How do you know if you blew out a power valve??
04-09-2005, 10:29 PM
#21
Team Owner
Thread Starter
Originally Posted by Sharky Guam
which carb do you have?
04-09-2005, 10:34 PM
#22
Team Owner
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Originally Posted by norvalwilhelm
I just checked the forum and this is the first post I read. You were bothering me Twin Turbo. I thought you thought that was the power valve and like 427V8 said that is only the check valve and not the power valve.
The power valve is located in the metering jet plate, If you know how to change jets you can check the power valve, Remove the float bowl and pull the metering plate, The power valve is that big nut located between the jets, Fuel pressure has nothing to do with power a valve, it is caused by a back fire and it is very rare that a power valve gets blown.
Anyway remove the power valve us use your lips to plow and suck on the valve. You can detect if the diagrahm is ruptured.
A rich floading idle is a indication of a bad power valve.
How is the cage comming?? I would like to see pictures of it painted and finished interior???
The power valve is located in the metering jet plate, If you know how to change jets you can check the power valve, Remove the float bowl and pull the metering plate, The power valve is that big nut located between the jets, Fuel pressure has nothing to do with power a valve, it is caused by a back fire and it is very rare that a power valve gets blown.
Anyway remove the power valve us use your lips to plow and suck on the valve. You can detect if the diagrahm is ruptured.
A rich floading idle is a indication of a bad power valve.
How is the cage comming?? I would like to see pictures of it painted and finished interior???
04-09-2005, 11:09 PM
#23
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St. Jude Donor '09
QUOTE]
I'm not a carburator expert... I don't even know where the power valves are located.. I just know that Holleys have them and they tend ot blow out with too high fuel pressure... The only thing that I know to do on a carb is to change jets
[/QUOTE]
And you're going to try and run and maintain a drag car? Godspeed
I'm not a carburator expert... I don't even know where the power valves are located.. I just know that Holleys have them and they tend ot blow out with too high fuel pressure... The only thing that I know to do on a carb is to change jets
[/QUOTE]And you're going to try and run and maintain a drag car? Godspeed
04-09-2005, 11:20 PM
#24
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Originally Posted by yellow 72
QUOTE]
I'm not a carburator expert... I don't even know where the power valves are located.. I just know that Holleys have them and they tend ot blow out with too high fuel pressure... The only thing that I know to do on a carb is to change jets
I'm not a carburator expert... I don't even know where the power valves are located.. I just know that Holleys have them and they tend ot blow out with too high fuel pressure... The only thing that I know to do on a carb is to change jets
[/QUOTE]Well, I'm still learning stuff.. I do 95% of all the mechanical work on my car but I don't get too much into internals... I can swap out engines, transmissions, rear end, intake, ignition, shafts, radiator, interior, shifter, gauges, electical goodies etc. etc. etc.. but I'm not skilled enough yet to get into carb internals, engine internals, transmission internals yet... but I'm still learning and will be able to do those things very soon...
04-09-2005, 11:36 PM
#26
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Originally Posted by GDaina
As norval mentioned, suck on the large end...if the valve is good it will hold the vacuum, if blown, it won't..and you will know right away.
Good thing you are a mod saying things like that :o
04-10-2005, 04:36 AM
#29
Senior Member since 1492
Originally Posted by SHAKERATTLEROLL
JugHead yes the newer ones should have that from the factory. 
lol
lol
04-10-2005, 08:24 AM
#31
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Originally Posted by Matt Gruber
flooding can also be caused by too much fuel pressure. back off to 5 psi (from 7.5?)
04-10-2005, 08:47 AM
#32
Race Director
i'd agree that dirt on the needle is a oommon cause of flooding. But since oliver cranked up fuel PSI, cranking it back down is too easy to ignore.
Carb bowls operate at ZERO psi. Entry psi is largly irrelevant. as long as there is flow it runs fine. Often G forces require more psi to overcome, the carb does not.
Carb bowls operate at ZERO psi. Entry psi is largly irrelevant. as long as there is flow it runs fine. Often G forces require more psi to overcome, the carb does not.
04-10-2005, 08:57 AM
#33
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St. Jude Donor '09
I know the now discontiued Holley 4010 and 4011 carbs couldn't handle anything over 6#. I chased the same symtoms, at cruise speed without warning the pressure would overcome the needles and dump fuel 
04-10-2005, 09:12 AM
#35
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Well, I don't know if it's the problem is the power valve. The only thing that I know is that my engine is flooding below 2000 rpm and I'm getting tons of black smoke and the carb is basically still brand new... (100 miles, 5 drag strip passes and a few engine dyno pulls on it)....
04-10-2005, 10:37 AM
#36
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What about a stuck float?
Could have a warped main body....Holleys are famous for warped main bodies also could be a hairline crack. Don't poo poo the crack remark...that's a distict possibility. Worked on a guy's 66 427...brand new 3310, out of the box. Once teh engine reached operating temps the C2 would belch and bellow black smoke like no tomorrow. When cooled down the C2 ran fine until it reached normal temp. We changed power valves, needle and seats, still the same symptoms..changed carb, the c2 has run fine since.
Could have a warped main body....Holleys are famous for warped main bodies also could be a hairline crack. Don't poo poo the crack remark...that's a distict possibility. Worked on a guy's 66 427...brand new 3310, out of the box. Once teh engine reached operating temps the C2 would belch and bellow black smoke like no tomorrow. When cooled down the C2 ran fine until it reached normal temp. We changed power valves, needle and seats, still the same symptoms..changed carb, the c2 has run fine since.
04-10-2005, 11:01 AM
#37
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Originally Posted by GDaina
What about a stuck float?
Could have a warped main body....Holleys are famous for warped main bodies also could be a hairline crack. Don't poo poo the crack remark...that's a distict possibility. Worked on a guy's 66 427...brand new 3310, out of the box. Once teh engine reached operating temps the C2 would belch and bellow black smoke like no tomorrow. When cooled down the C2 ran fine until it reached normal temp. We changed power valves, needle and seats, still the same symptoms..changed carb, the c2 has run fine since.
Could have a warped main body....Holleys are famous for warped main bodies also could be a hairline crack. Don't poo poo the crack remark...that's a distict possibility. Worked on a guy's 66 427...brand new 3310, out of the box. Once teh engine reached operating temps the C2 would belch and bellow black smoke like no tomorrow. When cooled down the C2 ran fine until it reached normal temp. We changed power valves, needle and seats, still the same symptoms..changed carb, the c2 has run fine since.
04-10-2005, 11:21 AM
#38
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Flooding not really a PV symptom at all...
My new Holley, with the PV blowout prot, blew like a big dog when exposed to not just a backfire, but one driven by cylinder pressure from a broken headgasket between #3 & #5 - 90 degrees out.
PV blowout symptom is classically like mine exhibited - surging rpm at idle and just off idle and inability to clean it up adjusting the four corners. When medium acceleration a stumble is sometimes noticed and the carb can seem to lose it's quick response to throttle opening.
Flooding is overwhelmingly needle stuck in seat or float problem (don't forget the float can leak too...although it's usually just set high.)
Fuel pressure being way too high (in the 12-15 psi range) can damage needle and seat, but more generally medium high fuel pressure (really 8-9) just overwhelms the needle and seat and floods the bowl.
PV blowout symptom is classically like mine exhibited - surging rpm at idle and just off idle and inability to clean it up adjusting the four corners. When medium acceleration a stumble is sometimes noticed and the carb can seem to lose it's quick response to throttle opening.
Flooding is overwhelmingly needle stuck in seat or float problem (don't forget the float can leak too...although it's usually just set high.)
Fuel pressure being way too high (in the 12-15 psi range) can damage needle and seat, but more generally medium high fuel pressure (really 8-9) just overwhelms the needle and seat and floods the bowl.
04-10-2005, 11:37 AM
#39
Race Director
once i forgot to tighten a pv(i snugged it by hand), it flooded as it worked itself loose. so i just tighened it up.
learn to clean/check carbs before sending it out. most problems are obvious when you look
learn to clean/check carbs before sending it out. most problems are obvious when you look
04-10-2005, 08:26 PM
#40
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Originally Posted by GDaina
What about a stuck float?
Could have a warped main body....Holleys are famous for warped main bodies also could be a hairline crack. Don't poo poo the crack remark...that's a distict possibility. Worked on a guy's 66 427...brand new 3310, out of the box. Once teh engine reached operating temps the C2 would belch and bellow black smoke like no tomorrow. When cooled down the C2 ran fine until it reached normal temp. We changed power valves, needle and seats, still the same symptoms..changed carb, the c2 has run fine since.
Could have a warped main body....Holleys are famous for warped main bodies also could be a hairline crack. Don't poo poo the crack remark...that's a distict possibility. Worked on a guy's 66 427...brand new 3310, out of the box. Once teh engine reached operating temps the C2 would belch and bellow black smoke like no tomorrow. When cooled down the C2 ran fine until it reached normal temp. We changed power valves, needle and seats, still the same symptoms..changed carb, the c2 has run fine since.
Of the last 3 new holleys I bought 2 had serious problems right out of the box. One had the floats severely bent when install and tended to flood the engine. The other had a bad metering plate and until I tried another from the mustang I didn't know it had an internal leak.I now completely strip any new holley down, reface all the gasket surfaces and totally go through the carb before it goes on my car. I spent a day each on the two 850 double pumpers I used on my blower motor.
Out of the boxes your chances of getting a good holley are slim. The double pumpers all run too rich even if they are free from defects.