Thread: 302 Timing

Tweet

OK I have a stock Ford 302 that I built from a PAW long block kit. Edelbrock 600cfm carb, Performer manifold and a PAW cam (very mild grind idle to 5000) I hear pinging under acceleration. If I remove the vacum advance it goes away. Timing has been set at 12*BDC, 9*BDC and 6*BDC less noticeable with less base advance. I don't know the year of the engine but it uses all standard hardware. At 2800 RPM I measured 42* of total advance with vacum attached. The advance is connected to the timed port of the carb. Is it possible to decrease the amount of advance put in by the distributor while under vacum? I think that if I could do that it would solve the problem. Driving without vacum advance makes the botom end real sluggish in my Scout. I might consider a mechanical advance distributor but I think it might hurt my off road performance. Thank You. Christopher.

Thank you. I will give it to JBA, they have a dyno and are good with Fords. I was trying to avoid the expense but it sounds like it will be monwy well spent. Thanks again.

I'm probably gonna piss Richard off by disagreeing with him on this one. He could be right on the reduced piston dome and head gasket size, but I won't speculate because you never gave the specs on the kit.

Here is where I disagree. If you reduce the dome of the piston and thicken the head gasket (assuming the heads themselves were not milled or changed) you are effectively reducing compression. An increase in compression, an increase in timing or a decrease in the octane level of the fuel can all effectively contribute to detonation. So a decrease (reduced piston dome and thicker head gasket) in compression will not by itself contribute to detonation or pinging; quite the opposite will occur.

I think that the total combined advance of 42* that you are running with today's octane rated pump fuel is the problem. You can get your distributor recurved and get your vacuum advance adjusted and you will probably be just fine.

That is what I want to try first. I trust the guys at PAW to give me a basic running engine kit. The vacum advance seems to be the problem because without it connected the truck runs fine. I know that I was able to adjust the advance on a chevy distrtibutor by inserting a small allen wrench into the vacum port opening and turning a small screw inside. Hope I can do the same with my NAPA distributor. Thank you for your input. Dyno time can be so damned expensive.

T2B; Why don't you just buy a weight kit for your Distributor and lose the vacum advance. That would do it, and it would be a lot cheaper then buying a new distributor to find out that it wasn't the problem. Just my thoughts.

Vegas
sorry I misunder stood, I thought you were going to buy a new distributor, but I would buy a weight kit for your distributor and lose the vacum advance.