Thread: 454 Missing and popping!

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Originally Posted by 1987BBMonte

Put a new power valve in it yesterday.

How much vacuum is it pulling at idle and what # power valve did you install?

Originally Posted by 98 SNAKE EATER

How much vacuum is it pulling at idle and what # power valve did you install?

It is pulling 9.5 psi at idle, and not sure what size power valve, didn't know there were diff. sizes. How do i find out what size i need? So far i have taken every valve spring out and checked to make sure one wasn't broken, changed the oil and cut the oil filter open to make sure there wasn't any metal in it, it was spotless, did a compression check 120-125 psi on every cylinder, checked vacuum, ohm the wires out, changed the plugs #7 NGK plugs, octane booster and water remover, checked the pushrods for being bent or broken, put a new ignition module on, i don't know wtf is goin on. Tomm. i am gonna put another carb. my buddy has and if that don't work im gonna put another distributor he has also with another rotor button and cap. If that dosent work well i have no clue!

Originally Posted by 1987BBMonte

It is pulling 9.5 psi at idle, and not sure what size power valve, didn't know there were diff. sizes. How do i find out what size i need? So far i have taken every valve spring out and checked to make sure one wasn't broken, changed the oil and cut the oil filter open to make sure there wasn't any metal in it, it was spotless, did a compression check 120-125 psi on every cylinder, checked vacuum, ohm the wires out, changed the plugs #7 NGK plugs, octane booster and water remover, checked the pushrods for being bent or broken, put a new ignition module on, i don't know wtf is goin on. Tomm. i am gonna put another carb. my buddy has and if that don't work im gonna put another distributor he has also with another rotor button and cap. If that dosent work well i have no clue!

OK, assuming your power valve is still good, with 9.5psi at idle, you're in the ballpark with a #4.5 PV

First thing I'd do is check that you have enough fuel pressure and that the gauge is consistent and not erratic...

If erratic, start the engine, remove the air cleaner and make sure fuel isn't dribbling out of the boosters.

If you don't notice any dribbling at idle, slowly increase the throttle and keep an eye on them...

In most cases, this is the cause of popping and plug fouling.

If a pair of boosters dribble evenly, adjust the float level a little lower for that pair.

If one booster shows dribbling, the cause is usually internal (clogged passage in the metering block, clogged air bleed, etc.)