<VV> dropped valve seats

[kevin nash]

> My nemesis with Corvairs (lately) seems to be with their valve seats coming loose from the heads. This has happened to me twice in about 25,000 miles. First was with 140HP heads (intake seat exploded) and then it was with 95HP heads. The 95 was an exhaust valve. Both of these heads were very deflashed long before the seats came loose. Neither of these were ever overheated in the time I owned them (don't know about previous history).What is the solution to this? Can something be done to keep this from occuring? Neither time was it warm outside nor was the engine under any extreme load. The vehicle is my '63 Rampside with a 1965 RN engine, 3.55 diff. and a PG.I am using the 12 plate oil cooler with both side covers and the OTTO parts pan and valve covers. I hope to get some answers and suggestions from ALL members regardless of race, sexual orientation, age, political beliefs, education, life experiences, etc.
> Thank you in advance for what I hope is an interesting thread.
> Timothy Shortle in Durango Colorado
> Getting ready for our tri state meet next weekend
> 
> Timothy- your experience is why you should have the seats and guides replaced on any head that you do not know the history of. If you do replace the seats and guides, have the "deep"

   seats installed, they provide alot more grip (because of the extra depth) than the stock seats do. Also, most "in the know" corvair head rebuilders put these seats in with a higher than

   stock interference, which gives more grip, but also gives somewhat better heat transfer from the seat to the head. Also, it is a very good idea to set the valve springs up

   with 10lbs more preload, as a underappreciated source of dropped valve seats is valve float. The extra preload also improves heat transfer as the valve is in contact with its seat

   longer.

   Kevin Nash
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