help me out please

[redyredfred]

Alright, i have a 1985 chevy silverado 4x4 it came with a 305 and the 700r4 tranny, i swapped the motor with a higher performance 350, i have the dart lightning heads with i believe a 9:1 compression ratio, a .450 lift .460 on duration cam, the crank was milled at the usual rebuild measure, a hundred thousands i think, and the block was bored .30 over, i have the stock quadrajet carb but it was rebuilt and i was told by the guy who did it that he tried to make it a little more hot rod to fit my motors specs, and his name is a pretty good one in my town for carb rebuilds, so i figure its rebuilt right, but when it came to getting my motor to run we had to put a new spring kit on my distributor and the carb was funny on adjustment, and the timing was a pain, but after was all said and done it ran pretty good, but now it has this thing it likes to do where it will run really smooth but randomly it will act like its bogging down when you hit the gas and the truck will shake more than usual when accelerating...what can i do to make this go away? i was told it could be a peice of trash in my carb, but im not too sure on that, i was also told my float could need readjustment but i just dont know.......id like some instruction on some things i could try and do....i know my way around a motor compartment ok so anything would help thanks.......Red

[sierrap615]

i don't know for a fact but i would start by checking the following:

exhaust backpressure/clogged cat.

ignition timing/vacuum and/or mechicnal advance - does the engine have a knock sensor?

carburatior adjustment - see if the rebuilder would be willing to adjust the carb on the engine(specs and the actual engine may differ, i'm not questioning his skill, i'm just saying somethings you can't always predict) manly the accerator pump and maybe the float level. did you change the fuel pump to match the larger engine/carb(if needed)

transmission - possible shudder? torque converter problem? does the torque converter have a lock-up?

vacuum - new cam specs affecting transmission vaccum modulatior/carb/vacuum advance?

sorry these are just ideas, i am more atuned to working on fuel injection and electronic ignitions

[beef_bourito]

if the guy has a dyno, you could ask him to dyno tune it or have him inspect it to find anything wrong with it. if he doesn't have a dyno, find someone who does and you can adjuct the carb and see what you've done.

[sierrap615]

i happen to come across a similar problem today a guy was talking about on some old car that was just rebuilt, good idle, ok when crusing, poor acceration, in his case the valves were adjusted to tight.

[redyredfred]

Originally Posted by sierrap615

i don't know for a fact but i would start by checking the following:

exhaust backpressure/clogged cat.

ignition timing/vacuum and/or mechicnal advance - does the engine have a knock sensor?

carburatior adjustment - see if the rebuilder would be willing to adjust the carb on the engine(specs and the actual engine may differ, i'm not questioning his skill, i'm just saying somethings you can't always predict) manly the accerator pump and maybe the float level. did you change the fuel pump to match the larger engine/carb(if needed)

transmission - possible shudder? torque converter problem? does the torque converter have a lock-up?

vacuum - new cam specs affecting transmission vaccum modulatior/carb/vacuum advance?

sorry these are just ideas, i am more atuned to working on fuel injection and electronic ignitions

I have three inch exhaust running all the way out, from the headers, with a y pipe crossover back out to dual,