off set seat fixture

General engine tech -- Drag Racing to Circle Track

Moderator: Team

KnightEngines
Guru
Guru
Posts: 1730
Joined: Fri Jan 09, 2009 8:51 pm
Location: Australia

Re: off set seat fixture

Post by KnightEngines » 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..........

sbcharlie
New Member
New Member
Posts: 49
Joined: Mon Jun 06, 2011 11:44 am

Re: off set seat fixture

Post by sbcharlie » Tue Nov 07, 2017 9:21 am

the 2017 honda crf450 heads are offset 3mm on both intake and exhaust. sbc

jcisworthy
Member
Member
Posts: 133
Joined: Sat Feb 09, 2013 4:22 pm
Location: Amsterdam NY
Contact:

Re: off set seat fixture

Post by jcisworthy » Tue Nov 07, 2017 10:55 am

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.
There is no place like this place, so this must be the place
Freedom Village
https://www.freedomvillageusa.com/

http://www.rbjracing.tk

Ron E
Guru
Guru
Posts: 1941
Joined: Wed Aug 03, 2005 9:35 pm
Location: nc

Re: off set seat fixture

Post by Ron E » Tue Nov 07, 2017 12:06 pm

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!

User avatar
modok
Guru
Guru
Posts: 1293
Joined: Sun Jun 06, 2010 1:50 am

Re: off set seat fixture

Post by modok » Tue Nov 07, 2017 7:57 pm

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.
Glen Urban

Frankshaft
Pro
Pro
Posts: 428
Joined: Sun Jul 05, 2015 6:01 pm

Re: off set seat fixture

Post by Frankshaft » Wed Nov 08, 2017 9:33 am

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.

User avatar
Dave Koehler
Guru
Guru
Posts: 3321
Joined: Mon Oct 04, 2004 11:19 pm
Location: Urbana, IL USA
Contact:

Re: off set seat fixture

Post by Dave Koehler » Wed Nov 08, 2017 11:41 am

One won't know until one tries.
Dave Koehler - Koehler Injection
Fuel Injection - Nitrous Charger - Balancing - Nitrous Master software
http://www.koehlerinjection.com
"Never let a race car know that you are in a hurry."

Post Reply