Author Topic: Mark 1 T35 Piston replacement  (Read 4365 times)

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Offline Denis

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Mark 1 T35 Piston replacement
« on: 14 Sep 2008 at 14:35 »
I have a 1948 Mark 1 T35 that has the high domed pistons. These are worn out and require replacement. I have read that 62mm Kawasaki pistons have been used as substitutes but for Mark 3 - 5 pistons, which have a shallower dome than the Mark 1. Can anybody out there advise me of a suitable substitute for Mark 1 pistons or where I could get new pistons and rings for the Mark 1?

Denis Pullon

Offline kmd

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Re: Mark 1 T35 Piston replacement
« Reply #1 on: 15 Sep 2008 at 08:15 »
Hi Denis

I have tried Kawasaki pistons,
They work but with out modifying the heads or barrels they give a very low compression ratio.
Honda 250n pistons are better but i found that  for best results you  need the compresson ratios raised as well.

If I  had to go past the max oversize pistons again I would have the barrels sleeved and go back to standard.

Hope this helps

Offline eddie

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Re: Mark 1 T35 Piston replacement
« Reply #2 on: 15 Sep 2008 at 09:03 »
Hi Dennis,
                 Probably the most economic way of solving your problem is to look for a pair of barrels and pistons from the Douglas generator engine. Although the pistons have a different ring configuration, they fit straight into the T35. The barrels also fit but need to have the fins trimmed away to clear the fins around the exhaust port on the head. It also pays to remove the key that prevents the cam followers from turning and then fit the free rotating followers from your original barrels.
             Oversize pistons used to be available for your machine up to +.030" but the early post war barrels were quite thin and any greater increase (including sleeving) left them prone to cracking or even breaking off above the base flange.