Piston ring gap

[dave bushell]

What is considered to be the correct piston ring gap these days?
I’ve been quoted everything from ten thou. to sixty thou. They can’t both be right!
Dave

[Roger Moss]

Hi Dave
I have always used the traditional figure of bore size in inches times three.
ie 3″ bore for Silk Pistons x 3 = 0.009″ (Nine thou)
So I work on the safe side and make it 10 thou.
When I am building engines, I put each ring on the piston, fit it in the bore, then twist the piston LH & RH.
You can feel the piston move and the ring stay still till the ring end hits the stop. You should be able to feel and see the free movment.
We usually put a clock on to check this in situ figure.
Usually, folks put the ring in the bore, then push it down a bit with the skirt of the piston to be sure the ring is square, then use feelers to check the gap. This is a tried and proved method, but I cannot resist belt and braces!
I will never win a prize for Brevity!
Kind Regards
Roger

[dave bushell]

Thanks Roger – that’s a great help.
Sometimes people can be a little too brief with their info and you have to ask more questions!
Thanks again
Dave

[Stan Thomas]

Hi Dave,

Who’s ha some spanners for Christmas then!

Piston ring gap is ten “thou” – although in reality, a little extra will not affect the engine diddly-skwatt, being a two-stroke. Thats one gap of ten thou, not two of five thou each if you break a ring fitting them!!!!

Kind regards,

Stan Thomas.

P.S.

I didn’t think you knew the difference between a piston ring gap and Watford Gap.

[dave bushell]

Thanks Stan

No I don’t – if it’s north of the Thames!

Dave

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