What would cause dropped exhaust seats?
 

I dropped 2 exhaust seats #4 & #7 (#4 completely gone, #7 1/4 of it dropped out) on 2 different motors months apart. The motors are 502 GenV's only about 130 hours on them with Merc dual plane manifolds and Carter carbs, 088 heads. One dropped the seats last summer, so I replace it with a Gen6, 3 weeks ago other motor did the same thing. The motors ran fine, on start up the banging began. All the other pistons are black, valves also black, 4&7 valves are tan colored.

Re: What would cause dropped exhaust seats?
 

There were some 502's that had bad seat material ...I am not sure what version. I just had some heads reworked on a 98 502 MPI Mag and the seats were fine .....I'm sure someone will know ....m

Re: What would cause dropped exhaust seats?
 

I have seen to much cylinder temp cause them to come out and go threw the motor. If they fall out on start up of a new motor it sounds like they were not installed correctly. Which I have seen also.

John S. :D

Re: What would cause dropped exhaust seats?
 

Water ingestion/reversion caused one of mine to drop out in an old motor.

Re: What would cause dropped exhaust seats?
 

becoming a common problem.

Been blamed on fuel additives lately. Causing higher combustion temps

I know a few builders are upping the jet sizes to help the problem