For the all out performance race builder. Expands at a rate very close to the expansion of the aluminum head so the seat does not lose the press fit at higher temperatures. Stops all seat movement when adequate valve springs and reasonable head temperatures are maintained. Allows many more hours of running without having to do a seat re-grind. This extremely high quality material (127,000 PSI) is excellent for both intake and exhaust. Will work fine on a street engine, but provides little benefit in relationship to cost. Sold by the ounce, (a 6" piece of GB 399-GB 399A tubing weighs about 42 ounces, GB 399B = 75 ounces) and is more than enough material to make 4 seats. |