Classic cars forum & vehicle restoration.

[1stpop]

Having consulted my workshop book and started on replacing the piston rings I have hit a snag.... two pistons are marked wellworthy 502.136 +030 and the other two are marked 11580 30thous o/s. Can anybody give me any clue as to the correct piston ring size? none of the ones listed in my book are stamped on the pistons

[1stpop]

Just cleaned the bottom of the crank case and spotted the following:

A +2 +4 +3 +2

I presume this is the re-bore sizing? Can you get mixed piston ring sizes?

[ukdave2002]

[1stpop]

am I correct in thinking they have been re-bored? and thats what the +2 +4 and +3 mean?

[Handyman]

No, these numbers have no reference to reboring. Whereabouts were they in the crankcases? Look more like running clearances for the mains or big-ends.

On your pistons, two are Wellworthy and two are Hepolite, but they are all plus 0.30", so the engine has probably been rebored two or three times.

I am not sure Wellworthy piston rings will fit into the Hepolite pistons, but I stand to be corrected or I'll check my piston service books and post again.

H

[peter scott]

The 11580 pistons have two rings of 2.22 mm width and two at 4 mm.

There appears to be 5 different Wellworthy pistons for the Series E.
There are ones with 3 rings which are two at 2.25 mm width and one at 3.00 mm.

There are also 4 ring pistons like the 11580 and they are stated as two at 2.25 mm and two at 4.00 mm.

There is also a few varieties of radial depth for the various Wellworthy pistons.

Rather than seeking rings for your existing pistons would you not be better looking for a set of four pistons with rings. At least you would have a better chance of obtaining reasonable balance.

Peter
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1939 SS Jaguar 2 1/2 litre saloon