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Originally Posted by lonewolf
Can you use the stock valve seats if they are in good shape or do you need new seats for the oversive valves thanks
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Quote:
Originally Posted by 36tbird
OK, let me beat this horse for clarification. First some background: the last flathead I rebuilt that I have not run yet, I bought a set of brand new stainless valves and a Neway seat cutter. So, I installed the new valves into the valve seats that I worked with the Neway. I did it this way because I did not want to sort through old valves and go to get a set ground because I do not have a set up for grinding the valves. If I do this again in the future, are you guys saying that I could get a set of Chevy 1.6 valves, treat the seats and then install them directly? This would give me the advantage of slightly longer valves that would work well with adjustable lifters? Also, I suppose that the Chevy valves are cheaper, true?
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Hi guys, in order to effectively install 1.600" valves the original seats should (must) be removed and larger corresponding inserts put in place!
You don't want the 1.600" valves "seating" at the very outer edge of the existing seats, not a real good move!!
I would also add this, in order to take full advantage of the larger valves you need to do some internal porting, not just the bowls, but the runners as well.
Thanks, Gary in N.Y.
P.S. Just for comparison purpose here, over the years when we did this procedure, 1.500" to 1.600" on the SBC's, we've found very little gain in power until we ran the units over 5000 RPM. In short, until that rpm band is approached, the 1.500" valve platform will get the job done!