backfire under acceleration - Third Generation F-Body Message Boards

92whiteta · 07-15-2009, 02:56 PM

i just finished my TPI to Carb swap and im having issues. the car starts fine but at idle i have a loud tick i cant tell where its coming from i dont think its mechanical. and when i accelerate the engine it backfires though the carb. not just a pop with smoke its a solid flame out the top of the carb and makes alot of poping noises the motor idles ok by itself it doesnt need help to stay running i think the backfire and the loud tick are from the same problem. they are in sinc the whole time.

thanks

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five7kid · 07-15-2009, 03:10 PM

Start with the basics: timing, spark plug firing order, vacuum leaks, something that may have gotten into an intake valve (very likely given the symptoms).

If it is something caught in the intake valve, a compression test will identify the cylinder.

92whiteta · 07-15-2009, 03:46 PM

i found the issue it is a roller rocker that is almost off. the problem is for some reason the push rod sits lower than the other pushrods. (way lower) low enough that i cant tighten the nut all the way down the pushrod and lifter are the same as the other 15 so i dont know what the issue is.i may have to replace the lifter i guess its not pumping up like it should. any other ideas?

five7kid · 07-16-2009, 01:13 AM

Did you pull the pushrod out and look at it?

Pretty weird that something like that would happen with a carb swap.

EvilCartman · 07-16-2009, 01:13 AM

On that one valve, is it coming up the same height as the others? Have you checked the pushrod for damage? Pull off the rocker and take the pushrod out and shine a light down to the lifter and see if you can see anything out of the ordinary.

92whiteta · 07-16-2009, 11:52 AM

i did take the pushrod out and it is in good shape. i looked in the hole and the lifter looks ok just sits lower than the rest. i am gonna take the lifter out and soak it in oil, maybe i can get it to pump up.