Hello guys. Over the years we have had a few conversations about crankshafts. I have learned a lot from you. I have decided to build 2 engines using the best of my hoarded parts. They will get forged pistons, forged H beam rods. I plan on doing the wedging operation to remove about 1/4 lb off each throw (rod side). I plan on a redline of 7500 to 8000 Now I have decided to cross drill the mains and I plan to use the seven enterprises crank as a template for the drill angle and size.
The issue I have is the connecting rod oil gallery size. I plan on using the single oil hole oriented at about 1 o'clock at tdc. I don't want to use the the seven crank as template because it has cross drilled rod journals.
I am thinking of increasing the diameter of the connecting rod oil hole from .170 to .1875 for an increase of cross sectional area of approximately 20% its not that much but I am hoping to get a bit more protection with an increase in potential volume delivery. What do you think of this ?
British 1275 road race crankshaft (oil galley size)
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hydrolastic
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Re: British 1275 road race crankshaft (oil galley size)
As you've had a limited response .......
Is this a modified standard crank, or something else ?
Enlarging the rod feeds I don't think will make much difference for the work involved, but if it makes you feel better I doubt it would do much harm either for the sizes mentioned
That part of the oiling is already 'assisted' by centrifugal force anyway
I'd be more concerned with longish thin drills even in relatively 'soft' material ....... it's often a sphincter clenching deal at best, and can go wrong rapidly ...... if the crank has been hardened forget it
If you do, resist the temptation to 'dig' out the journal openings as you sometimes see, a modest chamfer as per the better aftermarket cranks is all that's needed
JMO
Is this a modified standard crank, or something else ?
Enlarging the rod feeds I don't think will make much difference for the work involved, but if it makes you feel better I doubt it would do much harm either for the sizes mentioned
That part of the oiling is already 'assisted' by centrifugal force anyway
I'd be more concerned with longish thin drills even in relatively 'soft' material ....... it's often a sphincter clenching deal at best, and can go wrong rapidly ...... if the crank has been hardened forget it
If you do, resist the temptation to 'dig' out the journal openings as you sometimes see, a modest chamfer as per the better aftermarket cranks is all that's needed
JMO
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Sir Yun
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Re: British 1275 road race crankshaft (oil galley size)
Agree with BCjohnny I don't think it matters much. I would check the passages at the block and oil pump for casting mishaps, maybe clean that up. Check if bearing holes align. Just get the basics right. I would mostly build the whole spec down to <7500 redline
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