The message will be a little long, I apologize but I'm giving the most details I can to help you out and to proove that I have done my lessons and I have read A LOT ... my family thinks I'm crazy to always be reading on that topic...
I have been playing with my V8 327 chevy for the last month and now have it running pretty great... acceptable in fact...
I have rebuilt VERY carefully a told to be untouched quadrajet carb, adjusted everything, read a lot on the topic and did everything accordingly.
I have tested everything I could find, including vacuum leaks, compression, etc etc, and everything seems perfect, but still have a minor problem, I am addressing to you in case I'm missing something, nobody local has a clue about quadrajets, timing issues, etc etc...
My problem is the following:
The idling is unstable, it fluctuates once in a while, like a 50 (Sometime maximum 100) RPM variation, each 3-4 seconds... it doesn't sound very stable and healty. The vacuum flickers accordingly. I'm having a 2-3'' Hg variation while the idle fluctuates. The average approximate vacuum is 15-16'' , which is a little low, according to what I read. When put in ''D'' (on a rebuilt powerglide), the idle goes down a lot, it barely idles and sometime the engine dies. On ''D'', the vacuum is varying a LOT from 7 to 10'', very low!
My camshaft is a compcams XE256H, which is supposed to be a pretty mild cam with good Idle. http://www.compcams.com/Company/CC/c...x?csid=84&sb=2
Here are my other specs:
I am using Pertronix ignitor so I have nothing to adjust, no points, dwell to adjust, etc etc.
36 degrees all-in timing (VAC disconnected) (All in between 2800-3000 RPM, with the Mr. Gasket gold springs)
14 degrees base timing (VAC disconnected)
B26 VAC, tested directly within the specs, plugged to full manifold vacuum and it idles better than with ported vacuum.
30 degrees total Idle timing with VAC connected (So VAC pulls about 16 degrees, like it should)
While timing with the lamp, the timing sometime varies 1-2 degrees, I guess this is due do my unstable idle.
I'm unable to adjust the Idle mixture screws using the vacuum method because of the vacuum fluctuation of 2-3'' hg all the time. The screws doesn't seem to make a lot of difference on the vacuum. However, i am able to kill the engine with the screws all-in.
Ignition coil, spark plugs wires and sparkplugs are new and tested. Engine rebuilt. Steady 180 PSI compression cold on all cylindres, WOT.
I isolated all the vacuum circuits and plugged the ports. Then, I checked for vacuum leak everywhere using the ''propane torch'' method and also by spraying water everywhere there could be a leak. I also checked for a possible PCV valve leak, tested good.
I just changed the intake gaskets with no apparent difference.
Idle mixture screws kills the engine, so i'm idling on the idle circuit.
I can Idle anywhere in-between 2 to 6 turns out on the idle mixture screws without a difference.
Carb has oem jets, rods, float (and good float height) ; cleaned the idle circuit, removed the idle tubes to clean, etc etc..
I think I have listed here everything Needed... If any more information is needed I'll give needed info.
I will be posting on the chevelle forum too t reach more people, just letting you know!
thanks a lot everyone!!