I have an 87 Camaro with a 383, Holley 850, Hooker Super Comp Headers, Lunati Roller Cam .630 Lift, Pertronix Race Distributor, 230 Dart Heads. When timing the engine the mark jumps all over until 3,000rpms. Is it possible the advance springs could be too loose. The Dist. is new but because of the jumping around of the timing I thought it might be hindering the performance up to 3000.

 

Do you have a multi spark ignition? They fire multiple sparks until about 3000 RPM at whichpoint theyrevert back to single spark. Your timing lite may be getting confused at idle speed. Also check for crossfire between plug wires, that will also confuse the timing light. You could also have a very lumpy & lopeyidle, which also results in the timing going back an forth according to engine speed, this is pretty normal.You can always rev the engine to around 4000 RPM and set for the maximum advance that it needs and leave it at that. Somewhere between 30 to 36 deg, depending on your engine combination.

 

Do you have a aftermarket ignition as in multispark hi6 if you use a better timing light it will cause the light to be erratic. My light which has the timing advance feature also went goofy I hooked it up to another battery source and it seamed to help.Weaker advance springs would just let the advance come in quicker I would not think it would make it erratic. If the springs are actually loose itsounds like the wrong springs if so it could make it erratic.What may also be hindering low endperformance is 230 cc heads on a 383 you will need to scream that thing to get the performace out of them.

 

Pete and Griff thanks for your reply. I have set the timing at 36 at 3,500 rpms and ignored the bounce of the mark. In my thinking if the lightest springs are in the distributor with my lumpy cam won't that add to the rough idle. I was considering using slightly tighter springs to help control the bounce of the advance at lower engine speeds since I launch at around 2500 rpms anyway. Your thoughts, thanks

 

[X(] lumpy or lopey cams cause variations in engine speed at low rpm and in turn can cause dist flyweights to change erraticly this can also be where any and all slop in the timing/valve train will come into play and shows up in erratic timing. for built chevy's ive always timed at 3500 rpm for around 36 degrees(varies with each motor combo) usually all timing advance is in by this rpm. adjust to highest advance without detonation. changing the springs changes when the advance comes in and is specific to various engine combos. in most cases bring in as much advance as possible as early as possible without causing detonation. dont worry so much about the small variations at low engine rpm. the heavier springs will delay advance and possibly available power so dont do that just to control variations. remember you want advance but not detonation this is where the most power is made kurt