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Re: off set seat fixture

Posted: Tue Nov 07, 2017 7:55 am
by KnightEngines
If you built a few restricted class engines with 'no porting' rules you'd start to see the usefulness of offsetting stuff..........

Re: off set seat fixture

Posted: Tue Nov 07, 2017 9:21 am
by sbcharlie
the 2017 honda crf450 heads are offset 3mm on both intake and exhaust. sbc

Re: off set seat fixture

Posted: Tue Nov 07, 2017 10:55 am
by jcisworthy
Restricted heads, no porting, lol, 99 % of them have port work done to them as well as the "valve job any".

For me, a concentric valve job from the top of the chamber cut to the bottom of the bowl cut then shaping to and from all that is the way to go.

Re: off set seat fixture

Posted: Tue Nov 07, 2017 12:06 pm
by Ron E
KnightEngines wrote:
Tue Nov 07, 2017 7:55 am
If you built a few restricted class engines with 'no porting' rules you'd start to see the usefulness of offsetting stuff..........
You got that right!

Re: off set seat fixture

Posted: Tue Nov 07, 2017 7:57 pm
by modok
jcisworthy wrote:
Tue Nov 07, 2017 10:55 am

For me, a concentric valve job from the top of the chamber cut to the bottom of the bowl cut then shaping to and from all that is the way to go.
I think it is interesting you feel strong;y that it is "not for you", yet you have not implied it does not work.
Isn't that like saying
"yeah it makes the car faster but it's too much work?" LOL

Same thing can be achieved using an extra thick valve seat, it just ends up thicker one side than the other.
that raises the question....is it OK for a valve seat to be thicker one side than the other?? I think it's ok, but I don't really know.

Re: off set seat fixture

Posted: Wed Nov 08, 2017 9:33 am
by Frankshaft
Its an interesting idea. But doesn't mean it works on everything. Just because 1 manufacturer offsets the seats, doesn't mean it will apply to everything. It could be simply based on the engineering constraints they had, it was worth 6-8 cfm or whatever. But, throw porting in the mix, and the gain disappears, and adds a lot of complexity.

Re: off set seat fixture

Posted: Wed Nov 08, 2017 11:41 am
by Dave Koehler
One won't know until one tries.