Author Topic: Con-rod oiling holes  (Read 6555 times)

Offline coater87

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Con-rod oiling holes
« on: 15.08. 2009 17:18 »
 Hello,

 I have done a quick clean up of the con rods and found something odd I think. In reading the Haynes manual, only the drive side rod should have a hole for cylinder oiling. It looks as though one rod in this engine was replaced at one time, and now BOTH have that oiling hole.

 Is this a problem? I guess my concerne here is that the T/S rod having free oil flow will steal pressure from the drive side- and maybe starving that cylinder wall. Am I correct to worry, or am I way off track?

 Thanks,
Lee
Central Wisconsin in the U.S.

Online RichardL

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Re: Con-rod oiling holes
« Reply #1 on: 15.08. 2009 17:58 »
I agree. Pressure will be stolen and the left side will be short-changed versus original design intent. I say, plug the hole in the timing-side rod. Be sure hole in drive-side rod faces the flywheel (i.e., faces to the right).

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Online A10Boy

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Re: Con-rod oiling holes
« Reply #2 on: 15.08. 2009 22:16 »
I think you are thinking too much *smile*
Compare the oil loss from that tiny hole, to the loss from the sides of the big end bearing shells, its minuscule compared to that. Don't worry go ahead and use it as it is.
Regards

Andy

1960 A10 - Black Golden Flash
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Online RichardL

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Re: Con-rod oiling holes
« Reply #3 on: 15.08. 2009 22:36 »
A10Boy,

I think we must agree to disagree. If there is enough pressure at the left side to squirt to the sidewall of the cylinder, then there would seem to be excellent opportunity for pressure loss with an additional hole on the right. Are you so certain that you are willing to risk giving Lee information that could kill his engine? I am not that certain, but I know my advice will do no harm. I apologize if this sounds argumentative, because I respect your knowldge in so many other posts and hope to still benefit from your help when I need it myself.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Offline olev

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Re: Con-rod oiling holes
« Reply #4 on: 16.08. 2009 02:10 »

Quote
Be sure hole in drive-side rod faces the flywheel (i.e., faces to the right).

Richard, Are you sure, I heard the hole faces the other way.
cheers

Offline Josh Cox

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Re: Con-rod oiling holes
« Reply #5 on: 16.08. 2009 02:34 »
Olev,

I'm pretty sure Richard is correct, the conrod with the oil hole is the Lefthand conrod and the oil hole faces to the inside, towards the flywheel/crank centre.

Black 1953 Golden Flash Plunger

Online RichardL

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Re: Con-rod oiling holes
« Reply #6 on: 16.08. 2009 02:51 »
Thank you, Josh. I did find myself sprinting for the books. Haynes says explicitly that the hole goes toward the flywheel.  Bacon shows a section through the rods and crank with the oil hole shown in the section and pointing toward the flywheel. I would copy the Bacon drawing and share it, but it is from a copywritten book.

On  another aspect of this hole, after a lot of previous discussion, rather than arguing further, I started just accepting that the hole has a serious purpose in lubricating the left cylinder wall. I really can't understand why the left side should need such lubrication more than the right side. On re-reading Haynes and Bacon, both state that the hole is for promoting oil flow to the far end of the crank. This makes much better sense to me in terms of explainable engineering. I have also wondered if the hole prevented bubbles in the oil from pocketing on the left end of the crankshaft and, thus, holding back oil flow.

Gotta go.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Online RichardL

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Re: Con-rod oiling holes
« Reply #7 on: 16.08. 2009 02:54 »
Just saw this..

If you look at page 30 of the Haynes manual, you will see a little speck at the base of the left rod, I assume, representing the hole.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Offline Pollock

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Re: Con-rod oiling holes
« Reply #8 on: 16.08. 2009 15:36 »
i will be no help here at all but...I am amased every time I look at rods and think how much benefit is by this hole...don't it make more sense that oil splash fromt he crank does more to oil than anything.  And why only one hole one rod?what oils the other side? Splash?
Anyhow...
Good thread.
Pollock

Online bsa-bill

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Re: Con-rod oiling holes
« Reply #9 on: 16.08. 2009 16:04 »
BSA put it there after having problems with the left hand pot overheating.
Think about the cooling effect of the barrels, so the overheating would be on the inside of the bore away from the air cooling

I read this somewhere ( despite my antique look I was'nt there at the time ).

Al the best - Bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online RichardL

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Re: Con-rod oiling holes
« Reply #10 on: 16.08. 2009 16:08 »
I think this little hole has become one of my favorite topics (buyer beware *smile*). I have read and re-read my books and each emphasizes the need for the hole in order to avoid oil starvation to the left big end. I believe that, absent this hole, pressure bleeds off at the right-side big end. Then, if the right-side is slightly looser, even less pressure would get to the left side. With the hole, the pressure should be uniform over the length of the sludge trap. So why point the hole in one direction versus another, I think it is just so that the oil spurting from it has the least affect on anything, hitting the flywheel and shedding off. Nevertheles, Haynes says that pointing to the flywheel would "avoid problems in the future" (loosely quoted). What problems, I can only guess. (Why stop guessing now? Back to work. *sad2*)

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Online RichardL

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Re: Con-rod oiling holes
« Reply #11 on: 16.08. 2009 16:17 »
Bill,

My post was just after yours. Your point is interesting as a possible reason for splashing toward the center, however, I failed to mention that neither MAP nor SRM have the hole in the billet rods they sell. MAP said, "don't need it."  I was not that confident that they were correct with respect to equalization of pressure, so I drilled my own hole in my left-side billet rod (the drilling setup is shown under a different topic).  I guess, if MAP was completely correct, no additional cooling or pressure equalization is necessary. As I said, I opted for the engineering explantion I could understand.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Offline Josh Cox

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Re: Con-rod oiling holes
« Reply #12 on: 16.08. 2009 21:45 »
Having only just pulled my engine down, the LH conrod did not have the big end with the hole in the LH upper, it was in the RH bottom, as such my sludge trap was completely blocked and the LH big end looked like shite.
Black 1953 Golden Flash Plunger

Online chaterlea25

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Re: Con-rod oiling holes
« Reply #13 on: 16.08. 2009 21:52 »
Hi Lee,
To block the hole in the righthand rod just fit the bearing shell without a hole in that position!
Thats if I remember correctly that not all the shells have holes in them *conf* *conf*
I believe the hole is there to, (as others have said) to promote oil flow,
Regards
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline coater87

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Re: Con-rod oiling holes
« Reply #14 on: 17.08. 2009 10:44 »
 Guys,

 thank you for all the advice here. After a good read, I have decided to plug the hole on the T/S rod. I would flip the bearings but they each have the same hole ( these are glaciers, so maybe from a a65?).

 Now what do you think would be the best way to plug this hole without weakening the rod?

 Lee
Central Wisconsin in the U.S.