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Old 08-30-2012, 04:41 PM
oldbogie oldbogie is offline
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The fouled plugs could have been from the excess oil, or from an over rich mixture, or from too cold a heat range on the plug.

You've got an awful lot of compression for that cam. I compute a Dynamic Compression Ratio (DCR) of nearly 10 to 1 assuming 6 inch rods and only 7 ccs of volume in the piston crown for valve relief plus a zero deck block with a .030 head gasket. One usually looks to hit around a DCR of 8.5 to 8.8 with aluminum heads and 91 octane unleaded. The DCR is the Static Compression Ratio, in your case 11:1, then adjusting it for the piston position in the bore which is inches of lost stroke in crankshaft degrees for when the intake closes, Comp says 71 degrees ABDC at .0015 inch lift which still isn't completely closed but pretty darn close.

This cam wants more base (static) time than 10 degrees but this may be a reasonable compromise against the high DCR. Adding base timing must have a corresponding reduction in the variable timing in order to hold the maximum where the engine will tolerate it. If 34 is the upper limit of all timing and 10 degrees is in the base then the variables have to top out at 24 degrees. If the base timing is moved to 20 degrees (for an example) then the variables have to be limited to 14 degrees.
Detonation can be managed by reducing the amount of timing advance or slowing the rate at which it comes in. It is also controllable with a richer mixture, a cooler mixture, a cooler running temp, stiffer gearing, water/alcohol injection or lowering the compression ratio.
Generally a compromise between less or slower advance to manage detonation costs more power than compromising the compression ratio enough to quell the pinging. At least this is apparent at WOT/redline; but pinging tends to be present at mid RPMs due to excess advance for the power drain on the crankshaft (“lugging” could be a term here) and at WOT where everything is hot an heavy in the combustion chambers. The former is often excess advance but can be a bit of a lean mixture (both can happen a the same time for different reasons) the latter is most often a lean drop of the carb at WOT, this can often be an emulsion air correction issue as much as fuel jetting one. The safer route is to throw more fuel sooner. Messing around with air correction takes a lot of expertise and special, not to mention expensive, tools.

I really wouldn't think an additional quart of oil would cause plug fouling at least to the extent of your picture. This makes me suspicious that the pan may not have the parts needed to separate the flying oil and put it back in the sump. At a minimum the pan on an engine of this potential needs a very good windage tray or screen, an oil stripper on the right side of the crank to catch the flying oil and direct it down into the sump and a splash guard under the oil pump to keep oil from running up under acceleration and flooding the rear counter weight of the crank and the rear seal. Without a windage tray/screen and an oil stripper; the rings, especially if they are the ultra modern low pressure and thin cross section type, are just overwhelmed by the amount of oil that gets up on the cylinder walls. I'm also not a big fan of gapless second rings which quite a few builders use and your engine might have. If you get oil contamination from the valve guides, a Positive Crankcase Vent (PCV) or a leaking intake or head gasket, the oil gets trapped in the area between the second and top ring where the second ring cannot vent this stuff into the crankcase. Same goes with excess fuel. These conditions will show up as fouled spark plugs since this gunk has to ride around with the piston till it finds a way out with the exhaust by first contaminating the mixture.

Bogie
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