Symptoms of blown power valve - Chevelle Tech
Chevelle Tech join team chevelle as a supporting member  
Chevelle Parts at SS396.com      
GROUND UP & SS396.com         
Official Sponsor of Team Chevelle
     

Auto Insurance

Chevelles.com is the premier Chevrolet Chevelle Forum on the internet. Registered Users do not see the above ads.
Engine AdvertisementGeneral Engine Discussion.

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old May 4th, 10, 8:25 PM
Big Earl Big Earl is offline
Tech Team
 
Join Date: Feb 2010
Location: Thornton,Ont.
Posts: 169
Default Symptoms of blown power valve

468 Big block with a 4150HP / 950 cfm Holley was running very rich could not get to idle, them it developed a pop pop pop like a carb back fire. Could this be a blown power valve????

Tried to look at some old posts but could not find what I was looking for!!!
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old May 4th, 10, 10:19 PM
engineguy engineguy is offline
Senior Tech Team
Bill R
 
Join Date: Aug 2002
Location: Twin Lake, MI
Posts: 2,284
Default Re: Symptoms of blown power valve

A blown power valve will make the engine very rich at idle and adjusting the idle mixture screws will probably make no difference in the idle speed. Have never had a blown power valve cause popping though, could be that you have other problems too.
__________________
Bill
64 Chevelle Malibu Sport Coupe (original owner) car now has 427" BB, Jerico 5-spd. trans., Dana 60 rear end.

SAE Member (20+ years)
ASE Master Certified Engine Machinist
AERA Certified Professional Engine Machinist
Reply With Quote Quick reply to this message
  #3  
Old May 4th, 10, 10:46 PM
Red68SS Red68SS is offline
Lifetime Premium Member
Greg
 
Join Date: Apr 2007
Location: Katy, Texas
Posts: 176
Default Re: Symptoms of blown power valve

I had the power valve in my 850 cfm double pumper go out twice. Each time it would barely start and wouldn't idle. I got it home by never letting the rpms get below about 1500. Finally changed out to a power valve made for a car running alcohol and that was 2.5 years ago.
__________________
68 Chevelle
http://www.chevelles.com/showroom/da.../DSC_3033s.jpg
65 Corvette
http://www.chevelles.com/showroom/da.../Side_View.jpg

"We have to share the life lessons learned by our mistakes with others because no one person can possibly make all the mistakes in a life time." Admiral Hyman G. Rickover
Reply With Quote Quick reply to this message
  #4  
Old May 4th, 10, 10:52 PM
Tom Mobley Tom Mobley is offline
mod since about forever, old now :)
TerribleTom II
 
Join Date: Oct 1998
Location: Glendale, Az
Posts: 20,702
Default Re: Symptoms of blown power valve

popping is basically never caused by the carb unless you're talking about a cold backfire.

Need to start checking around your distributor and other ignition stuff.
__________________
Tom
Reply With Quote Quick reply to this message
  #5  
Old May 4th, 10, 11:34 PM
Big Earl Big Earl is offline
Tech Team
 
Join Date: Feb 2010
Location: Thornton,Ont.
Posts: 169
Default Re: Symptoms of blown power valve

Well maybe it wasn't a pop, more like a crack. The motor was running rich and started to load up increasing the rpm. Then I cracked the throttle and when the rpm came down it just started making a pop / cracking sound. Now it starts hard and has that sound, when I accelerate. I was thinking power valve because before it was impossible to set idle and ran very rich.
Reply With Quote Quick reply to this message
  #6  
Old May 5th, 10, 8:53 AM
engineguy engineguy is offline
Senior Tech Team
Bill R
 
Join Date: Aug 2002
Location: Twin Lake, MI
Posts: 2,284
Default Re: Symptoms of blown power valve

A blown power valve usually won't cause a hard start problem, nor any unusual sounds. I think your problem is something other than power valve.
__________________
Bill
64 Chevelle Malibu Sport Coupe (original owner) car now has 427" BB, Jerico 5-spd. trans., Dana 60 rear end.

SAE Member (20+ years)
ASE Master Certified Engine Machinist
AERA Certified Professional Engine Machinist
Reply With Quote Quick reply to this message
  #7  
Old May 5th, 10, 9:27 AM
onovakind67 onovakind67 is offline
Senior Tech Team
 
Join Date: Jan 2001
Location: Fairfield, CA
Posts: 4,400
Default Re: Symptoms of blown power valve

A blown power valve will let fuel directly into the intake manifold through the vacuum passage that operates it.
__________________
"For those that will fight for it...FREEDOM ...has a flavor the protected shall never know."
Semper Fi! L/Cpl Edwin L. "Tim" Craft, B Co 3rd AT's, Khe Sanh Combat Base, February, 1968
Reply With Quote Quick reply to this message
  #8  
Old May 5th, 10, 1:39 PM
Big Earl Big Earl is offline
Tech Team
 
Join Date: Feb 2010
Location: Thornton,Ont.
Posts: 169
Default Re: Symptoms of blown power valve

Man o man due I feel like a dork!!!!!!!

I set the valves the other night and then started tuning on the carb.

Thinking that everything I touch is golden (not) and the valve timing shouldn't be an issue.

After reading the posts you guys put up got me thinking. Couldn't sleep so got up @ 5am pulled the rocker covers off and guess what? Found # 5 was loose as goose. It must have backed off or I didn't tighten it properly.

Anyways is all good now guys thanks. I'm off to live another day.


Again big thanks to you all. Sometimes all a guy needs is a little nudge in the right direction. The power valve was shot as well LOL.

Thanks Big Earl
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply
Chevelle Tech > Mechanical > Engine      Current Topic: Symptoms of blown power valve
Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Chevelle Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address. Note, you will be sent a confirmation request to this address.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 6:58 AM.


Is there a site like this for?    El Caminos Camaros Novas Impalas GTO Chevy Punch All Chevys

2009 Team Chevelle - AutoForums