[Jeff Higgins]

Hi Grady,
I'll answer as much as I can, but I don't have all of the information you are asking for. Hopefully with my answers, you can provide some more insight into what happened here.

The rings and lands look as new as the day I put the motor together. No evidence of cracking on the top land, or closure of the gaps between the lands. All rings look brand new, with crisp edges and no cracks.

I examined the rod bearings and saw no evidence of cracking or wear. They did not look any darker on the "top" side, closest to the piston. I will, however, at this point replace them. It will take me half an hour to do that, and will provide immeasurable peace of mind.

The pistons are JE's with a nominal compression ratio of 9.5:1, riding in reconditioned cylinders from EBS (Kobelschmidts re-plated in nickasil). Heads are stock '83 SC save for welding up the CIS scallop and drilling the MFI port, and matching the intake ports to 36mm S throttle bodies. I don't remember the deck height offhand, but I do remember using two base gaskets to get it into the acceptable range. Cams are from John Dougherty; .485"/.470" lift and 254/238 degrees duration at 1mm lift, timed to 4.5mm. It's running a single plug (NGK BP7ES) sparked by a Barry Hershon recurved SC distributor and an MSD 6AL box. Plug gap is .045". Total timing is 33 degrees at 6,000 rpm.

Two electrodes on other plugs were burned back almost to their bends. All head studs appeared to be properly torqued. I'm not sure what the cranking compression was; I'll have to wait to get it back together to check that. Fuel was locally available 93 octane from Chevron. I'm not sure if there is any ethanol content.

The oil temperature did get unusually high (250 degrees), and I was actually getting ready to come in on the next lap. I was going to finish out the one I was on, do a cool-down, and go in. I was a little puzzled as to why temps got that high, as at my previous lapping day (with the sport muffler installed) they never went over 210 or so. I have an Elephant Racing "widemouth" front cooler and their finned lines. I do not have a head temperature sensor.

Conditions at the time of failure were an ambient temp of around 50 degrees, overcast with some light drizzle. Pretty typical Northwest early spring day. No one else was having overheating issues.

Other than the damage shown in the photo and the burned plugs, there was one other indication of excessive combustion temperatures. My relative new SSI's, and the stainless steel track mufflers, both turned a light straw color. The motor just turned over 5,000 miles and had been out to a couple of other track days, and the pipes looked as silver as new. They must have gotten fairly hot to discolor like that.

Anyway, that's what I know at this point. These appear to be the classic symptoms of a lean condition, to me, anyway. I would really appreciate further insight. This is kind of an unusual motor, especially in regards to the short duration / high lift cams; maybe that increases low rpm dynamic compression too much or something. I don't know, but I would like to be able to put it back together without lingering doubts about the combination. Replacement parts are already on their way...