Cylinder Bore Wall thickness.

Phil Gillespie

Phil Gillespie

Well-known member
221 cu in 3.75 stroke 80 thou oversize. Standard cam in use.
Block has been cleaned and is presently away for Ultra Sonic wall thickness at bores.
Want to go out from existing 3.1425 to 3.1875.
Whats the good safe wall thickness to be looking at?
0.100 a good figure.
Phil NZ
 
Ive just bored mine out to 1.00 over, fitting Egge pistons previously was at .085 with 12thou wear so cleaned up pretty easily (Previously sleeved I believe) just reassembling now I didn't ultra sonic test so fingers crossed. Hope I don't learn the hard way!
 
It depends on which year 221 block you have. Some early versions were cast with thinner cylinder wall thickness than others. There was a previous post on this subject. You might want to do a search and read that one.
 
.100 is pretty thin . . . usually I see a number like this with about a 3 3/8 bore. (like .090 to .110).

Unless it is a 100% race engine where you need all the cubes you can get, I'd prefer to have a cylinder wall thickness of at least .150. Also, you need the thickest walls on the "thrust side" of the bores - they take the most load. When you have it sonic tested, you need to take about 12 measurements per bore. Three locations up/down the bore and on all four sides.

Good luck!
B&S
 
Bored&Stroked said:
.100 is pretty thin . . . usually I see a number like this with about a 3 3/8 bore. (like .090 to .110).

Unless it is a 100% race engine where you need all the cubes you can get, I'd prefer to have a cylinder wall thickness of at least .150. Also, you need the thickest walls on the "thrust side" of the bores - they take the most load. When you have it sonic tested, you need to take about 12 measurements per bore. Three locations up/down the bore and on all four sides.

Good luck!
B&S
Click to expand...
B & S
Appreciate your advise. Will await and see how it measures up and hopefully will have the required reserve thickness at the wall thiskness.
Phil NZ
 
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