You can probably improve the bearing and therefore crank life in the
Spit motor as follows:
1) The oil feed holes from the main oilway to the middle main bearing
then splits in the crank to supply TWO rod bearings whereas the front and rear
main bearings supply one one rod bearing each. Maybe someone into fluid
dynamics may be able to tell me if this is correct, but maybe this could cause
some oil starve problems or the oil becoming hotter or something. But
the Spit comp prep manual suggests drilling the oil feed hole to the center
bearing so making it larger. This increases oil supply to the center bearings.
Plus you can make the hole in the crank tear drop shapped to aid supply
at higher revs.
Use 77 MGB rod bearings instead of Spit rod bearings. You will need to regind
the crank to suit and rod bearing life will be indefinate.
2) I am also told that an oil cooler is madatory for the 1500 used in midgets.
maybe it would help for Spits. The real ackilles heel of the spit engine
is the thrust bearing. Convert to a full circle thrust bearing. Maybe this
will help with lower end bearing problems.
3) Have the crank nitrate hardened after shot peening to releive stress.
I have NOT done these mods, so can't comment from experience. But i am in
the process of doing them. So ask me in 70 K miles time :)
Cheers Dennis
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