Quote:
Originally Posted by Dangerous Doug
I plan on 185's unless I pull my current heads on identify obvious clearance issues---like flat-top pistons with little cut for valve clearance. Then I'd go with the 165's, but with the shorter intake runners (180 in current heads) actually create a performance drop? Are there sufficient gains with the AFR 165's heads to order the shorter intake runners?
So, the first order of business is the wet/dry compression test, which I may try to squeeze into this weekend.
Question: I have a MSD mech-advance distributor. At cruising speed I think I can hear an intermittent miss. Each plug wire removal causes the expected sloppy rpm drop, so I don't suspect the wires. I suspect the magnetic module inside the distributor. What is the probability that the module has an intermittent electrical problem?
DD
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You wouldn't see a performance drop at WOT (with a 185cc vs 165cc head), but you could see some slugglishness at lower rpm operation. Of course you don't spend 100% of your time at WOT, so I would pick a head based on how you drive the car. For a street engine, I personally would not use a larger head. Keep in mind that a smaller head that flows more is the optimum situation. I have flow numbers for both the World 180cc head that you have and an AFR 165 and the AFR's outflow the World heads by about 20 cfm. That would be a difference (in both performance and throttle response) that you could feel.
As for your miss, try looking at some spark plugs. If you do have a sealing problem, you could have some fouled plugs.