DOHC Head Info

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09-21-2010, 10:26 PM
GordonRamsey

DOHC Head Info

Today I learned a little bit on resurfacing heads and what not. And one of the things I learned was that most overhead cam engines, if bowed up (yes, bowed, not blowed (up)), the cam will stop spinning because the head is warped. And the only way to fix this is to put it in an oven and rebend it. Now I see the need for this, and don't find fault in it. (If there is in the case of our heads, please tell me.)

Now, another thing. I was told that the with most foreign aluminum heads you can only resurface up to .0010 (10 thousandths if I typed it wrong), and after that you will need a "head saver shim" for between the head and block so the valves don't hit the piston obviously. What is the limit of resurfacing for the 6G72 heads?
09-22-2010, 01:08 AM
toddrs93

Quote:

Originally Posted by GordonRamsey

Today I learned a little bit on resurfacing heads and what not. And one of the things I learned was that most overhead cam engines, if bowed up (yes, bowed, not blowed (up)), the cam will stop spinning because the head is warped. And the only way to fix this is to put it in an oven and rebend it. Now I see the need for this, and don't find fault in it. (If there is in the case of our heads, please tell me.)

Now, another thing. I was told that the with most foreign aluminum heads you can only resurface up to .0010 (10 thousandths if I typed it wrong), and after that you will need a "head saver shim" for between the head and block so the valves don't hit the piston obviously. What is the limit of resurfacing for the 6G72 heads?

I'm not sure off hand on the limit because I have a machine shop that does that but, if the heads have been done before or are warped badly in some cases it is also possible to get a thicker headgasket to compensate and create a little more space.
09-25-2010, 11:30 AM
BaadVR4

Quote:

Originally Posted by GordonRamsey

Today I learned a little bit on resurfacing heads and what not. And one of the things I learned was that most overhead cam engines, if bowed up (yes, bowed, not blowed (up)), the cam will stop spinning because the head is warped. And the only way to fix this is to put it in an oven and rebend it. Now I see the need for this, and don't find fault in it. (If there is in the case of our heads, please tell me.)

Now, another thing. I was told that the with most foreign aluminum heads you can only resurface up to .0010 (10 thousandths if I typed it wrong), and after that you will need a "head saver shim" for between the head and block so the valves don't hit the piston obviously. What is the limit of resurfacing for the 6G72 heads?

.012" according to Mitsubishi.