89Turbocoupe

So I have an 89 coupe with a single 67mm turbo on it and just had the engine rebuilt. After doing a lot of little things I am ready to fire it up. It starts but runs like crap and what appears to be popping sounds coming from the valve covers and not up through the intake??
Pulled the upper intake and valve covers off, put the plenum back on and started it up. RUNS FINE with no popping or idle problems..... put valve covers back on and back to running like crap and popping sounds.
I tried taking the oil fill cap off the passenger side to see if it wasn't getting enough ventilation into the crank but it didn't change anything. Pulled PCV vacuum line off to see if it made a difference, NOPE.... I am at a loss. This is where I need you guys to help me out.

barnett468

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sounds like your rocker arms might be hitting the valve covers.

you can set the idle low, loosen the bolts, let it idle and put your hand on the cover to feel if it lifts up or look at it to see.

mjr46

what type of rockers are you running?? and what heads are on it??

89Turbocoupe

1.6 rollers on Edelbrock performer heads. I have ford motorsport valve covers on it right now. I am thinking the valve covers are interfering with rockers.....

mjr46

if they are the tall motorsport covers they are designed to clear roller rockers and thus would not be the issue.......however I have a very old set of motorsport ones that don't clear but they are the shorter design.....so do you have any pics of the ones you have??