AC type AF fuel pumps

[pfarber]

This is probably one the most misidentified part on a CCKW/DUKW. People see that left side primer handle and thing 'CCKW!' Not that easy. A proper CCKW fuel pump is a rare bird.

First, the SNL data:

fp0.JPG (13.11 KiB) Viewed 10772 times

fp1.JPG (28.81 KiB) Viewed 10772 times

GM-1538616 is the 6 valve pump covered elsewhere.

So there where THREE seperate fuel pumps used on the CCKW (early, mid, late). The SNL has pics of the first two, and only an exploded diagram of the third.

GM-1537272	GM-1537714
fp3.JPG (24.22 KiB) Viewed 10772 times	fp4.JPG (37.62 KiB) Viewed 10772 times

Externally not a lot of difference. The key point is the BAIL. Note how BOTH fuel pumps have a bail that is perpendicular to the inlet/outlet. THAT IS THE KEY. There are no other flanges, or holes.

There was a part number stamped on the flange (TM9-1828A page 3)

b. Identification. The pump part number is usually stamped
on the edge of the mounting flange. Some high production pumps
have the part number cast into the body beneath the diaphragm
flange.

The 'series' of fuel pump is "AF" but that was simply AC's classification. There are AC type AF fuel pumps with primers on the right side (ie the jeep) or none at all (mostly civilian models).

From the SNL here is a proper CCKW fuel pump (2 valve) with the key casting markers highlighed:

pfp.JPG (44.4 KiB) Viewed 10771 times

Here are some 'CCKW fuel pump wanna b's':

Bale not perpendicualr	Part numbers may be stamped
fpw1.JPG (25.14 KiB) Viewed 10772 times	fpw2.JPG (28.64 KiB) Viewed 10772 times

Astute reads might say "but there are holes to orient the bale perpendicular like the SNL!' True, but there were never any holes to mount it diagonally.

Also, mixing and matching tops to bottoms is not hard. Just because the bottom is proper does not mean it has the correct top!

fpw3.JPG (29.77 KiB) Viewed 10772 times

At first glance this looks like a winner, but note the flange just in front of the inlet (that's for a diagonal bale) and the boss where the bale IS attached looks drilled, not a cast hole.

[retro-roco]

Is it possible they used different top casting, yet kept the same part number? The reason I ask, it that one of the pics you posted clearly has one of the correct part numbers stamped right in the lower housing flange. The last illustration that you say shows there is no diagonal flange, just is not a good view to try and determine that. The diagonal bail flange would actually be hidden by the outlet port casting (it would be behind it), in that view. Even the first illustration (that you identified as part no. 1537272 doesn't seem to rule out the possible presence of a diagonal bail socket immediately next to the inlet port. It MIGHT be easier to tell if it was a photo rather than an illustration (ie artists rendition). I'll have to get out my fuel pump and see how it compares.

[pfarber]

The SNL lists ONE part number:

SNL G508 GM-1537103 COVER, fuel, pump body, top on one listed July, 1945
TM10-1563 GM-1537103 COVER, top cover, fuel pump body. May, 1943

Neither were superceeded.

One cool thing: both the metal AND glass pulsator dome ('bowl') ARE listed. and early trucks did come with glass pulsators/bowls/domes.

I have the 42 parts list at home TM10-1562 July, 1942, and the TM10-1501 from 1941.

Its more than likely that they batch rebuilt a ton of AC type AF's and mixed in whatever top fit. The images are fairly clear. The Doyle book has some close up engine pics, I will include them when I get home.

But no, as presented, that pump with the stamp is not correct. The top cover is not what the manuals would indicate as correct.

[retro-roco]

Paul,

You should be more careful with your absolute declarations. In this case, I have photographic proof that you are wrong, at least with with regard to the additional bale holes allowing for "diagonal" bale installation. I'm not talking about some artist's interpretation of a fuel pump (ie illustration), but a photograph.

First a little background. Like the CCKW, the Chevy G506 used an AC fuel pump with a primer lever. The pump has a different base and primer lever (and thus a different pump part number); but the cover was exactly the same part number as that used on the CCKW pump. The part number is 1537103, and it is the only part number listed among any of the parts books that I checked.

Here is a photo of an early truck, in a photo aptly titled "Filling the Carburetor Bowl".

Filling The Carburetor Bowl

Filling the Carburetor Bowl-100dpi.jpg (148.52 KiB) Viewed 10766 times

I have the same pic at a higher resolution, but couldn't attach it due to the size.

Regarding the other photos and illustrations you posted, lets start with this one:
Note the fuel pump is mounted to the side of engine (passenger side), and the visible bump for the diagonal bale is on the left side, towards the rear of the engine, next to the inlet port.


Now looking at the following illustration, we are looking from the FRONT of the engine, meaning the bump shown above, is now hidden by the flange marked 'G'. The other diagonal bump (opposite the one just discussed) would be hidden by the outlet port marked 'F'. You can just see the back, perpendicular flange, right above and to the left of the screw marked 'H'.




Even this illustration, seems to show SOMETHING (see the red arrow) where you say there should be nothing...

What is this???

fp4-arrow.jpg (182.91 KiB) Viewed 10766 times

So I am convinced that the diagonal bale "bumps" are NOT proof of an incorrect fuel pump, but rather are a feature that they should have (and Chevy's too).

What do you think?

[pfarber]

If you could post what TMs/source of your photos that would help... also its kinda required by this forum so everyone can look at the documents in full and not just see a small snippet.

I did find the image you posted as far back as July 1942 (TM10-1557 Ch 1) page 3-7. Whats funny is that the cutaway of the fuel pump on the same page is a stock photo that also appears in the 42-46 Chevrolet Shop manual for cars and trucks. Most 41 and early 42 TMs have only line drawings

I looked in the doyle book and could only find ONE image that showed the left side with any clarity.. but was so far away that you cannot make out the fuel pump. Its on page 21, center. It is inconclusive as to a 'secondary' bale mount at 45Deg to the engine. I say no, and I also say that the bale hole boss is unique.

I don't have enough books to research anything Chevvy related, but YES, the part numbers are the same in the SNL-G506 and G508. But that would be expected as in Late 42/early 43 there was a huge push to rid the supply chain of duplicate parts. If you WERE to order a pump you would order G085-3004460 ad that could have gotten you a GM-1537272 OR GM-1537714 well, the 7272 was superseded, but that doesn't mean you would not have gotten one!

[pfarber]

I did find this image in TM9-809 (AFKWX-353) page 14.

coe005.jpg (23.44 KiB) Viewed 10765 times

The TM is from 43, but its hard to know if the pump is original to the motor as it had a deep sump oil pan. TMs state that the deep sump started at engine #270-266551 and the first references are early 43.. so late 42 early 43??

Plus we don't know when pump GM-1537714 superseded pump GM-1537272. Although part numbers for the 'cover' are the same that does no meant that the part did not change (GMC is somewhat famous for that.... part numbers out of 'order' or parts changing but the same part number).

So right now we have lots of undated, unknown images that show both

[retro-roco]

Paul,

The photo I posted is from this manual, which is early (40, 41 and 42) Chevy G4112 trucks.

Early G4112 Maintenance Manual

G506 Maintenance Manual Cover-small.jpg (171.46 KiB) Viewed 10763 times

Early G4112 Maintenance Manual Index

G506 Maintenance Manual Index-small.jpg (164.35 KiB) Viewed 10763 times

The same picture, though larger, is also in the TM9-805 manuals. Do you have one of those? It actually is visible in two photos. the second is labeled Figure 31 - Engine Assembly, Right side. The photo shows the entire engine, including transmission, and deep sump oil pan (obviously a military specific photo).

I'm not buying the idea that this might somehow be a left over civilian photo. I've never seen or heard of a civilian fuel pump with a primer lever (that IS the whole point of the photo).

[pfarber]

I'm not a really keen on using G506 TMs to figure out G508 parts. Hopefully this will be the last reference to a Chevvy TMs.

Fuel pump image is the same:

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rsfpex006.jpg (25.71 KiB) Viewed 10761 times	rsfpex007.jpg (26.36 KiB) Viewed 10761 times

[pfarber]

I believe I have a found an original GM-1537714 base. The stamping is light, but it does have the bale boss at 45 degrees.

To cold to stay out in the garage and clean it up/take photos. Tomorrow should be warmer.

[pfarber]

This is labeled as a CCKW fuel pump. Its off my truck.

The part number stamped on the mounting flange

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Side

rsDSCN0046.jpg (136.86 KiB) Viewed 10760 times

Side

rsDSCN0047.jpg (105.37 KiB) Viewed 10760 times

AC cast logo

rsDSCN0050.jpg (165.22 KiB) Viewed 10760 times

Bale detail

rsDSCN0051.jpg (112.29 KiB) Viewed 10760 times

Looking at this image you would think that the cover is correct. But this image bothers me:

ccv1.JPG (32.86 KiB) Viewed 10760 times

From this angle I should be able to see the 45degree bale in front of the rear bale.

So, I present the one true fuel pump
Note NO bale at 45 degress, both front OR back:

rsDSCN0060.jpg (67.06 KiB) Viewed 10760 times

rsDSCN0061.jpg (85.41 KiB) Viewed 10760 times

rsDSCN0062.jpg (86.69 KiB) Viewed 10760 times

If I wanted to, I could have taken the top off the marked bottom and put this one on it and have EXACTLY what the SNL shows. But I am not here to 'win' but figure out the PROPER fuel pump.

[pfarber]

Here are some side by sides (man my Nikon L820 KICKS ASS)

rsDSCN0063.jpg (159.15 KiB) Viewed 10760 times

rsDSCN0065.jpg (157.22 KiB) Viewed 10760 times

Now just in case you're thinking the extra hole above the primer pin hole on is not on the marked AC pump:

rsDSCN0064.jpg (153.91 KiB) Viewed 10760 times

There it is!

One thing I will not about the unmarked pump... the casting is rough. The part lines are not ground/sanded down and there is a sprue gate on the mounting flange:

rsDSCN0058.jpg (75.91 KiB) Viewed 10760 times

There is a number... but from what I can tell its not a GM/GMC part number:

rsDSCN0059.jpg (128.32 KiB) Viewed 10760 times

It looks like the primer pin hole is sealed with two caps... like I could punch them out... I will take the pump arm out and if there is the tell tale primer pin wear then at some point this fuel pump had a primer arm. Its doubtful, as the rebuild kits DO include an new lever arm.

S

[pfarber]

I did find this:

http://www.vapinc.com/chevy/Fuel%20Pumps/main.html

6 Cylinder Engines Part #
1937-51, 6 cylinder fuel only 429

But why would a civvy pump have the bosses for a primer arm cast???

[pfarber]

I'm really starting to think that CCKWs are bi-polar.

So I'm in my office (aka the crapper) reading over some CCKW TMs (as we all should be) and I see this:

sadface.PNG (774.72 KiB) Viewed 10749 times

And I think to myself.. god dammit. How could I be wrong about this.

Saddened by my predicament, I flip a few more pages to make sure that what I am seeing is right.

Then I saw it ON THE VERY NEXT PAGE:

FUCKYA.PNG (680.94 KiB) Viewed 10749 times

WHAT THE FUCK.

How could I have missed this? Well, its easy. The image is reversed. This is what it should look like:

reversed.png (146.05 KiB) Viewed 10749 times

Note the red line parallels the dip stick.

Here is the full page, with the image as it appears on page 327 of TM9-1802A

So I'm kinda right... in opposite world. Buy hey.. I ACTUALLY found a fuel pump that matched a reversed photo from a 65+ year old manual. That should get me some credit.