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232 Head Thickness on a 262
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Thinking about putting a 232 head on my 262, to bump up the performance, mileage, etc. I know that the stock head thickness is 2.00". Just wondering what is the thinnest head thickness one can safely use without overstressing the bottom end of the motor. I've got one that looks to have had .025-.030 removed from it previously. Seems like I read one can remove up to .060 safely, but wanted to make sure.
Thanks for the help. -
Typical minimum is .060" under, or no less than 1.940" thick. The weak link in the chain isn't the bottom end of the motor, it's trying to keep a head gasket sealed. When the head thickness gets too thin, the deck surface of the head will flex between head bolts, especially with an aluminum head. The added compression compounds the problem. You can't keep a head gasket sealed, although the new BEST brand gaskets will still seal well under conditions where the Fel-Pro gasket would seep. Another concern is that the spark plugs will get smacked with the exhaust valve.Workin Stiff
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As far as I can tell, by putting a 232 head on my 268 (262 bored .040 over), I'll raise the compression ratio a full point. From 6.7:1 to 7.7:1, which is even more than the 7.2:1 from an aluminum head. Actually, it would be even more than that, because the 232 head I've got would have to have at least .050 total shaved off of it, which would raise it even more. Maybe I'm setting myself up for future problems if I raise this up into the 8:1 area????
On a side note, I bought a new FelPro gasket from Russ Maas at the Nats. He didn't have any Best brand gaskets to fit a narrow block 262, which is what I've got. The FelPro is a sandwich style (metal/fibre/metal). Have you used this one before?
I'd appreciate any and all opinions or suggestions on whether I should do this, or just leave well enough alone.
Thanks for the help -
I had some seepage on the driver's side using a new Fel Pro gasket with a .060" undercut aluminum (262) head on my '49 262, and again with a .060 undercut aluminum 308 head on my '52 308. The problem went away after using the Best gasket. Another point to consider is that since there is NO relief cut in the '48-49 262 deck surface between the valves and cylinder, you may be choking off flow by using the smaller head. My understanding is that any losses in compression you get by cutting that block relief are more than made up by the flow you gain. Bottom line is that you may get a power boost with a 232 head if your 262 is a '51 or later, but you might not if it's an earlier motor with no block relief. I assume you know that the '48-50 heads are not interchangeable with the '51-later engines (and vice versa).Workin Stiff
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Actually, there is SOME block relief on my '49 block. My original '49 block didn't have any at all, but that engine has been replaced by one that was produced toward the end of the '49 year that I picked up. It's got large circular cuts, whose axis is angled about parallel with the valve stems, right in between the bore and it's two valve openings. It's not on par with a full 7X relief, but it sure looks like it must increase the flow a lot more than my original block. I also smoothed off and polished all the sharp corners left between the machined cuts when I rebuilt the engine.
Coincidentally, the failure of my original block was a crack that developed between the #6 intake valve and bore. I believe this was a problem that had been addressed by Hudson by the end of that year with the above 'fix'.
Were you able to find a Best gasket to fit your narrow block 262, or had you switched over to the 308 by then?
Oh yeah, I'm aware of the block differences. That's why I had to find a '50 Pacemaker head for a 232 that would fit my block width.
I should probably leave well enough alone since it's running great these days, but working on the Hudson is almost as much fun as driving it, and I've got just about everything else 'done'. Plus, it would be nice to up the mileage a little. I'll decide next winter....for now I'm just driving it as much as I can.
