The spec on a stock 2000 head is 4.528-4.530", so this head has been cut about
.060". Anything over .030" will require that the cam towers be shimmed up to
compensate.
Also the compression ratio will be increased a significant amount. My guess
would be around a full point, so figure 10.5:1. That's a lot for pump gas unless
the engine is really set up right. Even then it will depend on the gas in your
area. You can compensate by having a whole bunch of combustion chamber work
done, milling the tops of the pistons or running two head gaskets (not
recommended). BTW, if you do the two head gasket thing, don't shim the cam
towers. The extra gasket will raise the head about .040-.050, thus making up for
the thinner head.
Have a good machinist check both the top and bottom surfaces for flatness. Some
shops will just mill the bottom when a head is warped, but with an overhead cam
engine, you have to mill both top and bottom to keep the cam towers parallel.
Gordon Glasgow
Renton, WA
> -----Original Message-----
> From: owner-datsun-roadsters@autox.team.net
> [mailto:owner-datsun-roadsters@autox.team.net]On Behalf Of Allen
> Blackmon
> Sent: Wednesday, April 17, 2002 10:46 AM
> To: datsun-roadsters@autox.team.net
> Subject: Non smog head and measurements
>
>
> To List,
>
> I prove I am a complete moron when it comes to engine measurements and head
> wear, I present the following. In my continuing quest to get my 1970 2000
> back on the road, I have a question about cylinder heads. Is a head that
> "averages about 113.5mm or about 4.4685" in good shape or not? What would I
> need to know? I've got the smog head and was considering replacing it with
> the above measured non-smog head. Is it worn? Good shape? Help!! I have
> no idea what the above means in relation to cylinder heads.
>
> Thanks!!
>
> Allen
>
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