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Grady Clay Grady Clay is offline
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Join Date: Dec 2003
Location: Arapahoe County, Colorado, USA
Posts: 9,032
Iím pretty sure that when you see that on a bearing it could conceivably start to shed flakes of copper the next time it is run. At least not far off. When that happens, things go to hell in a hand basket pretty quickly.

I like the philosophy of starting conservative on service intervals, deck, piston-to-valve, redline, etc. and carefully work toward the extreme. I think it counterproductive to start very radical and then be fixing things.

What parts do you replace every time? Bearings, rings, rod bolts & nuts, other?

Getting control of your fuel will be a big help, not only in reducing the propensity for detonation but event to event consistency.

The other thing I see that aggravates the detonation is your cooling the heads and cylinders. Do you have head temperature thermocouples? Many 616 racers use a 911 fan and put a LOT of air across the engine cooling surfaces. It is combustion chamber temperatures that matter, not oil temps. If nothing else I would crank the fan faster.

With the ignition pickup in the old distributor, are the clearances tight where there isnít any timing scatter?

You need a pressure relief valve in your oil circuit. Where are you measuring the pressure? 200 psi is too much, you will damage things. You sure donít want to twist the oil pump drive or pop a cooler. It might be useful to have a propane forced air heater to get the oil hot quickly. Do you have piston squirters?

Everything looks pretty normal. You are properly paying attention to the details.

When you measured the CR, what were the measurements on each of the four cylinders?

Have you seen this thread Detonation, Knocking & etc.? Ignore the sophomoric banter; there is some good stuff and links there.

Best,
Grady
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Old 11-14-2005, 05:56 PM
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