5.7GL Volvo Timing Advance Question

[lee42lee]

I have a 1996 Volvo 5.7GL and have been having a problem running it at wot. When I would try to run it at wot it would bog and sometimes pop back through the carb until I pull back to about 3/4 throttle. I checked the timing this morning and found it was not advancing. I took the ignition module out and it has centrifical advance under the module and both springs were off and messed up. So I went to my Volvo dealer and got a set of springs and put them on but still have a problem. Now when the secondaries open it will still pop back through the carburetor. I had a timing light borrowed this morning when I found it wasn't advancing but I don't have it now to see if it is or not. What does it sound like now? I have just replaced the 2bbl carb with a rebuilt 4bbl Rochester Quadrajet. Could it be getting to much fuel and cause it to do this? I pulled one of the plugs and it was sutted up pretty bad but I thought it was because of it not advancing the time. Thanks for any help.

 

[Reel Poor]

Re: 5.7GL Volvo Timing Advance Question

Popping thru the carb possible causes

1. Lean fuel @ WOT
2. crossed plug wires
3. cam lobe problem/valve adjustment
4. ignition system controls

If your plugs are fuel fouled real bad they should be changed.

 

[John_S]

Re: 5.7GL Volvo Timing Advance Question

Need to varify the advance and shound map it for every 1000rpms. I don't know Volvo specs, but would assume around a 6-10 degree advance at idle, and 30-32 degrees total at wot. Most, if not all of that would be in by 3500 rpms. If that is good, you may be looking at a lean condition (popping) with the carb. Might be caused by vacuum leak (carb or manifold), so would check that before trying to tune carb. Did you have any issues doing the mixture and idle speed adjustment?

 

[Silvertip]

Re: 5.7GL Volvo Timing Advance Question

Popping back through the carb when getting into the secondaries on a Q-jet is an indication that the secondary air valve spring is not adjusted correctly or is disconnected. With the engine warm, but shut off, open the throttle about 3/4 and then with one finger, push on the secondary air valve butterflies. It should take very little pressure to open them. If there is too much pressure they won't open when running. If there is too little pressure they open too soon. Any GM factory service manual has the procedure for adjusting that spring. As for the sooted up plugs, the choke probably needs to be adjusted as well. Never adjust a Q-jet choke on a warm engine. I have no idea what year/style/model Q-jet you have but the choke and secondary spring adjustments will be similar but things may look a little different. The choke pull-offs should also pull the choke partially open when the engine first starts. If not, they are bad or plumbed wrong, or you don't have vacuum lines routed/connected properly.