Machining for outside oiler

Lubrication System (oil feed pump and scavenger pump, reservoir, filter, and lines)
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aaharp

Machining for outside oiler

#1

Post by aaharp » Wed Aug 10, 2005 12:17 pm

Hello all,
New guy here....Can the -56 heads be machined for outside oilers?



Cotten
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Re: Machining for outside oiler

#2

Post by Cotten » Wed Aug 10, 2005 12:45 pm

Yes, but I must start out by warning you that you will depreciate the value of your original hardware immensely.
When looking between the fins on the pushrod side of the head, you will see a raised portion of the casting that forms a "V". This corresponds to the galleries inside. Back when castings were cheap as dirt, it was not uncommon to tap in where the galleries intersected at the bottom apex of the "V".
They usually leaked from thin thread purchase, and the lines between the pushrods were awkward (and ugly).
If you add up machining time ($$$) and the depreciation factor, you would approach the price of modern hardware that uses conventional lines. (And you would still have the original heads left over!)

aaharp

Re: Machining for outside oiler

#3

Post by aaharp » Thu Aug 11, 2005 1:00 am

I see what you are talking about. I was hoping there would be a nicer way to do it (and keep things a little cooler) but I don't want the lines between the pushrod tubes. I'm not running original cases so I'm not worried about keeping things exactly original but you're right about the depreciation and originality. Seems like more trouble than it's worth.

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Re: Machining for outside oiler

#4

Post by Cotten » Thu Aug 11, 2005 1:41 am

The notion that outside oilers run cooler than earlier vintages is hypothetical conjecture.
It's an air-cooled engine.
If you are over-heating, pressuretest your intake manifold!

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Re: Machining for outside oiler

#5

Post by caschnd1 » Thu Aug 11, 2005 5:04 am

Cotton,

I'd agree with you that running outside oilers may not have a dramatic effect on overall running temp. But I think it's a pretty safe bet that the temperature of the oil when it reaches the top end is measurably lower. The original oil supply galley runs right up the right side of the cylinder and your oil is going to be heated by all the surrounding iron as it move up the oil galley. I've seen data (didn't perform the measurments myself) that showed a 50 degree drop in the temperature of the oil in the tank after installing top end oiler lines. This is attributed to not heating the oil on it's way up to the rockers.

I don't disagree with anything you said about preserving the value of your OEM parts. But for some of us, that cat was out of the bag long before we got our hands on our bikes. My bike is a classic example of 1970's chopper. Not much attention was paid to keeping anything original all those years ago. I don't mind making mods that might help my bike deal with everyday riding more easily. Here in AZ we regularly go over 110*F during the summer. Since my bike is my everyday year round ride to work, I thought the outside oiler lines made sense. Don't regret making that mod at all. The lines don't have to go between the push rod tubes. My lines are routed towards the center of the motor inboard of the intake push rods. Mostly hidden by the carb/air-cleaner.

-Craig

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Re: Machining for outside oiler

#6

Post by Cotten » Thu Aug 11, 2005 12:57 pm

Similarly, I cannot buy the cooler oil theory, as the head is the hottest part of the motor, and you still feed the oil into the same galleries, still passing over the combustion hotspots, back down the cylinders, and through the mass of the lower end before returned through the pump!
It is obvious that whoever found a change in oiltank temperature failed to sort out some extraneous variables.

A personal note about boogering OEM parts:
I only preach authenticity, I don't practice it myself.
It is just prudent economics to preserve un-boogered hardware, and choose previously boogered hardware to play with. There is certainly plenty of the latter!

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Re: Machining for outside oiler

#7

Post by caschnd1 » Thu Aug 11, 2005 3:07 pm

Agreed, the oil will pass over the combustion areas and back down the same return galley, through the bottom end and back to the tank even with outside oiler lines. But the difference is the starting temperature of the oil as it begins that path. If the path results in a 100*F rise in oil temp (just picking nice round numbers), and the starting temp without outside oil lines is 200*F your return oil temp is now 300*F. But if you have a starting oil temp of 150*F with outside oil lines then your return oil temp is 250*F. The temperature of your oil is a function of 1) the temp of the hot surface it's in contact with, 2) the length of time it's in contact with the hot surface. Outside oil lines are mainly changing #2 by reducing the amount of time the oil is in contact with a hot surface.

I'd love to have the equipment and the time to really investigate this and figure out all the subtleties. I'm sure the model I described is way way too simple.

-Craig

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Re: Machining for outside oiler

#8

Post by kell » Thu Aug 11, 2005 3:46 pm

My oil temp, no matter how hot the heads get, always reads about 170. I don't keep close tabs on it, but I've never seen it go much higher even on the hottest summer days when the heads are mad hot. It would be nice to get some of that heat out of the heads and into the oil. You'd think external lines would help by providing cooler oil to the heads, but that's kind of speculative. Maybe there isn't enough heat transfer to the oil in the time it's in the heads to make a big difference. What is the specific heat of oil? How much oil, in grams per second flows through and how efficiently does heat get transferred? Or ditch the theory and bench test the engine under controlled conditions where you can get an actual measure of heat transfer to the oil at specific temperatures. Failing that, I guess you would have to ride one summer with internal oiling and record the oil temps, install external lines the next summer and record oil temps, and compare. And don't change anything else -- no changes to the carb jetting or exhaust or timing.

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Re: Machining for outside oiler

#9

Post by caschnd1 » Thu Aug 11, 2005 3:55 pm

Hey Kell,

Those are exactly the thoughts I was having too. All the theory stuff is fine and dandy but I'd like to be able to actually mock up both systems and compare real life data. Not over two or three measurements but over a long period of time with varying conditions.
You think I could get one of those government grants to let me quit my day job and do that? ;D

-Craig

chucktx
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Re: Machining for outside oiler

#10

Post by chucktx » Fri Aug 12, 2005 2:25 am

stranger ideas have been given grants!!!!!!!
chucktx

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Re: Machining for outside oiler

#11

Post by fourthgear » Mon Aug 15, 2005 11:52 pm

I just use Syn.oil and not worry about it .

kell
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Re: Machining for outside oiler

#12

Post by kell » Sun Aug 21, 2005 3:45 pm

Has anybody here changed their bike from internal to external oiling, and noticed a change in head temps?

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Re: Machining for outside oiler

#13

Post by pzokes » Sun Aug 28, 2005 11:34 pm

I had a set of heads modified in the '80s using the info for outside oiler conversion that was in one of Easyrider's "tech" books. It placed the fittings very close to the M74 carb and I had to use 1/4" rubber hose to get around it. I didn't notice any difference in the motor being cooler.

matco
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Re: Machining for outside oiler

#14

Post by matco » Mon Sep 05, 2005 9:23 pm

you will only be changing the flow TO the rockers not FROM the rockers...........temperatures at the oil tank will not be changed. temp of the oil at the rockers will only be slightly reduced.

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Re: Machining for outside oiler

#15

Post by bibs » Mon Dec 12, 2005 5:39 am

I have STD heads on my pan and the temp. drop claimed by them is 50 degrees !!! probobly due to the increase in fin area. They have outside oiler fittings and I use them and have never experienced any type of over heating problems.

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