I say your valves will be fine, but about resurfacing the head; the more you remove the more chance you have for valve to valve and valve to piston contact using high lift cams. I prefer not the resurface the head unless i need too and just get a set of pistons that will yield your static compression, if that is what your aiming for (Higher Compression).

 

Stock valves will be fine. Shaving the head to add/increase compression is a perfect way to ruin it. The only reason I see for "shaving" a head is achieve a completely flat surface for a pefect seal on the head gasket.

 

How would shaving the head ruin it? Surely more compression on the correct internals = more power....
I calculated I'll need to take around 30thou's or 0.47mm off the head to hit around 11.7ish compression on my set up. Would this be safe to do. I am wanting to up the compression this way as I keep my stock pistons. higher compression forged ones tend to get hot spots because of their design and I am wanting this build to be as reliable as possible without risking detonation.
I am still not fully sure what I should do......I know what I want to do but need alot more help off here first.

But any input on this would be welcome.

Thanks

 

There are problems with shaving the head. First off .030 is ALOT to shave. .003-.005 is usually normal to just clean up the head. .015 is pretty much the most you would want to take off.

2 things that you need to keep in mind when shaving the head to gain compression. The first one is piston to valve clearance. You should plastiguage to accuratly measure and determin how much clearance you have between the two. That will ultimatly determin how much you can shave the head.

The second issue is that by physically bringing the whole valvetrain closer to the pistons, you are effectivly changing the valve timing. This is where adjutable cam gears will help. But again, you will need to plastiguage to determin clearances so you know how much you can adjust the gears. Last thing you want is to slam a piston into your new valves!!

You don't need to get high CR forged pistons to up the CR. A set of honda OEM ITR pistons would do the job nicely (or CTR b16b pistons if you're really ambitious.) I'd reccomend this route over shaveing the head.

You can also use a thinner head gasket or thicker, flat faced valves to gain smaller bumps in CR as well.

 

RacerZook is right. Also a rebuilt of a new motor you will be better off getting new pistons to get a better piston to wall clearance.

 

Shaving the head down is a bad idea in so many ways it isn't even funny.

Want more CR? Flat faced valves and higher CR pistons. OEM will work, but if you want ease of disassembly, get some full floating wristpins and aftermarket pistons and conrods. But thats also more cash. I haven't heard of good aftermarket pistons getting hotspots, but I don't know everything.

ITR or CTR pistons should jump the CR a good bit.

I'm basically just reinforcing what Chris said.

And whatever you do, use the adjustable gears and get it tuned...

After they playdoh the combustion chamber to make sure nothing hits, lol.

 

im not super smart but ill back everyone stuff up CTR pistons are a good idea aftermarket rods and what are you doing with your crank?

for the head shaving it .30 yes it way to much but you should at least get it cleaned so do .002 then your not taking really anything off but thats just me and everyone can say im dum but when your headgasket dosent seal well then you would of wish u would taken he .002 off it.

are you doing oem bearings or like ACL racing bearings?

 

Mmmm, thanks for all the input guys. I guess I may just go with pistons so. Is the P72 head any good for higher compression pistons. And how high compression could I go. The car will be running on pump gas as a daily driver.

 

I'd stay around 11-12 CR. I don't know the highest RoN petrol you've got there, but really even over 11.5 CR on a daily seems not worth it,

 

I think the fuel here is 95oct....I am planning for around 11.5-11.7, my aim would be around 220fwhp or 190+whp. Do you think this would be possible or can it be achieved on my current set up with a mild head skim and making full use of the cam gears and tuning it after the rebuild. This is going under the knife next week somtime so any help from you guys now is much appreciated as always!

 

Ok guys, update here. Plans and parts are, New piston rings, new oil pump, Toda adjustable cam pulleys IN and EX, Buddyclub head gasket and new stock P72 valves all running with the exsisting Toda Spec A cams, SK2IM, ITR ported TB and full breathing mods. Plan is to skim about 15-20 thous' off the head aiming for 11.5ish compression in conjuction with the BC HG. It will be tuned using a neo as only mild fuel corrections should be needed as it ran near perfect last time. If fuelling is off more than the neo can cope with I will get a stand alone. With the head off I might look into doing a little polishing on the ports just to open them up a snidge. Every little helps and all LOL.

What else can you guys reccommend. As I said I am aiming for around 190+whp on a daily driven motor. Will or should the above set up hit it.