305 timing - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 07-22-2009, 11:04 PM
Registered User
 
Join Date: Jul 2009
Location: las vegas
Posts: 9
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
305 timing

Hey all I have an 81 k10 suburban with a 305. I keep setting the timing and it keeps changing. I'm not sure what the problem is. it has an H.E.I. distributor. Someone told me that the vacuum advance may be sticking, but I'm not sure how to check. I unhooked the vacuum advance and still have the same problem. Any help would be greatly appreciated. Thank you

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 07-22-2009, 11:59 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 60
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 598 Times in 547 Posts
Quote:
Originally Posted by suburbanguy
Hey all I have an 81 k10 suburban with a 305. I keep setting the timing and it keeps changing. I'm not sure what the problem is. it has an H.E.I. distributor. Someone told me that the vacuum advance may be sticking, but I'm not sure how to check. I unhooked the vacuum advance and still have the same problem. Any help would be greatly appreciated. Thank you
The mechanical advance mechanism will over time rust and wear, springs will break and pivot points wear out their plastic bushings (if so equipped- not all were).

Bottom line, you likely need to take it apart and clean it.

This requires the entire dist. to come apart, the advance plate rides on the main shaft and if it's sticky, it'll need to come apart for cleaning, too.

It's not a hard job, but there are a lot of small parts, and you do need to pay attention, make notes as you go along and take pictures if possible.

A decent description of taking an HEI apart is HERE.
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 07-23-2009, 12:45 AM
Registered User
 
Last photo:
Join Date: Jan 2009
Location: Springfield, MO
Age: 29
Posts: 1,108
Wiki Edits: 0

Thanks: 5
Thanked 0 Times in 0 Posts
Is the shear pin at the bottom of the distributor broken? If it is, the timing will slip when you start the engine because the gear will spin on the shaft instead of turning it.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 07-23-2009, 01:20 AM
Registered User
 
Join Date: Jul 2009
Location: las vegas
Posts: 9
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by Torque454
Is the shear pin at the bottom of the distributor broken? If it is, the timing will slip when you start the engine because the gear will spin on the shaft instead of turning it.
The shear pin is good. I reaplaced it about a month ago. Thank you though.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 07-23-2009, 01:25 AM
Registered User
 
Last photo:
Join Date: Jan 2009
Location: Springfield, MO
Age: 29
Posts: 1,108
Wiki Edits: 0

Thanks: 5
Thanked 0 Times in 0 Posts
Better recheck it. If you replaced it, i would guess that it was broke. If it broke once, it will probably break again. I had it happen to me twice. Coincidentally, it was one month after the first time it happened. Also, the new shear pin could be defective, or not as strong as the original one.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 07-23-2009, 01:35 AM
Registered User
 
Join Date: Jul 2009
Location: las vegas
Posts: 9
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by cobalt327
The mechanical advance mechanism will over time rust and wear, springs will break and pivot points wear out their plastic bushings (if so equipped- not all were).

Bottom line, you likely need to take it apart and clean it.

This requires the entire dist. to come apart, the advance plate rides on the main shaft and if it's sticky, it'll need to come apart for cleaning, too.

It's not a hard job, but there are a lot of small parts, and you do need to pay attention, make notes as you go along and take pictures if possible.

A decent description of taking an HEI apart is HERE.
Thank you for your help. I'm going to check the spring in the advance. That may be the reason the timing wanders.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 07-23-2009, 01:41 AM
Registered User
 
Join Date: Jul 2009
Location: las vegas
Posts: 9
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by Torque454
Better recheck it. If you replaced it, i would guess that it was broke. If it broke once, it will probably break again. I had it happen to me twice. Coincidentally, it was one month after the first time it happened. Also, the new shear pin could be defective, or not as strong as the original one.
It didn't break before it had something stuck inside it. The timing doesn't go around it goes back and forth. It just doesn't stay constant. When I drive it the idle goes up and sticks. Then when I shut it off it back fires.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 07-23-2009, 01:55 AM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 60
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 598 Times in 547 Posts
Quote:
Originally Posted by suburbanguy
I'm going to check the spring in the advance. That may be the reason the timing wanders.
While you have the cap off, one thing you can do, is to turn the rotor against the springs and see if it returns completely when you release it. It should, and the springs should hold the advance mechanism "closed" against the stops when at rest, it shouldn't want to stay "open"- which will be advanced.

But it sounds like you will be able to see what's going on. Good luck.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
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 for yourself.
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.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

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
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Timing Marks ??? Zeder Engine 10 06-18-2013 05:19 AM
What to set timing at? SBC 305 / CS274 hon_jr Engine 19 10-23-2007 06:06 PM
305 chevy timing raymond spaugh Engine 1 02-09-2007 05:06 PM
vacuum advance help batman09 Engine 14 09-09-2004 10:42 PM
305 timing shaine32210 Engine 3 02-21-2003 10:55 PM


All times are GMT -6. The time now is 05:35 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.