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so ive got a 01 engine and im pulling it apart to shave the head and do a few other things to it, what i want to know is whats the most i can shave thead before it becomes and interference motor and how do i go about adjusting the timing on the intake cam cause from what i understand it will cause a bit of retarding in the timing when you shave massive amounts off.

i know the exhaust cam will need an adjustable cam gear just not sure about the intake, Cheers~!

Not sure about how much you can take from a VVT head. I've taken about 60 thou off an NA8 one without having to mess around with modifiying cam idlers. Beyond that you need to substitute an adjustable idler on the exhaust cam to crank sprocket side. For the NA8 70 thou is usually quoted as the limit as far as head soundness goes. I haven't seen anyone talk about interference.

For timing change I guess the diameter of a cam sprocket is about 120mm, so its circumference is 377mm. This means that each mm of sprocket circumlerence is near enough to 1 degree of rotation: 377/360 =~ 1. It follows that each mm that you take off the head will retard the timing by 1 degree. Taking off 60 thou (1.5mm) would retard both cams 1.5 degrees - not enough to bother about for me. Does that sound right or do I need to double the retardation calculation to allow for the 2:1 crank:cam gearing?

I have heard of 60 thou being done with a VVT on a stock bottom end with good results.

The engine will almost certainly become interference with a 60 thou shave.

All of this assumes your bottom end is stock - no machining on the deck, etc, and stock head gasket (around 31 thou thickness).

zossy1 wrote:I have heard of 60 thou being done with a VVT on a stock bottom end with good results.

The engine will almost certainly become interference with a 60 thou shave.

All of this assumes your bottom end is stock - no machining on the deck, etc, and stock head gasket (around 31 thou thickness).

ive heard f 80- thou but not sure ahha i just wanna know how to get around the vvt thing so i can adjust the mechanical timing of the motor

I'd replace pistons before attempting to shave the head. Gaining 0.2:1 compression just isn't worth the time and money.

project.r.racing wrote:I'd replace pistons before attempting to shave the head. Gaining 0.2:1 compression just isn't worth the time and money.

taking the head off to get it cleaned up, and i thought why not while im in there, and isnt 80 thou rasing the compresion by 1.2 or something? i saw some write up about it somewhere

you only need 10 or 20 thou for clean up. or not at all if head is in good condition.

project.r.racing wrote:you only need 10 or 20 thou for clean up. or not at all if head is in good condition.

im doing valve stem seals and valve springs and seat and getting some cams in there. so once all thats done ill see how much i can shave