Here is an interesting problem.
Project is to use a crankshaft from an in-line engine in a vee engine. The original crankshaft is capable of being remachined to accept a pair of narrowed connecting rods on each big end journal. The trouble lies with the oil supply to the rods.
On the big end journal the oil hole is located exactly half way between the adjacent webs. That means that for the in-line engine application the oil is supplied right under the connecting rod big end. All well and good and as it should be. However when a pair of rods is to be swung on the same journal (for the V engine) that oiling arrangement is not satisfactory. The oil needs to be introduced directly under each of the two rods, not off to the side. A pair of oil holes is required, each would need to be about 25% of the journal width away from an adjacent web. So the question is how to achieve that.
Is it permissable to plug the existing oil hole and redrill two new ones in the desired locations? Or would this catastrophically weaken a crankshaft? Comments, thoughts, advice?
Thanks & Regards
Crankshaft alteration for a V-engine
Started by
Gerald Ryan
, Apr 14 2008 19:12
3 replies to this topic
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#2
fastcarl
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Posted 14 April 2008 - 21:19
how about grinding a channel from the origional hole along the journal to the desired point, some oil will escape through the gap between the two rods but i'm sure enough would get to where it would be needed, drilling more holes should not reduse its strength. just the same as retro crossdrilling.
carl
carl
#3
Gerald Ryan
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Posted 26 April 2008 - 20:09
I've no idea if that would work. There have been a number of projects where a pair of motorcycle engines have been spliced together to make a V engine. Some of them used a new crank but I've heard that a few kept the original. It'd be interesting to know what how they did it.
#4
McGuire
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Posted 26 April 2008 - 21:37
In the distant past, one way fours were converted into V8s with the existing crank was with a master/slave rod arrangement. Like a radial aircraft engine, in other words, but with a single slave rod per master rod, four master rods.
I don't see why you couldn't plug the existing oil gallery and drill two new ones to suit adjacent rod pairs as you suggest above. It's a bit dodgy but then so is the whole program. I believe most of the four/eight motorcycle engines use billet cranks.
I don't see why you couldn't plug the existing oil gallery and drill two new ones to suit adjacent rod pairs as you suggest above. It's a bit dodgy but then so is the whole program. I believe most of the four/eight motorcycle engines use billet cranks.
