Connecting rod bleed holes

This same discussion is on a bunch of car websites with the same results: Either you need oil holes pointing in the correct direction OR you need oil holes and it doesn't matter which direction, OR you don't need oil holes at all.

I found it interesting in searching that the Ford 289 motor originally (1963) had con rod squirt holes but in 1966 Ford deleted them. Other factory engines retained them. SO perhaps some specific aspect of individual engine design affects whether they are actually needed or not. IOW, if the Commando motor didn't need them, why are they there on the OEM assembly? Of course, one answer could be that they were commonly used in the day on most engines and Norton, being a relatively small motorcycle producer, had no reason to do any research/testing to determine whether they were really necessary for the Commando.

OR...maybe Norton did and they are. :rolleyes:
 
kommando said:
You best tell the German performance engine builders to fit the best performing splutter hearing to top and bottom instead of just top then. A splutter hearing is 5 times the cost of a normal shell bearing so only fitted for good reason.
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You got me there. I have no idea what a "splutter hearing" is. Maybe a PVD bearing shell like used in a diesel?

Short stroke motors with lower reciprocating weight may be a different story but on a Norton motor the peak load is on the bottom shell unless the engine is supercharged or detonating.

Not that it makes any difference as the load capacity is more than adequate -hole or not. Jim
 
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Probably makes no real difference. With the way these bikes are generally used nowadays, there isn't much strain/load applied and they don't get many miles put on them. It's not like the days where we rode them every day back/forth to work and raced them on weekends! ;)

IOW, stuff that matters under "severe service" over long term may not matter at all with "light duty service."
 
Here's my take on oil squirter holes.

On the early "Gen III" Chrysler Hemis, the lower output 5.7 did not have squirter holes in the rods while the high output 6.1 did. This was for piston crown cooling.

As for the "outboard" orientation spelled out by Norton?

Could that be for cooling the piston crown near the exhaust port location?
 
MexicoMike said:
Probably makes no real difference. With the way these bikes are generally used nowadays, there isn't much strain/load applied and they don't get many miles put on them. It's not like the days where we rode them every day back/forth to work and raced them on weekends! ;)

IOW, stuff that matters under "severe service" over long term may not matter at all with "light duty service."
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But the irony there is that most serious high performance Norton builds seem to run without holes…
 
I seem to remember a Norton guru once told me the holes were added to solve a problem that Norton was having with piston scuffing, but that the addition of the holes did not solve the problem. A change in piston design cured the problem but the holes stayed- for better or for worse...
 
If the pressurized oil can't squirt out the conrod holes maybe more oil would flush out the sides of the big end bearing perhaps keeping them cooler
 
1973x75 said:
Well I just took It for a 25 mile ride, and it came back in one piece, no leaks, no noises, no over heating. I love that machine. So in the very short term, all is well.
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And I predict much of the same for many thousands of miles!

Save your worry energy for the next thing…
 
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