Are there two different Walbro 340's???

[Beware The Beast]

Just a simple question regarding Walbro 340's here. I purchased one from a vendor a few years back that came with a filter sock and performs very well. Recently I have purchased a couple more used units off the boards to set up a double pumper system. The used units I received have Walbro 340 factory stamped on them, they have a built in filter screen, and the spare sock I have doesn't fit on them. Was a 340 ever used in a OEM stock application and these are the units I've been getting? If they have a built in filter screen can I delete the filter sock? I just want to make sure I'm using the right part, no flame intended to the persons I've purchased these pumps from. Thanks :racer:

[jmidolo]

Just a simple question regarding Walbro 340's here. I purchased one from a vendor a few years back that came with a filter sock and performs very well. Recently I have purchased a couple more used units off the boards to set up a double pumper system. The used units I received have Walbro 340 factory stamped on them, they have a built in filter screen, and the spare sock I have doesn't fit on them. Was a 340 ever used in a OEM stock application and these are the units I've been getting? If they have a built in filter screen can I delete the filter sock? I just want to make sure I'm using the right part, no flame intended to the persons I've purchased these pumps from. Thanks :racer:


I don't think they were used in a factory app, but there are 340s, and 340Ms I do believe. The M puts out a little more. The one I have used came with a universal type sock that was not quite as large as a GM sock. It's likely the screen is not as fine as the sock filter is going to be, so I would use the sock.
I know some vendors grind off the walbro 340 stamp because it's "Theirs" and "special" :) I've seen that before.

[jastrckl]

the 307 from what I recall looks cosmetically similar, but has some different internals. If the # is ground off, you wouldn't be able to tell the difference on the outside I don't think.

[jmidolo]

the 307 from what I recall looks cosmetically similar, but has some different internals. If the # is ground off, you wouldn't be able to tell the difference on the outside I don't think.
Yea, 307 flows less than a 340 and a 340 is less than the 340m

WRONG. A 307 and a 340 are the same pump but the 340 has a stronger bypass spring so it has a higher operating pressure. The 340M is a "M"achined 340 it is machined for a GM style sock instead of the Walbro sock (they also do NOT make "special" pumps for certain vendors or have ANYTHING bigger at this time)
Mike Licht

[Dominic Mizzi]

I have seen some pumps out of my customers cars that have the name ground off too! problem is you can't tell if it's a 307 or 340

[d0n_3d]

is there anything that flows more than a 340? i'm looking for a single in-tank fuel pump that will flow high 10's safely...or is the 340M good for that?

[GNut]

Check these out.. Says Walbro 340 with a hand etched "M" beside it. Is there a sock available for this pump?? If so, where do you get one??

[Mike Licht]

Check these out.. Says Walbro 340 with a hand etched "M" beside it. Is there a sock available for this pump?? If so, where do you get one??That is a 340 M they take a 340 out of stock and machine the end down. Then hand scribe the M on. We have socks for those
Mike Licht

[HairDrier]

is there anything that flows more than a 340? i'm looking for a single in-tank fuel pump that will flow high 10's safely...or is the 340M good for that?

These will outflow a Walbro but big $$$$


http://www.fuel-pump-shop.com/

[turbodave]

These will outflow a Walbro but big $$$$


http://www.fuel-pump-shop.com/

Problem with those is, you also have to add the multi $100 "dial-a-flow" to the pump, other wise it would completely overwhelm the fuel systems we have on most streetable T/R's.

[jastrckl]

I've heard that there was more difference than the relief spring. supposedly there's a difference in the 340's coil as well.