Max bore on a standard head gasket?

4

49r

Senior Member
My 8BA is bored +60 and I had issues with an unknown make of gasket compressing over the bore and the piston audibly hitting it. A standard bore Felpro replacement has fixed this but it still looked close when fitting. I'd heard that a standard head gasket should do up to +80 before a 'big bore' gasket is needed?
 
I talked to Fel Pro and they told me 0.060" was max for a 7283B gasket, but alot depended on the chamfer that the machine shop put on the top edge of the bore after boring.
 
Most gaskets for the later ('49/'53) builds will not make the +080" oversize, they should make a +.060" however.

I have here Fel-Pro's and some early McCords, the fire-ring on the McCord's #6244R/L's ('49/'53) measures 3.265", and the fire-ring on the Fel-Pro's #7525B/7526B ('49/'53) is 3.255".

Fel-Pro has the bore size listed (on the above part numbers) on their "print" as 3.270", but in reality they actually do measure the 3.255".

The earlier Fel-Pro gasket's #7283B (24 stud '46/'48) does measure 3.270", so I'm assuming they simply carried the dimension "across the board" to the later pieces??

Thanks, Gary in N.Y.

P.S. Any gasket that measures 3.270" will make the +.080", the others are questionable at best! You don't want any of that fire-ring "hanging" in the bores if possible!
 
49r said:
My 8BA is bored +60 and I had issues with an unknown make of gasket compressing over the bore and the piston audibly hitting it. A standard bore Felpro replacement has fixed this but it still looked close when fitting. I'd heard that a standard head gasket should do up to +80 before a 'big bore' gasket is needed?
Click to expand...

I e-mailed Best Gasket co. about the std gasket size...this is the std 49-53 gasket set.


Hello , you should be fine with the std RS521G. Our gasket bore actual measurement is 3.295


Roy Lucero

www.bestgasket.com
Ph (888)333-2378 Ph (562)699-6631 Fax (562)699-5034
 
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