check valve relief spring

[chop1543]

Bought a repop cast iron oil pump for the project I'm working on. The cavity that takes the ball and spring for the relief valve has a spring in it. I took the old pump apart just to compare parts, and noticed that the spring in that pump is longer than the one provided with the new pump. The part numbers are 26363-36 and 26353-56. Which one is the short one and which one is the long one, and which one would be correct for a '58 motor? Obviously, the dash 56 one is the one that goes in, but is that the long one or the short one?

[1950Panhead]

Check valve on top, spring is approx 1.250"
Bypass valve on side, spring varies from 1.5" to 2.2", many bypass springs were used through the years.

[Mongrel505558]

And probably quite a few were stretched in the attempt to get more oil pressure.

[nifty]

Bought a repop cast iron oil pump for the project I'm working on. The cavity that takes the ball and spring for the relief valve has a spring in it. I took the old pump apart just to compare parts, and noticed that the spring in that pump is longer than the one provided with the new pump. The part numbers are 26363-36 and 26353-56. Which one is the short one and which one is the long one, and which one would be correct for a '58 motor? Obviously, the dash 56 one is the one that goes in, but is that the long one or the short one?

Chop.
26363-36 SPRING, check ball, same part number used to 1980, however, possibly circa 1968, apparently MoCo changed the spring, without changing part number (yet we still love them), the Shovel era 26363-36 is approx 1.625".
More data here
https://www.hydra-glide.net/phpBB3/view ... 87&t=13570

Be very careful, assume nothing.

Nifty

[RooDog]

Surely you will use the spring that came with that AM oil pump. and not try to second guess what the manufacturer intended. At least not until you run it and prove it to be either good, or not good.
....RooDog....

[chop1543]

Surely you will use the spring that came with that AM oil pump. and not try to second guess what the manufacturer intended. At least not until you run it and prove it to be either good, or not good.
....RooDog....

Actually, I wrote the first one wrong. It's the relief valve hole, not the check valve hole. And you're probably right, I should leave the short one in and see if oil bleeds by. But when ya think about it, a longer spring might aid in not having oil sump into the lower end when the bike's off. Of course, this is assuming that the ball and seat are functioning the way they're supposed to.

[Mongrel505558]

The check valve prevents the oil from sumping into the crankcase. I think you should be careful here. Seems to me you would want this valve to open at a fairly low pressure so you don't starve the motor on start up, but I could be wrong. I'd rather replace the ball and clean up and burnish the seat to prevent sumping than to play with this spring. The bypass valve spring determines how much pressure the pump makes before the bypass valve opens and shunts some of the oil into the return side of the pump. It's basically a pressure regulator.

[RooDog]

The check valve prevents the oil from sumping into the crankcase. I think you should be careful here. Seems to me you would want this valve to open at a fairly low pressure so you don't starve the motor on start up, but I could be wrong. I'd rather replace the ball and clean up and burnish the seat to prevent sumping than to play with this spring. The bypass valve spring determines how much pressure the pump makes before the bypass valve opens and shunts some of the oil into the return side of the pump. It's basically a pressure regulator.

If I bought a brand new pump, OEM, AM, or name brand, which I have done, I would only open it up to be sure it is clean and free from production debris, which can happen to any new product. Why try to re-engineer a "new" item. If you don't trust the product, then don't buy it in the first place.
I have an early $&$ cast pump (all later production pumps are billet) for Pan or Shovel, I would sell....
....RooDog....

[Hogey]

A cast pump would last

[RooDog]

I have an early $&$ cast pump (all later production pumps are billet) for Pan or Shovel, I would sell....
....RooDog....

Let me qualify that. The $&$ cast pump , their nomenclature, is die cast aluminum,superseded by their billet aluminum version. The billet pumps have no provision for a front chain oiler line, nor adjusting screw.
"cast" is a process not a material...
[/quote]

[Mongrel505558]

I have an early $&$ cast pump (all later production pumps are billet) for Pan or Shovel, I would sell....
....RooDog....

Let me qualify that. The $&$ cast pump , their nomenclature, is die cast aluminum,superseded by their billet aluminum version. The billet pumps have no provision for a front chain oiler line, nor adjusting screw.
"cast" is a process not a material...

[/quote]

And the billet pumps look way out of place on an older motor. I have an old S&S cast pump on my panhead and it's a very good pump - delivers a fairly high flow and looks somewhat like the cast aluminum pump H-D came out with in 1968. Still has the chain oiler adjusting screw, although I'm running a 3" open belt primary so I have it screwed all the way in. The main thing with any oil pump is that the passages have to match up with the passages in the engine case. S&S sells templates for drilling, but I would avoid that unless the cases were split so the drill cut could be cleaned out.

[RooDog]

Do note that case drilling for an $&$ pump is not required on all applications.

S&S Oil Pump on eBay.jpg (516.68 KiB) Viewed 232 times