Thread: 454 Missing and popping!

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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!

yep i said that on post#6 your going to want to check vacuum in gear with your foot on the brake and 1/2 of what you read on vacuum is what you want for a power valve of 4.5 that s how i done it .as for a miss could be fuel low psi or they never fail much i would be using a nother coil just to check the one you have

Originally Posted by pat mccarthy

yep i said that on post#6 your going to want to check vacuum in gear with your foot on the brake and 1/2 of what you read on vacuum is what you want for a power valve of 4.5 that s how i done it .as for a miss could be fuel low psi or they never fail much i would be using a nother coil just to check the one you have

So i checked the power valve and it is a 4.5 and i used another coil, cap, and distributor, and changed the carb. Still the same problem, i took it to a mechanic tonight. Is 125 psi compression good for a big block with flat top pistons?

Originally Posted by 1987BBMonte

So i checked the power valve and it is a 4.5 and i used another coil, cap, and distributor, and changed the carb. Still the same problem, i took it to a mechanic tonight. Is 125 psi compression good for a big block with flat top pistons?

hey man what did u find out what problem was i am having same type of issues.

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.)

his last post was 9-1-010 he may have fix it or not .we get a lot of that on here

Another month later. The least he could do is let us know what was wrong or what fixed it. Isn't that part of our purpose here?