Burnt head gasket? Options

[rglracing]

OK, I was starting to make some progress and now this. On our last run the engine blew some smoke at the top end and developed blow by. I did a leakdown test today and pulled the heads to find the headgasket burned and blown out at the top of cylinder #2. The spark plug looks good and there is no scouring on the piston or cylinder. My question is what is the most common cause, too lean,too much boost or a combination of both. All the other cylinders are fine. Rob in AZ
I am using sce copper head gaskets with an internal sealing ring ISC

[Dragcars]

You could have a plugged nozzle on that cylinder, however your spark plug should show a lot of heat. Do you run water in the heads? How much boost, compression, timing, etc? SBC's can be a pain to seal. I would recomend O-ringing the block and receiver grooves in the heads.
frank

[rglracing]

It is a BBChevy,11.0-1 comp,30 degrees timing, 10.71 16% over.I checked the nozzle and the plug looks good,heat on second thread.

[Veneys Vega]

Heat on 2nd thread,..well I guess it has heat,..how old or used where the head gaskets, and
when was the last time you torqued the heads down ?? or runs ago..
If you had more boost on this run, whether you shifted at a higher rpm without knowing it,
it probly made more boost and boost will cause lean,.. lean with good boost will cause detenation or torching and or pushing a head gasket.
I would check your upper rod bearings out, especially #2,..I know it sucks to pull a pan on a BBC
I have one too,....but it will tell you if you detenated from being lean on that cylinder.
Burning or showing heat on two threads is on the too aggressive side in my opinion.,...unless you like to pull your motor
down after each race.


Vic

[BackMotor]

Sorry for your engine woes. Wow heat down to the 2nd thread, says something went wrong to cause it. See some very valid theories posted above, all worth investigating Please let us know what you come up with !!

[rglracing]

The head gaskets had 12 runs and a little break in time. I did not retorque them. I will pull the pan Saturday and check/replace bearings. I will keep you posted. Rob

[rglracing]

OK, the block and heads are out getting machined for o-rings/reciever grooves. The pistons are ok and as Vic said the upper bearings are little worn. I have some minor scoring on the cylinder walls that the machine shop says are from the ring gap being too tight. According to the formula that Total Seal gave me with the rings I shoould have .019 gap. What are you guys running on a 4.310 bore. I want to put this back together next week,fatten it up a bunch and get back to racing. Thanks Rob