Thread: Question 9:5:1 USDM Head on a 10:1 JDM BLOCK

hi guys i think i have a problem with the set up of my car i have a head of a USDM 9:5:1 on a 10:1 JDM block, the difference is that the exhaust valves on the 9:5:1 are smaller by 1mm wide so, i don t know if the spark on the ignition timing in restricted to the exhaust manifold and cause some fatigue in my motor, if you guys can help me a would really helpfull

tks

The 10:1 motors got the sodium filled valves like the bluebird and avenir. The other head will work fine though.

so the difference is in the material of the valves??? so the size does not matter, great to know that

Yeah, the size isn't a huge deal. I'm sure they flow slightly better, but nothing you would ever notice.

The sodium filled ones also help dissipate heat from the combustion chamber. Those would provide an extra bit of protection against detonation, but the standard valves will work just fine.

great to heard that because my head gasket it wasnt a good one and it broke down in the practice this last saturday in the race, the post was made by my teamate, tks for the info

any one with another opinion

tks

make the valves with mirror finish

tks for your advice, i ve already done that jeje