Poor Running Vette

[STREETRODS]

HI-i have a 79 vette we just bought. never had one before. it is really hard to start and when idling in gear will load up and die-then is flooded and harder to start.
the carb-quadrajet- has been rebuilt and mech. tried two other carbs on the car and same problem. the vacuum at idle is about 16, and in gear at idle about 11. the dist. shaft is new and the mech. advance rebuilt. the fuel pressure is a bit high with new fuel pump on it. plan on putting a pres. regulator on.
could my problem be timing chain? the engine has never been apart-71,000 miles. and compression is 150lbs. give or take 5 lbs.
vacuum advance is hooked to the no vac. at idle side of carb.
Is the vacuumn headlights possibly the culprit?
any ideas would be appreciated.

 

[1979toy]

Welcome to the CAC!

If the fuel pump is an aftermarket pump you may be overpowering the float seat at idle. This is one of the places where the stock part is best. The factory pump with it's return line will support all of the horsepower you can make with a street driven small block and keep the fuel pressure in the correct 4 to 6 psi range.

 

[69MyWay]

David,

Start out by unhooking all the vacuum from the engine and plugging it off.

It is possible you have a failed PCV?

This is an automatic? Any chance the vacuum modulator to the trans is either the culprit?

Try the vacuum plug and let us know what happens.

Although I hate vacuum headlights, I doubt that alone is causing your problem.

If you plug the vacuum with no luck, I would suggest going through the distributor and making sure it is set up right, and you are working from an appropriate base idle. It almost sounds like the car is retarded way too much.

Let us know.

 

[Robin7TFour]

CHRIS, how ya doin'? the modulator on the tranny, what's a good way to diagnose if it is truly a problem?

robin

 

[69MyWay]

CHRIS, how ya doin'? the modulator on the tranny, what's a good way to diagnose if it is truly a problem?

robin

You can pull a vacuum on it and see if it holds.

 

[Robin7TFour]

thanks chris, hope everythings going ok in jax.



robin

 

[STREETRODS]

good running vette

HI GUYS, i'm back. the problem with the 79 ended up being a faulty coil!!!!!!!!!
after lots of work and a lot of money, a friend of mine,s mechanic found it.
Sometimes it had full spark and other times not enough to start it. I always thought they either worked or didn't. we re-did the valves,rebuilt the carb-replaced everything in the dist.-in fact the new module i put in was faulty, that cost lots of lost time.-replaced plugs,wires,cap,rotor-finally ending up at the coil.
I appreciate all the ideas and comments, it's nice knowing i can jump in here and get some ideas.
thank you again
dave

 

[bigvette1]

I would still do some diagnosis on the engine.

1. Do a full tune up. Plugs, wires, cap rotor, PVC, fuel filter
2. Make sure the carb is not flooding out. NO DRIPS from primary venturi at idle. Adjust curb idle to spec.
3. Make sure the choke is opening fully.
3. Check the timing both idle, total and advance mechanisms.
4. Put the vacuum gauge on it and check out what it is doing, not just how much or how little.

The basics will make it a much better running car and fun to drive.