2 replies [Last post]
Micha's picture
Joined: 10/12/2007
Posts: 414

Hi. I am starting to think seriously about an engine overhaul and would like to know if there is a possibility to use an other substitute for the pistons, i.e. a matching piston from a modern vehicle or, at least, a more common one. The original pistons are very expensive. Thanks and regards, Michael.


Michael Steinmann
R51/3 1952
Engine Nr. 529466

EuroIron's picture
VBMWMO #7266
Joined: 04/23/2007
Posts: 414
Replacement pistons for R51/3

I don't know how much originals cost but I highly recommend contacting Keith Black and pricing appropriate blank pairs even of their HyperEutectic low expansion pistons and then Total Seal for their mighty fine Gapless RIng sets.

I know for a fact Total Seal has rings that will fit the stock pistons and they are cheaper than OEM, amazing sealing qualities and easy to find 2-4% leak down with no extraordinary preparation...... stock in good shape does well to leak down any less than 20%

The Gapless rings work very well.

The KB pistons set up with 0.0005" - 0.0015" skirt clearance and have worked phenomenally in every engine I've used them in, especially the vintage ones

If you will post the critical dims, I do have the Internal Engine Parts catalogs which list pistons by their physical dimensions and ya never know when a modern piston out of a semi-universal Japanese or whatever engine may just all but drop in place

I think the last time I crossed some over I found some Alfa pistons, think so anyhow, that worked in a Bevel Drive Duck Twin with only a bit of massaging

saved about 500 bucks

comet's picture
Joined: 10/27/2006
Posts: 161
Replacement pistons for R51/3

A few years back John Landstrom at Blue Moon Cycle sold, I believe, Fiat pistons that worked well in the pre 55 BMWs. You might contact him.........Comet

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