Ok here's the problem im getting around 3 miles per gallon. I have a 82 Z28 pace car, it originally had the crossfire 305 but now it has a carbed 350 put in by the previous owner. I don't know anything about the heads or cam, it has an Edelbrock TM1 single plain manifold with a q-jet with open element breather. stock exhaust manifolds with duel exhaust. And it isn't leaking anywhere. I have given it a tune up and it didn't help at all, and I cant figure out what might be causing it to be so bad.

Thanks in advance

 

Take the Q-Jet off and put a Holley on it. The Q-Jet is probably shot and rebuilding them is an iffy thing at best and Holley's are easier to tune and easy to rebuild.

Obviously check your ignition system, should have a strong blue spark. If not it could be part of the problem.

 

Wait on the Holley (or any other aftermarket brand) until you've got the ignition sorted out.

If the car was originally cross-fire and now has a carb but still has the original distributor, that's your problem. It needs the proper type of distributor (vacuum/mechanical advance) for the carb (q-jet or Holley or whatever aftermarket brand).

That's assuming the q-jet is not a computer-controlled type. If it is computer-controlled, that's your problem (and maybe the distributor, too).

The message here: All the parts need to be of the proper mix to work properly. A computer-controlled carb needs a computer-controlled distributor with the proper computer. A non-computer-controlled carb needs a non-computer controlled distributor.

And this engine most likely does not need a single-plane manifold, but that isn't the main problem with 3 mpg.

 

The distributer is an HEI vacume advance and both it and the carb are non computer controled and the Q-jet came of of a 79 van. And its pretty nastsy right now. I have a Holley 4150 on my back porch that i had on it for about a week a couple of months ago. I took it back off cause it would not idle right and was leaking gas out of the sides.
How hard is it to rebuild one of these if you have never done it before?

Heres a pic of the moter with the holley on it

 

First of all scrap that single plane intake. Check the timing and firing order. Next check to see if the diaphram in the distributor for the vac advance is busted. See if it holds vacuum. Check and make sure the weights are moving in the distributor, and finally check to see if the floats are ont seating properly. Your fuel pump could be pumping gas straight into the motor if the floats are not closing. Also gas will be leaking out of everywhere on the carb if this is the case.

 

A Holley is one of the easiest carbs out there to rebuild.

 

rebuild your carb and go from there doesnt matter what brand your rebuilding they are all iffy ....depends on the condition of the carb and why it needs rebuilt to begine with ....not to step on any toes at all here ......i would just try to rebuild the one that will cost the least to buy the kit for now especially if your on a budget of anykind ....