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DougF
02-17-2008, 01:37 PM
I've been working on the head for my '72 TR6 and am look to buy larger intake and exhaust valves. Looked at BP Northwest gas flow valves, but it will take me a good while before I can justify $300. I'm not going racing.
What is eveyone else using? The head should be breathing pretty well when completed.
Looking at 10.1 compression. I basically want to match pi performance.

tomshobby
02-17-2008, 02:36 PM
Hi Doug,

I intended the same when I had my head done. I received a lot of information and comments. After a lot of consideration of the pros and cons I did not even go with bigger exhaust valves.

I had hardened exhaust seats installed and left the intakes as they were. When I inspected the work I was very relieved that I did not do both and stayed with the original valve size. It turned out that the inserts took so much space that I would have been concerned if both intake and exhaust would have had inserts installed. However, I do have the older head with different spacing.

I had the shop only go to 9.8:1 cr. When all was done, I am very happy with the performance.

DougF
02-17-2008, 03:43 PM
Tom, thanks for you response. I was going to stay original size, and may still if I can dress up the seals on two cylinders. When cleaning my grinds in the chamber, I bumped them with abrasive cloth and did a bit of damage. I'm using this as an excuse to spend more money.

Brosky
02-17-2008, 07:56 PM
Doug,

When I was at the Roadster Factory CAR Shop and also at the machine shop that is doing my work, both Tom at TRF and Bob at Mason's strongly suggested at staying below 10-1 compression, with 9.5 being the ideal for todays gas on a street engine. Who knows what tomorrow's will be.

I was going to follow Tom's path and will probably be somewhere between 9.5-9.7, but I don't plan to go any higher.