On this B31 engine I am building I only split the crankcases to clean the inside as the engine arrived in a dirty condition with the barrel off. All the bearings look and feel fine so I havnt touched them.
After I tightend the crankcase bolts the crank did not spin freely-- there was a bit of tightnes.
When I eased the bolts it span freely.
I had used Wellseal on the case joints. Do you think that Wellseal could be to thin for this application--it leaves a very thin film after being compressed? Do I need a thicker gasket compound that will space the cases apart a bit further?
Sorry to ask so many dumb questions
All help is very much appreciated
email (option): gasboy@btinternet .com
Hi Peter, These engines dont rely on gaskets/compound to correctly space the cases so it won't matter what compound you use.
The tightness you have is caused by something else.
First check that the spacer between the main bearings on the drive side is within tolerance..1.000"-1.005".
Also check that the oil flinger plate behind the drive side inner bearing looks undamaged and is sitting flush against the flywheel boss.
If you haven't checked it yet, check the oilpump to make sure it is not tight..it may well be and will require rectification if that is the case. Check the oil pump drive spindle and crankshaft pinion for damage to the teeth of the oil pump worm drive.
If/when all that is correct reassemble the crankcases...
Fit the crank pinion and the timing gear outrigger plate along with the crank nut on that end.
Finally fit the engine sprocket carrier and crank nut on the drive side..tighten the crank nut just over hand tight.
It is important the sprocket carrier and nut are fitted as this pull the crank assembly over to the drive side of the cases...its correct position.
If not fitted, and with the crankpinion in place, rotating the engine in the normal direction will pull the crank to the right, forcing the crank pinion against the back of the outrigger plate bush and the engine will go 'tight' after a few revolutions.
Turning it backwards will slacken it off again as the pinion moves away from the bush....|Ian