milled head question? help wisemen!

[keltalon]

here is my question. i just picked my head and block up from the machine shop and the machinist gave me the specs on my head and block. the head was decked about 20 thousand. and the block was decked 5 thousand. how much should i retard my timing in degrees on my timing gears to bring my cam timing back to specification. any ideas?

 

[Tallen]

Use a thicker headgasket.

 

[Defiant]

Apparently you have adjustable cam gears? If so, you need to degree the cams regardless.

If you don't have adjustable gears, there's not much you can do. Including worry about it.

 

[exzercist]

they took .020" off! the limit is .008"! thats not good they give limits for a reason.

 

[keltalon]

yeah i have ajustable gears. i just wanted to know how many degrees per thousandth do i retard the cams. i already have the mitsubishi mls .054 head gasket.

 

[Defiant]

yeah i have ajustable gears. i just wanted to know how many degrees per thousandth do i retard the cams.

I've not heard of such a spec. But it wouldn't matter if you're degreeing them anyway.

 

[exzercist]

the specs are in the service manual check it out.

 

[keltalon]

Apparently you have adjustable cam gears? If so, you need to degree the cams regardless.

If you don't have adjustable gears, there's not much you can do. Including worry about it.

thanks defiant! we bougth a cam degree kit today and degreed the cams. come to find out that my cams because of the milled head was about 3 degrees retarded. so we advanced the cam timing with the adjustable gears 3 degees. it made the world of a difference in power and spool up thanks again!

 

[Defiant]

the specs are in the service manual check it out.

Tell me where, I'd not seen it. Does Mits supply offset dowels for degreeing cams on milled heads?

 

[keltalon]

Tell me where, I'd not seen it. Does Mits supply offset dowels for degreeing cams on milled heads?

AMEN!

 

[keltalon]

they took .020" off! the limit is .008"! thats not good they give limits for a reason.

The dealer/service manual will not allow more than .008 because of cam timing alteration. but my head to be exact has 40 thousanth shaved off of it. and the valve seats has been cut to allow for valve clearance of the pistons. i am working side by side with a guy here in atlanta who build race mitsubishi 4g63 for a living and this is what he told the machine shop to mill off the head for whatever reason but the guy knows what he is talking about because i have personally seen some of his 4g63 car run 11s all day long. with the ross pistons i have and the mitsubishi mls head gasket this puts my compression ratio at 8.79 to 1. and we have tuned everything from here to work with the 14b turbo. the car pulls like a mofo and i am pleased i will take it to the track next week to get a time and when i do i will post the slip.

 

[Cesar]

The dealer/service manual will not allow more than .008 because of cam timing alteration. but my head to be exact has 40 thousanth shaved off of it. and the valve seats has been cut to allow for valve clearance of the pistons. i am working side by side with a guy here in atlanta who build race mitsubishi 4g63 for a living and this is what he told the machine shop to mill off the head for whatever reason but the guy knows what he is talking about because i have personally seen some of his 4g63 car run 11s all day long. with the ross pistons i have and the mitsubishi mls head gasket this puts my compression ratio at 8.79 to 1. and we have tuned everything from here to work with the 14b turbo. the car pulls like a mofo and i am pleased i will take it to the track next week to get a time and when i do i will post the slip.

Are you able to give me compression test results for your motor??

What clearances are you running?? What pistons? What't the mileage on the motor?
What headgasket?

Thank you

 

[keltalon]

Are you able to give me compression test results for your motor??

What clearances are you running?? What pistons? What't the mileage on the motor?
What headgasket?

Thank you

ross 30 over
brand new rebuild
mitsubishi mls .057 thick
.018 gap on the rings
.043 shaved from the head
ferrea 1mm oversized ss valves
finally got to run the car at the track recently. numbers was pretty good

60 1.873
330 5.624
1/8 8.681
mph 80.78
1000 11.339
1/4 13.589
mph 101.22


i am running a ported 14b boost set @14.5 psi (low do to feul cut) ported o2 housing carsound high flow cat custom 2.5 turbo back exhaust super afc stock ecu stock mas i know this is crazy but i am running one hks 264 on the intake side and stock exhaust cam. donnot have the money to buy the other cam. this run was made @ silver dollar raceway! i am very pleased! any more questions i will be glad to answer them. ps we recessed the valves and grinded the height to accept the 43 thousand being shaved from the head.

 

[Cesar]

Thank you for your reply...did you have a psi reading from a compression test???
I assume you had your comtiming done, I've never heard of anyone removing that much material from the head...

Thanks

 

[keltalon]

Thank you for your reply...did you have a psi reading from a compression test???
I assume you had your comtiming done, I've never heard of anyone removing that much material from the head...

Thanks

psi reading from compression test cylinder # 1 186
# 2 181
# 3 181
# 4 180


well a lot of people will not shave that much off the head. because of the valves and cam timing, and compression. with that much being shaved off my cams were indeed retarded opening late and closing late. so we had to advance them about 8 degrees both intake and exhaust to get them in sync with the pistons. the reason he chose to decrease combustion chamber volume is he figured that the increased compression would work well with the small 14b turbo. we are use to building hondas and i am no expert with turbos. this whole thing with the head is just an experiment based on basic mathematics. i think with 550 cc injectors , tmo chip , the 264 exhaust cam and front mount intercooler ,18psi i can reach my goal of mid 12s with the 14b. everybody have different goals in terms of performance i just want to keep mine simple 12s will almost gurantee respect on the streets.