Hey guys, I need a little help here since i will be removing the head soon. I have done a few hours of searching on related topics but couldn't find a definate answer to my question. So...does anyone know how much to mill the head to raise compression by 1 point? i.e. 10.6:1 My guess at the moment is .030" but i want to make sure. Thanks for any help.


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i dont know that anyone has milled their head to acheive 10.6:1 compression. the standard is 10.1:1 and for that youll need to shave your head .035"

You can also remove the middle layer of your MLS head gasket. You might wanna invest in cam gears if you go this route.

Tony

for every 4 thousands you will see an approximate .1 increase in compression so I.E. 20 thousands will yeild an approx comp ratio of 10.1:1 so having your head milled about 35 thousands will set you pretty damn close to 10.5~6:1 compression. This will also play havoc with the timing of your engine. When reseting the timing you will be about 1/2 tooth off. GET ADJUSTABLE CAM GEARS!!!!! and play with your timing a lil bit, if you have more questions let us know

my car will sound like, bumbabumbubavrooooooooooooooomrooooooooahhhhhhhhhhhhh, kishhhhhh
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VW= The joy of driving
DSM= The frustration of fixing

Originally posted by totaleklipse97
for every 4 thousands you will see an approximate .1 increase in compression so I.E. 20 thousands will yeild an approx comp ratio of 10.1:1 so having your head milled about 35 thousands will set you pretty damn close to 10.5~6:1 compression. This will also play havoc with the timing of your engine. When reseting the timing you will be about 1/2 tooth off. GET ADJUSTABLE CAM GEARS!!!!! and play with your timing a lil bit, if you have more questions let us know my car will sound like, bumbabumbubavrooooooooooooooomrooooooooahhhhhhhhhhhhh, kishhhhhh www.dsmregistry.com/detail.php?carid=643 VW= The joy of driving DSM= The frustration of fixing

totaleklipse97 (my spelling from memory sucks)... did you have your head milled? if so... could that have played a factor in the tip of your spark plug coming off?

edit: how's that going by the way? have you found a new piston? (what brand of spark plug so i might try to avoid it, or did you bend it too many times? or was it detonation?)

Originally posted by SilverEclipse
Hey guys, I need a little help here since i will be removing the head soon. I have done a few hours of searching on related topics but couldn't find a definate answer to my question. So...does anyone know how much to mill the head to raise compression by 1 point? i.e. 10.6:1 My guess at the moment is .030" but i want to make sure. Thanks for any help. Turning is fun too! go to www.sccaforums.com -Do it...do it-

your inj will be off, you will need some gears to compensate

Why don't you just get 10.6:1 pistons instead of fucking up your head? By the time you get the work done, buy good cam gears, and spend all that time and hassle reconfiguring shit to get your timing working you would be better off with just getting pistons. And if you go turbo later you can just change pistons again instead of buying a new head that isn't milled.

Originally posted by a_miller_76
Why don't you just get 10.6:1 pistons instead of fucking up your head? By the time you get the work done, buy good cam gears, and spend all that time and hassle reconfiguring shit to get your timing working you would be better off with just getting pistons. And if you go turbo later you can just change pistons again instead of buying a new head that isn't milled.

why change the pistons? you just have to tune a little more carefully (i plan on doing this high-comp + boost method in the future)

well my head was not milled at the time the sparkplug fucked up. My car was almost stock!! and to be honest there are alot of advantages of having a milled head, even though getting your timing right is a pain in the ass. You can buy very common 8.8:1 j/e pistons and be back at stock compression ratio... so if you are waiting for turbo you will not notice the drop in tq due to lower comp. It is not that hard to tune a turbo to stock compression ratio, even though alot of guys here would not do it. If you really want to be safe you can go low comp and just boost at stage 2 levels for daily driving and you would have a *fairly* reliable turbo car. Oh and my car will be done closer to the end of the month, i bought some nice goodies!!!

my car will sound like, bumbabumbubavrooooooooooooooomrooooooooahhhhhhhhhhhhh, kishhhhhh
www.dsmregistry.com/detail.php?carid=643
VW= The joy of driving
DSM= The frustration of fixing

Please do not mill your head. I know that people have had decent luck with tuning but i have to say it was the biggest pain in the ass ive ever had to encounter. I couldnt find the correct setting for the exhaust cam, nor for the intake and i couldnt tune the car worth a shit. If you want to go high compression buy the pistons and stop messing around with the piddley crap. I have to say that was the biggest mistake i ever made. People are going to disagree with me and honestly i dont care, speaking from experience should be all the info that you need.

you had your head milled quite a bit more than alot of the guys here have. I do believe that micheal97rs has got his cam posistion sensor to read back to stock posistion. He said it was about a 1/2 tooth off. u just kinda have to play with it quite a bit, and i understand that you tried quite a bit and i fully respect your hard work to make that head work. Im hoping i don't have 1/2 the problems that you did but im wishing upon a star cause i know if i don't give the shop the correct info i will have a major PITA also.

my car will sound like, bumbabumbubavrooooooooooooooomrooooooooahhhhhhhhhhhhh, kishhhhhh
www.dsmregistry.com/detail.php?carid=643
VW= The joy of driving
DSM= The frustration of fixing

Hey thanks for all the help guys. I knew that if I were to mill it much i would need cam gears and all but i just wanted to hear some more about this. Of course I would much rather get high compression pistons but that is a lot more work and money, and i wouldn't do pistons without doing rods etc. which is not necessary at this point. I doubt i will mill the head more than just to get the surface smooth because the small gains are probably not worth getting gears and tuning time. Oh well, its good to know those numbers now. Thanks.:thumbsup


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go to www.sccaforums.com
-Do it...do it-

The adjustment to compensate for the milling wasn't bad at all. If you do it and get it all lined up when you put the timing belt on you'll be good to go. All you really need to do is mark the inner portion of the adjustable cam gear and then line those marks up once the engine is at TDC. Put a few extra minutes into the timing procedure and you're set.

A thought occured to me Chef, what octane gas were you running when you had problems? and I can't remember if you got the cam code or not.



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i ran 89 and 93 octane