Technical Different SBC mechanical fuel pump styles

Which is the better of the two mechanical fuel pump styles? Is it just a matter of preference? I do like the one that has both inlet and outlet as threaded, and would prefer that.

 

One can be rebuilt and one can't. The later model pumps wee made to be throw aways while the earlier model pumps were designed in a time when [people regularly rebuilt things as opposed to just replacing them. I am not sure that you can get diaphragms and springs for them any more though.

 

A quick look at fleabay netted me this, looks like the real deal and even had the correct part number.

 

I wonder, can you clock the rebuildable one as you need it?

 

The rebuildable ones are the way to go--they can be clocked as well. There are some for 5/16" fittings and some with 3/8" . We use the ones with 3/8"

 

Are they NPT?

 

Yes, but you can get the fittings to convert them to AN connectors.

 

Hey Beano,
It's a mouse motor! Rebuild parts can be found everywhere, even on Mars

 

Is the bottom one a Carter?

 

That specific one is an Airtex, but I have seen them as AC Delco as well.

 

I always try to use the rebuildable style pumps for just that reason; you can reassemble them to point the fittings where ever it works/looks best. Plus they fit the look of an early engine better.
There are adapter fittings available for AN, tube flares and all kinds of stuff......

 

If that's how you roll, I don't judge.

 

Anyone have a part number for the clockable one?

 

I had to order one to today. Part number was M4891 on the invoice. They clock from the box dry, but I could not find an actual rebuild kit to use if fuel had been introduced into the pump (this was Carter). I know I have been able to get Stewart kits in the past, but now they are not so easy to even find.

 

I use "Hypalon" type material to cut new diaphragms for fuel pumps. This is a fuel tolerant material with a kind of cloth in the middle. I believe I learned about this material from the old "Skinned Knuckles" magazine many years ago, before the interwebs. It is used in Zodiac boats.

When I first got a piece of this material I placed a bit of it in a jar of gasoline for a few weeks to make sure it indeed held up.

Unfortunately the diaphragm is often attached to the pull rod by the rod end being peened over, so that has to be ground off and the rod drilled and tapped for a screw. It's easier if you have a lathe, but back then I got by with an electric drill.

I never worried about changing the check valves, they seem to last forever.

When assembling a fuel pump, even if it is taken apart just for clocking purposes, it is important to compress the arm to pull the diaphragm up and then tighten the pump body screws, so that the diaphragm has slack when the arm is released. This allows the diaphragm to have its full flexing motion in use.

 

Airtex 4657

 

From Speedway Motors, Part # 91602046, (new) fuel pump can be disassembled to index the inlet/outlet area. Plus the rated output PSI is 6. Edelbrock carbs need 6 PSI, while Holley carbs need 7 PSI. I have seen this fuel pump to work correctly with either of these 4 barrel carbs, thus without the need to install a fuel pressure regulator.

 

Holley carbs can run on 5 psi with no problems.....

 

I know the top one is a Carter, same one I’m using cause it’s small. I wanted a clockable one but they are bigger. Edelbrock makes a clockable pump too

 

Anybody here watch Engine Masters on the Motortrend site? Just finished a fuel pump test with a SBC

 

I saw that Rich