Will soon need some good Gaskets to complete my engine rebuild ( Dommi 88 1959) . I have a `spigot` type barrel so presume a copper one is the only option ? What I want some advice on is what are the best to buy and who to deal with ?
Also .... Having built the bottom end with a 11 ball bearing and a `superblend ` on the crankshaft I dont really understand why this eliminates the necessity to do any shimming ?
Can anyone explain please !
Crank is pulled into the…
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The ball bearing limits the…
The ball bearing limits the end float as the crank can only move due the amount of tolerance in the ball bearing itself.
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Thanks for the reply Robert…
Thanks for the reply Robert and Ashley. If the crank is pulled up against the timing side bearing after Torque tightening the `worm` drive nut why would you need to shim at all ( If you had Ball races both sides ) ? Is the reason for me NOT having to Shim because I`ve fitted a Roller bearing ( Superblend type ) on the drive side and that can `adjust `sideways ? Should I have any End float at all (before tightening the worm drive nut up ?
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If you use ball races both…
If you use ball races both sides and you had enough movement to shim then you have two lose outer races in the cases - this would be a problem. When you tighten the worm this only pulls everything up against the the shoulder on the crank and has nothing to do with alignment. If you have a ball bearing one side and a roller the other then there should be no need to shim and you would struggle to find any lateral movement as this is constrained by the tolerance in the ball bearing and this is the reason you don't need to shim. If you have end float with this configuration that is any more than the tolerance in the bearing then the outer race could be lose in its recess - not good.
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I dont want to appear daft…
I dont want to appear daft but if you torque up the worm drive nut pulling the crank tight into the timing side Ball Race there will be no end float , So should I measure any end float before tightening the worm drive nut up or is there no point ? Just want to be sure having spent so much time and cash . At present the bottom end is all assembled and torqued up and turns free and smooth.
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Ashley - for my future…
Ashley - for my future reference do the so-called superblend roller bearings have the lipped roller feature on the outer or inner part of the bearing? On my Dominators I still use the brass-caged MRJA 30 on the drive-side and the ball bearing on the timing side. On smaller racing engines the notched 10 or 11 ball bearings but on road engines the standard MJ 30 works well. As you say shimming is not necessary unless the outer of the roller bearing has worn the crankcase receptor.
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Crank is pulled into the Timing side bearing by the nut next to the oil pump drive. I have always used the copper faced composite head gaskets with extra sealer around pushrod holes and oil drain ,plus seal off the front bolt/stud holes .Several re-tightenning sessions needed as they settle down .