Poor man's LS6 (Valve clearance issue??)
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Intermediate
Joined: Dec 2005
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Poor man's LS6 (Valve clearance issue??)
Can anyone tell me if the '02 LS6 had valve reliefs in the pistons? I'm putting a '02 LS6 cam in my 98 LS1. I've milled the heads about 0.015" to get the compression ration to 10.5:1 and am concerned about valve/piston clearance. Should I be and do I need to measure this clearance with clay or is this a relatively safe swap?
Also I heard about geometry issues with the higher lift of the LS6 cam in an LS1. Do I need to compensate for this somehow with longer valve stems or different roller tip rocker arms??
Also I heard about geometry issues with the higher lift of the LS6 cam in an LS1. Do I need to compensate for this somehow with longer valve stems or different roller tip rocker arms??
Drifting
Joined: Apr 2002
Posts: 1,614
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From: DFW TX
LS6's had no valve reliefs in the pistons. The 02 LS6 valves I think were slightly longer - probably to compensate for the smaller cam base circle. You may need a slightly longer pushrod with the LS1 head/valve combo I suspect. You should assemble with the current length, then check lifter preload, and rocker geometry to check for sure. Search on LS1Tech to see what others have doen with that combo to be sure.
Race Director
Joined: Sep 1999
Posts: 12,439
Likes: 920
From: CONCORD NC
no valve reliefs, and as said. You won't have any problems, guaranteed.
Yes, you will need to compensate for both the smaller base circle AND your milling. You can either wait until you get it together and cut down one of your pushrods, then measure the right size. OR go aftermarket, and get adjustable rockers. My sources at GM racing says shimming the rockers is a big no-no, as it weakens the bosses in the heads.
Yes, you will need to compensate for both the smaller base circle AND your milling. You can either wait until you get it together and cut down one of your pushrods, then measure the right size. OR go aftermarket, and get adjustable rockers. My sources at GM racing says shimming the rockers is a big no-no, as it weakens the bosses in the heads.
Race Director
Joined: Sep 1999
Posts: 12,439
Likes: 920
From: CONCORD NC
did a little figurin'
The 02' valves are .6mm longer than yours to make up for the smaller base circle. 0.6mm x 1.7 (rocker ratio) means you need pushrods 1.0mm shorter than stock.
THEN, you need to compensate for your heads. 0.015" twice=.030, so that's another .76mm you need to remove.
The 02' valves are .6mm longer than yours to make up for the smaller base circle. 0.6mm x 1.7 (rocker ratio) means you need pushrods 1.0mm shorter than stock.
THEN, you need to compensate for your heads. 0.015" twice=.030, so that's another .76mm you need to remove.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
I am doing heads in the spring. I bought a Comp Cams adjustable push rod to determine what length I will need. Turns out that Comp uses Gauge Lenght while Crane and Manley use overall length so be careful, but I would measure and determine exactly what you need as the pushrod length with stock rockers is critical.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I never had to do anything during a cam swap on the old school Chevy engines except stab in a new cam and install new stock or hardened stock size push rods. This LSX cam and push rod stuff is new to me too. There are a lot of people out there that have school of hard knocks expierence and or have deeply researched this tech issue.
As I also have a heads cam swap due sometime in the near future, this subject is near and dear to my heart also!
Im going to need all the help that I can get on proper push rod installation and push rod selection.
1- What is the best push rod length checking tool to use?
2- What is the proper procedure to check for the correct length pushrod on a LSX engine?
3- How much pre load is correct for the LSX engines?
Thanks
Bill Curlee
As I also have a heads cam swap due sometime in the near future, this subject is near and dear to my heart also!
Im going to need all the help that I can get on proper push rod installation and push rod selection.1- What is the best push rod length checking tool to use?
2- What is the proper procedure to check for the correct length pushrod on a LSX engine?
3- How much pre load is correct for the LSX engines?
Thanks
Bill Curlee
