ET Head Combustion Chamber Question
11-20-2005, 01:02 PM
#1
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ET Head Combustion Chamber Question Guys, i'm looking at some ET heads for a customer's 01 z06 and have a few questions. I'm mainly interested in the 215 cc head but want to know how the piston to valve clearence changes when specing different combustion chamber sizes. We will be going with the 11 degree head (it's my understanding that all the stock valve train parts work with the 11 degree head) and I understand the 11 degree valve angle gives you more p/v clearence over the 15 degree head. How do they change the combustion chamber volumes though? Are they milling the head, bringing the whole combustion chamber down closer the piston, shrinking the diameter of the combustion chamber, etc. etc.??? I need to know cause this guy wants a huge cam for huge power and i'd prefer for him not to have to flycutt. Thanks.
11-20-2005, 05:26 PM
#3
It's my understanding that the chambers are specifically cut to the size you want. Kinda like Patriot does with their heads. A larger chamber just has alot more material removed in certain places. I don't think the valve location moves up or down any at all. FWIW, with the 11 degree, you'll gain about .150" over the stock heads.
11-20-2005, 05:58 PM
#4
Nick what specs do you wanto know? I have some sets in the shop, we are WD with ET, they will send me whatever we may need. If you have the cam for the motor your talking about, bring it by the shop early this week and we can check free drop with the head on a 2.08 valve. A 2.04 valve would definitely clear whatever that does 
If you dont have the cam yet, I have a few coming from Comp they can send out with them in time
If you dont have the cam yet, I have a few coming from Comp they can send out with them in time
11-20-2005, 05:58 PM
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Originally Posted by Beast96Z
It's my understanding that the chambers are specifically cut to the size you want. Kinda like Patriot does with their heads. A larger chamber just has alot more material removed in certain places. I don't think the valve location moves up or down any at all. FWIW, with the 11 degree, you'll gain about .150" over the stock heads.
11-20-2005, 06:05 PM
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Originally Posted by GrannySShifting
Nick what specs do you wanto know? I have some sets in the shop, we are WD with ET, they will send me whatever we may need. If you have the cam for the motor your talking about, bring it by the shop early this week and we can check free drop with the head on a 2.08 valve. A 2.04 valve would definitely clear whatever that does If you dont have the cam yet, I have a few coming from Comp they can send out with them in time
If you dont have the cam yet, I have a few coming from Comp they can send out with them in time
11-20-2005, 06:11 PM
#7
They have two standard deck heights, standard and +.060" I believe. Bolt holes are all raised .060 to match the taller deck height I believe.
From those two deck heights they are milled to reach chamber size. To do the 61cc chamber we have on a set in the shop, they were standard deck (.800") milled .006" for a total .794 deck height. I think my math and thinking is working right lol
From those two deck heights they are milled to reach chamber size. To do the 61cc chamber we have on a set in the shop, they were standard deck (.800") milled .006" for a total .794 deck height. I think my math and thinking is working right lol
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11-20-2005, 06:20 PM
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Originally Posted by GrannySShifting
They have two standard deck heights, standard and +.060" I believe. Bolt holes are all raised .060 to match the taller deck height I believe.
From those two deck heights they are milled to reach chamber size. To do the 61cc chamber we have on a set in the shop, they were standard deck (.800") milled .006" for a total .794 deck height. I think my math and thinking is working right lol
From those two deck heights they are milled to reach chamber size. To do the 61cc chamber we have on a set in the shop, they were standard deck (.800") milled .006" for a total .794 deck height. I think my math and thinking is working right lol
11-20-2005, 06:25 PM
#9
its supposed to be roughly that. Its not just the rolled over valve angle thats buying that I dont think. I think the valve seat sits slightly higher then dead nuts stock location.
Cary is going to say it should buy you .150 free drop clearence. Then he will tell you to check your exact combo just to make sure
Cary is going to say it should buy you .150 free drop clearence. Then he will tell you to check your exact combo just to make sure
11-20-2005, 06:31 PM
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Originally Posted by GrannySShifting
its supposed to be roughly that. Its not just the rolled over valve angle thats buying that I dont think. I think the valve seat sits slightly higher then dead nuts stock location.
Cary is going to say it should buy you .150 free drop clearence. Then he will tell you to check your exact combo just to make sure
Cary is going to say it should buy you .150 free drop clearence. Then he will tell you to check your exact combo just to make sure
11-20-2005, 07:35 PM
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Originally Posted by GrannySShifting
stock valvetrain components an be used, but you must use a provide rocker pedastool from ET.
You know, I was thinking to that they could have moved all the bolt holes for the rockers as well (which may explain the need for their rocker arm cradle) and move the position of the valve stem tip to not move the valve too far up toward the intake (away from the headers). I would certainly think the closer the valves got to the intake the less p/v clearence there would be. I guess I just really need to talk to Cary. Thanks again Jeff
11-21-2005, 12:01 PM
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valvetrain we have moved all the rocker bolt holes and pushrod holes for proper geomentry. It also makes for more clearance on the tail end(pushrod) of the rocker to the inside of the casting where most other guys have clearance issues with adjustable rockers. note, they are also clearanced for a 3/8 pushrod. They do require using our pedestal mount for use with stock rocker arms, but that is the only special item required.
11-21-2005, 12:11 PM
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Originally Posted by GregP@ETPerformance
we have moved all the rocker bolt holes and pushrod holes for proper geomentry. It also makes for more clearance on the tail end(pushrod) of the rocker to the inside of the casting where most other guys have clearance issues with adjustable rockers. note, they are also clearanced for a 3/8 pushrod. They do require using our pedestal mount for use with stock rocker arms, but that is the only special item required.
11-21-2005, 12:23 PM
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Originally Posted by GrannySShifting
yup pretty much nick. We have a 61cc set here 62cc base chamber minus .006 mill for 61cc