Ka-pow!

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The PV anti-backfire protection ball used to be on the bottom of the throttle body. You had to flip it upside down to see it. It was set into a pocket and the opening was folded over to keep it from falling out. Modern ones are a little different.
You may not be able to see a rupture in the PV.They make a tool to test them. When they develop a leak in the diaphragm, the engine can inhale extra fuel right thru it at idle. This makes the low speed circuit very rich, and turns the plugs all sooty and the engine can run like crap. And the power circuit who knows how bad it will run. But the clincher is that when you shut the engine off, fuel can continue to seep through the ruptured diaphragm and dump into the intake through the vacuum circuit. When it drips onto the hot intake manifold it will flash to vapor and rise up thru the throttle bores past the valves, and on up thru the air horn where you can see it as a wisp of smoke, to a cloud,depending on the severity of the rupture. If this continues long enough the fuel may puddle there, providing a nice rich boost to the start mixture or flood the engine, depending on the time to restart. If left long enough it can all evaporate, and it's a non-issue. 'Course it can also run into a cylinder past an open intake valve......... which can lead to hydrolock, or a bent rod in a worst case situation, or a eventually,a crankcase full of diluted oil at the very least.
When you take the metering block off, there should NOT be fuel in the vacuum cavity that remains on the main body. That would be the clincher.
But I don't think you have this problem,lol

Tight bolts do not guarantee a leakfree seal.
 
Thanks AJ, I may just have that problem though. I wish you would have posted this info before I put everything back together.
The thing is sure running pig rich for some reason I can`t see how the power valve ruptured, but I guess anythings possible, I just pushed a little on it`s plunger to check it`s operation and it sprung back good but did`nt pull out to inspect closer because I did`nt have a spare gasket. This thing went from running plugs that looked like they never been fired to sooty wet, and near eye watering rich. Something happened...
I guess I should pull the damn thing again and inspect the power valve for ruptured diaphragm. If rupture can`t be seen, maybe just replace it and hope for the best.
Thanks for the input
 
mopar head said:
Thanks AJ, I may just have that problem though. I wish you would have posted this info before I put everything back together.
The thing is sure running pig rich for some reason I can`t see how the power valve ruptured, but I guess anythings possible, I just pushed a little on it`s plunger to check it`s operation and it sprung back good but did`nt pull out to inspect closer because I did`nt have a spare gasket. This thing went from running plugs that looked like they never been fired to sooty wet, and near eye watering rich. Something happened...
I guess I should pull the damn thing again and inspect the power valve for ruptured diaphragm. If rupture can`t be seen, maybe just replace it and hope for the best.
Thanks for the input
Click to expand...
I would think that if your power valve was ruptured you wouldn't have much acceleration (especially "off idle" in gear). When you have a bad PV or the wrong PV you get a distinct stumble when you try and accelerate. But it doesn't hurt to check??

treblig
 
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Treblig
 
In my experience,Gaskets are reusable many times over. Except those crummy old brown paper ones,lol, they tend to tear the first time you loosen them. But I haven't seen those for decades.
 
I was actually referring to the metering block gasket,forgot The PV gasket too. I highly doubt the PV has ruptured, I see nothing dripping fuming after shutdown.
I adjusted idle screws to the highest vacuum, seemed to help quite a bit. I rechecked float levels, good... This engine will take and like even more than 18 deg. timing. 24 and still will not kickback on starter on hot starts. ?? Makes me wonder what`s the most initial guys have run on street machines?
Still waiting on making it legal, to do any real tuning, too many LEOs in the area to chance it.
The fume smells could be the tank vent and open element breather. where on break in It was running off a fuel can close to the pump. I guess I should wait and get it on the street, with engine under load and a few blasts then check plugs before I get too excited on diagnosis.
Still getting that initial Crack out the exhaust on cold startup although not as bad.
but still don`t like it. I`m sure it won`t cure itself.
 
mopar head said:
I was actually referring to the metering block gasket,forgot The PV gasket too. I highly doubt the PV has ruptured, I see nothing dripping fuming after shutdown.
I adjusted idle screws to the highest vacuum, seemed to help quite a bit. I rechecked float levels, good... This engine will take and like even more than 18 deg. timing. 24 and still will not kickback on starter on hot starts. ?? Makes me wonder what`s the most initial guys have run on street machines?
Still waiting on making it legal, to do any real tuning, too many LEOs in the area to chance it.
The fume smells could be the tank vent and open element breather. where on break in It was running off a fuel can close to the pump. I guess I should wait and get it on the street, with engine under load and a few blasts then check plugs before I get too excited on diagnosis.
Still getting that initial Crack out the exhaust on cold startup although not as bad.
but still don`t like it. I`m sure it won`t cure itself.
Click to expand...

I have no fascination with ramming initial timing at the engine. The correct initial timing Within a couple of degrees,always comes out in the wash at the time you set the T-port sync.
 
Long over due update on this problem that still exists.
Recently discovered secondary booster nozzle, R side only, must be slowly dripping fuel because plate below is always a little wet.
Float level seems ok, checked with and without running, expecting fuel to pour out when plug removed.
What would cause this nozzle to drip? I`m stumped...
 
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