| FAQ |
| Members List |
| Social Groups |
| Calendar |
| Search |
| Today's Posts |
|
#1
03-05-2023, 11:22 AM
|
||||
|
||||
Surging at idle
Hi all,
I have a '69 GTO that just got back from restoration.. has been sitting for 2 years... Original Rochester carb was rebuilt by Paul Spotts (he sends them out) 10 years ago. Only about 150 miles on the car total since then. Engine was rebuilt a few years ago by gtofreek. Car is surging somewhat at idle. I'm not very skilled with carbs... was wondering are there some basic things to check for this? I've read vacuum leaks (unlikely - maybe the brake booster?). Thanks!
__________________
1969 Judge, 4-speed, CR/Parchment, Quasi-Survivor, #'s match - under restoration |
|
#2
03-05-2023, 01:10 PM
|
||||
|
||||
|
Some things to look into:
|
| The Following User Says Thank You to Kenth For This Useful Post: | ||
|
#3
03-05-2023, 04:30 PM
|
||||
|
||||
|
The first thing you want to do with the motor idling is confirm that the boosters in each primary are not dribbling fuel, if so you really want to run the motor as little as possible so you do not wash out the rings and cylinder walls.
If it’s surging from being lean while that is a problem at least your not killing the motor..
__________________
I do stuff for reasons. |
|
#4
03-06-2023, 06:30 PM
|
||||
|
||||
|
Your primary rods spring is too light, put a heavier spring in and surging will stop.
__________________
Rich Johns Owner/Operator of Pure Stock Auto Restorations Inc. www.purestockauto.com 1969 GTO Judge Ram Air IV M21 4 speed 3:90 1970 GTO Judge Ram Air III M21 4 speed 3:90 Oshawa Built 1970 GSX Stage 1 M21 4 Speed 3.64 # 67 of 678 Original Paint 1970 GSX Stage 1 Auto 3.64 # 603 of 678 12.44@109.73 mph 2011 Buick GS Nats Pure Stock, 12.71@110.64 mph PSMCDR 2011 1970 GS Stage 1 Convertible Auto 3:64 12.71@109.15 mph PSMCDR 2009 1970 GS 455 M21 4 Speed 3.42 1987 GN Astro Roof |
|
#5
03-06-2023, 06:41 PM
|
||||
|
||||
|
If your car has hideaway headlights with new actuators, the upper seal in the vacuum actuator can wad up when operating the headlights and cause a vacuum leak. Easy enough to check, just temporarily plug your vacuum source for the hideaways and see if the idle clears up.
Last edited by John Milner; 03-06-2023 at 06:46 PM. |
|
#6
03-07-2023, 07:15 AM
|
||||
|
||||
|
With the motor fully warmed up and at idle it's easy to check if the condition is from being lean, all you need to do is close off the Choke flap little by little to see if that richening up helps stabilize the idle or makes it worse.
To do this you will likely have to pull off the vacuum source to the Choke pull off and plug that vacuum line with a small bolt or machine screw .
__________________
I do stuff for reasons. |
| Reply |
|
|
The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Founded in 1991, it was also the first online forum for people to gather and talk about their Pontiacs. Since then, it has become the mecca of Pontiac technical data and knowledge that no other place can surpass.
Linear Mode
