Holley Question? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Mudder · 07-15-2003, 06:24 PM

Will a serious backfire blow the power valve out of a Holley? Have heard that Holley's are bad for this?

chevymaz · 07-15-2003, 06:49 PM

I am not sure if a backfire will blow the power valve out or not but, Holley are notorious for the power valvesgoing bad. I had to just change mine a month or so ago.

**FRENCHBLUE72** · 07-15-2003, 07:01 PM

Yes I have had it happen before!!!

flyin99 · 07-15-2003, 09:38 PM

Yes they sure will..............changed one out not too long ago..............

ozarkhippie · 07-15-2003, 09:49 PM

It doesn't take much of a backfire through the carb to blow a powervalve. You can buy a kit and some newer holly's have them fact. a checkvalve that prevents this.

Mudder · 07-15-2003, 10:26 PM

This is a new street avenger but it hasn't ran right since this happened. Hot wire to the coil came off one night and i was doing like 75 mph. It runs decent but something just isn't right. It hesitates a little at times and falls on its face out on the highway after you let off it and then get back in it. I have one here so I think I'll go ahead and change it.

Mudder · 07-15-2003, 10:27 PM

Hey thanks for the replys!

Chevy409 · 07-16-2003, 02:56 PM

Sorry for the retard question

but how would you know if the powervalve is gone? I run a Holley, so just wanna be prepared. Thanks

Mudder · 07-16-2003, 03:17 PM

Well someone correct me if I'm wrong but I would say using too much gas, the smell of raw gas after a short time with you foot in it and then letting off, hesitating, etc.

chevymaz · 07-16-2003, 05:24 PM

When my power valve went I was having issues with my engine flooding...it was almost like the choke was sticking.

*Piston* · 07-16-2003, 08:15 PM

Blown power valves will cause a huge drop in gas mileage, black smoke out the tail, rough running, hard starting and eventually fouled plugs. It's taking gas right from the float bowl and sucking it down the intake, UNMETERED!

If anyone needs a ANTI-Backfire kit ( Orfice and a drill bit ) made by Mr. Gasket just let me know. 10.00 shipped anywhere in the US. I have about 20 kits.

It prevents a large volume of air to enter the power valve chamber quickly. It won't affect the performance at all. Most newer holley's come with it.

Chevy409 · 07-16-2003, 09:50 PM

Cool, thanks for the info guys

Mudder · 07-16-2003, 09:53 PM

Piston doesnt really sound like I have a blown power valve then. What could be casuing my hesitation fro a dead stop?

07-15-2003, 06:24 PM	#1
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	Holley Question? Will a serious backfire blow the power valve out of a Holley? Have heard that Holley's are bad for this?

07-15-2003, 06:49 PM	#2
chevymaz What are you looking at? Join Date: Jul 2003 Location: Kellyville,Oklahoma Posts: 308	I am not sure if a backfire will blow the power valve out or not but, Holley are notorious for the power valvesgoing bad. I had to just change mine a month or so ago. __________________ 1971 GMC LWB 2005 Honda Element 2007 Honda Fit

07-15-2003, 07:01 PM	#3
FRENCHBLUE72 PROJECT 7DEUCE Join Date: Dec 2002 Location: GRANTS PASS OR Posts: 21,590	Yes I have had it happen before!!! __________________ GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P..

07-15-2003, 09:49 PM	#5
ozarkhippie Registered User Join Date: Nov 2002 Location: Eureka Springs AR Posts: 494	It doesn't take much of a backfire through the carb to blow a powervalve. You can buy a kit and some newer holly's have them fact. a checkvalve that prevents this. __________________ Buy Sale or Trade 71 3/4 4x4 72 1/2 ton cheyenne 4x4

07-16-2003, 02:56 PM	#8
Chevy409 Giddy up giddy up... Join Date: Feb 2001 Location: US Posts: 483	Sorry for the retard question but how would you know if the powervalve is gone? I run a Holley, so just wanna be prepared. Thanks __________________ 72 with 69 grille and custom 73-87 stepside. BIG BLOCK 409, SM465, NP205, 3/4 axles slung under a 5" lift, 3"bodylift, 112" frame, and 35inch Pro Comp X-terrains... "BUILT NOT BOUGHT" Here's the site...

07-15-2003, 09:38 PM	#4
flyin99 creator of kong Join Date: Mar 2001 Location: Kentucky Posts: 538	Yes they sure will..............changed one out not too long ago..............

07-15-2003, 10:26 PM	#6
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	This is a new street avenger but it hasn't ran right since this happened. Hot wire to the coil came off one night and i was doing like 75 mph. It runs decent but something just isn't right. It hesitates a little at times and falls on its face out on the highway after you let off it and then get back in it. I have one here so I think I'll go ahead and change it.

07-15-2003, 10:27 PM	#7
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	Hey thanks for the replys!

07-16-2003, 03:17 PM	#9
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	Well someone correct me if I'm wrong but I would say using too much gas, the smell of raw gas after a short time with you foot in it and then letting off, hesitating, etc.

07-16-2003, 05:24 PM	#10
chevymaz What are you looking at? Join Date: Jul 2003 Location: Kellyville,Oklahoma Posts: 308	When my power valve went I was having issues with my engine flooding...it was almost like the choke was sticking. __________________ 1971 GMC LWB 2005 Honda Element 2007 Honda Fit

07-16-2003, 08:15 PM	#11
Piston Account Suspended Join Date: Oct 2002 Location: Olathe, KS Posts: 2,301	Blown power valves will cause a huge drop in gas mileage, black smoke out the tail, rough running, hard starting and eventually fouled plugs. It's taking gas right from the float bowl and sucking it down the intake, UNMETERED! If anyone needs a ANTI-Backfire kit ( Orfice and a drill bit ) made by Mr. Gasket just let me know. 10.00 shipped anywhere in the US. I have about 20 kits. It prevents a large volume of air to enter the power valve chamber quickly. It won't affect the performance at all. Most newer holley's come with it. Last edited by Piston; 07-16-2003 at 08:17 PM.

07-16-2003, 09:50 PM	#12
Chevy409 Giddy up giddy up... Join Date: Feb 2001 Location: US Posts: 483	Cool, thanks for the info guys __________________ 72 with 69 grille and custom 73-87 stepside. BIG BLOCK 409, SM465, NP205, 3/4 axles slung under a 5" lift, 3"bodylift, 112" frame, and 35inch Pro Comp X-terrains... "BUILT NOT BOUGHT" Here's the site...

07-16-2003, 09:53 PM	#13
Mudder Registered User Join Date: Feb 2001 Location: East Central, MO Posts: 11,336	Piston doesnt really sound like I have a blown power valve then. What could be casuing my hesitation fro a dead stop?



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