I've just removed the piston from my 1950 B33. It's a heplex 11341 with maximum skirt diameter around 86.4mm. There are no markings to indicate whether it is standard, +20, +40 etc and would like to fit new rings.
Does anyone know what size it's likely to be?
Can anyone suggest where I might obtain some rings?
And when I reassemble, should the split in the skirt be at the front or back, or doesn't it matter (it was facing the front)?
Cheers
my go-to place is Cox and Turner at Tintinhull near Yeovil - loods of rings and pistons and rebores/regrinds on classic vehicle
chap to ask for is Kit
sorry , I cannot answer the other part of your question
I'm not sure about the split skirt but the smaller valve cutaway goes to the exhaust side. I can't see from your picture if the cutaways are different sizes though.
With an 86.4m max dia it is more than +40
The split goes to the front. It does matter.
11341 is a 6.8 compression piston. See below page from old Hepolite catalogue
The oversize should be stamped on the piston top if you carefully clear the carbon.
Many thanks for your help. Having polished the piston top to within an inch of its life and with the sun now shining, under the very clear 11431 was a faint 'Made in England', under that was +060 and under that was 'Front'. I phoned Drags for some parts and enquired about the rings and they had one set in stock; so now ordered. I'll be replacing the small end bush while I'm in as I found a small amount of play.
Re the valve cutouts, they're the same size on this piston.
Cheers