I'm rebuilding my engine and was wondering should I use 3mm. seals? The engine is street ported and pinned or am I better off using 2mm.? I searched through the other posts and there were different opinions and really need help with this....

Thanks

 

There are alot of pros and cons for both. Supposedly the 3mm seals can handle detonation a little better, but the 2 mm seals seal better, thus making more power. The 3mm seals will probably wear out the housings faster, as some have observed.

 

Thanks for the reply. My shop I get my work done is owned by Marcos Acosta and he recommends 3mm. but I will talk to him about the 2mm. seals...

 

My motor has 3 mm Hurley 2 peice seals, and they have held up to 17-18 PSI on pump gas. I wound up cracking my rear side housing--probably due to a spike over 20 PSI--but the seals were fine.