I'm sure this question has been asked 100 times before, but how fast have you gone with this old pump? And how much power can it support (in your experience)?

I run one in my Challenger with 3/8" factory line, sender and tank, and honestly I really like the simplicity of this fuel system. Havnt raced it yet, but ran it hard through the gears a few times and never noticed any fuel delivery issues. Its a 505 w approx 550hp, 4 speed and 3.55's. I plan to throw a few more horses at it this winter (maybe get it closer to 600)and I'm guessing I'll be pushing it at that point...

121mph, 3600 lbs. With 5/16 fuel line.

3/8 from pump to carb.

512 with unknown hp and 3860 lb.
With 3/8" factory sender and fuel line and Carter M6903. It fell on its nos at finish line in 1/8.
Now running a CV Product fuel pump

Hyd. cam 440, Modern ported Stealth heads, 750 holley, stock 5/16 fuel line and stock tank, 3850lb 67 Belvedere. 11.23-123 With a 150 shot of nitrous. Carter pump fed both engine and plate, makes for a great street car.

My D50 ran a best of 6.29 @ 108 in the 1/8 with the Carter mechanical pump and 3/8 fuel line and a AutoZone plastic fuel filter. Switched to a big MagnaFuel pump and -8 line and saw no improvement.

That pump was failing om me about 520 HP. It is rated flow wise for more then that, but when you add in all the twists and turns, variables that's about it. Your there.... ,time for a upgrade now.

Type of fuel, temperature and usage are big variables.

An engine compartment mounted pump sucks the fuel from the back. If the fuel gets hot and boils, pump capacity does not matter. It won't pump anything useful sucking vapor.

Current pump gas is made for EFI systems and boils easily.

A suitable electric pump mounted in the rear where it is cooler often works much better vs engine mounted pump. It gets some pressure in the fuel before it gets into the hot engine compartment. That would be my suggestion.

Cool!

Moparbilly - cool car and nice set up. I wouldn't have guessed that pump would feed the nitrous too!

D-50 - that's moving for sure and I guess better safe then sorry when it comes to fuel delivery and your upgraded fuel system...But your before and after is a perfect example of the overinflated pump requirements that we often hear about.

Good points, and I'm definitely not opposed to electric pumps. My car also has a fuel filter with a 5/16 return line to prevent vapor lock. At least that what the claim is. I havnt had any hard starting issues when hot, so could be working.

My before and after. purple cam 440, inconsistent 10.80,s and .90,s with the carter pump, switched to a electric pump, 10.40,s no other changes.

Apparently that carter pump and/or system wasn't working for you. Were you experiencing stumbles? Also just curious, was it just the pump that you replaced, or were there other system items switched out as well?

The best test I know of for fuel system is to keep jetting the carb. up until it slows down in the 1/4 mile, if it won't you don't have enough fuel supply
On my old pump gas Duster I had to go to .120 needles and seats to be able to jet it rich enough to slow that car down in he 1/4 mile

Yes with the carter strip pump I was experiencing some nosing over at the top end. When it would nose over it would run 10.9,s. When it didn't nose over, still felt like it was pulling, 10.8,s. Figured I would up grade to stop the nose overs at the top end figuring I could get Consistant 10,8,s. Well ended up getting consistant 10.47/10.50,s

Wow, wasn't expecting that, sometimes you can be starving for fuel and you Wont even know it. And yes Pump change only, nothing else. Thought I was just having some occasional fuel starvation nose overs.

Thanks Cab, that's great info.

You must have been thrilled with that improvement! Thanks for the info.

I agree with this. I know many guys run the mechanical Carter pump but I run the Holley black pump mounted right by my fuel tank. I use a 3/8 stock type sending unit and run 3/8 line. Just the fact to have the fuel coming up to the front under pressure rather then being pulled under vacuum will help fight vapor lock a lot, The one problem I see is fuel boiling in the carb which can happen with either mech or electric pump. I like having my electric pump mounted by the gas tank so my fuel is under some pressure coming forward. But that's just me as many do still like to run the mechanical pump. Good luck with which ever setup you use. Ron

Thanks Ron - I'll be honest, if I thought I would race on a fairly regular basis, I would have an electric pump back there for sure. My car is really not set up for racing, but hopefully at some point I throw some sticky tires on and see what it can do. Or in my case w the 4 speed, see what I can do! I do smile when I hear about the guys running 10's with 5/16 line and mech pump, but I understand why that's not going to work for everyone.

Running 91 No Ethanol fuel and having a 1/2" phenolic spacer under the carb help with summertime issues.

11.40 at 117.4 mph at 3700 lbs all motor. Carter strip mechanical pump w/ 3/8" line.
10.60s on a 150 shot, but the nitrous had a separate fuel system w/ an electric pump. Motor still fed by the mechanical Carter.

Later on I changed to -8 line w/ a Holley blue pump and put a sump in the tank. Ran no different.

Pump gas? Modern pump fuel is designed to vaporize very quickly, not a problem for fuel injected cars which keep fuel under pressure until it leaves the injector, but is a problem for a mechanical pump that puts the fuel under a vacuum for 15+ feet, fuel vaporizes much easier under a vacuum.

My Carter 6903 (the one you don't need a regulator for) would drop from 7 to 3 PSI AT WOT in 1st gear, before it was heat soaked. Once heat soaked static pressure at idle was down to 5 or so PSI, dropping to <3 @ WOT.

Some seem to have good luck, but seems to be a crap shoot. Dwayne Porter's 383 Satellite was pretty darn quick with a mechanical pump, he finally swapped in an electric and he picked up. I'm sure he will chime in.

One day GY3 will make the switch and everyone will be shocked when he gets a 10 second slip with 3.54s and that mild cam.

I do love the simplicity and quiet of a mechanical pump. I installed a Carter m6903 on my C body driver (440, 474 purple shaft, manifolds). It might run 15s or 16s on a good day, but to be honest I have not actually tried it. Just an old family sized car with a big motor for fun. I've got a plastic spacer under the carb and it hasn't given me any trouble as of yet, but if it acts up I'd probably first try a return line before doing anything drastic. I've had pretty good luck with return systems in the past keeping the fuel cool...

Haha, car never noses over even beyond 1/4 mile. The car runs exactly what the Virtual Dyno says it will, usually within a tenth. ...even with nitrous!

The nitrous does have a dedicated fuel system.

All I need is some good track prep, a little shock tuning and weather to get that 10 N/A in the quarter.. It has been 101mph in the 1/8th mile.

A 10.99 is there for sure. Obviously you've already gotten it on nos, but on motor too. Maybe the stars need alignment, but it's there. My old wagon ran consistent 11.0-11 teens at 119-121 and then the perfect weather and possibly a tail wind and I got that 10.98. I wouldn't have called it 10 sec. car necessarily, but legally I could have .

Let's see that C body! Wish I had the space for one.

Oh man, OK here are pics but it's just a big ol' 4 door with some police wheels.

After the original 400 went dead in a couple holes and had 3 lbs oil pressure, I put this 440 in it. It's the same '73 440 I originally had in the GTX with a few "cheap rehash" changes (dual plane, HP manifolds, 750, 474 cam) and a go-through.

It's still standard bore after all these years but bore taper is now approaching service manual maximum at .006. (max is .010, ahhh...it's not a race engine...whatever). It also has an awesome 3.23 peg leg, and the very first high stall converter I had in the GTX which is an 11" B&M holeshot from like 1989 LOL.

On this big tank I am experimenting with ignition ideas that I picked up from carbureted Jeep enthusiasts. A GM HEI module and Ford TFI coil, fired by a Mopar distributor. Not only is it dirt cheap but it seems to work well. I like it better than the previous chrome box/msd blaster.

Are you kidding me! That's awesome. I would love to have something like that for a daily driver. In nice weather of course. I love the color too. I need a bigger garage.

Thank you.

Only a true Mopar Man like yourself appreciates 'em all.

It took forever but I eventually created a decent place to work indoors. I laid it out making sure it could accomodate a C body or 4 door long bed truck on the ground, or up in the air.

Out of respect, I won't hijack your post with 100 shop pictures LOL.

Feel free to hijack! Nobody cares about Carter
mechanical pumps anyways

LOL ok, but just enough to keep the conversation going.

Garagejournal.com has been an inspiration, and a few moparts dudes are over there too.

More or less the whole story of the shop is told over at garagejournal...Will send you a link if you'd like to join up and check it out....Other than the hoist, the big thing that isn't visible (the slab insulation hints at it) is the radiant floor heat. I can lay on the floor in the dead of winter and work, and never feel cold which really helps... Back to your regularly scheduled fuel pump discussion...

I would be one of those dudes.

My Garage Build Thread

BTW, I used a Carter small block street/strip pump on my old W2 340 combo that went 12.0s at 110+. I believe it was starving for fuel on the top end but I was never exactly sure.

When I built a 416 a few years ago I wanted to stay with a mechanical fuel pump so I chose a Clay Smith over the Carter. The CS is capable of moving a lot of fuel but it has a HUGE body, requires removing a boss on the block for clearance and can interfere with the water pump too. I wouldn't go that route again, no way too much hassle.

Zippy, your garage is awesome! You have officially made it to hot rod heaven my friend.

Thank you Tony....RMCHRGR's shop is super nice too...but can't see the pictures on that site unless logged in. That's how they get you LOL....