What are the best positive valve seals? viton or teflon? any brand preferences? I don't want to have to change these again.

I have better luck with Viton, the Teflon in my Ed heads (early) were leaking badly after 10k miles. I get mine from eBay Alex's Parts.

richard i could not find alex's parts on ebay. is it listed in another way or name????GOPHER

First, I buy direct from US SEal as I suspect most everyone does that buys in bulk

Second, I think Barry Robotnick is selling these in single engine packs, so go to him first, he's one of the gang

Third, I have bought from Alex multiple times and he is a straight shooter, so you cant go wrong thatw ay either. Here is his Ebay page

http://cgi.ebay.com/ebaymotors/Viton-Valve-Seals-3-8-X-500-FE-Ford-BB-Chevy-Chrys_W0QQitemZ370108600244QQcmdZViewItemQQptZMotors_Car_Truck_Parts_Accessories?hash=item370108600244&_trksid=p3911.c0.m14&_trkparms=72%3A727%7C66%3A1%7C65%3A12%7C39%3A1%7C240%3A1318


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- 70 Fastback Mustang, 489 cid FE, TKO-600 5 speed, 3.70 9 inch
- 71 F100 shortbed 4x4, 397 cid FE, headers, Street Dominator, 280H, 5 lug Dana 60, 4 speed