6.2l bore clearances

[Bojangles]

Rebuilding a 6.2l. The bores had some pitting which was probably caused by water in the oil. Engine has been sitting for a long time.
I honed all the cylinder bores and the look good.
I then measured the bores and found that They exceed the maximum bore size tolerance.
The pistons are standard and within tolerance.

Measurements of the oversize are below.
No 1 0.945 Thou
No 2 2.52 Thou
No 3 0.945 Thou
No 4 3.701 Thou
No 5 3.307 Thou
No 6 3.701 Thou
No 7 5.26 Thou
No 8 0.157 Thou

My question is is it ok to run the engine with the above parameters?

My thoughts are that the only real worry is the 5.26 thou No7 cylinder bore

Thanks

[DmaxMaverick]

If your figures are simply the overbore of standard pistons, they need to be bored, and oversize pistons used. If you were able to "clean up" pitting with a hone, then they weren't pitted. If they were pitted, and you honed (excessively) until they weren't, the cylinders aren't round or straight. Good luck getting new rings to seat. Honing is no substitute for a proper bore. A hone is intended to only scuff the surface to allow oil adherence, and should never change the diameter. They need to be properly bored to get squared up. Numbers 4-7 are concerning.

If your figures are overbore of the maximum bore diameter, then they are out of acceptable range. Either scrap the block, or run what you have. New rings won't likely seat, so prepare for a lot of blowby. Toss a coin, or cut your losses. I've seen acceptable results with a worse start, but that's an exception, not the rule.

[Bojangles]

Thanks for your advice.
Looks like I have 2 options.

1. Bore it and fit oversize pistons.
2. Buy a new block .

Can anyone advise where to buy a new block?

Thanks

[DmaxMaverick]

New blocks are pricey. Optimizer or P400 6.5's is it. Navistar castings and AM General builds. 10 grand plus, but it will likely outlive you. If your block is good otherwise, there's no reason to not bore/oversize it. It isn't that big of a deal, no more than any other big block build, and parts are still available at reasonable prices. Check it for cracks and such, and source some Navistar heads, Navistar forged or Scat cast steel crank, Fluidampr balancer, and make a good one. Not cheap, but you already have cheap, and it ain't moving.

A couple members here recently did stock-like 6.5L rebuilds (in the 6.5L forum, Arveetek and More Power), and posted them. Read them, for starters, and get a feel for what's ahead of you.

[Robyn]

Stock bore size on a stock 6.2L diesel is 3.98" (These are metric engines)
Piston to cylinder wall clearance can be quite happy in the ,003" to .004" ranch
Even .005" between the cylinder and the piston will not be terrible......

Factory was around .002"
I am not a fan of that tight on these engines...

[Robyn]

AS Maverick said.
Get the block tanked and magnafluxed for cracks
Bore to .020" oversize or even .030"

I am looking at your numbers ?????
What is the exact bore size on the cylinders
What are the exact clearances between the pistons and the cylinder.

Post those numbers please and lets just see what you have before we start spending the $$$$$$$$$$$$