Power valve vacuum side halfways wet....

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sc2dave
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Power valve vacuum side halfways wet....

Post by sc2dave » Mon Oct 09, 2017 10:56 pm

Whenever I disassemble my Holley, I notice that the vacuum side of the power valve metering block gasket is wet. Is this normal? If it isn't new gasket or double up on them? They are the blue silicone reusable ones.

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Re: Power valve vacuum side halfways wet....

Post by mag2555 » Tue Oct 10, 2017 7:04 am

The Blue ones are reusable, but so are the stock ones if you lay a film of wheel bearing grease or silicone grease on them.

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Re: Power valve vacuum side halfways wet....

Post by My427stang » Tue Oct 10, 2017 7:46 am

Shouldn't be fuel on that side.

Bad PV, bad PV gasket, or warped body allowing cross channeling.
70 Mustang, 489 FE, TKO-600, Massflo SEFI, 4.11s
71 F100 SB 4x4, 445 FE, hot rod 4x4

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Re: Power valve vacuum side halfways wet....

Post by mag2555 » Tue Oct 10, 2017 8:54 am

In regards to the fuel seen on that side, if your using a power valve plug many times they act as being too deep and bottom out on the center section of the Carb body and cocking the metering plate.
Look for signs of contact by the plug on the center section and correct for the excess thickness of the Carb body with a 3 second grinding session!

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Re: Power valve vacuum side halfways wet....

Post by DaveMcLain » Tue Oct 10, 2017 10:12 am

That is probably just from the gasoline vapor that is in the intake when the engine is running. After all that cavity behind the power valve is connected directly to the intake. It doesn't necessarily mean that there is anything wrong with the carburetor.

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Re: Power valve vacuum side halfways wet....

Post by pamotorman » Tue Oct 10, 2017 12:55 pm

make sure the PV vacuum passage holes in the main body, gasket and base plate all line up. I never cared for holleys anti backfire valve in race engine base plate

sc2dave
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Re: Power valve vacuum side halfways wet....

Post by sc2dave » Tue Oct 10, 2017 8:02 pm

DaveMcLain wrote:
Tue Oct 10, 2017 10:12 am
That is probably just from the gasoline vapor that is in the intake when the engine is running. After all that cavity behind the power valve is connected directly to the intake. It doesn't necessarily mean that there is anything wrong with the carburetor.
How would vapor get in there if there's nothing sucking it up into that space, especially through a tiny hole, and it leaves a Horizontal wet line???

sc2dave
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Re: Power valve vacuum side halfways wet....

Post by sc2dave » Tue Oct 10, 2017 8:03 pm

mag2555 wrote:
Tue Oct 10, 2017 8:54 am
In regards to the fuel seen on that side, if your using a power valve plug many times they act as being too deep and bottom out on the center section of the Carb body and cocking the metering plate.
Look for signs of contact by the plug on the center section and correct for the excess thickness of the Carb body with a 3 second grinding session!
No plug ,but I do use a plastic p/v gasket. Would that do it? I do get 15"HG at idle.

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Re: Power valve vacuum side halfways wet....

Post by DaveMcLain » Wed Oct 11, 2017 7:35 am

sc2dave wrote:
Tue Oct 10, 2017 8:02 pm
DaveMcLain wrote:
Tue Oct 10, 2017 10:12 am
That is probably just from the gasoline vapor that is in the intake when the engine is running. After all that cavity behind the power valve is connected directly to the intake. It doesn't necessarily mean that there is anything wrong with the carburetor.
How would vapor get in there if there's nothing sucking it up into that space, especially through a tiny hole, and it leaves a Horizontal wet line???
When the engine is running and you open and close the throttle the pressure in the intake manifold as well as the pressure in that chamber behind the power valve changes. That's how liquid fuel can be drawn into that area. How would it leave a liquid line if the vacuum hole to the intake was actually open would be a better question.

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Re: Power valve vacuum side halfways wet....

Post by sc2dave » Thu Oct 12, 2017 7:41 pm

DaveMcLain wrote:
Wed Oct 11, 2017 7:35 am
sc2dave wrote:
Tue Oct 10, 2017 8:02 pm
DaveMcLain wrote:
Tue Oct 10, 2017 10:12 am
That is probably just from the gasoline vapor that is in the intake when the engine is running. After all that cavity behind the power valve is connected directly to the intake. It doesn't necessarily mean that there is anything wrong with the carburetor.
How would vapor get in there if there's nothing sucking it up into that space, especially through a tiny hole, and it leaves a Horizontal wet line???
When the engine is running and you open and close the throttle the pressure in the intake manifold as well as the pressure in that chamber behind the power valve changes. That's how liquid fuel can be drawn into that area. How would it leave a liquid line if the vacuum hole to the intake was actually open would be a better question.
I also have the p/v blowout obstruction there also,so less chance of it getting in there.

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