Hi Folks.
All the OHC engine details I have seen, including the Hepolite piston catalogue, talk about a 9/16in dia piston gudgeon pin, and a 36mm compression height.Hepolite number RS7759 and RS7811. Later than 1933 engines have a 15mm gudgeon pin and 25mm compression height.RSW11578. I have a spare block, which came with its pistons. That has 15mm gudgeon pins and 36mm compression height. The matching con rods also have the normal pinch bolt arrangement, but for a 15mm pin. It is a 1930 engine. Can anyone throw any light on this, and why are these pistons not shown in the Hepolite catalogue? Thanks. Roger.
Small end size.
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Small end size.
Last edited by RLucke on Tue Jan 29, 2008 11:47 am, edited 1 time in total.
Roger Lucke
Re: Small end size.
Roger,
Have you looked in the hepolite book under Wolseley Hornet. I have a recollection from somewhere in the past that the Hornets used metric dimensions. Are those pistons domed? Are the con rods steel or aluminium? Hope this is of some use. Simon
Have you looked in the hepolite book under Wolseley Hornet. I have a recollection from somewhere in the past that the Hornets used metric dimensions. Are those pistons domed? Are the con rods steel or aluminium? Hope this is of some use. Simon
Re: Small end size.
Check the pistions for a Morris 10/6 and the 10/6 special. I have dome top pistons in DF with a slightly larger gudeon pin than standard and a different pin to top distance. The sides of the pistons don't come to the top of the bore, but the dome part does - if you see what I mean. We thought these came from a Wolseley at first but the actually came from a came from a 10/6 special. You can make the gudeon pin holes a little bigger if you need to! Who knows what my compression ratio is! Shame they didn't add the other 2 cylinders!
Cheers
Jeremy
Cheers
Jeremy
Re: Small end size.
Wolsley Hornet pistons RS 7811 appear to be the same compression height,36mm, and gudgeon pin size 9/16in, to the Morris piston. The pin does have a flat for the clamp screw, instead of a groove. Morris 10/6 pistons RSW 11579, have a higher compression height, 40mm with a domed top, and 15mm gudgeon pins.
Post war Morris 803cc Minor RSW 12587 have similiar pistons and 9/16in gudgeon pins, but only 33mm compression height, and a concave top.
RSW 12003, also for the 803cc engine are flat.The standard size is 57.9mm.
I think the real answer to my pistons, is that whoever last rebored it, used the pistons he had to hand, and slightly enlarged the small end eyes to suit. Regards. Roger.
Post war Morris 803cc Minor RSW 12587 have similiar pistons and 9/16in gudgeon pins, but only 33mm compression height, and a concave top.
RSW 12003, also for the 803cc engine are flat.The standard size is 57.9mm.
I think the real answer to my pistons, is that whoever last rebored it, used the pistons he had to hand, and slightly enlarged the small end eyes to suit. Regards. Roger.
Roger Lucke