One more fuel pump question.

[Bingster]

So when installing the AC fuel pump for my 1947 Desoto, do I just screw it in or does the arm have to be set in some certain position?

[keithb7]

Arm has to be on proper side of cam shaft lift lobe. Look at pump arm. Which side of the arm rides on the cam?  Top or  bottom surface of arm? Turn engine accordingly to line  up cam lobe. Then install.  

[Bingster]

Thanks. That's what I wanted to know.

[andyd]

In theory the fuel pump should only fit one way, ie, when the two bolt holes and flange are lined up against the boss on the side of the block the actuating arm should be hard against the cam............some ride underneath the cam, some ride above the cam, it doesn't matter which way so long as you have the arm against its"correct" side on the cam.............the rubbing area on the arm should tell you whence it goes........against top or bottom of the cam and you generally have to exert some pressure against the arm to insert the bolts that hold the flange against the block....................andyd 

[Bingster]

Thanks!

[Bingster]

I'm assuming that since the fuel pump arm and cam were lined up when I removed the pump, if the engine hadn't been turned they will re-align if I just bolt the pump right in?

[keithb7]

Depending on where the fuel pump arm was in relation to the cam lobe when removed, it may be a little more challenging to install. If the cam lobe was pushing the pump arm, it will be a little harder to line up and install the mounting bolts.The cam could be pushing the lever arm, compressing the fuel pump return spring. You will be trying to hold the pump in place, to line up a bolt to thread into the block, all the while fighting the return spring. This is why I am suggesting you look at the pump arm. Where it rides on the cam lobe. Turn the engine by hand so you have no pump arm leverage compressing a spring at installation.

 

By chance you may have no pressure on the spring. Depends where the cam lobe positioning is when the engine was last shut off.  Take a look, and think things through when you are installing it. The pump is not timed to ignition or valve timing. You can put it in the easy way, or the more challenging way. Up to you. Either will work. Depends how many cuss words you want to use up.

[andyd]

As Keith says it will make no difference to the fuel pump if the engine has not been turned over or has been turned over 100 times, the pump arm fits against the specific cam lobe on the camshaft for the fuel pump.......the only real issue is that as Keith says it can be relatively easy to attach the pump to the block or you may have to use the pump to push against the arm and therefore the spring pressure to locate the pump flange and then the bolts into the block..........but its no big deal............andyd