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

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 10-15-2009, 12:10 AM   #1
vtwinsport
Registered User
 
vtwinsport's Avatar
 
Join Date: Nov 2008
Location: edmonton, alberta
Posts: 293
drunken idle

My idle wanders up then steadies, then wanders down for no obvious reasons and repeats. Will do this 2-3 times in a 5 minute period.
76 with rebuilt 350 (5K), turbo 350, new edelbrok carb and intake- 2101/ 1406 w elec choke. New MSD streetfire ignition w vac advance. 22hg vaccum at intake at idle and steady needle.

Is my vac advance messed up?
Could my fuel pressure be too high?
Do I have a vacum leak?
Timing chain already worn after 5K?

Thanks in advance for any suggestions.
__________________

76 Silverado, 2wd, long box, 350/th350, 3.42 posi, edelbrock performer 64cc heads, edelbrock 1405, 2101 intake, Hedman Headers, Comp Cam XE262
http://beerbreadbike.wordpress.com/

Last edited by vtwinsport; 10-15-2009 at 12:15 AM.
vtwinsport is offline   Reply With Quote
Old 10-15-2009, 08:51 PM   #2
77shortybawx
Registered User
 
77shortybawx's Avatar
 
Join Date: Jan 2009
Location: belmond
Posts: 22
Re: drunken idle

vacuum leak sounds like the culprit.
__________________
1977 Chevy c-10 Scottsdale
1978 Chevy Camaro
1979 Mercury Cougar
77shortybawx is offline   Reply With Quote
Old 10-15-2009, 09:02 PM   #3
bitchin85
Registered User
 
bitchin85's Avatar
 
Join Date: Aug 2009
Location: Lambertville MI
Posts: 962
Re: drunken idle

__________________
"I'll keep my guns, money, and freedom. You can keep the "change"
bitchin85 is offline   Reply With Quote
Old 10-16-2009, 09:09 AM   #4
swb85
On a budget like Fred Sanford
 
swb85's Avatar
 
Join Date: Oct 2005
Location: Topeka, KS
Posts: 2,031
Re: drunken idle

Unless something has changed in the last couple years, the vac advance can on those streetfire distributors are junk. Mine lasted less than a week before it died. Got a cheapie adjustable accell can and it's been on there for 2yrs now.
__________________
'85 Silverado swb: 383 stroker, 10.5:1, vortec heads, 232/238 roller cam, RPM air gap, performer 750 carb, stainless longtubes, 3" duals/super 44's, T56/4.11 383ci build / exterior refresh thread
'98 Camaro z28: 370ci twin turbo 370ci build
'01 Tahoe LT 4x4: 5.3, longtubes/ory, magnaflow duals, custom tune....wife's DD
swb85 is offline   Reply With Quote
Old 10-20-2009, 02:06 PM   #5
vtwinsport
Registered User
 
vtwinsport's Avatar
 
Join Date: Nov 2008
Location: edmonton, alberta
Posts: 293
Re: drunken idle

Thanks guys,
I've been driving with a vaccum gauge attached to my ported and manifold side to see whats happening.
I appear to have between 7-14 HG when driving and monitoring both ported or manifold vaccum. Thing I have noticed is my throttle plates appear to be opening for no apparent reason when its warming up because I get vaccum on my ported side when I'm off idle.
Sounds like a choke issue may be at the heart of this. Also think my msd vac can is doing nothing. Feels like its missing with any vaccum upon acceleration.
__________________

76 Silverado, 2wd, long box, 350/th350, 3.42 posi, edelbrock performer 64cc heads, edelbrock 1405, 2101 intake, Hedman Headers, Comp Cam XE262
http://beerbreadbike.wordpress.com/
vtwinsport is offline   Reply With Quote
Old 10-31-2009, 03:08 PM   #6
vtwinsport
Registered User
 
vtwinsport's Avatar
 
Join Date: Nov 2008
Location: edmonton, alberta
Posts: 293
Re: drunken idle

found out the msd can is fine. pulls 18 degrees advance at 14HG vaccum. Put my timing tape on to check the mechanical and my darn water pump is in the way. My timing tab is at 12 oclock. Looks like I'll have to pull the pump and change the cover or put on a bolt on tab at two and then reset TDC and timing- Nice.
__________________

76 Silverado, 2wd, long box, 350/th350, 3.42 posi, edelbrock performer 64cc heads, edelbrock 1405, 2101 intake, Hedman Headers, Comp Cam XE262
http://beerbreadbike.wordpress.com/
vtwinsport is offline   Reply With Quote
Reply

Bookmarks


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 05:06 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com