SteveJ

Cut down some of the wiring you're trying to trace. Pull the ignition relay. It's around the passenger kick panel Put in another 30A fuse. Turn the key to ON. See if you smoke the fuse again. If not, get with me on tracing down the short downstream of the relay.

This video showed up in my YouTube feed. I can see a variation of this working to fill the differential or transmission while under the car.

If it gets to working on the switch, this thread may help:

Get some Tarn-X, dielectric grease, rotary tool (Dremel) with a small wire cup brush. Here is a fusible link I replaced many years ago. I put it in some Tarn-X for less than a minute, rinsed, and beat the water out. Here is how the fusible link box looked when I took off the links. Here's how it looked after some work with the wire brush. I coated the terminals with dielectric grease and replaced the links. Try that, and re-test.

Here is some recent action from this past weekend at Laguna Seca: Saturday: Sunday:

I had a slave cylinder hose get blocked up, but that was from years of brake fluid sitting in it.

I was thinking of trying something different on the old tank. I was thinking of buying this stuff: https://www.amazon.com/dp/B0031HQJWW I'd mix it up in the tank and let it sit for a week or two since it's cold right now. After that I would dump it out and rinse the tank with denatured alcohol. After that dried, I could do some Redkote or similar product. Even if I wait to coat the inside, I could use some fogging oil to keep it from rusting. That would just require a soapy rinse afterward and denatured alcohol to give a good surface for the coating material.

There are two things that could cause the voltage drop If the starter is turning and the battery is not good, you could see that kind of voltage drop. There is corrosion between the battery and the ignition switch. From the battery positive, you have a cable going to the starter. It goes out of the starter to a white wire to the fusible link and comes out of the fusible link as a white wire. There it goes through the shunt (for the ammeter) and comes out white/red. The white/red wire goes to the fusible link and comes out as white/red, going to C-5. From C-5 it goes down to the ignition switch. Lots of connections to get corroded. It measures fine with everything off, but when you try to power other things, the corrosion could limit the current flow and drop the voltage downstream.

So I finally had some energy and motivation today. That meant I could drop the old tank. In case anybody needs a primer on dropping the tank, this may help. I already had the trim panels removed and the gas tank drained. Next is taking hoses off the expansion tank to give slack underneath. The only hoses that IMHO have to be removed is the large vent hose that goes through the floor on the right side near the tail panel to the tank and the hose from expansion tank to filler neck. Taking off the other hoses just ease access to the large vent hose. It's good to have some small picks to run along the inside of the hose where it is on the neck of the expansion tank to break loose the hose. I replaced all of the vent hoses only 24 years ago, so they are in fairly good shape. Go ahead and remove the 3 screws on the filler neck. There is only one vent hose that is somewhat accessible before starting to drop the tank. It's on the left side of the tank. Even then, you'll need to loosen the nuts on the J-bolts some to get full access to it. Before you take off the J-bolts, on the passenger side, remove the leads to the fuel sender and the supply and return hoses. With the driver side vent hose removed, and the tank straps disconnected from the J-bolts, you should be able to access the small vent hose on top of the tank. It is a good idea to support the left side of the tank with a floor jack or jack stands to keep from stressing the hoses. You'll also want to get the filler neck down to access the hose clamp holding the filler to the tank. That was a challenge for me this time. At first I tried to pry the lip in. That didn't work so great. Then I got out the big honkin' pliers and squeezed the neck enough to get the lip through the top hole. At that point, I fed the large vent hose through the floor to give enough slack for the tank to come down more. I got the large vent hose off the tank. Then I used a small pry bar to push the filler neck hose off of the tank. The tank was on the ground. I don't think it was as bad inside as the one @siteunseenhad with his display of chips that he likes to use, but I don't want to take any chances. The old tank is in the shed for now. I'll probably try to clean it up. The new tank will go in the week of Thanksgiving since I'm taking off from work that week.

Here are a couple of pictures of a new stopper. The lower rubber piece is about 10 mm tall at the thickest point. I think that ridge is about 3 mm thick. As you can see it is quite pliable. I hope this helps in your thoughts to restore them. Frankly for me, it was too easy to spend a little money and never have to think about it again.

Yep. @One Way The lower block that disintegrated is made of rubber on the factory ones. I just put a set on my 240Z recently. It is a relatively soft rubber, too. Maybe I can shoot some photos and video after I'm done wrestling with the gas tank today.

Post photos of the front calipers showing the bleed screws.

Did you adjust your rheostat for the dash lights to confirm?

I haven't finished designing that. I have a plug & play in my mind's eye, but I need an intact 78 or 77 to study and test with.

Other things to consider: LED bulbs would put less strain on the circuit. Check the side markers for corrosion. The front ones especially are subject to water infiltration and corrosion. Rebuild the headlight switch and clean the contacts.

Oh, and I bought one of these 7 years ago, but it doesn't have a tachometer. https://www.amazon.com/gp/product/B000BSWEHS/ It still works, but I have to use a separate tachometer when tuning.

Timing lights are hit and miss anymore. The Innova Digital should do what you need for a timing light. https://www.amazon.com/dp/B000EVYGV4

It is possible your readings will go up since the other cylinders won't be pushing as hard against the cylinder under test.

From the FSM on compression testing. Of course, you'll have to do it cold right now, but follow the rest. Note that the compression ratio will probably be lower with the engine cold, but there should not be a lot of variation in readings.

Use this stuff for starting. It's the cheapest you'll find.

Wow, how about shooting some video of you taking measurements just to make sure you're doing it right. Those measurements are way off.

Considering the engine was worked on, the readings seem low and all over the place. However, there can be variability in compression gauges. Also, technique is important. Make sure you look at what the ET section of the FSM says.

They also changed from the spade terminals to the round Yazaki terminals for that connector in 77. As @Captain Obvioushas pointed out in other threads, the dash to engine harness changed to AMP connectors. At least we can track those down easily.

Here is a good tutorial on how to do the valve adjustment: https://web.archive.org/web/20080720024048/http://www.picturetrail.com/gallery/view?p=12&uid=786489&gid=1803105

Lash pads are not the same as setting the valve lash. I can't speak to the technique to measure for the proper size lash pad, but maybe someone who does will chime in. This is the wrench set I like to use for adjusting the valve lash. They are not as thick as your typical wrenches, so it makes it easier to put both wrenches on the nuts for the valve adjustment. https://www.tme.com/us/en-us/details/wp-w003300we/wrenches-sets/workpro/w003300/