Does there exist a list or thread anywhere that details for each year a respective block was manufactured, the maximum bore one can safely achieve w/o new sleeves? I'm working on putting together the essentials to get an 83' block bored to 101.6mm and I want to be absolutely sure I can do so safely before I drop the cash at the machine shop.

 

Just follow Harts advice, nitrogen sleeve it.

 

Nope.... most agree that a "thick" 5.0 with 100 mm can be run out to 104-104.5 mm normally aspirated. I think some 97 mm "4.7" blocks have been opened up to 100 mm and run 85-86 pistons..... There has been much discussion about core shift in the casting process where the cylinders are not centered and the wall is thinner on one side or the other.

 

I wonder how often it all looks good, but once the block is bored its no good?

 

Agreed... exactly what I want to avoid.

 

the largest pistons anyone runs in a conventional stroker is 104.5mm with most 104mm....the early blocks are "thinner" castings so they can't go quite as large....but 101.6 doesn't seem too extreme....especially if you start with an 85-6 32V block as they tend to be quite thick

 

I'm starting with an 83' 16V block... to the castings are a bit thinner. I'm working on squeezing some 4" [101.mm] pistons in it for giggles.

 

It depends on how thick the cylinder towers are to begin with. Reynolds quoted a minimum tolerance of .250" thickness, which you means you can bore until the thinnest part of the cylinder wall (due to core shifting the bore center doesn't run through the center of the cylinder tower) is .250". I think Mark Anderson had stated on one point one of his motors went down to .220" thickness with no issues. If anyone is running thinner cylinder walls than that, they haven't spoken up. I have a block that has been bored out with the alusil lapping process but the cylinders have a few sections where they are .200" thick, which is 20% less than Reynolds minimum. Rather than running the block I started over and went nikasil.

 

I can't remember what the minimum thickness "should" be......someone has to know......then just measure your actual block to see how large you can go.....I do remember someone saying most early blocks can go to 100mm no problem and most S4+ blocks can go to 102+..... but the benefit of staying 4" is the cost of the rings will be FAR less...

 

just a "boring" 104mm here. With some nikasil.

Supposedly other S4 blocks can handle more, but then you have to find pistons to fit....

Stroke is vastly more fun. torque torque torque!

 

atb, I will measure it and see what I come up with. Your note about 0.250" wall thickness is *extremely* helpful.

iceman, the benefit of staying at 4" is two-fold. Pistons *and* rings are much cheaper. I don't have to purchase custom versions of either.

Thanks everyone for your inputs.

 

A good machine shop should have a ultrasound to check for thickness I would think.

 

I'm adding stroke as well... having the crank worked on to accommodate to fun rods.

 

Why not take the block to the machine shop and let them tell you yes or no?

OTOH the more I hear about the boring process, the more concern I have to it working out well.