Increasing intake valve size sbc

[Little Mouse]

If you have an alumium head with a 2.02 valve and you wanted to increase the valve to a 2.08 do they have to change the seats or do they cut the seat already in it bigger.

[Carnut1]

If you have an alumium head with a 2.02 valve and you wanted to increase the valve to a 2.08 do they have to change the seats or do they cut the seat already in it bigger.

That would depend on the size of the insert.

[swampbuggy]

This question is for the O.P. (original poster). Insert meaning existing valve SEAT, correct Charlie ? Mark H.

[mag2555]

Besides that in the average SB 23 degree chamber your more than likely to loose flow at lifts above .350" by going up to a 2,08" valve without a good chamber unshrouding job being done.
Then after that the chamber work 99% of the time increases the chamber CCs by more then what you picked up from the bigger valve size so now your milling the heads to get back to your starting compression ratio!

[Carnut1]

All al heads have a valve insert for all valves. The diameter of that insert may vary by manufacturer. I would approach max valve size with caution due to some inserts not being perfectly centered. Give more info on the heads in question. I am with Mag if you can get needed flow with the smaller valve that would be the best way to go.

[Little Mouse]

Ok thanks for the replies.