Hey guys, maybe you can help me with a couple issues here... First off, I have a 100% original 1977 Camaro Z28, 350, auto, a/c, 225,000 miles, original engine rebuilt to stock specs appx. 15,000 miles ago... First issue, took the car out for a Sunday cruise yesterday, car runs great as always, but has seemed to have developed a fuel issue, drives fine all around, but when I get into it, it takes off and accelerates fine, but upon deceleration, it starts sputtering and missing like it's being starved of fuel, fuel pump and engine lines are all new... Second issue, my tachometer appears to be way off and it's been that way for awhile, the car has dealer installed 3.73 gears, so when I'm at 70, it should be around 3500-4000 rpm's give or take, but the tach will only be showing like 1500-2000, are these tachometers prone to failure or could this be an electrical current shortage somewhere or something?... Any help with these issues would be greatly appreciated...

 

When was it last tuned up, and have you checked the timing? The sputtering could be timing related, or could be a vacuum issue causing timing to vary.

 

I just went thru and restored the engine compartment a few months back, cap, rotor, plugs, wires, fuel filter, idle solenoid... It is perfectly tuned and runs great, you just give it a good amount of throttle, which it's good all the way thru, until you let off the throttle, than it acts like a car that's out of gas...

 

Since it's happening at deceleration after a hard acceleration, I'd be looking for fuel starving issues also. If the fuel filter and system are new, then I wonder if the inlet filter that's built into the carb was replaced? It sits inside the inlet and is a sintered bronze. These are prone to plugging, and don't usually get replaced, as many don't know they are there. I usually toss them out, and use a good inline filter.
Also check fuel float level, as if it's set too low it will create a fuel starvation situation.

 

The filter on mine at the inlet is a standard paper filter and is also new... I somewhat doubt that it would be the float as it always worked and performed perfectly, it has just started doing this and appears to get worse everytime I drive it... Anymore it seems to do it after even a medium acceleration, works perfect, but when you let off the fuel, you have to kind of pump it to keep it running, and it even seems like pumping it makes it worse, yet if you stay off of it, it returns to idle fine... I know, it's a weird one...lol

 

This may sound stupid... but are you sure that you didn't put the fuel filter in the carb "backwards"??
I've seen this more than once.

 

No, I didn't put it in backwards...lol But yes, I have also seen that done as well... Nothing has been done to the carb or car for that matter since it was running flawlessly, this problem has slowly started to occur and is slowly getting worse... At first when you'd romp on it, it'd take off fine but kinda sputter a bit in third gear and definitely on deceleration... Now it does it more frequently, but still only when it hits 3rd or your decelerating... Does this make sense?...

 

Look for a vacuum leak. Start with all the hoses, make sure all are on tight and have no splits. Then with the engine running, spray some brake cleaner or starting fluid on the sides where the intake manifold meets the heads. If the idle speeds up, you have a gasket leak. Don't use carb cleaner btw, as that stuff dulls and removes paint.

 

Alright I will give it a quick look over to see if I can find any vacuum hoses coming loose... I used to use WD40 for that vacuum leak test, I guess brake cleaner would work best as it dries so quickly, but you're sure that it won't mess up the engine paint?... Thanks for the tips, I'll give them a shot, but somewhat doubt that's the issue, but hey, one less thing to worry about I guess...lol

 

Brake cleaner won't hurt the paint. If you're at all concerned about spraying flammable liquids on a hot painted engine, then you can use the dry method; turn on the nozzle to your propane torch (if you have one), don't light it, and move it around to different areas to check for a vacuum leak. If you have a leak, the engine will react the same when it sucks in the gas (speed up), and you won't be spraying anything on the engine.