SOHC.co.uk Forums > CB350/400
Engine rebuild Parts list
McCabe-Thiele (Ted):
--- Quote from: Bryanj on March 07, 2024, 11:30:27 AM ---If you never used thousanths you are knackered as you need to measure to a tenth of one
--- End quote ---
As Bryan says you are dealing in Microns of clearance - even the temperature of your hand can alter the journal readings as you hold the Micrometer.
Dolomite_:
Where is 45 coming from?
I understand the + and - I just can't figure out + and - from what figure.
McCabe-Thiele (Ted):
--- Quote from: Dolomite_ on March 07, 2024, 12:23:03 PM ---Where is 45 coming from?
I understand the + and - I just can't figure out + and - from what figure.
--- End quote ---
Sorry my typo error as I was relying on my memory from your tables link - I'v amended the figures now
When you measure the crank journal itself that reading will become obvious in the tables tbh I get confused between the journal allowance & the crank case allowance - it's the journal you are actually measuring so it will be 32.00 to 32.010 iirc.
Dolomite_:
Ahh ok got it now. I didnt realise the graph was in millimeters.
McCabe-Thiele (Ted):
--- Quote from: Dolomite_ on March 07, 2024, 01:05:20 PM ---Ahh ok got it now. I didnt realise the graph was in millimeters.
--- End quote ---
Correct it will fall into place once you measure your crank & look at the chart figures.
I'm not an engineer so the terms like crankcase allowance appear to be not something you can measure at home if I am making sense now.
I was lucky as I was using my original crank so the one Green Shell gave me a starting point - I bought a pair of new Green Shells then using Plastigauge I was able to work out where I needed thicker shells from there as the Plasigauge Gap changed..
My casing code was C A A B A I ended up using Black,Green,Green,Brown,Green. shells for the Mains. My Plasigauge clearances were all around the 38 microns mark. My crank web markings were not all visible hence my reliance on Plastigauge - a fidly process but you get better at it with practice - worth looking on U tube to get an idea of how to do it.
Additionally As the crank wears for a particular casing code you fit a thicker shell as you can't have the crank ground to fit oversize shells as you would for some car cranks.
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