3.2L engine noise after track event

[jager911]

I have a semi-dedicated street legal track car, '74 911 with '85 3.2L. Stock engine except for bolt-on mods: K&N open filter, headers and megaphones on track and Steve Wong tune. I installed low-mileage 40k engine in 2003 and it has always run like a top. It has about 55k now.

I was running at Watkins Glen and noticed a louder than normal exhaust sound with a deeper tone, around Turn 9 and pulled into the pits immediately, i.e. only drove 2 turns at reduced speed. I parked the car and only drove it up on the trailer and into garage at home. There is a loud tick-tick-tick sound from the right bank and a minor vibration. Engine was not over-revved, no missed shifts. I did have an issue earlier in the day with stuck throttle due to bent linkage and turned off engine and coasted into pits but car ran fine after I fixed that.

Looking for opinions where to start diagnosis:
1. Valve adjustment? What is symptom of broken rocker arm?
2. Broken exhaust stud? The megaphones were not supported and do vibrate.

[Elombard]

Hopefully somthing 'relatively' simple - with the unsupported mega phones maybe it broke a header where you cant see it and its just an exh leak? Kinda sounds like what you are describing.

[kyhunting]

Check to make sure that your header to exhaust port nuts are tight. Happened to me in a race once.

[jager911]

Originally Posted by Elombard

Hopefully somthing 'relatively' simple - with the unsupported mega phones maybe it broke a header where you cant see it and its just an exh leak? Kinda sounds like what you are describing.

Keeping fingers crossed, I'm hoping it's that simple too. Engine's been running really strong, car keeps up with GT3s on slower infield courses. It's due for valve adjustment, so figured I'd take off megaphones, check for leaks, maybe install street M&K, then adjust valves.
I noticed the muffler gaskets have deteriorated over time so could be a leak there too but the ticking and vibration are troubling.

Obligatory picture of the patient when she's running good.

[CCM911]

Before you panic, just do a valve adjustment. I would think if something bad happened, there would be a LOT of movement on your rocker arm.

I wonder if you could have done something to the exhaust?

[Elombard]

Hmm yah, the vibration does not fit in with the diagnosis very well.

[jager911]

Originally Posted by kyhunting

Check to make sure that your header to exhaust port nuts are tight. Happened to me in a race once.

Yep, will check that first. Haven't had time to look into anything yet.

[CCM911]

He has a tick-tick-tick sound. Either an exhaust leak or a valve flung out of adjustment(best case).