I have read about an alternate technique in setting engine timing by using a vacuum gauge. I have tried this method on both my TR6 and my 65 Stingray, both resulted in outstanding performance. Having said all that, I am learning this advanced timing afforded by vacuum setting may result in excessive cylinder head temperatures and could cause bearing failure. I have returned my timing on the TR6 back to 4 degrees ATDC but has resulted in lesser response and poor performance. On the other hand, I do not wish to destroy a perfectly good engine either. Does anyone have any experience in this area?