Rebuild of Chevy 350 - Texas 4x4 Forum

Go Back   Texas 4x4 Forum > Technical > Gas\Diesel Engine & Transmission

Photo Gallery Places to Wheel Gallery III Home Forum Tech Section IRCChat FlashChat

Gas\Diesel Engine & Transmission Engine, Transmission, Transfer case

Texas4x4.org is the premier All All Forum on the internet. Registered Users do not see the above ads.

Gas\Diesel Engine & Transmission:

Rebuild of Chevy 350



Reply
 
Share LinkBack Thread Tools Display Modes
Old 10-15-2006, 03:27 PM   #1
 
Join Date: Aug 2005
Posts: 61
Redneck Rampage just gettin started
Rebuild of Chevy 350

I have an 85 Chevy with a rebult 350. For the last couple of months my truck has been backfiring through the carburator when it's still cool. It's not knockin at all so I know it's not a lifter. I'm thinking it's the exaust lobe on my cam. Any suggestions on what it might be? Also it's only a two bolt main so I was wondering if it's even worth rebuilding or should I start with a 4 bolt main core?
Redneck Rampage is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 10-15-2006, 04:28 PM   #2
Flex Master
 
Join Date: Oct 2005
Location: San Antonio
Posts: 1,321
GIJoe4500 is a name known to allGIJoe4500 is a name known to allGIJoe4500 is a name known to allGIJoe4500 is a name known to allGIJoe4500 is a name known to allGIJoe4500 is a name known to all
From what I have read on alot of forums, 2 bolt mains are stronger than 4 bolt mains. You just have to have the other two bolts splayed (sp?) in or somethin' like that. I wish I could elaborate more, hopefully someone can.
GIJoe4500 is offline   Reply With Quote
Old 10-15-2006, 04:36 PM   #3
Flex Master
 
dubbyx's Avatar
 
Join Date: Aug 2005
Location: Lubbock
Posts: 1,515
dubbyx Axle snapper extrordinairedubbyx Axle snapper extrordinairedubbyx Axle snapper extrordinairedubbyx Axle snapper extrordinairedubbyx Axle snapper extrordinairedubbyx Axle snapper extrordinaire
When was the last time you checked your timing?

I had a rebuilt 350 in my burb that was really hard on cams, but it never caused me any backfiring issues. Motor just gradually lost power and the valves started making a lot of noise.

After having mine rebuilt once and swapping it out to the 455 Olds, I don't think I'd bother with it ever again. Next time I'm just going to throw in a crate motor. After all the little odds and ends that needed replacing, the quirky tuning, and never knowing how good of a job the builder really did, I think the crate is the way to go.
__________________
Chunky Dunk'n Custom Lures
Visit us at www.chunkydunkn.com
dubbyx is offline   Reply With Quote
 
Old 10-16-2006, 09:45 PM   #4
Cooler'na13floorelevator
 
4x4Freak's Avatar
 
Join Date: Dec 2002
Location: Kermit, TX
Posts: 6,117
4x4Freak Surfs Venus with Anubis4x4Freak Surfs Venus with Anubis4x4Freak Surfs Venus with Anubis4x4Freak Surfs Venus with Anubis4x4Freak Surfs Venus with Anubis4x4Freak Surfs Venus with Anubis4x4Freak Surfs Venus with Anubis4x4Freak Surfs Venus with Anubis4x4Freak Surfs Venus with Anubis4x4Freak Surfs Venus with Anubis4x4Freak Surfs Venus with Anubis
Most likely, the ignition timing is too advanced. Could also be that one of the intake valves is adjusted too tight or it is leaning out. An exhaust valve will not cause backfiring through the carb.
__________________
Zach


Quote:
Originally Posted by RVREDDOG
Thats pretty much how I feel about it....You gone yet?
Reality is an illusion caused by the absence of alcohol.

75 IH Scout II
79 Chevy K10
80 GMC K25
97 Chevy S10
05 Dodge 3500

Collect the whole set.
4x4Freak is offline   Reply With Quote
Old 10-24-2006, 12:28 PM   #5
 
Join Date: Nov 2005
Posts: 35
88K5Blazer just gettin started
you might check to see if your head gaskets are ok. My 88 had some backfiring and turns out that the head gasket was blown between 4 and 6. while the engine is running, pull the plugs from the cap and if the motor doesn't bog down when you pull them, then you know that your not getting any fire from those cylinders. pull one at a time until you go all the way around.
88K5Blazer is offline   Reply With Quote
Old 10-24-2006, 12:29 PM   #6
 
Join Date: Nov 2005
Posts: 35
88K5Blazer just gettin started
also check your cold start sensor
88K5Blazer is offline   Reply With Quote
Old 10-24-2006, 04:08 PM   #7
Rock Monkey
 
Join Date: Mar 2005
Location: corpus christi
Posts: 169
88351 rock stacker
The 2 bolt main chevy block is good well past 500 hp the with proper parts. Its not like it can't take any power. Have it balanced use good pistons, rings, rods/rod bolts, etc. If you splay the main caps (adds two extra bolts to each main at a ___??? angle that ties into the main webbing of the block) of couse the two bolt block will take more power, however, the 4 bolt block can take some abuse. It is capable of producing more hp than the 2 bolt when prepped. In stock form the 2 bolt is weaker than the 4 bolt. Also, some sneaky rebuild shops like to charge more for work on 4 bolt blocks. (They assume some people don't know what the hell is going on, damn crooks.)

As for your backfire problems, You said it only does it when it is cool? I would do like 4x4Freak said, and check the timing first. What kind of carburetor do you run? When was the last time you cleaned it? You probably have already checked your spark plugs, if not, that would be something I would look into. Also if you decide to clean your carb, you might want to retune it. Edelbrocks (AFB style carbs) seem to need more attention than Holley's and quadrajets. As far as the rocker arms being too tight, I would make that a last resort, because if it was running fine when you first got it back together, how could it get even more tight? If anything, I would think in that siuation it would it would be that a rocker arm loosened up. Also an exhaust valve can cause a motor to backfire, specifically in the event that it is not opening causing all of the backpressure to exit the way it came in. Hope this helps.
__________________
When the turbo spins, the b.s. ends.
2001 F350 4x4, 1999 F-350 4x4, 1993 Lightning, 1991 Mustang GT, 1990 Mustang Lx

Last edited by 88351; 10-29-2006 at 08:42 AM..
88351 is offline   Reply With Quote
Old 10-24-2006, 07:06 PM   #8
Rock Stacker
 
Join Date: Apr 2006
Location: austintexas
Posts: 242
zukidave will become famous soon enough
If it run's good when warm I think I would look at the choke. Sound's like a lean miss fire.Bad cam, timing, lose rocker, They would effect the moter at all temp,s.As far as the two bolt four bolt thing the two bolt block has stronger main web's more meat. The main cap's are weaker that's why the hod rod guy's convert the 2 bolt block. GM say's the 2 bolt bolk is good to 500 hp or 7000 rpm's if built right.In 20 year's drag racing I never had a 2 bolt block let go in 10 sec car's
__________________
87 sammi waggy dana44,s 538,s locked f/r 5.1t.case 36 ,full cage not much sheet metal left
getting parted out now.
87 sami buggy build (see above)
90 sami 1.3L. efi, spoa, 5to1 t-case, locked rear,
rollin 31" ltb's with the tune's going chillin in the AC
zukidave is offline   Reply With Quote
Sponsored Links
Advertisement
 
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
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
chevy 350 muddyblzr Wanted 5 10-11-2006 06:32 PM
89 Chevy Ext Cab Long Bed 4x4 - $2,300 JAVO For Sale 2 08-26-2006 10:00 AM
96 Z71 Chevy 5.7L 1500 for Sale Dustin's CJ7 For Sale 5 08-24-2006 05:25 AM
WANT chevy 10 or 12 bolt rear and other chevy parts!!!!!!!!!! have cash in hand justin90chevy Wanted 23 12-08-2005 03:42 PM


All times are GMT -6. The time now is 06:55 PM.


3.8.8 - Powered by vBulletin
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright 2002-2012 Texas4x4.org
 

SEO by vBSEO 3.6.0