carb power valve question
Thread Starter
Melting Slicks
Joined: Feb 2001
Posts: 3,330
Likes: 13
From: Europe , Luxembourg
carb power valve question
Hello
How do I see if the carb's power valve has blown ?
My 750 Holley double pumper is more or less all of a sudden pumping more fuel into my 68th BB, meaning the consumption went up about 25 %. Since there where a few backfirings lately, I am a bit worried.
Thanks a lot and brgds. Gunther
How do I see if the carb's power valve has blown ?
My 750 Holley double pumper is more or less all of a sudden pumping more fuel into my 68th BB, meaning the consumption went up about 25 %. Since there where a few backfirings lately, I am a bit worried.
Thanks a lot and brgds. Gunther
Racer
Joined: Sep 2000
Posts: 485
Likes: 1
From: Dallas Texas
Not sure how to check but if it has backfired a few times it may be toast. Summitt sells a kit for ten bucks that is basically a check valve that supposedly prevents blow outs from backfires. It is ez to install.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
Originally Posted by Fevre
Believe if you put your finger over the vent tube(s) and it floods the car (stahls) then the pv is blown.
Thread Starter
Melting Slicks
Joined: Feb 2001
Posts: 3,330
Likes: 13
From: Europe , Luxembourg
Hi
How does a blown power valve show off during operation ?
The car is still pulling strong , just the fuel consumption jumped up enormeously.
Sorry for this questions, I do not know a lot about this carbs except how to adjust them.
Don't even know where the power valve lives and what it exactly performs.
Any clearification is wellcome.
Rgds. Gunther
How does a blown power valve show off during operation ?
The car is still pulling strong , just the fuel consumption jumped up enormeously.
Sorry for this questions, I do not know a lot about this carbs except how to adjust them.
Don't even know where the power valve lives and what it exactly performs.
Any clearification is wellcome.
Rgds. Gunther
Le Mans Master
Joined: Jan 2003
Posts: 6,575
Likes: 1
From: Tuttle OK
Cruise-In VIII Veteran
hey WESCH...
click here for some good holley info, it's helped me a lot...
scroll down, there is good info on specific parts - their function and settings... you are looking for power enrichment system....
click here for some good holley info, it's helped me a lot...
scroll down, there is good info on specific parts - their function and settings... you are looking for power enrichment system....
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
EDIT: Read below or follow the link in the post above. 
There are 2 pv's in your double pumper, each is screwed into one of the plates that are between the main body of the carb and the fuel bowls, you have to take the fuel bowls off the get to them. Their function is to provide additional fuel in relation to load, when you press the gas (or go up a hill, etc) the vac level of your car drops, the pv are held closed by vacuum so when the vacuum level drops the pv opens. If the valve is blown the seal leaks and will not be held closed by the vacuum thus fuel will flow through it constantly.
There are 2 pv's in your double pumper, each is screwed into one of the plates that are between the main body of the carb and the fuel bowls, you have to take the fuel bowls off the get to them. Their function is to provide additional fuel in relation to load, when you press the gas (or go up a hill, etc) the vac level of your car drops, the pv are held closed by vacuum so when the vacuum level drops the pv opens. If the valve is blown the seal leaks and will not be held closed by the vacuum thus fuel will flow through it constantly.
Le Mans Master
Joined: Jan 2003
Posts: 6,575
Likes: 1
From: Tuttle OK
Cruise-In VIII Veteran
you have to remove the metering blocks as well...
for what it's worth, the one and only time I blew a power valve, my car would barely run...it was flooding terribly at an idle...so bad that I had to keep it revved somewhat in order to even keep it running..might have been an extreem case though...
for what it's worth, the one and only time I blew a power valve, my car would barely run...it was flooding terribly at an idle...so bad that I had to keep it revved somewhat in order to even keep it running..might have been an extreem case though...
Last edited by Avette4me; Sep 23, 2004 at 11:52 AM.
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Thread Starter
Melting Slicks
Joined: Feb 2001
Posts: 3,330
Likes: 13
From: Europe , Luxembourg
Thanks.
Looks like if I can get to the power valve from outside ( underneath ) the carb as it's a 4010 Model.
It has the power valves installed similar like the accelerator pumps.
Will check them up.
Brgds. Gunther
Looks like if I can get to the power valve from outside ( underneath ) the carb as it's a 4010 Model.
It has the power valves installed similar like the accelerator pumps.
Will check them up.
Brgds. Gunther
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Never mind , found an exploded view of one, new to me!
http://www.holley.com/HiOctn/TechSer...nfo/f4010.html
http://www.holley.com/HiOctn/TechSer...nfo/f4010.html
Last edited by Fevre; Sep 23, 2004 at 12:43 PM.
