene or xylene, the math is the math.

Gnosez is right. If you look at the bottle of octane boost, it will tell you what is in it. Usually xylene or tolulene or some combo of the two. It's been some years since I messed with this stuff, but tolulene is 114 octane if I recall, and xylene is 118. From there you can do the math. If you have 5 gallons of 92 octane and add 1 gallon of 118 octane, you'll end up with 96.3 octane. (5*92) + (1*118) / 6 total gallons = 96.3 octane. Tolulene gives 95.6. If you search "home brew octane boost" you'll see lots of sites and they talk about adding mineral spirits and ATF to the mix for top end lubrication. There just isn't any way for 8 oz of tolulene or xylene to affect the octane that much. It is plain ol false advertising IMO to say that it gives a 2 point boost and mean two decimal point boost, but that's really what they're doing. I screwed around with this on my 11:1 L28/E31 combo (shaved and ported and all that) and found that for my build I needed about 95 octane in order to run advance in the mid 30s. If I were to build a hot street motor I would always choose to reduce the compression and I would definitely go for a bigger cam than I did previoiusly (.490/280 is what I had). Mixing your own octane boost isn't fun, and it's damn expensive. A gallon of tolulene was about $10 when I was screwing with it, I think it's closer to $20 now.

Just my $.02, a "mild" cam isn't going to give the best results with triples. I went with a .490/280 cam and wished I had gone bigger. When I put the triples on my Z, my wife was afraid to drive it because it had so much more power. I would guess ~40 whp by the butt dyno. It was SIGNIFICANT. I believe Dan Baldwin documented 50 whp on his motor here some years back.

I have a small booster, worked when pulled about 8 years ago. $40 + shipping if you're interested.