69 Coronet R/T fuel pump

[70b5bluerunner]

Where can I get the correct fuel pump for my Coronet R/T 440-4 barrel. It has a vapor canister/ fuel filter with a return line. Supposedly I need a compatible pump with more pressure due to this canister. All the pumps I see on line have an adapter like the one on my car and I don't think that is correct. If I block the return line the car runs fine. If i leave it operational the engine surges on hard acceleration. Any thoughts out there?

 

[lewtot184]

Pretty sure rock Auto has the high pressure pump. I use a 6903 Carter pump but reduce the size of the return orifice in the separator.

 

[70b5bluerunner]

I can find the N4434 pump but not the M4434S pump. Any ideas out there?

 

[70b5bluerunner]

Pretty sure rock Auto has the high pressure pump. I use a 6903 Carter pump but reduce the size of the return orifice in the separator.

Can't I just plug the return line?

 

[turbine68rt]

If you have a stock setup why would you need a higher pressure pump than what was originally used? I'm using an M3672 pump with both an AVS2 and the original Carter 4429 in conjunction with the oem vapor separator and have zero issues with fuel delivery. What carb are you using? Might need a bit more info.

 

[lewtot184]

The vapor separator with a stock lopo 3-5lb pump is a definite power loss. The return orifice reduces pressure to the carb so even with the stock hipo pump, that can do 8lbs, the carb will only see 5 or 6 pounds. A 5-6lb 6903 with with .stock 060"+ orifice will drive ok but will loose power and that's why I reduce the orifice size. The vapor separator and hipo pump were designed to work together. It's ok to eliminate the return if you want just don't use a high pressure pump without the return.

 

[70b5bluerunner]

If you have a stock setup why would you need a higher pressure pump than what was originally used? I'm using an M3672 pump with both an AVS2 and the original Carter 4429 in conjunction with the oem vapor separator and have zero issues with fuel delivery. What carb are you using? Might need a bit more info.

Stock AVS but it supposedly calls for that pump

 

[turbine68rt]

Try to get around 5.5 psi not over 6.
Do you have a fsm?

 

[turbine68rt]

A 5-6lb 6903 with with .stock 060"+ orifice will drive ok but will loose power

I've been running the stock setup for close to 40 years and had equal or better timeslips than when they were new using a stock pump.

 

[lewtot184]

I've been running the stock setup for close to 40 years and had equal or better timeslips than when they were new using a stock pump.

i'm curious. are you running a stock low performance pump with the separator or a high performance pump and separator? i'm assuming a stock 375hp 4bbl 440? what were your e.t.'s?

 

[turbine68rt]

4-5.5 psi carter pump with separator. I used to race it at a few different events every year late 80's-early 90's. 14.20 at Maple Grove. Stock 440 mag including single point ign.

 

[lewtot184]

4-5.5 psi carter pump with separator. I used to race it at a few different events every year late 80's-early 90's. 14.20 at Maple Grove. Stock 440 mag including single point ign.

don't know if this is apple to apples but i ran my '69 r/t at the track in '86. engine had been rebuilt but was completely stock cam, heads, pistons, intake and carb. exhaust was original factory manifolds, pipes and mufflers. stock 3.23 gear, 5lb pump and no separator. best e.t. was 14.01/99mph. string of 14 teens. i didn't run with a separator because i didn't have one.

fast forward several years and i converted the engine to unleaded gas (9.3:1 compression), 272/.455 mopar cam, 6bbl, same 3.23 gear. 13.13/106mph no separator same 5lb pump; 13.60's/103mph with separator.

a few years back i started doing some pump with/without separator testing and checks. something i noticed that the repop separators i had had much larger return orifices than stock. i hooked the separators up to my parts washer just to see how much fluid they were bypassing. my parts washer has a 3psi pump and i was amazed at how much fluid was flowing thru that small orifice. unfortunately i didn't check flow volume. i also did some on the car testing with different orifice sizes but kept the same pump. the larger the orifice the greater the lower rpm pressure swings were and lower psi at the carb when the pulse swings started to merge together. i started reducing orifice sizes and came up with less pressure swings and higher psi at the carb. maybe not perfect but didn't seem to have a performance negative. i do have the original high pressure pump from my car but i've only bench tested it. not sure how long a 50+yr old pump would last driving. anyhow, it did 8-9psi cold and almost pumped as much as the 3 valve 6903's i've been using. pressure wise that old pump is probably perfect for the original .060" orifice return with the factory separator.

 

[turbine68rt]

Keep in mind back then the engine was still factory assembled, 85k+ miles, and F70-14 redlines. I wanted to see how it could perform in showroom trim. Never got to find out what it could do with a decent set of tires.