As some of you know I have run into the problem of high compression on my engine rebuild. I have a rebuilt engine bored .020 with flat tops. Sitting on top is an mn47 head that is rebuilt but stock. I now know that the compression will be too high and am looking for a 2mm copper headgasket.

I haven't found one that is reasonable but did find someone here in the Phoenix area who could make one but it would be 2.33mm thick.

How do i find out what the compression would be with a gasket this thick??

Try this link...

http://www.rbracing-rsr.com/compstaticcalc.html

Googled calculating static compression ratio...

Bear in mind that aluminum headed engines will tolerate a little more CR than cast iron heads. I run 10:1 on my aluminum headed 350, but I have the advantage of a knock sensor and I run it on regular pump gas unless it is very hot outside. Post up your info so others can follow along.

Charles

  Patcon said:

Try this link...

http://www.rbracing-rsr.com/compstaticcalc.html

Googled calculating static compression ratio...

Bear in mind that aluminum headed engines will tolerate a little more CR than cast iron heads. I run 10:1 on my aluminum headed 350, but I have the advantage of a knock sensor and I run it on regular pump gas unless it is very hot outside. Post up your info so others can follow along.

Charles

I would not use 3.14 for pie you will have rounding errors in the equations, I'd use 3.14159

Look up the shop BMC in Pheonix http://hammondsplains.com/z/zworld/bmc/index.htm

and get it O-ringed

or DIY

http://www.iskycams.com/pdfcatalog/2004-05/page16.pdf

Edited April 15, 201113 yr by Blue
'cause

I think that is more than I can afford.

I've tried to get in touch with Blake but haven't had any luck. I did find a calc on Atlanticz and it showed a ration of 9.95:1. Now I'm trying to find a stage 1 or 2 cam. Is it better to find a new one get one of mine reground.

Paul, i would have a Nissan cam send out for a regrind, by far better steel try Delta, it's not that expensive.

Chris

You might see if you can find a Gretty or Trust head gasket set. They are copper that you layer to get the right thickness

I checked Gretty but they don't show an 28 on their web sight.

  az240z said:

I checked Gretty but they don't show an 28 on their web sight.

They don't make it any more but I have seen sets for sale on ebay. Also check with someone who gets stuff from Japan they might be able to get it. I don't know how hard it will be to get the item with what happened, but I would not let that stop me from trying.

The guy on ebay that sells/makes copper headgaskets for datsuns can make any thickness of gasket you want. you supply the material he cuts the gasket, i think he is in the Phoenix area could be the same guy. Also Tomei makes a 2mm headgasket that i use for a 3.1 stroker.

Rex

I have spoken with him. In fact he lives about 10 miles from me. He can make me a 2.33 mm copper gasket for a reasonable amount. It would give me a ratio of 9.96:1. I was thinking that a stage 1 or 2 cam may lower that down a little, to say 9.00 to 9.30:1.