Holley power valve block off?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

n737nc · 09-30-2004, 12:08 PM

What are the disadvantages of running a power valve block off in a Holley 700DP?

Thanks,
Nick

72C203503ONTHETREE · 09-30-2004, 12:31 PM

If you block off the power valve you will need to install larger jets in the metering block you plugged the power valve on to make up the difference in fuel delivery. You may cause it to run way too rich though, you will have to experiment with different size jets to get the right mixture.

n737nc · 09-30-2004, 12:53 PM

Thats it? Just need to run bigger jets?
Why doesn't everyone just block them off then instead of jacking with these power valves?

Thanks,
Nick

Tx Firefighter · 09-30-2004, 01:18 PM

Holley made a running change some years back and starting putting power valve protectors in all of their carbs. Only the carbs that are some years old still have any real worries about backfiring blowing the power valve.

Ever since I bought my first Edelbrock carb, I've never personally wanted another Holley.

**1970 CST Short Wide** · 09-30-2004, 01:36 PM

Funny how some people have better luck with different products. I have had 3 different Edelbrock carbs on 3 different trucks. 2 now have Holleyâ€™s and the 3rd will very soon. The Edelbrock just seemed to have more problems after some time. Personally I like the Holley 4777. Just my 2c

tom hand · 09-30-2004, 05:42 PM

Blocking off the power valve is a racing trick where the carb is only going to be wide open all the time. Will run like crap on the street, and what little gas mileage these trucks get will be down the toilet....get a new power valve

djracer · 09-30-2004, 06:02 PM

I agree I'd leave a power valve in the carb! You can get a kit to install in the base plate to protect the power valve!

Longhorn Man · 09-30-2004, 06:40 PM

I agree with everything he said.

Quote:

Originally Posted by Tx Firefighter

Holley made a running change some years back and starting putting power valve protectors in all of their carbs. Only the carbs that are some years old still have any real worries about backfiring blowing the power valve.

Ever since I bought my first Edelbrock carb, I've never personally wanted another Holley.

*1972C10* · 09-30-2004, 06:55 PM

Just get the proper power valve for your engine /application I have ran power valve blockoff plugs but like stated they are for RACE .

bigjimzlll · 09-30-2004, 09:26 PM

i block off the secondary PV...I tried last week blocking off the primary..ran good at the track..but off idle was crap..back to a primary PV

68C15 · 10-01-2004, 07:20 AM

average rule of thumb depending on which metering block you have is to go up 10 in jets. but I suggets using PV on street as it introduces needed fuel when needed.
the lower # on PV the later (lower vac) it opens.
install a PV saver kit like the ones from Mr. Gasket.
even better yet if budget allows get a Demon. <has anyone here ever had a problem with Demons?>

09-30-2004, 12:08 PM	#1
n737nc Registered User Join Date: Jun 2004 Location: Dallas, Tx Posts: 207	Holley power valve block off?? What are the disadvantages of running a power valve block off in a Holley 700DP? Thanks, Nick

09-30-2004, 12:31 PM	#2
72C203503ONTHETREE Registered User Join Date: Apr 2004 Location: Grant, Alabama Posts: 504	If you block off the power valve you will need to install larger jets in the metering block you plugged the power valve on to make up the difference in fuel delivery. You may cause it to run way too rich though, you will have to experiment with different size jets to get the right mixture. __________________ 72 Chevy C20, SOLD (Dang it.) 09 Challanger RT six speed in all black. 74 Datsun 710 wagon, all 1.8 liters of screaming Datsun power. 73 C10 long bed, 350/350 combo, nice shape.

09-30-2004, 01:18 PM	#4
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Holley made a running change some years back and starting putting power valve protectors in all of their carbs. Only the carbs that are some years old still have any real worries about backfiring blowing the power valve. Ever since I bought my first Edelbrock carb, I've never personally wanted another Holley. __________________ I'm on the Instagram- @Gearhead_Kevin

09-30-2004, 01:36 PM	#5
1970 CST Short Wide Senior Moment Join Date: Mar 2002 Location: Pittsburg Ca Posts: 4,043	Funny how some people have better luck with different products. I have had 3 different Edelbrock carbs on 3 different trucks. 2 now have Holleyâ€™s and the 3rd will very soon. The Edelbrock just seemed to have more problems after some time. Personally I like the Holley 4777. Just my 2c __________________ 1970 CST LS 1 6 speed Ford 9 inch Detroit Tru Track, Dakota Didgital, Vintage Air, QA1 Coil Overs Front & Rear Lots of FUN 2013 GMC PU, Oldest Son 71 GMC LWB. QA1 Suspension, Angry SB. Youngest Son 2019 GMC Diesil Dually. Youngest Son 2017 Toyota SUV Daughters car 2018 Traverse , Wife’s Ride Pittsburg Ca 94565 Last edited by 1970 CST Short Wide; 10-01-2004 at 11:58 AM.

09-30-2004, 05:42 PM	#6
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	Blocking off the power valve is a racing trick where the carb is only going to be wide open all the time. Will run like crap on the street, and what little gas mileage these trucks get will be down the toilet....get a new power valve __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

09-30-2004, 12:53 PM	#3
n737nc Registered User Join Date: Jun 2004 Location: Dallas, Tx Posts: 207	Thats it? Just need to run bigger jets? Why doesn't everyone just block them off then instead of jacking with these power valves? Thanks, Nick

09-30-2004, 06:02 PM	#7
djracer Registered User Join Date: Feb 2001 Location: Wetumpka, Al, U.S. Posts: 8,891	I agree I'd leave a power valve in the carb! You can get a kit to install in the base plate to protect the power valve! __________________ Kevin Special Thanks to All who have helped on the TRUCK! My Pass Time Show http://s129.photobucket.com/albums/p...Chapter1-0.mp4 So Far my best Times are: Motor only: 6.44 1/8 @ 104.13 10.39 1/4 @ 125.83 Nitrous Times: 5.785 1/8 @ 118.65 with a 1.336 60ft 9.168 1/4 @ 142.58 with a 250 shot dead out of the hole!

09-30-2004, 06:55 PM	#9
1972C10 Account Suspended Join Date: Dec 2003 Location: Texas Posts: 2,686	Just get the proper power valve for your engine /application I have ran power valve blockoff plugs but like stated they are for RACE .

09-30-2004, 09:26 PM	#10
bigjimzlll Senior Member Join Date: Dec 2001 Location: Redding,CA...USA Posts: 4,736	i block off the secondary PV...I tried last week blocking off the primary..ran good at the track..but off idle was crap..back to a primary PV __________________ It's called "drag racing" if they called it "tic..tic..WHAM!..BANG! F*&K!!!", they'd have to keep the magazines under the counter with the other men's publications click the clicky to join the site.... http://67-72chevytrucks.com/vboard/payments.php 67 lwb..first hotrod in 25 years..540 best ET is 9.45 @ 141.44 Anderson,CA

10-01-2004, 07:20 AM	#11
68C15 blood type; Retumbo Join Date: Jan 2004 Location: next to my reloading bench Posts: 10,269	average rule of thumb depending on which metering block you have is to go up 10 in jets. but I suggets using PV on street as it introduces needed fuel when needed. the lower # on PV the later (lower vac) it opens. install a PV saver kit like the ones from Mr. Gasket. even better yet if budget allows get a Demon. <has anyone here ever had a problem with Demons?> __________________ Man rule #77...if you own a 67 stepside with a caddy 472 you will never be in danger of loosing you man card

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