I want to have my SB400 bored .060. Before I go have it sonic checked, and hear their opinion, i'd like to hear your opinions on minimum cylinder wall thickness. Approx 525-550 HP, no N2O, 6700 max rpm. 95% drag race. I plan to fill the block, short fill. Thanks.

Lonnie

YOU SHOULD HAVE A MINIMUN .160 ON SKIRT SIDE OF CYLINDERS AT YOUR FINISED SIZE.

Lonnie,
Carl is correct on the thickness. If you are only going to be racing it, fill it up to the bottom of the water pump outlet holes. Personally, I would sell the block and spend your money on an aftermarket one. By the time you spend the money having it sonic tested, filled and fully machined...you would be better off with a Dart or World Products block.
Just my opinion,

I agree but just want to add the .160 minimum is what you want from about the center of the cylinder up on the thrust side.
You will find the cylinders get a lot thinner at the lower part on a lot of blocks & this is not a problem. It would be nice to see .160 everywhere but it will be a pretty rare block that is this thick down low.
I have seen a lot of 400's in the low .100 to as thin as .080 at the bottom of the bores.
Again, I don't feel this is a problem, built a lot of them & they are still fine.

And as Bill said, if it's a race deal fill it to the bottom of the pump holes or if you can afford to, get an aftermarket block or the Bow Tie Sportsman block, they have real cylinder walls ;)

Thanks for the info guys!

I would like to have an aftermarket block, but they are pretty expensive. How much is sonic testing? I don't see how a bore/hone will come anywhere near the cost of an aftermarket block. If I have to spend that much I'll build a 454 instead.

If it is too thin, I'm just going to run it the way it is. It is .040 with no wear, but wasn't done with torque plates, and I do get a little blow by. At .040 it runs about 5 degrees cooler now than my .060 383 with identical cooling systems, so I'm hoping it will go .060.

I don't want to do a tall fill cause I will still be driving to the track and back.

Are the Dart and World blocks ready to go? Or does more money need to be spent on honing, decking ect...

Lonnie

Lonnie,
The new blocks come semi finished in the bores & decking isn't necessary except for setting to a specific height
we charge $80 to sonic a clean bare block.
For what you are doing I would bore it & run it.
Lots' of .060 400's out there running fine. Also lot's of blocks a lot thinner than .160 running fine.
The .160 number is what we would like for a minimum but I can guarentee you that there are 350's & 400's with cylinders in the low .100 range doing just fine but my preference along with the others here I am sure is to not build a performance engine with thinner cylinders.
That said, I do not usually run 400's more than .040 over, preferably .030.
That's my preference because of head gasket issues around the bore more than bore thickness.
The 4.200 gasket gets real close with .060 over cylinders(4.185), that's only .0075" to the gasket & I find a lot of blocks where someone has chamfered the block to where the fire ring is hanging in the bore or the bores are not exactly where they should be.

I've ran .022" steel shims on my 406 fine but did work with them over by drilling the needed holes and relieving the overhang around the intake valve sides so they fit my old -461 big valve heads better.

pdq67