Timing issue - Pontiac GTO Forum
User Tag List

 
LinkBack Thread Tools Display Modes
post #1 of 4 (permalink) Old 05-19-2018, 04:32 PM Thread Starter
 
Join Date: Mar 2016
Location: Fort Worth, TX
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Garage
Timing issue

My 1967 GTO 400 4V AT is starting to get my goat (pun intended). It seems to want to idle & run best at ~40 deg BTDC but bogs down & stalls when I put it in gear. I've looked at the post by 69 267 originally posted 2/18/18 because I seem to have similar problem. I went through the diagnostics/solutions posted there without getting any improvement.

I had the block rebuilt by a reputable machine shop, experienced Pontiac builder. He installed new rings, bearings, valve job and installed a 9779068 grind cam. I verified the timing marks were correct before I started re-assembling the engine.

I rebuilt the carb myself as per Cliff Ruggles book using his rebuild kit. There's a good chance it's a carb problem since this was my 1st attempt at rebuilding a QJet. I may look for an inexpensive, new carb to run temporarily & send my QJet off to Cliff Ruggles so he can go through it (if new carb makes a difference).

I've played around with indexing the distributor, moving it 1 gear cog in either direction, but that seems to make matters worse. I rebuilt the distributor as per Lars tuning tips posted in this forum. New coil, condenser, points, rotor & cap. Dwell is dead on 30 deg.

I've checked the valves according to some of the posts on this forum and everything seems to be correct. There doesn't seem to be much adjustment for the stock hydraulic lifters/rocker arms.

It's only pulling about 10" vacuum at idle so it could be a vacuum leak, but I've checked the intake as suggested in the thread started by 69 237 it seems ok. I've installed all new vacuum lines, PCV valve & grommet.

I'm stumped. Any advice is greatly appreciated.

Alternatively, can anyone recommend a good mechanic/diagnostician/tuner in the North Texas area (Fort Worth)?

Thanks
NDExpat is offline  
Sponsored Links
Advertisement
 
post #2 of 4 (permalink) Old 05-19-2018, 05:17 PM
 
integrity6987's Avatar
 
Join Date: May 2017
Location: NW Ohio
Posts: 160
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 50 Post(s)
Garage
new harmonic balancer? Sure mark is at zero degrees TDC, rotor at #1 ?

DK

<)))>><

"Pray as though everything depended on God. Work as though everything depended on you." - Saint Augustine
integrity6987 is offline  
post #3 of 4 (permalink) Old 05-19-2018, 08:13 PM Thread Starter
 
Join Date: Mar 2016
Location: Fort Worth, TX
Posts: 17
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Garage
Original harmonic balancer. Rotor points to #1 position on distributor @ TDC with mark on 0. I rolled it around with a compression gauge in #1 spark plug hole to verify.
NDExpat is offline  
 
post #4 of 4 (permalink) Old 06-04-2018, 04:52 PM
 
Bob Young's Avatar
 
Join Date: May 2018
Posts: 51
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Idle speed? If out of the idle circuit it will do stuff like that. Even with the 068 cam it should idle down to 500 in neutral, with timing set per spec. If not, you/or somebody did something to the carb or worse case the cam wasn't ground right if the marks line up.

Are you using an aftermarket roller chain? I remember some have 2-3 key ways for altered cam timing. Running 10.75 comp?
with the timing set at 6 the centrifugal advance should be 0-2 @500 and will run up to 10.5-12.5 @ 1000

Here's the correct placement of the keyways.
Attached Thumbnails
Click image for larger version

Name:	IMG_4498.jpg
Views:	33
Size:	1.71 MB
ID:	113097  

Last edited by Bob Young; 06-05-2018 at 10:33 AM.
Bob Young is offline  
Sponsored Links
Advertisement
 
Reply

  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Pontiac GTO Forum forums, you must first register.
Please enter your desired user 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:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
What do you make of this timing issue? Bredfan 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance 1 01-14-2018 09:25 PM
1966 Ignition and Cam Timing Issue Stretch 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance 14 06-10-2014 01:06 PM
Help me timing or carb issue my67goat 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance 19 04-08-2013 06:07 PM
Another timing issue, or is it....... 68greengoat 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance 32 04-07-2010 08:56 PM

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

 
For the best viewing experience please update your browser to Google Chrome