I have an 86 Trans Am with a brand new 350. Everything has been replaced including the fuel pump, carb, intake blah blah blah. I have this horrible bog whenever I stomp the gas but it only happens when the engine temp is above 190 degrees. I have tried replacing the ventilator cap (I though I had vapor lock), repaced the fuel filter, and I tore the carbon canister out. The fuel pump was replaced a year and a half ago with a stock replacement from auto zone. I have a larger cam and headers. I have noticed that every time it bogs the fuel filter is only filled half way with gas and the gas has air bubbles in it. ???. Its got me going crazy trying to figure this out. Any help would be appreciated.

 

You mentioned the carb has been replaced...did you change the jets to match the old carb?

On Q-Jet carbs the jets are screwed into the bottom of the float bowl area in the intermediate casting, just pull the top plate casting and check the size of the installed jets. May have to remove them to see the size # etchings.

 

I replaced the computer controlled piece of s*** Q jet with a Edelbrock performer 600 cfm carb and performer rpm intake. I just bolted them right on after replacing the dist. with a new one that had vacuum advance on it.

 

The new carb must have jets in it somewhere, dig thru the docs and figure out how they're changed. There's no way a carb can bolt up and be jetted right out of the box.

Pull the spark plugs and read for rich or lean operation, if rich go with smaller primary jets and if lean gow with larger ones.

 

I have already done this and I'm running it about where it needs to be ( just slightly rich). But my problem isn't with the primaries, if anything it would be with the secondaries because it only bogs at WOT. The car runs perfectly when just cruising around. I only get the problem after the engine gets hot.

 

it sounds to me like you are 'boiling' the gas. check your fuel lines and make sure they arn't running too close to the exhaust or headers. if they are, you could be heating the gas till it boils which releases the gas vapors. this could be causing vapor lock or even your pump to loose prime for a little. i would have also said to check for rotton hoses or a cracked line that the pump could suck air in (aformentioned bubles in filter) but you said it is only a problem when it warms up which mainly means vapor lock.

 

Thanks for the help. I didn't think of that but that is probably the problem. The rubber lines look worn and cracked anyway so I think I'll replace them.
thanx

 

have you checked your timing also? that will make a huge difference. on one of my cars I moved the time 4deg. and it was a whole nother car. I was having the same problem you were by the way.

 

The timing should be fine...I do mine by ear and by power tuning it.
sounds like your problem was the timing was retarded too much.