br8crumb

So factory spec for b series vtec motors range from 5.589-5.593'. factory resurface limit is .008' head has stock size exhaust valves and .5mm oversized intake valves.

Machine shop measured 5.550' which leads me to believe it was milled a tenth a couple times. Would you guys keep or trash the head since it's past the factory resurface limit? Was planing on bolting it down to a stock b18c rebuild with a .033 head gasket.

Plans are not to boost just na. And I see cometic sell .05-.06 hg even though I've heard they leak.

Just looking to see what I'm in for when assembling and looking at clearances thanks

motoxxxman

most honda heads that I'm aware of can be shaved 0.060" or more before reaching a service limit. best way to tell is to look at the corners of the surface of the head. look for a tab with a circle in the center, cast. there should be 2 or 3 of them. if the circle is untouched, good to go. if the circle is touched, it's shaved too far. those circles are depth indicators.

br8crumb

Already know how much it's been milled though. Figuring on p2v issues with a mild cam and possibly degreeing to avoid issues or looking into thicker hg to compensate

stock specs
141.95mm-142.05mm
5.589'-5.593'

Factory service limit
0.2mm
.008'

motoxxxman

hate to say it, your specs are wrong. read my above comment again regarding the depth indicators.
if your specs were right, almost every honda head in existence would be past the service limit after shaving it just one single time. Almost every honda head I've seen in my lifetime as a career performance import tech has been shaved AT LEAST once, often 2 or 3 times, and still operates flawlessly with stock or aftermarket internals. Hell, I have over 0.080" shaved off my personal head lol

TomCat39

Side question for you experts:

Besides Piston To Valve Clearance. Is there any other issues with shaving a head past "service limit" (Honda Depth Marks)?

Will the head crack or worse?

Caoboy

timing belt issues maybe?

motoxxxman

I forget the exact numbers, it's in my notebook which I don't currently know the location of. But I think it was somewhere in the vicinity of: for every 0.025" shaved off it retards the cams 1 cam degree (2 crank degrees).
the only issue I've run into with shaving PAST the service limit (0.075" on my head, currently at 0.080" removed) is PS pump alignment with the bracket. I had to drill one of the holes slightly larger in order to get the bolt to thread in without binding crooked. Basically meaning anything that bolts to both the head and block may need minor mods to the holes to still be capable of bolting up.
And as you mentioned; piston to valve clearance. With the simple fact of bringing the valves closer to the pistons, combined with the retarded valve timing, it caused my exhaust valves to start kissing the pistons at higher rpms at my current shaved level. I simply bought some gears and advanced the exhaust cam a couple degrees.

PyroProblem

Adjustable cam gears will take care of this.
As far as clearances go, I see .035" minimum piston to head/piston to valve clearance usually recommended. High RPM or Aluminum rod engines may need to increase this number.
Definitely check clearances and degree the cams in on this build, really any performance orientated build IMO.

solomon93

Shave too much off the head and slap it on a "stock" bottom end your asking for a bad time. (oil consumption) If this is a rebuilt/new engine you should be fine

93h2beg

id be more concerned with piston to head clearance. This can be remedied with a head gasket, if you do no use a thicker head gasket then you will need to use adjustable cam gears.