Classic cars forum & vehicle restoration.

dave 35 · Joined: 30 Nov 2009 Posts: 41 Location: west sussex

hi, I wonder if anyone can help me. I am restoring a 1935 Hillman 16 in which the engine has been rebored to plus 60. I wonder if anyone can tell me what the piston ring gap should be when the ring is sitting in the bore. I have no technical information on this engine at all. Has anyone got any literature on a 1935 Hillman 16 which might help me. Any help would be very much appreciated.

regards Dave 35

Salopian · Joined: 05 Jan 2010 Posts: 354 Location: Newport Shropshire

For water cooled engine compression rings I was always told 4-5 thou times the bore in inches so 3 inch bore 15 thou etc. As it has been rebored I assume need not consider top ridge and barrelling etc.
Oil ring a little less is permissable say 12 thou.
Its always worked for me but its your risk!
Good luck.
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Jonathan Butler
Alvis SD 12/50 1928 MG TD 1950

dave 35 · Joined: 30 Nov 2009 Posts: 41 Location: west sussex

Thanks Salopian i have today filed the rings and fitted the pistons so far so good regards dave35

peter scott · Joined: 18 Dec 2007 Posts: 7118 Location: Edinburgh

Hi Dave,

Probably not critical but the post war 1256cc side valve Hillman workshop manual quotes 6 to 10 thou for the ring gaps. It has a bore of 2.563".

Peter
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1939 SS Jaguar 2 1/2 litre saloon

Jim.Walker · Joined: 27 Dec 2008 Posts: 1229 Location: Chesterfield

I was taught 3 to 4 thou/inch for water cooled engines and 4 to 5 thou/inch for air cooled including oil control rings.
Always worked for me.
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