The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board > The 1973 - 1991 Blazers, Jimmys, and Suburbans Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 03-14-2018, 12:08 AM   #1
Cooter0003
Registered User
 
Join Date: Jun 2017
Location: Hodge Louisiana
Posts: 13
Carb backfire issues....I need some advice

On my 83 suburban 4x4 with a 350, I’m having light/medium throttle back firing issues, I’ve tried everything. Timing is at 12 degrees initial, 38 total I’ve got 18 inches of vacuum at idle float bowls are set right as best as I can tell, it’s a Holley 4160, I can’t figure this out it’s driving me nuts. What y’alls opinion??

Last edited by Cooter0003; 03-14-2018 at 12:09 AM. Reason: Typo
Cooter0003 is offline   Reply With Quote
Old 03-14-2018, 09:27 AM   #2
geezer#99
Registered User
 
geezer#99's Avatar
 
Join Date: Aug 2009
Location: Bowser
Posts: 10,076
Re: Carb backfire issues....I need some advice

Could be the dreaded ‘flat cam’!
Pull one valve cover at a time and check all the rockers are moving the same.
geezer#99 is offline   Reply With Quote
Old 03-14-2018, 11:29 AM   #3
Cooter0003
Registered User
 
Join Date: Jun 2017
Location: Hodge Louisiana
Posts: 13
Re: Carb backfire issues....I need some advice

I will on Friday when I can get new gaskets, the previous owner of this truck rtv’d the hell outta the gasket, but I put a buddies Edelbrock carb on it this morning, and so far no popping or backfires at all. It may have a bad cam the last owner wasn’t very kind to this truck at all
Cooter0003 is offline   Reply With Quote
Old 03-14-2018, 12:17 PM   #4
geezer#99
Registered User
 
geezer#99's Avatar
 
Join Date: Aug 2009
Location: Bowser
Posts: 10,076
Re: Carb backfire issues....I need some advice

Drive it awhile before you pull the covers.
Might be a power valve or something plugged up in your Holley. Or a vacuum leak. Or the po did some mods to the Holley.
geezer#99 is offline   Reply With Quote
Old 03-14-2018, 01:58 PM   #5
Cooter0003
Registered User
 
Join Date: Jun 2017
Location: Hodge Louisiana
Posts: 13
Re: Carb backfire issues....I need some advice

I think it is a cam, it popped once with the Edelbrock
Cooter0003 is offline   Reply With Quote
Old 03-17-2018, 12:40 PM   #6
andyh1956
Registered User
 
Join Date: Mar 2010
Location: thomastown mississippi
Posts: 1,182
Re: Carb backfire issues....I need some advice

Pull your plugs & check the color. You COULD have a part throttle vacuum leak.
andyh1956 is offline   Reply With Quote
Old 03-17-2018, 09:02 PM   #7
amberkalvin
Registered User
 
amberkalvin's Avatar
 
Join Date: Jul 2013
Location: fayetteville, nc
Posts: 102
Re: Carb backfire issues....I need some advice

I assume it's only popping back through the carb when it happens? I had something similar happen mainly out the exhaust pipe, checked cam and rockers, timing etc. Turned out to be fouled plugs. Sometimes it's the little things.
__________________
2015 Silverado CC Z71
1986 Crew Cab Dually Silverado 3+3 (http://67-72chevytrucks.com/vboard/s...d.php?t=603854) -SOLD
1984 SWB C10 (http://67-72chevytrucks.com/vboard/s...d.php?t=687521)
1976 K5 super rusty fitech truck(http://67-72chevytrucks.com/vboard/s...d.php?t=740582)
amberkalvin is offline   Reply With Quote
Old 03-18-2018, 01:01 PM   #8
Cooter0003
Registered User
 
Join Date: Jun 2017
Location: Hodge Louisiana
Posts: 13
Re: Carb backfire issues....I need some advice

Yea it only pops through the carb, and it has new accel plugs in it, and the color on them is light tan on the porcelain. Could a stretched timing chain cause the problem?
Cooter0003 is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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 04:25 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.
Copyright 1997-2013 67-72chevytrucks.com