heads milled or not??? (how to check)
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heads milled or not??? (how to check) I need to check my heads to see if they are milled or not. They are '98 LS1 heads that have been ported & polished but the chambers are untouched and I'm not sure if they were milled or not. Should I "cc" the chambers with water/syringe or can I measure the heads somehow or what?? The heads are off the car so this shoud be easy.
*This is an old thread that I read a long time ago... does the 1.60" measurement sound right or what?? What's my best bet.
https://ls1tech.com/forums/showthrea...ghlight=milled
Thanks!!
-Jeremy
*This is an old thread that I read a long time ago... does the 1.60" measurement sound right or what?? What's my best bet.
https://ls1tech.com/forums/showthrea...ghlight=milled
Thanks!!
-Jeremy
A lot of shops will stamp some numbers on the deck of the head to signify if they have been milled. For example, when my heads were milled, they stamped a "24" on them to signify that they have been milled .024". I'm not saying that if they dont have numbers that they arent milled, but like I said, a lot of shops do that.
I had to figure this out a while back...so I have the answer you are looking for.
You have to measure the deck height from where the valve covers bolt on to the bottom of the head. Measure at either end of the head in the center.
Unmilled should be 4.750, give or take a slight amount.
CC'ing them would probably be a better and more accurate solution.
But you could find out fairly accurately this way. CCing them would be most accurate...but I couldnt tell you how to do that. A shop will charge you 50 bucks or so.
I used a digital feeler gauge to measure mine.
You might be inconclusive on a minor mill such as .010 or less...but you will definately be able to see if they were milled .020 or more...which is what you should worry about...this could cause clearance issues, compression issues etc in the future depending on your set-up....if that is the reason you are measuring of coarse. A minor mill could also throw you off a bit...but as long as your not on edge with limitations on your set-up...you can have a good amount of peace of mind using the deck height method
You have to measure the deck height from where the valve covers bolt on to the bottom of the head. Measure at either end of the head in the center.
Unmilled should be 4.750, give or take a slight amount.
CC'ing them would probably be a better and more accurate solution.
But you could find out fairly accurately this way. CCing them would be most accurate...but I couldnt tell you how to do that. A shop will charge you 50 bucks or so.
I used a digital feeler gauge to measure mine.
You might be inconclusive on a minor mill such as .010 or less...but you will definately be able to see if they were milled .020 or more...which is what you should worry about...this could cause clearance issues, compression issues etc in the future depending on your set-up....if that is the reason you are measuring of coarse. A minor mill could also throw you off a bit...but as long as your not on edge with limitations on your set-up...you can have a good amount of peace of mind using the deck height method
Last edited by UltraZLS1; Apr 12, 2006 at 06:44 PM.
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Thanks! I heard you can measure them from the bottom surface of the head up to the head bolt "pad" on the perimeter head bolts (the ones under your exhaust manifold/header). Anyone else heard this??
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Originally Posted by UltraZLS1
If you could find the proper distance from where you are talking about that would work also...same concept.
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yeah if you could find the other measurement for sure...you could get a very solid idea if you checked them both.
I could measure my heads when they come in in a week or so...but you will probably know by then. They are the ls6 castings though...and Im not positive if they would be the same.
I could measure my heads when they come in in a week or so...but you will probably know by then. They are the ls6 castings though...and Im not positive if they would be the same.
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I brought a head to work today and used some digital calipers on it... I measured at location "1" in my drawing... I was getting right at 1.600". I need to try measuring the location you were referring to as well but the valve cover plane and deck plane of the head are not parallel so I don't think that's a good measuring spot... unless of course I'm misunderstanding where you're referring to!
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Originally Posted by UltraZLS1
Yes I know the plane isnt parallel. that is why I said it wasnt exact...and was told to measure in the center.
Measure it in the center and see what you get.
Measure it in the center and see what you get.
I'll try and measure it there but that is very poor way to do it. Where I measured it alot more accurate plus you have 5 spots to measure at and compare. I'll let you know what I get!
