Fuel Pump Question With Weber Carbs

[rabobian]

I am doing a full restoration on my 1980 320Is. I am converting it to twin Weber 40 DCOE carbs, 10:1 compression and an IE 292 cam. I'm using a Carter fuel pump from IE. I have to mount the Carter fuel pump where the original pump was mounted because of space and that pump likes to push and not pull. The 2002 guys can mount the Carter pump right above the tank because the tank is below the trunk. That is not the case with an e21. Should I use the lift pump in the tank along with the Carter or will the Carter pump be able to draw fuel from the tank being 2 feet behind the tank? I only need about 4 psi for the carbs and I have a fuel pressure regulator in the engine compartment.

Any suggestions would be appreciated. Thank you.

[autox320]

I am doing a full restoration on my 1980 320Is. I am converting it to twin Weber 40 DCOE carbs, 10:1 compression and an IE 292 cam. I'm using a Carter fuel pump from IE. I have to mount the Carter fuel pump where the original pump was mounted because of space and that pump likes to push and not pull. The 2002 guys can mount the Carter pump right above the tank because the tank is below the trunk. That is not the case with an e21. Should I use the lift pump in the tank along with the Carter or will the Carter pump be able to draw fuel from the tank being 2 feet behind the tank? I only need about 4 psi for the carbs and I have a fuel pressure regulator in the engine compartment.

Any suggestions would be appreciated. Thank you.

Anywhere in the trunk is fine. Carter works best as a pusher pump being close to the tank not in the engine bay. Anywhere above the tank level is fine and anywhere in the trunk is fine. No need for the regulator using a carter pump. Nice motor combo, will be fun.

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For the E21 just remove the in tank pump; keep the guts of the intank lift pump tube assembly. Use the return line that goes to the bottom of the tank ....connect a line to the carter pump then can use the return hard line under the car to bring it up to the engine bay via hardline...connect to carb.

[rabobian]

autox320, that was one of the options I was thinking of doing, Thanks for the advice!

[m60b30530i]

I ran the same setup as autox320 described.

[Layne]

You don't need 4 psi, you need 2.5. The Carter works, but requires a regulator as you know, and is exceptionally noisy (probably depends somewhat on what you attach it to, don't mount it to the trunk floor). For these reasons I plan to switch to an SU pump that is natively 2.5psi.

[rabobian]

Thanks for the input Layne. If the Carter doesn't workout I'll look into the SU also.

[m60b30530i]

You don't need 4 psi, you need 2.5. The Carter works, but requires a regulator as you know, and is exceptionally noisy (probably depends somewhat on what you attach it to, don't mount it to the trunk floor). For these reasons I plan to switch to an SU pump that is natively 2.5psi.

Ran 4psi on my dual webers for 4+years. Never any issues, there is so much info on what pressure people run from 2.5psi to 6psi. Also I can report on a hot summer day the gauge would read around 3psi.

[Layne]

I suppose I should not assume that I'm running 2.5psi just because I set my Mr. Gasket regulator on 2.5. Need to get a gauge. But without the regulator, the Carter easily overpowered the float valves and it ran terrible.

[autox320]

I may check pressures when finally get my new setup up and running. But with that being said never used a regulator per TEP's recommendations with a carter and 38/38 weber. I honestly can hear when the float bowl is full and the pump sound changes the carter is a loud mouth girl

[Layne]

I'm pretty sure the downdrafts require, or can at least tolerate, a higher pressure than the sidedrafts.

[autox320]

I'm pretty sure the downdrafts require, or can at least tolerate, a higher pressure than the sidedrafts.

Yeah kinda figured that. I just ordered a slew of jets last week in anticipation of carb work. Plan to strip mine down and refurbish it. Definitely check line pressure but once setup I think the 40's will serve well. One thing I've always heard is don't cheap out on linkage for DCOE's.

[cgifool]

DCOE 40's worked very well with shrick cam and headers on my old 2002 once I got the jetting figured out. Never did figure out a choke cable setup, but I tried two different throttle linkages - the first try was to use the original "rod" linkage, but the movement of the engine had a way of also transferring to the throttle. The second setup used a cable to the carb linkage, which worked much better.

As far as rebuilding them, I found the Haynes book very helpful (in contrast to their e21 book).

[autox320]

Far as choke on the 38 for how we used it never figured it out either. Had electric at first but it always seemed to close between runs if cooled enough which of course hindered WOT. So went to manual if needed it on the cold mornings when street driving it. That eventually became an issue to and one day broke the cable at the carb end. We didn't notice right away. The choke flaps had a mind of their own closing intermittent till we figured out why. A bit fed up with it hindering performance when we needed it, gutted it. Removed the entire choke, and flaps. Just feather it till get some heat in it and worked like a champ every time.