We'll, I finally got to drive the Vette on the road today for the first time. I finally got the interior back in last night. I had 3 issues.

1. The amp gauge is showing charging all the time. And when I have higher rpm's, the gauge pegs out on the charge side.
2. About half way through the drive, the tach stopped working. It did this once before when I was working on it and I thought I broke the cable. I took it off and the cable was fine. I plugged it back in and the tach started working again. Does this tell anybody anything?
3. Got afterfire (through the exhaust) after getting speed up to about 55 in 4th, after full warm up. It doesn't happen at lower speeds. When working on engine a few months ago, I was getting backfire through the carb (Holley) and wondered if I trashed the power valve. Would this cause afterfire at higher speed? Like I said it's not doing it at lower speed even at high rpm 's. I know the timing is correct ( at least initial timing), I set it to with a timing light. And the motor sounds good and smooth. I have not tried to adjust the carb.

Thanks for any help!

Mark

 

Rookie suggestions:

The engine won't idle as smoothly when the power valve ruptures/blows.

The tach cable might need lubing.....the cable ends could be rounded and not turning the cable....the crimped "stop" on one end of the cable could be loose causing the cable not to stay inserted in the drive. The tach drive gear might be worn?

 

I found a way to test the power valve, which I'll try tonight. Good thoughts on the tach cable. I'll pull it and check if the ends are rounded. I just hope it's not the tach itself. I just got the dash all back together!

 

I connected a battery-powered drill to the cable instead of screwing it to the distributor---I set the drill on LOW speed and slowly turned it on and increased the rpm to test the tach while it was in the dash....just be careful not to let the drill pull the tach-end of the drive cable out of the tach drive hole while testing the rotation---keep a slight pressure on the drill motor to keep the cable end seated in the tach drive hole, or you will think the tach or cable is faulty as it will not be fully seated.

The tach worked great/the needle did not skip-jump-or stop which showed that the cable on the tach was not rounded and the tach was not binding internally. Then I noticed the the distributor end of the inner drive cable was rounded on the end.

I tested the drive gear of the distributor by sticking a small screwdiver into the hole that the tach cable would fit in---then I put slight pressure on the handle of the small screwdriver with the tips of my fingers and cranked the car over---the screwdriver kept spinning/no slipping/jerking/stopping as I held the handle with a little pressure. Next----looking at the dist. cable end, I then saw that only the tip of the inner drive cable was rounded----which helped me realize that Bubba had never fully inserted the end of inner drive cable fully into the hole in the drive gear and he did not tighten the cable retaining thread "cap" all the way down.

I cleaned the grime off the external threads on the tach housing/dressed-up and cut away the I/8" long tip of the rounded drive cable end and fully inserted it into the tach drive/tightened the retaining cap all the way by hand.

I also re-stabbed the distributor so the cable wasn't in a bind against the firewall and re-clocked the distributor to the "1 cylinder/set the timing again.

It works perfectly now

 

Thanks! I'll check all that tonight on the tach. Also, on the afterfiring issue, I might have a gasket leak where the right side header connects to the side pipe. That could cause the popping, right?

 

Being a rookie.....I'll say yes--even though a bad exhaust gasket at the head would be more likely.....I also had corroded wire terminals at the distributor connectors which I had to clean well that caused me lots of wasted time searching in other areas.

Buy one of those $10 remote start switches that you connect one lead to a constant hot source in the engine bay and the other lead to the wire on the firewall that goes to the starter solenoid (check your wiring diagram for the correct colored wire) to provide 12 volts for cranking the engine....it saves you lots of trouble when working with the engine by just being able to press the remote start button to rotate the crankshaft or even start the engine (with the key in the on position).

 

Adjusted carb and fixed leak in exhaust and no backfiring tonight! One problem solved, two to go.