So I bought a ported head off someone on here and when I got it to the machine shop they said it was really close to being at the minimum thickness. I had them go ahead and resurface it after it pressure tested fine and it came out being .001 below minimum thickness with a 10.54 RA finish. It’s an 03 evo 8 and I will have 9.5:1 CP pistons and GSC S2 cams with aftermarket springs/retainers (not sure what kind yet).

Would you guys be comfortable using this head? Could I use an evo 9 head gasket and essentially make up some of the difference since it’s thicker? Or are there any precautions you would take before using this head?

I’ll obviously do a mock up and see what the clearances are but I just wanted some more opinions or a plan of attack that you guys would take.

Thanks,
Anthony

 

I don't see why not if you use a thicker headgasket. I would definitely do a clay test on the Pistons to make sure your valves aren't hitting. It should be fine with s2 cams.

 

That was my thought on it as well. My tuner just wasn't too sure of it but I wanted other opinions since I didn't want to basically scrap a head that I spent a good amount of money on. But I also didn't want to run into problems later down the road.

Anybody else?

Thanks again.

 

I would be concerned about deck integrity. There is a spec for a reason...

 

I understand that that's why I was asking hoping to get some opinions from people far more knowledgable than me on the subject.

 

A lot of the issues are with valve geometry and being able to line everything back up---deck thickness could also be an issue but I wouldn't think so. Cutting the head reduces the overall height causing cams to either be retarded or advanced throwing everything out of spec unless you degree the cams back to spec-- The issue of the piston clearance is also a concern--but I if you did both ie confirmed the correct valve to piston stuff/ which is directly related to cam timing- so degree the cam-- everything should come out as planned.

 

.011 is not a lot for timing. Consider a 4g64 block is 6mm taller deck height and only skews the timing about 3.5 - 4 degrees with a longer belt and the 4g63 head on it, .011" is only .28mm. The timing difference will be negligible, <.5*.

You could always run it. Check piston to valve clearance. The worst that will happen is you push the head gasket out of it, or crack the head. Like likely won't hurt anything except the head, which you already know to be questionable.

 

Not sure I follow---we are talking about the head on and evo viii 4g63. Don't know where .011 came from either--- do you have an actual number for the std head thickness? and the cam measurement would subtract the distance before tdc and after tdc--so twice. Bottom line is degree the cams and check piston clearance. Good luck.

 

Did you possibly mean the .001" that I'm over the minimum?

According to the national database that the machine shop uses that I went to, the new spec for the head thickness is anywhere from 5.193" - 5.201" and the minimum thickness is 5.185". My final thickness came out to 5.184" hence the .001". I have adjustable cam gears so I could easily retard/advance the cams as necessary.

 

No, I meant .011. I assumed the head has a total of approximately .011 take off. Because I remember reading somewhere the max allowable change in deck height was .010 between machining the head and block.

I brought up the 4g64 block with 4g63 head because it shows us that a 6mm taller deck skews timing by 3.5-4 degrees. So, going by percentages, if his head has .011' taken off of it, timing will be skewed about .3*, a negligible amount.

Regardless, at most his head is .017 shorter than the thickest OEM spec, timing is not his concern. I would be concerned about deck integrity....

 

Excuse my ignorance but when you speak of deck integrity do you just mean that it might warp easier or something?

 

Not so much warp, as much as it will flex more. The more it flexes, the greater chances of popping the head gasket.

Like I said, you can go for it. At worst you'll blow the hg and then you'll knowndir sure the head is no good..

 

I'll be on stock turbo and e85 with arp2000 studs. I know that doesn't mean I'll take it easy in the car but should I go with L19's for so extra insurance?

 

nothing wrong with more clamping force from better studs..