Author Topic: Conrod Measurement  (Read 295 times)

Online Gavin

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Conrod Measurement
« on: 26.08. 2016 14:54 »
Hi, I need to have the diameter of the small journal conrod hole to check it before inserting new shells. If someone has that fine detail I'd be very appreciative. I think after this one my machinist will bankrupt his delaying tactics, and his company will then bankrupt me !!

Many Thanks.

Gavin.

Online KiwiGF

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Re: Conrod Measurement
« Reply #1 on: 26.08. 2016 20:46 »
I can't really help as I've not done this, not properly anyway, but obviously you will need the right measuring equipment for measuring an internal diameter, I reckon the micrometer will have to be accurate to 0001" eg a tenth of a thou. Unless you have that I think you will need the machinest to do this for you.

You may be able to make a rough measurement with a vernier, that will tell you if your rods are oval at least.

What you are looking for is generally ovality in the rod I.d. Which obviously started life round. The top and bottom of the rods sometimes get beaten out of shape by the forces of compression/firing, a machinest can fix this by taken a little metal off the joining face of the rod and then machining the id round again, due to the accuracy required this machining of the I.d. may be done by a special honing machine. This fix only works if the id when measured at the side of the rods is correct eg not worn or out of shape as no metal is removed from the sides when making the rod round again.

Rather than spend money on getting this sort of work done on my oem rods I simply bought new rods from thunder engineering, it did not cost much more!
New Zealand

1956 A10 Golden Flash EA7-168x, CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

1949 B31 rigid “400cc hot rod” (favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, missing parts so mission impossible?

1952 Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why, maybe cos it always starts