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 1969 - 1972 Blazers and Jimmys Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 05-30-2012, 12:03 PM   #1
jsweet
Registered User
 
Join Date: May 2012
Location: Santa Barbara, CA
Posts: 12
Plugged Vacuum Advance line

I'm having some problems with acceleration (see WOT post) but also found vacuum advance line going to distributor is plugged. Seems like previous owner purposefully put a ball bearing into the vacuum line next to distributor. Is there a reason for that? Doesn't make sense to me and can't find any similar posts.
jsweet is offline   Reply With Quote
Old 05-30-2012, 05:39 PM   #2
old man jimmy
Registered User
 
Join Date: May 2007
Location: texas
Posts: 329
Re: Plugged Vacuum Advance line

I'm guessing po was an old school racer. That's what we use to do to stock dist. That and put re-curved weights and lighter springs in them. It actually worked pretty good. Sounds like it came from a smog testing state. Usually we just took the vacuum advance off all together. Not knowing what cam you have, can't tell you what to set your timing. I run mine at 32 deg. total advace. That is, i set the timing with engine at 2400 rpms at 32 deg. But you can do it by ear. Take engine up to about 2000 rpms advance dist. till it really starts to run then back it off a tad. if it drags down too much when you start it, retart it a little till it starts ok.
old man jimmy is offline   Reply With Quote
Old 05-30-2012, 06:10 PM   #3
old man jimmy
Registered User
 
Join Date: May 2007
Location: texas
Posts: 329
Re: Plugged Vacuum Advance line

i just noticed you're from ca. that explains the ball bearing. Kinda like gutting out the old air pumps. or drilling holes in the back of stock air cleaners. In Ca. things had to "look" stock.
old man jimmy is offline   Reply With Quote
Old 05-30-2012, 08:21 PM   #4
jsweet
Registered User
 
Join Date: May 2012
Location: Santa Barbara, CA
Posts: 12
Re: Plugged Vacuum Advance line

Quote:
Originally Posted by old man jimmy View Post
i just noticed you're from ca. that explains the ball bearing. Kinda like gutting out the old air pumps. or drilling holes in the back of stock air cleaners. In Ca. things had to "look" stock.
So does that mean it runs better with it plugged? Since it doesn't need smog, why have it connected?
jsweet is offline   Reply With Quote
Old 05-31-2012, 01:01 AM   #5
old man jimmy
Registered User
 
Join Date: May 2007
Location: texas
Posts: 329
Re: Plugged Vacuum Advance line

I don't run any vacuum advance on any of my old iron. But I ran on the strip for many years, and i guess old habits are hard to break. The only purpose i could see the vacuum doing was to retart the timing to make it start easies (actually turn over easier) But if you've ever ran a vacuum gauge, and watch what happens to your vacuum when you mash it. You don't want your timing retarted when you come off the line. Without it, you have a pretty steady engine timing with just the springs and weights. I guess you could probably get 20 different opinoins on it, but that's just mine. I never knew any old school racers who kept them on their cars. And small blocks like a lot of timming. since you don't know the history of what's been done to your engine, i would forget the timing light and set it up by ear. if it's cammed, and you're trying to set it at stock timing it will never run right. make sure your dwell is 30 deg. and give it some advance. you'll know if you go too far, it'll turn over like a weak battery if at all. small block chevys are super easy to tune, and not at all tempermental.
old man jimmy 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 08:45 AM.


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