Basically what the title states. I ran across a good deal on some afr 210 lt1 heads. But see the problem enlies where the combustion chambers are only 55cc i need as close as i can get to 62cc combustion chamber. So my question is can i port the combustion chamber that much, and exactly which location of the combustion chamber should be ported out? Ive heard of people doing this but not to much on afr. I would think that AFR uses the same head casting just the amount of carving in the combustion chamber department changes the cc's so please enlighten me. Thanks Matt

 

you cant take that much material out and not destroy the head. the chamber is specifically designed and balanced to the valve and ports in the head with shape and contour. grinding up the chamber design will completely change the head and how the combustion process works if you aren't careful ruining power output. 55 to 62cc is 12cc you would be better off running a dished piston to make up the difference or sell the heads and get the proper ones. the chamber is designed into the head and the final cc's are determined by how much its milled down for the final size. if you had a larger chamber and wanted to go smaller you could angle mill.but going smaller to bigger you don't have much choice.

 

"55 to 62cc is 12cc you would be better off running a dished piston to make up the difference or sell the heads and get the proper ones"

My math aint to great but aint that only 7cc's instead of 12cc's. There maybe something i dont know about though. What would be the max cc's i could carve out?

 

sorry i made a mistake, your right its 7cc's i was thinking about a -5cc flat top to a -13cc dish type to make up the difference, my bad brain turned off.

 

and its not about the max you can carve out so to speak, its making sure the chamber design isnt compromised by cutting large amounts of metal out of them. call AFR and ask them, they will tell you to never touch the chamber without totally reworking the head. you'd be better off running a different piston.

 

Ive already bought -21cc dish pistons im trying to stay around 9.1:1 ratio. Do yall think i can buy a thick head gasket and get it down. Oh yeah, the heads are 58cc chambers

 

My AFRs were about 58-59 and I took a couple cc's out of them to get my static compression down to 9.1 or so. I don't think it causes as much problems as milling the heads way down to get the smaller LT1 combustion chambers in the first place. They even state that their flow is all based off of their original combustion chamber volumes and a larger cylinder than your engine has. I doubt it matter quite as much on a blower engine as it would NA.

 

Just use thicker gasket.

Rich

 

im worried if i use a thicker head gasket its more likely to blow, that why i was wondering about opening up the combustion chambers.

 

well bottom line is everyone ive talked to thats a cyl head porter says its a big no no to go carving that much metal out of the chamber. go over to yellow bullet or speed talk and ask the question and you will get the same answer i gave you but in more detail from people in the know. running a large gasket may help you but you sacrifice quench but luckily in a boost app. its not as critical as the intake charge provides enough turbulence. you have a certain amount of options, you can limit the boost to compensate for the raised static compression, you can sell the heads and get the ones you need for your application, or you can add a thick gasket and grind away a teaspoon of aluminum in the chamber.... id suggest doing it right because you will end up leavinga bunch of power on the table if you start cutting away IMO

heres a 65cc chamber, where are you going to take it all out from without ruining the chamber design and shape?

 

Rig yourself up some outside calipers and measure the thickness all around to the waterjackets from the chambers and just emulate the shape that is alreay there, smooth and unshroud. But this will probaly only get you 3 or at the most 4 cc.

 

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first that valve is designed to have that for that specific port design and chamber, if you change the characteristic of the valve it will change how the air enters the chamber from the bowl affecting everything down the chain.he wants to make it bigger, not smaller. and that will only be more like 2-3 cc tops in the wrong direction. im not a cyl head expert but the red flags are up on this one, id suggest to the OP go talk to someone that can give you more insight to what you want to do. maybe lloyd can chime in or something. 7cc is ALOT of material to remove.

 

You are right. The wrong direction. I will remove my post.

 

What do you think happens when they mill it down to 55-58cc?