Do you have this info for the 6270 small block pump?

Top: MO-3032 12 (Bulge and multi holes)
Middle: M80-730 R 8 C Round shaped cavity OD 3.5”, ID 2 9/16” Hole ring dia 3 1/16” 1/4" NPT
Bottom: M118-276 3 C R (Different Design no boss C R/90 Clocking/Course Thread) Modified opening
Lever: 177-381 Lever Spring Gray 1.55”L x .390” Dia
Diaphm: None 364 Stud 2.20” OL stud, 8 hole 3 5/8” OD, 2 3/16” Lower Disc, 2 3/16” Upper Disc, Steel Spring

This was a pump with no date code, but the later manufacture with bulge on Top that marine pumps would have a vent installed. The Bottom was modified outlet to accept larger fitting by previous owner.

I did not cut off rivet to release spring and measure it.

The other portion of the diaphragm that effects volume and pressure of the pump is those steel disc that sandwich the rubber diaphragm. They are actually different diameters on original pumps depending on the model. They also have stamped ridge that had a patent by orig carter. If you think of the captured volume of fuel in the pump outlet chamber under the diaphragm when pulled up fully the size of that washer determines how much outside area of the diaphragm can actually stretch, tapered volume and what is solid surface for the built up fuel pressure to resist the downward push of the spring.
I have post picture of chamber before, here they are again. Notice gear shaped hemi chamber which increases volume under diagram per stroke, which also would lower pressure required to stop stroke when carb needle closed. Hence the larger spring force to compensate. I also have seen orig hemi with extra washers under the stud to increase preload of that specific spring. Also notice the bottom of the hemi pump does not have to have inlet fuel flow through a casting to get to chamber. The inlet fitting opens directly into the inlet chamber.

The round chamber is the typical 6903/4862/6270 modern pump parts.

Dragon, What can you tell me about this pump?

more pics

Carter 3497 71-75 Freshwater 361/440 Marine and Industrial pump. Did you get that one off ebay? I was going to buy one to open it up, but they sold out. Take it apart and tell me the internal casting marks in the middle section and bottom. The Top has the hemi casting. That serial number after the 3497 is a much later 2000 date code serial data. Would be a good BB pump, and depending on the internal configuration and spring, may be Hemi type, or just a normal pump like the 6903. But considering marine use may very well have a higher volume per stroke.

has anyone had to grind on the pump casting or engine block, when changing to a carter pump from a crimped together factory low performance pump, to get the carter pump to fit flush with the mounting pad on the engine block ?
i picked up a chromed carter pump that looked almost new, cheap, at a swap meet one time. i went to install it on a mock up block, and couldn't get it to fit flush with the mounting pad. it appeared it could fit if either the pump ear or the block [or possibly both] were ground down a bit, but i didn't bother because i just bolted on a crimped style pump. no pump push rod was involved because this was a gutted block.

Not for the types shown they all fit fine. The race pump 6 value unit, and I guess some of these knock off types may be larger and require that. I have installed plenty on built motors no issue. These rebuildable types were standard on the early engines and hemi.

Coated all the surfaces with Dykem then sanded every surface flat. There were a few definite low spots. Haven't checked it yet.

dragon slayer - can you find out anything on this pump?
It's for a small block.

No I focused on the big block especially hemi type. Looks period original and the F3 date code would be Jun 63. The carter book has it for a Dodge Desoto and truck starting late 1957. Listed as a 5 to 7 psi pump. The mopar service manual have the carter pump number so you could look up for more specifics.