i just swapped out the tpi 305 in my 85 trans am for a '72 350 bored .060" over with headers, cam, ported and polished 305 heads, edelbrock torker intake, 850 holley and full 3" exhaust... and the engine starts up and runs great while in park. like i can let it idle (about 900) and rev it up to about 6500rpm, and its running decent temperature, like under 195..but once i try driving it, it gets all messed up. i know i need a stall converter, but other than that, when ur driving it and go to give it like half-or-more throttle it almost dies out completely..??? and sputters and just doesnt run good at all.
my timing is at approx. 10 degrees advanced (i dont have a progressive timing gun, so im hoping that its somewheres around 27- 32 degrees total timing...)
i've looked at the whole engine and there are No vaccuum leaks that ive found..
and the only thing i can think of that might be causing this is i have the electric pump in the tank still but its disconnected and im using a mechanical, drawing through the electric, i dont know if maybe the carbs too big and demanding more fuel than can be drawn thru the stock pump or what??????

i neeeeed help tho, its frustrating to hear it run (parked) and not be able to drive it...

ANY ideas would eb gretaly appreciated!!! thanks

 

leave the timing alone, it won't cause such a symptom.

Most likely it's running out of gas at the carb. To check for fuel starvation:

Run the car hard up an uphill expressway ramp or some similar spot, where there's a place and time that you can safely pull off to the side of the road. Go through 1st, 2nd, and as far through 3rd as it will go. When it's gotten to where it malfunctions real thoroughly, suddenly take it out of gear and turn the key OFF at the same time; remember, OFF, NOT LOCK. The object is to cut it clean at the moment of truth, in order to see how far your WOT run has drained the carb down, without giving the engine the chance to refill the fuel bowl. Do not let the engine idle, do not restart it, do not let the engine brake the car. Pull over to the side and look in the fuel bowl and see how much fuel is in it.

I'm betting it will be nearly empty.

You need to get rid of the in-tank pump. It's too much of an obstruction for a mechanical pump to pull through reliably. Even if it seems to work for a while, it isn't a good idea. Mech pumps have very little "suction" power. Any restriction in that side of the system will incapacitate one.

 

so how do i fix the problem if i want to keep and use the electric pump?,
do i get a regulator, knock the pressure down to 7-or-so psi and block off the mechanical? (i still have the relay and everythign for the electric pump..)

thanks for the insite, it sounds like youve dealt with this same problem once or twice.