valve to piston clearance
Thread Starter
Instructor
Joined: May 2011
Posts: 135
Likes: 0
From: Horicon Wisconsin
valve to piston clearance
So im looking to gain some more out of my 79 L48 and have been looking at different heads. Can i go to a 2.02 intake head with a max of .575" lift without having to change the pistons?
Another question is. Is there a noticeable difference in buying heads that are as cast vs cnc bowl blended and gasket matched?
Another question is. Is there a noticeable difference in buying heads that are as cast vs cnc bowl blended and gasket matched?
Drifting
Joined: Dec 2005
Posts: 1,360
Likes: 3
From: NORTHEAST
So im looking to gain some more out of my 79 L48 and have been looking at different heads. Can i go to a 2.02 intake head with a max of .575" lift without having to change the pistons?
Another question is. Is there a noticeable difference in buying heads that are as cast vs cnc bowl blended and gasket matched?
Another question is. Is there a noticeable difference in buying heads that are as cast vs cnc bowl blended and gasket matched?
CNC version is alwya best!!
Thread Starter
Instructor
Joined: May 2011
Posts: 135
Likes: 0
From: Horicon Wisconsin
https://www.patriot-performance.com/...&cat=40&page=1
think they will work with stock L48 bottom?
Drifting
Joined: Dec 2005
Posts: 1,360
Likes: 3
From: NORTHEAST
these are the heads im looking at getting
https://www.patriot-performance.com/...&cat=40&page=1
think they will work with stock L48 bottom?
https://www.patriot-performance.com/...&cat=40&page=1
think they will work with stock L48 bottom?
The chinese is just melted down alumimum we have sent to china.
Do a search on Porcomp heads and patriot heads which are the same castings
Race Director
Joined: Nov 2006
Posts: 19,445
Likes: 353
From: Athens GA
St. Jude Donor '12-'13, '15- '16-'17-'18-'19, '21
Not a bad idea to look on ebay for some bare heads also.
I picked up a pair of GM Fastburn alum heads bare for $500. Never used.
Perfect for me as I am putting in springs to match the roller cam I am installing.
Assembled heads with generic springs are not always the best match.
IMHO
Good luck and stay away from China.
Bman
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Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
The point of minimum clearance is typically 5 to 12 degrees prior to TDC for the exhaust valve and 5 to 12 degrees after TDC for the intake valve. The intake VPC is more critical as the cam is advanced; the exhaust is more critical as the cam is retarded or timing set wear occurs.
Although it's best to check the VPC with any engine build, if your cam is wider than 109 LSA and has a duration (at .050") of less than 250 degrees you are probably fine unless your heads have been milled a lot. YMMV
Last edited by larrywalk; Mar 9, 2012 at 05:03 PM.