Here is my set-up: 1977 Maverick Stock 302 shortblock D0OE heads with 58.5 cc chambers (about 10:1) Comp Cams Xtreme Energy 256H Comp Cams Cam gear and chain set (Cam 4 deg. advanced) Stock C-4 with stock converter-stock 3.00 rearend Stock manifolds with custom dual exhaust and crossover Holley 600 cfm Weiand intake No emissions conneted. My question is this: When I installed the 4 bbl and manifold and removed the VV carb and related emissions, it ran a LOT better and got better mileage, but pinged excessively with the vacuum advance connected. Now that I am istalling the head/cam combo next month, what to do about ignition? I fear the curve and advance will be all wrong and may ping all the time, but I dont know what it is. I know there is mechanical advance in the distributor, but how much does the ignition control module effect this? Are there options? I don't want to go aftermarket, if possible, I would rather re-curve. Also, if there a performance version of the module? Thanks in advance...
Its all in the advance spring setup. There is an adjustable vacuum control also on the market. It take a lot of trial to achive the advance curve you want but is worth the time and education. You need a good timing light to see the results of the changes as well a road testing. I can't tell you of any easyer way.
Thanks K. Merring. I know that vacuum advance must come from ported sources, they are easy to discern on a Holley. I think part of the problem is that Holley ported vacuum goes from zero to manifoild vacuum in the blip of the throttle. I fear it may be way to fast for the advance weights presenty employed, that's why I am pinging now. Do the adjustable vacuum advances work for duraspark factory distributors? I'm guessing they do.
The only difference between the dists are the pick up for the electronic module. The vacuum part works the same by pulling the plate around in both types. There is a lite and a heavy spring and tangs to bend to adjust the tension. I have info on doing this somewhere in the library. It has been 7 years since I last done it.
balancing act The vacuum line has to go to the side of the metering block on a Holley carb. Your timing should be between 6-12 initail and 36-40 total. Without the vacuum line attached. Just start with the lower setting and play with it to find what works on your combo.
I wouldnt use the vac advance...i curve my mechanical advance aln leave vacuum alone..I have found on a 302 38 degrees total is the best I have found others may have better spec.s for your cam/intake/exhaust combo
Your Maverick ignition I just read your posts from 2002. I have the same problem today. Can you tell me what you did to fix the advance curve problems? I am thinking of having my old distributor re-curved, or buy an aftermarket dist. Thanks.
youll need a few distributors. take the advance piece off of the top and use the one with the greatest cut out, OR use a die grinder and lenghthen the one inside your distributor ( the cut out space )
I just ended up running without the vacuum advance. I think the curve is not optimum, but I have bigger things to worry about these days. I'll get to it when I am caught up with other car projects.
