Atlas rocker oil feed pipe

Karl Johnson · Aug 12, 2023

Hi Folks,

I'm nearing completion on a 1966 Atlas project and fired it up for the first time and noticed in all my excitement that oil was leaking from a bodged repair on the original rocker oil feed pipe. On closer inspection it looks like there has been a few repairs done already in the same place so not really wanting to play that game any more.

I do have a spare set braided oil rocker oil feed lines from a Commando and I'm wondering if anyone has tried using a set of Commando oil feed pipes on an Atlas. Any issues with doing this? I do have a spare set that I am able to use. I know that the Commando feeds from the side and Atlas from the top. TIA - Karl

Schwany · Aug 12, 2023

I've done it on a straight up P11 motor with a top oil fed head. It works. I think I did it in the 1990's, but I doubt the parts have changed all that much over the years. I run the main long line over to the drive side feed on top of the head and the short section from there to the other side. Not sure if that is the recommended way to do, it is just the way I did it. Point is it's not a problem.

gpzkat · Aug 12, 2023

Do you mean the metal fitting? Or the line? Or are there two questions? Sorry, I can't picture multiple repairs on a line. Mine (N15CS, Atlas engine) has a double input fitting and a single fitting on the head as Schwany describes. I think I have a spare fitting, the one with two inlets.

dculgan · Aug 12, 2023

On an Atlas with low pressure oil feed from the return line at the oil tank inlet, would a Commando style oil line ( with the double fitting on one side) feed more oil to one side compared to the original Y configuration?

texasSlick · Aug 13, 2023

dculgan said:
On an Atlas with low pressure oil feed from the return line at the oil tank inlet, would a Commando style oil line ( with the double fitting on one side) feed more oil to one side compared to the original Y configuration?

I am not sure what it is you contemplate doing:

A) Replace the low pressure Atlas oil feed line with a Commando high pressure oil feed line tapped into the Atlas return line at the oil tank. That is, trade out one type of pipe for another .

Or

B) Replace the Atlas low pressure feed with a high pressure tap off the timing case.

If A), I see no problems except containing the leaks at each of the necessary connection points.

If B), don't do it. You will flood the rockers. This mod can be done, but must be accompanied by high pressure type rocker spindles with the flats placed opposite to the Atlas placement. And then, you may find that oil seals on the intake valve stems may be necessary.

Slick

Thomasa · Aug 13, 2023

I believe I have an oil-feed pipe that I will never use. It became surplus when I swapped for a commando head. PM me if you're interested.

possm · Aug 13, 2023

Karl, the Atlas changed to the 6 start oil pump drive in 1966, so is your rocker feed pipe fed from the timing cover or the earlier type that is fed from the return side of the oil tank?

Karl Johnson · Aug 13, 2023

Schwany said:
I've done it on a straight up P11 motor with a top oil fed head. It works. I think I did it in the 1990's, but I doubt the parts have changed all that much over the years. I run the main long line over to the drive side feed on top of the head and the short section from there to the other side. Not sure if that is the recommended way to do, it is just the way I did it. Point is it's not a problem.

Thanks for sharing. I can't see any issue but thought I'd tap into the collective wisdom.

Karl Johnson · Aug 13, 2023

gpzkat said:
Do you mean the metal fitting? Or the line? Or are there two questions? Sorry, I can't picture multiple repairs on a line. Mine (N15CS, Atlas engine) has a double input fitting and a single fitting on the head as Schwany describes. I think I have a spare fitting, the one with two inlets.

There are a couple of brazed blobs on the join between the pipe and the right hand banjo.

Karl Johnson · Aug 13, 2023

possm said:
Karl, the Atlas changed to the 6 start oil pump drive in 1966, so is your rocker feed pipe fed from the timing cover or the earlier type that is fed from the return side of the oil tank?

Mine is the same as the Commando, from the timing cover

Karl Johnson · Aug 13, 2023

texasSlick said:
I am not sure what it is you contemplate doing:

A) Replace the low pressure Atlas oil feed line with a Commando high pressure oil feed line tapped into the Atlas return line at the oil tank. That is, trade out one type of pipe for another .

Or

B) Replace the Atlas low pressure feed with a high pressure tap off the timing case.

If A), I see no problems except containing the leaks at each of the necessary connection points.

If B), don't do it. You will flood the rockers. This mod can be done, but must be accompanied by high pressure type rocker spindles with the flats placed opposite to the Atlas placement. And then, you may find that oil seals on the intake valve stems may be necessary.

Slick

I'm contemplating option A. The oil feed comes off the rest of the timing case...just like a Commando. I would be looking at simply swapping the original pipe for a braided line made for a Commando

Karl Johnson · Aug 13, 2023

Thomasa said:
I believe I have an oil-feed pipe that I will never use. It became surplus when I swapped for a commando head. PM me if you're interested.

Thanks, but now you have me thinking. I have nice Commando cylinder head on the shelf...

possm · Aug 13, 2023

"Thanks, but now you have me thinking. I have nice Commando cylinder head on the shelf.".

I have a 1966 Atlas on it the 4 cylinder head bolts closest the spark plugs are 5/16 Commando ones are 3/8

Schwany · Aug 14, 2023

Karl Johnson said:
Thanks, but now you have me thinking. I have nice Commando cylinder head on the shelf...

I did that Commando head swap when waiting to get my P11 head surfaced in the previous century. You have to drill and tap the older iron barrels for the 4 3/8 bolts (2 each side next to the plugs). I ended up taking the Commando head off and putting the P11 head back on. My P11 head was ported by Fred Barlow and was at the time and still is better for my style of riding. I did have to drill the P11 head for the 3/8 bolts. By the way, those 3/8 bolts work better for clamping down the old head. I also still have that Commando head on the shelf. Well, actually it's sitting on top of a rolling tool box.

dculgan · Aug 15, 2023

texasSlick said:
I am not sure what it is you contemplate doing:

A) Replace the low pressure Atlas oil feed line with a Commando high pressure oil feed line tapped into the Atlas return line at the oil tank. That is, trade out one type of pipe for another .

Or

B) Replace the Atlas low pressure feed with a high pressure tap off the timing case.

If A), I see no problems except containing the leaks at each of the necessary connection points.

If B), don't do it. You will flood the rockers. This mod can be done, but must be accompanied by high pressure type rocker spindles with the flats placed opposite to the Atlas placement. And then, you may find that oil seals on the intake valve stems may be necessary.

Slick

Sorry I wasnt more clear. I am running the low pressure rocker feed and will continue to do so. For a while I had been using a commando line tapped into the low pressure feed. This line fed the timing side scrolled rocker first, then crossed over to the drive side. At one point in my decades long ownership of this Atlas I experienced a lot of wear on the drive side rocker, where it contacts the valve end. I assumed this was a result of insufficient oiling of that side and changed back to the original line with its Y configuration as I thought it might provide more even oiling and not favor the one side over the other. I don’t know enough about fluid dynamics to know whether a few inches of relatively thin ID tubing would effect flow but I opted to fix the metal line and go back to the original Y config.

texasSlick · Aug 15, 2023

dculgan said:
Sorry I wasnt more clear. I am running the low pressure rocker feed and will continue to do so. For a while I had been using a commando line tapped into the low pressure feed. This line fed the timing side scrolled rocker first, then crossed over to the drive side. At one point in my decades long ownership of this Atlas I experienced a lot of wear on the drive side rocker, where it contacts the valve end. I assumed this was a result of insufficient oiling of that side and changed back to the original line with its Y configuration as I thought it might provide more even oiling and not favor the one side over the other. I don’t know enough about fluid dynamics to know whether a few inches of relatively thin ID tubing would effect flow but I opted to fix the metal line and go back to the original Y config.

With the low pressure system, it is important to balance the pressure drops to each side. The Y configuration does that balance. The Commando routing delivers oil to the timing side, where some oil is bled off, which results in less pressure to push the oil further down the line. With the low pressure system, the pressure drop on the timing side may be too great to adequately feed the drive side. With a high pressure system, there's plenty of pressure available, but not so with the low pressure system.

I hope this is clear for you..... I think you reasoned it out on your own.

Slick

Atlas rocker oil feed pipe

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