Can an 850 engine be sleeved?

I recently bought a 903 engine that turns out to be little more than a boat anchor. One cylinder wall is badly pitted and turns out the engine was previously bored out to the max oversize. Looking at the 1-2 & 3-4 bore clearances I'm wondering whether it's possible to sleeve the block; assuming a sleeve so small is even available. Does anyone know?

Mark

Yes.

Yes, an 850 engine can be sleeved. I used to have a few sets of Borgo sleeves for the 850, but that was ages ago (sold them back in the 1990's). A quick search on Google under "Fiat 850 cylinder sleeves" (or "Fiat 850 cylinder liners") might get a few sources for them (mostly in Europe). This one looks legit, decent price on the parts but shipping may be pricey (they're in Australia):

http://mail.precisionintl.com/Part.aspx?ID=33658&EID=772

You might also contact Chris Obert (C. Obert & Co, aka Fiat Plus) or John Edwards (Costa Mesa R&D Machine) as a possible source here in the USA.

If you just need a stock-bore (65mm) 903 block, I may have a few bare blocks in storage for you to choose from (I know I have a few 903's, just not sure exactly how many are bare blocks vs. complete). Everything on your 903 can swap over, but you'll need to source new pistons (some 65.6-65.8mm sets have been selling at decent prices on eBay in the last few months).

Did you know that you can OFFSET bore the 903 block (65.0 /66.0) to 67.2/68.2 oversizes using OE Fiat parts!

That's 965cc to about 990cc on the stock stroke and rods / pin size.

Head gasket / Pistons from some Panda 4x4 / A112 Abarth...

SteveC

Yup!

fiatfactory said:

Did you know that you can OFFSET bore the 903 block (65.0 /66.0) to 67.2/68.2 oversizes using OE Fiat parts!

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Really the most you'd want to go would be 67.2/67.4-ish, otherwise the 850 cylinder walls get really thin near the water jackets. To offset-bore to this size, it's most desirable to start with a bore that's as close to stock (65mm) as possible, otherwise you can't achieve the "offset" properly. PBS used to do this conversion often back in the 1990's (903 bottom end with 67.2mm pistons).

I was actually considering off-set boring but will need to see if it's possible considering the block is already at 65mm. If not, I will be interested in finding a bare block or a complete engine. Jeff, please PM details. Thanks, Mark

Mark said:

I recently bought a 903 engine that turns out to be little more than a boat anchor. One cylinder wall is badly pitted and turns out the engine was previously bored out to the max oversize. Looking at the 1-2 & 3-4 bore clearances I'm wondering whether it's possible to sleeve the block; assuming a sleeve so small is even available. Does anyone know?

Mark

Click to expand...

Any machine shop (that's good) can sleeve your block for you. They will supply the sleeves.
Often the sleeve material is superior to the Fiat block material, so it's a good upgrade.
I have found the blocks are so sturdy that they don't distort during the process. But be prepared to have it checked.

Chris Obert