Steel head shim ???

art leong · 08-01-2008, 05:42 PM

I pulled the head today and found the intake valves just slightly kissed the pistons. I was using a custom head gasket .074 thick.
I have a steel shim.060 thick and a stock mls head gasket. 045 thick.
This will give me enough clearance.
I don't know wheter to take the stock muti layer gasket apart and put the shim inside?
Or to put the shim on the bottom against the steel block and put the gasket on top against the aluminum head?
Also should I use copper spray?
Thanks.

Daran Summerton · 08-01-2008, 07:46 PM

I'd guess giving up the quench will not be a good thing. Can you grind a lil more clearance in piston or move the cam?

Bub Whitaker · 08-01-2008, 07:57 PM

do pistons have valve pockets or is it a flat top w/ no reliefs?

art leong · 08-01-2008, 08:30 PM

The pistons are domed with valve reliefs. I sent them back to the manufactureer (JE) To lower the compression. (originally 17 to 1) They cut the valve reliefs as deep as they could without weakening the piston. (only picked up .020) and shaved the dome to reach 12.75 to 1 with the .074 gasket.
With the shim the total thickness will be .105. So I'll pickup about .030, and lose a little quench and compression.
I've used copper shims a lot. And never had a problem. But never used the steel ones.

Bub Whitaker · 08-01-2008, 08:56 PM

Art... generally if you move the cam, you pick up .005 to .007 per degree/ advance loose on the Intake pick up on the Exhaust.. retard pick up on the Intake lose on the Exhaust. Another solution would be to machine the valve face, combustion chamber side , for additional clearance. My experance on the flow bench has shown that the margin thickness on the intake valve doesn't affect flow...Exh is a different.So if your cam is in the happy place and the int valves are just kissing and your worried about it, then top those intake valves what you think they need...

Woodro Josey · 08-01-2008, 09:02 PM

Art, if the valves just lightley kissed the piston, i believe i would look at facing the Valves about .015! Be sure and reshim the springs! You could retard the cam a couple degrees and pick up .005-.007 more clearance!

Woodro Josey · 08-01-2008, 09:04 PM

Sorry Bub, i hadn't seen your post!

Bub Whitaker · 08-01-2008, 09:13 PM

no problem Woodro.. however you don't want to face the valves for more clearance as that does affect flow / changes te back side- under head radius- been there...

art leong · 08-01-2008, 09:22 PM

Quote:

Originally Posted by Bub Whitaker

Art... generally if you move the cam, you pick up .005 to .007 per degree/ advance loose on the Intake pick up on the Exhaust.. retard pick up on the Intake lose on the Exhaust. Another solution would be to machine the valve face, combustion chamber side , for additional clearance. My experance on the flow bench has shown that the margin thickness on the intake valve doesn't affect flow...Exh is a different.So if your cam is in the happy place and the int valves are just kissing and your worried about it, then top those intake valves what you think they need...

Thanks. If the valves are bent (I don't think they are). I'll have the front side dressed a bit. I don't think they are bent(will pour alcohol in runner to make sure).
I'm running a dual cam motor. The intake cam is a couple of degrees advanced. the exhaust is straight up.
Thats what it liked on the dyno.
If the valves are good I'm just going to throw the thicker head gasket in and race it. I can't run a bigger cam till I design a new piston. (Over the winter)

Woodro Josey · 08-02-2008, 09:01 AM

Yep excuse me Bub, i am not saying thats the right thing to do, but the amount of flow lost to having bent valves, i think i would face the valves if all else has been tried, either on top side or with a valve refacer, whatever he has access to,! But then what do i know!!!!!!! lol

08-01-2008, 05:42 PM	#1
art leong VIP Member Join Date: Dec 2001 Location: Richmond Hill, Georgia Posts: 2,003 Likes: 0 Liked 1 Time in 1 Post	Steel head shim ??? I pulled the head today and found the intake valves just slightly kissed the pistons. I was using a custom head gasket .074 thick. I have a steel shim.060 thick and a stock mls head gasket. 045 thick. This will give me enough clearance. I don't know wheter to take the stock muti layer gasket apart and put the shim inside? Or to put the shim on the bottom against the steel block and put the gasket on top against the aluminum head? Also should I use copper spray? Thanks. __________________ Art Leong 2095 SS

08-01-2008, 07:46 PM	#2
Daran Summerton Senior Member Join Date: Jun 2003 Location: Las Vegas nv Posts: 600 Likes: 18 Liked 66 Times in 37 Posts	Re: Steel head shim ??? I'd guess giving up the quench will not be a good thing. Can you grind a lil more clearance in piston or move the cam?

08-01-2008, 07:57 PM	#3
Bub Whitaker Member Join Date: Feb 2005 Location: Dayton, MD Posts: 222 Likes: 0 Liked 1 Time in 1 Post	Re: Steel head shim ??? do pistons have valve pockets or is it a flat top w/ no reliefs?

08-01-2008, 08:30 PM	#4
art leong VIP Member Join Date: Dec 2001 Location: Richmond Hill, Georgia Posts: 2,003 Likes: 0 Liked 1 Time in 1 Post	Re: Steel head shim ??? The pistons are domed with valve reliefs. I sent them back to the manufactureer (JE) To lower the compression. (originally 17 to 1) They cut the valve reliefs as deep as they could without weakening the piston. (only picked up .020) and shaved the dome to reach 12.75 to 1 with the .074 gasket. With the shim the total thickness will be .105. So I'll pickup about .030, and lose a little quench and compression. I've used copper shims a lot. And never had a problem. But never used the steel ones. __________________ Art Leong 2095 SS

08-01-2008, 08:56 PM	#5
Bub Whitaker Member Join Date: Feb 2005 Location: Dayton, MD Posts: 222 Likes: 0 Liked 1 Time in 1 Post	Re: Steel head shim ??? Art... generally if you move the cam, you pick up .005 to .007 per degree/ advance loose on the Intake pick up on the Exhaust.. retard pick up on the Intake lose on the Exhaust. Another solution would be to machine the valve face, combustion chamber side , for additional clearance. My experance on the flow bench has shown that the margin thickness on the intake valve doesn't affect flow...Exh is a different.So if your cam is in the happy place and the int valves are just kissing and your worried about it, then top those intake valves what you think they need...

08-01-2008, 09:02 PM	#6
Woodro Josey Senior Member Join Date: Jul 2007 Posts: 805 Likes: 0 Liked 3 Times in 1 Post	Re: Steel head shim ??? Art, if the valves just lightley kissed the piston, i believe i would look at facing the Valves about .015! Be sure and reshim the springs! You could retard the cam a couple degrees and pick up .005-.007 more clearance! __________________ Woodro Josey 2002 STK

08-01-2008, 09:04 PM	#7
Woodro Josey Senior Member Join Date: Jul 2007 Posts: 805 Likes: 0 Liked 3 Times in 1 Post	Re: Steel head shim ??? Sorry Bub, i hadn't seen your post! __________________ Woodro Josey 2002 STK

08-01-2008, 09:13 PM	#8
Bub Whitaker Member Join Date: Feb 2005 Location: Dayton, MD Posts: 222 Likes: 0 Liked 1 Time in 1 Post	Re: Steel head shim ??? no problem Woodro.. however you don't want to face the valves for more clearance as that does affect flow / changes te back side- under head radius- been there...

08-02-2008, 09:01 AM	#10
Woodro Josey Senior Member Join Date: Jul 2007 Posts: 805 Likes: 0 Liked 3 Times in 1 Post	Re: Steel head shim ??? Yep excuse me Bub, i am not saying thats the right thing to do, but the amount of flow lost to having bent valves, i think i would face the valves if all else has been tried, either on top side or with a valve refacer, whatever he has access to,! But then what do i know!!!!!!! lol __________________ Woodro Josey 2002 STK