can you shave stock head?

16bit · Postby **16bit** » Wed Jul 31, 2013 1:49 pm

is it possible to simply shave the stock head to bump it up from 9.5 to 10 comp ratio?

by that i mean take the stock head off, shave it and put it back on?

more of a theory thing that actually thinking about doing it.

hks_kansei · Postby **hks_kansei** » Wed Jul 31, 2013 1:57 pm

Can't see any reason you can't.

Depending of course on things like piston/valve clearance, and how it effects the water/oil galleries.

Postby **NitroDann** » Wed Jul 31, 2013 1:59 pm

We just did PaulFs head from 9:1 to over 10.

It flies

Dann

16bit · Postby **16bit** » Wed Jul 31, 2013 2:16 pm

did you crack open the head at all Dann? or just shave it and put it back on?

Postby **NitroDann** » Wed Jul 31, 2013 3:07 pm

Pulled it apart as cleaned the lifters and ported it.

Stock hardware though.

made a VERY good difference with almost no money spent.

Dann

16bit · Postby **16bit** » Wed Jul 31, 2013 3:08 pm

sweet, this is tempting.

16bit · Postby **16bit** » Wed Jul 31, 2013 3:15 pm

how much did you shave off?

Postby **NitroDann** » Wed Jul 31, 2013 3:25 pm

Lots, like 27 passes. So 27 thou I think.

Shaved it until the valves were even with the surface.

Dann

Postby **NitroDann** » Wed Jul 31, 2013 3:25 pm

Might have been 2 thou per pass.

Dann

16bit · Postby **16bit** » Wed Jul 31, 2013 3:30 pm

cool, this dude says 0.060"

does that sound right?

http://clubroadster.net/vb_forum/59-irt ... rting.html

Postby **NitroDann** » Wed Jul 31, 2013 4:19 pm

27x2 is 54 thou, which I think is correct.

Ill confirm.

Dann

Mr Morlock · Postby **Mr Morlock** » Wed Jul 31, 2013 8:57 pm

machining heads has been done for ever but you must take proper advice on what to remove. Its also wise to actually work out what you expect to achieve and what are the risks in doing it. There is a $ cost in doing it and a $ cost running it because an increase in the compression ratio may result in the need for 98 fuel. Longevity may be affected. You may need a new headgasket etc. Paying for the work to be done - which most people do- is going to cost more than one might imagine

Postby **NitroDann** » Wed Jul 31, 2013 9:12 pm

I confirmed it, pauls was aiming for 50 thou (1mm) but couldnt do it without removing the valves so stopped at 48 thou.

Then we removed the valves and ported it lol.

Dann

noobee · Postby **noobee** » Wed Jul 31, 2013 9:50 pm

48 thou(inches) is close to 1.2 mm.given a stock engine with 9.4CR and stock head gasket,your new compression ratio should be somewhere around 10.7CR.you cleaned up any sharp edges/hotspots in combustion chamber when porting I assume.
Mick

Postby **NitroDann** » Wed Jul 31, 2013 10:01 pm

Yes we cleaned it up and smoothed the edges.

Is it really?

Wow, thats a lot, I thought it was 10.3 ish, I never sat down and did the calcs just asked the advice.

Dann