My new 644 arrived

[Eugen]

I find it interesting that the original inlet fitting is just a push in o-ring type. I should be able to turn on the lathe an adapter from sae orb 12 to 1" female o-ring push in thingy hole.

[DavidBarkey]

I find it interesting that the original inlet fitting is just a push in o-ring type. I should be able to turn on the lathe an adapter from sae orb 12 to 1" female o-ring push in thingy hole.



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I test fit those , mark the position. Then with new oring and add a bead of loctite to the tube outside of where the oring is ,so that when fully pressed in the loctite only engages on the out side of the pipe to prevent movement . Might be over kill , but over kill is underrated in my mind .

[Eugen]

I would do that Dave, but I think I'll get the fitting from @FUTZ and call that done. He also gave me a good idea to mount a small electric fan right to the hydro oil cooler.

[thebuildist]

Note how much larger the ID of the push-in o-ring pipe is than the SAE12 fitting. That's why they chose that.

I'm not saying the SAE can't work, I'm just pointing out the logic of the original choice, and the the priorities it reveals.

You might consider boring out some of the threaded portion of the SAE to barb fitting. It's currently designed to contain 3000 psi, and it really only needs to be strong enough to physically not fall out of the hole, much like the original pipe. I'd personally err on the side of strength, but I'd guess you could remove around .100" from the ID and still have more than plenty of meat.

Bob

[DavidBarkey]

I would do that Dave, but I think I'll get the fitting from @FUTZ and call that done. He also gave me a good idea to mount a small electric fan right to the hydro oil cooler.

I run a 12v electric fan from a car on Frankie for years now . Never a problem . Something like this would be all you need .
https://www.amazon.ca/DNA-Motoring-Radi ... LK0D&psc=1
If you use it only in summer have it run all the time like the mechanical fan , but if you plan on useing it for snow then put a thermo switch in to control it .

[thebuildist]

If you're going that route, I recently saw this bargain: A set of 2 slim fans plus a mounting kit.

https://www.amazon.com/dp/B09STMX2CS?ta ... th=1&psc=1
Click the box to apply a 10% off coupon.

And at checkout add in this promo code for another 20% off 209KVD9B

26 bucks for two fans isn't too shabby...

It all came from a website I keep an eye on: https://struggleville.net I have no connection to or relationship with the site.

Bob

[Eugen]

Note how much larger the ID of the push-in o-ring pipe is than the SAE12 fitting. That's why they chose that.

I'm not saying the SAE can't work, I'm just pointing out the logic of the original choice, and the the priorities it reveals.

You might consider boring out some of the threaded portion of the SAE to barb fitting. It's currently designed to contain 3000 psi, and it really only needs to be strong enough to physically not fall out of the hole, much like the original pipe. I'd personally err on the side of strength, but I'd guess you could remove around .100" from the ID and still have more than plenty of meat.

Bob

I did notice that and was wondering why. But what you said made me dig a little more into this. Found some info about the recommended size of hoses for various hydraulic application. turns out that the hose ID depends roughly on two factors: flow rate (gpm/min) and flow velocity (feet/s). If you do a search, you'll find something called a nomogram, which is a chart on which you choose the flow rate, the flow velocity from a recommended range, and draw a line between the two, which will intersect a column of numbers that gives you the diameter of the hose in inches. But there is also a formula:

d = sqrt ( 0.408 * GPM / V)

The recommended flow velocity for suction hoses is between 2 and 4 feet/second. The original 644 pump is spec-ed at 9.5 GPM at 3600 RPM. Let's choose V = 4. Then we get

d = sqrt (0.408 * 9.5 / 4) = 0.98 in

I guess this explain the 1" suction hose?

This newer pump I got has 12.7 GPM. If I were to do things properly I should get a hose with diameter

d = sqrt (0.408 * 12.7 / 4) = 1.14 in

Will a 1" suction hose collapse?

How about we calculate the velocity given the 12.7 GPM and 1" hose?

V = 0.408 * 12.7 / d^2 = 0.408 * 12.7 = 5.18 feet/second

I think this is probably fine.

Now, how about the pump inlet diameter? This newer pump has a SAE #12 ORB inlet. The nominal size for ORB #12 fittings is 3/4 in. Also the max flow rate for a 3/4 fitting is way higher than what the pump is capable (12.7), so I don't think the pump will get tired sucking oil through the SAE 12 fitting.

Finally, what to make of the transition from 1in hose to 3/4in fitting? Not sure, but can't think of anything to be worried about.

Obviously I'm just thinking out loud here, so please step in and point out if my thinking is wrong.

[Eugen]

@thebuildist and @DavidBarkey thank you for your suggestions regarding the radiator fan. I will look around and see what reasonable option I will go for.

[thebuildist]

It sounds like you're approaching this in a calm, methodical fashion as you usually do. That portends well. And I think you're right based on your calculations your approach will work.

Having said that, if it were me and if I had a lathe, which it sounds like you do, I would totally take the 15 minutes to set up that inlet part in the lathe and skin out of its ID however much I could without being over concerned about its overall strength. It's free, and it certainly can't hurt anything. Your 1-in line is a smidgen undersized as you've already pointed out. And this is a smidgen undersized in relation to the 1-in line. So as I say if it were me I would just minimize that undersizedness in so far as I easily could.

Now I've been thinking this whole time that the tubing part, the part with the barb / bump, is for a 1-in hose. Is it only for a 3/4 in hose? If so I think I would look for one for a 1-in hose. To me that would be the best way to make the transition from the one inch hose into the 3/4 SAE.

For what it's worth.

Bob

[thebuildist]

The other thing to consider, and I know I'm willing to go farther off the reservation than most people are, is to consider mounting up your new pump in the lathe and bore it out identical to the inlet area of the old pump. And reuse that old inlet tube.

Again strength is totally not an issue. So even if it doesn't have a cast boss that's fully big enough for that, as long as The aluminum is at least a half inch thick, and the ID of what you bore out is the same as the id of the original pump, that inlet tube would seal without the slightest issue.

Just worth throwing out there...