VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 '25 Superior K Oil Pump

Hi guys,
I am about to overhaul the generator driven oil pump on my '25 and have a few to pick through for the best parts. I have noted there are two versions, one with a relief valve and one without but both carry the housing number 341 231. This will be because the valved type has an added drilling. When this valve is unseated, pressure oil will by-pass to the low pressure side of the pump. My question is which type is the best?

Best regards and thanks
Al

If they are both made of pot-metal, I would recommend you replace with the reproduction oil pump. Like so many items, you have a chance at a reproduced item and pass it up only to find a few years later it is no longer reproduced and you missed your chance.

Hi Ray,
Thanks but I have a number in very nice condition and one appears NOS. It does not have the relief valve I refer to so I am trying to nail the change point. As a matter of interest, does somebody do reproduction pumps?

Thanks and regards
Al

Hi Al,


Here is a photo of the reproduction pump that I purchased recently.



Roger

Hey Roger,

Did you see the string on the choke rod and bracket for the 23-28 cars? I have never seen one with the choke rod and bracket located on the dash and left side of the steering column. Have you?

Hi Ray,

No, this was new to me.
Both my 25s have the choke above the light switch as shown.


Here is another question. I know this is an artist depiction of a 1925 dash, but notice the speedo white letters on black drum. I have seen both black on white and white on black. Any insights?

Roger

Hi Roger,
Nice pump, where can I find out more? I notice it doesn't have the relief valve I have been speaking about.

Regards
Al

Hi Roger,
Although your question was not for me, so far as I know, the black background instruments are K and the white are V. The steering wheel and spark/throttle levers appears to belong to a K so that all lines up.

Regards
Al

The picture in the thread Ray mentions is of a 24 not a 25. It is my car if you need me to check something else for information.

Dave

Hi Dave,
So far as I know, '24 and '25 were the same in that area, the V was a little different. Thanks for your offer. Maybe you could look at your oil pump and tell me if it has a relief valve fitted, opposite side of the pump to the oil pressure gauge/center main feed please?

Thanks
Al

According to the parts list, '24 and '25 oil pumps are the same with no listing for relief valve.
Here is a photo from the showroom catalog.


Roger

Hi Al,


Look up eBay listing, 261717344253.

Here are some details,

1924-25 Oil Pump for Chevrolet cars and trucks.

The oil pump is new reproduction.

The casing is made of Aluminum with brass gears.

The machining has been done on a CNC machine.

I have new Generator End plates and distributor housing.

Call with any questions 314-293-1991.


Roger

Hi Roger,
Thanks for that. If we can be sure that is an accurate image of the pump, it must mean the one with a relief valve is a supersession. This may have been an attempt to reduce the oil pressure and thus strain on the not-so-strong oil pump drive coupling on the back of the generator.. Just me thinking aloud !!

Al

Any possibility of posting a picture of the assumed improved oil pump?

The one with the relief valve.

I am afraid I am not set up for a hosting service but could I take some pics and e-mail them to you at all ?

brass at xtra dot co dot nz

Thanks
Al

Ray,
Sorry to hijack the oil pump thread but...
The string you referred to is for 23-25 chokes. With the exception of a very limited early production V models all 25-28 cars had the choke mounted to the right of the steering wheel above the ignition key. If you look carefully in some of the 23-24 parts manuals photos you can see the choke on the left of the steering wheel. According to my 1924 Chevrolet Parts Manual, the choke consists of three parts, the dash Bracket, Friction Tube and Choke rod. The choke bracket is mounted to the dash with 2 straight slotted screws.
Cheers, Tom

Hi Ray,
I have e-mailed you the pics and posted some PM's but I have yet to receive any response. Have you received anything from me?

Regards
Al

Sorry so late answering. I lost my older brother the 13th and have been working on arrangements and such.

I have restored several of those oil pumps. They are also being remade.

Now I understand what you mean by the pressure relief device. A good cleaning does a major improvement in operation.

Hi Ray,
Sorry to hear about your dear brother passing, my sincerest condolences. I was thinking we were continuing to have e-mail problems.

You can see the oil pump has a valve and so, is this version later or earlier? As pointed out, there is no mention of it in the manual and so I assume it is later so the question is, why? Are there any bulletins surviving?

Regards
Al

I have handled many oil pumps and all of them had the pressure unit. The oil pump on the far left of the pictures you sent me appeared to be an attempt to make the pump. To save money they eliminated the pressure unit.

PS: My brother made it to 91, and then cancer outran him.

Hi Ray,
"Pressure unit" ?? Do you mean relief valve? The plain pump on the left of the pic I sent you is a standard pump without the valve but the casting number is identical. From the way your message reads, you think the one with the valve is an early one and not later as I am inclined to think. Hmmmm.

Al

The "pressure?" relief valve is a spring loaded brass ball,and the spring doesn't have much tension.As the pump is merely a flow pump to ensure a good oil supply to the troughs & centre main bearing,the word "pressure" doesn't really apply,but flow does.When I made the pumps out of bronze,I left the pressure relief valve out and all the pumps worked just fine.

Correct, flow needs a restriction to produce pressure and there should be very little restriction in the design so what purpose does the valve serve I ask?

Regards
Al