bucking and surging at idle

[metalgod]

80 full size k5 blazer 350 with no emission equiment on it at all. it has a holley 600 cfm carb eletric choke, petronix flame thrower dist. and coil.......................now to the problem this truck when at idle surges at a stop light, in drive it lerches the truck, if you then put it in neutral it stops or barly hold the gas down it will stop lerching....but the idle is not set to low and when its surging its not to low...now this morning while warming it up (btw hot or cold it does this) it was surging so i poped off the air cleaner (i had suspected the choke was stuck) and im just watching the engine rock from side to side so it messed with the air screws and the idle......nothing no change!! so i put it all back to where it was and here i am begging for your help........this is my girl friends truck and shes out beating the crap out of my truck untill i figure out this problem so help me swiftly please....sorry about my spelling

[Damien]

It sounds like a mis. I would check the plugs and wires.

[metalgod]

Originally Posted by Damien

It sounds like a mis. I would check the plugs and wires.

brand new just did them. problem was there before i replaced plugs and wires.........im leaning twards carb or ignition problem.........drives great no problems at all under load or cruzing just at idle

[77 350 Shorty Wide]

Vacuum leak? God Bless, Terry

[slednD1]

vacuum leak sounds right,check hose or cap at back of carb and also if you are running a pcv valve make sure the other valve cover is sealed! if not it's a leak..run another breather and do away with the pcv,then re-adj. idle mixture screws.another note..poss power valve failure???ever backfire throuhg carb?? were the old plugs fouled??

[metalgod]

Originally Posted by slednD1

vacuum leak sounds right,check hose or cap at back of carb and also if you are running a pcv valve make sure the other valve cover is sealed! if not it's a leak..run another breather and do away with the pcv,then re-adj. idle mixture screws.another note..poss power valve failure???ever backfire throuhg carb?? were the old plugs fouled??

all good possables im going to check for a vacuume leak here in a moment i needed to let it drip dry fing raining out today.. if theres no air leaks what is the way to know for sure if the power valve is blown it was a used carb and its been running fine and the surging just started as intermittint and now all the time...........im not going to give up till this is fixed so if anyone can help just ask for info and ill give it to you

[metalgod]

im pulling out my hair and i was told that the torque converter may be to blame its a 700r4 thats in there is it possable that the converter is making it surge i unpluged the lock up plug and it was the same but i just dont think unpluging it will be a proper test

[powerdriver 1958]

does the distributor have a vacuum advance?Diaphragm in it could be just starting to go bad and are the mechanical advance springs weak? also the power valve in the holley carb could have a pin hole in it and thats why the air jets make no difference.

[metalgod]

Originally Posted by powerdriver 1958

does the distributor have a vacuum advance?Diaphragm in it could be just starting to go bad and are the mechanical advance springs weak? also the power valve in the holley carb could have a pin hole in it and thats why the air jets make no difference.

all possabilties bu tthe finger points at vacuume leak is that what im hearing?.........i just dont want to tear the carb apart if its a dead end

[OrangeAnimal]

Pull the distributor cap off and test the vacuum advance for a leak. it is very possible that could be the problem. You can use a vacuum pump to test it or you can try and push the rod in then put a vacuum cap over the connection see it goes all the way back out. HTH.

[metalgod]

Originally Posted by OrangeAnimal

Pull the distributor cap off and test the vacuum advance for a leak. it is very possible that could be the problem. You can use a vacuum pump to test it or you can try and push the rod in then put a vacuum cap over the connection see it goes all the way back out. HTH.

thanks for that im going to test it tommorow when i get home from work.....if not whats next?

[fiyaweed06]

any info on this matter yet.im curious