Does anyone know the larged diameter piston that can be installed "safely" into the inline 200? I'm just wondering. I know it will effect the valves but how? Any info. would be great! :D

Howdy Chris:

IIRC I've seen .010", .020", .030", .040", and .060" listed as cast, dished replacement pistons for 200/250. Custom forged pistons could, conceivably, be made to your specifications- pricy though!

Due to the thin wall casting FoMoCo used to cast these blocks, I'd be cautious of going beyond .040". There comes a point of deminishing returns- Where loss of cylinder wall rigidity and consequently, loss of piston to cylinder seal more then offset any gain from an extra cubic inch or so. If you must go beyond .040" plan to do some cylinder wall thickness testing with a sonic thickness tester first. If there appears to be enough thickness then take the following extra precautions. Bore and hone with main caps torqued in place and, if at all possible use a torque plate on top. Honest to goodness torque plates for our six are very rare, but can be made out of an old head, bar stock or get creative. This will stress the cylinder wall to their finished form and, hopefully, get them close to there finished form when the engine is finally assembled.

That's my two cents.

Adios, David
Thanks David.

I think I'll drop that idea now that I know the numbers. I just wasn't sure what would be a safe size to use in lue of stock. I thought 3.75 in. would be ok but now, I don't think that would advisable. ;)

8) basically you want to use the smallest overbore possible to clean up the bores. the amount of power increase you get for an overbore is something like 1 o2 hp at best.
Howdy back:

A 3.75" Overbore may not be out of the realm of possibilities, but I would start by Sonic testing several blocks to find the thickest and to give me the thickness needed to safely and reasonably proceed. I'd be hoping for .100" thickness on the thrust side, after boring, so add half of the overbore diameter increase to .100" as a goal thickness before boring.

3.75" minus 3.68" + .070" / 2 = .035" + .100"= .135" goal thickness.

Good luck.

Adios, David