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#2455610 - 02/22/18 11:28 AM MP P4876074 SB Mech Fuel Pump
BcudaChris Offline
enthusiast

Registered: 03/31/05
Posts: 253
Loc: Colorado front range
Has anyone run one of these? I've run across a sweet deal on one, but it is listed as a high RPM circle track unit.

The descriptions I can find say it doesn't need a regulator, but I'm concerned it may push too much fuel pressure at low RPM for street driving. I can find pretty much zero info on it on the interwebs.

The alternative I'm looking at is the over priced Edelbrock mech pump with 3/8 NPT I/O

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#2455617 - 02/22/18 11:35 AM Re: MP P4876074 SB Mech Fuel Pump [Re: BcudaChris]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 34402
Loc: Lincoln Nebraska
the MP catalogue just says "nascar truck (special high RPM for circle track apps)"
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#2455707 - 02/22/18 02:03 PM Re: MP P4876074 SB Mech Fuel Pump [Re: BcudaChris]
BcudaChris Offline
enthusiast

Registered: 03/31/05
Posts: 253
Loc: Colorado front range
Thanks Rapid. Summit has a little more info, but I kind of doubt the veracity, it looks like they copied the entry from the other MP fuel pump and added the MP catalog description you provided.

Summit says 6.5 max psi, which is what I want obviously, but if that rating is at say 4-8K, what is it at idle? I just don't want to eat up the savings from a sweet deal with the added cost and complexity of plumbing a regulator.

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#2455753 - 02/22/18 04:00 PM Re: MP P4876074 SB Mech Fuel Pump [Re: BcudaChris]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 34402
Loc: Lincoln Nebraska
I'm wondering if a person called one of the fuel system companies & asked them generically if a pump on paper the psi is rated at 6.5 would that be at idle or high RPM
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#2455832 - 02/22/18 06:45 PM Re: MP P4876074 SB Mech Fuel Pump [Re: BcudaChris]
BcudaChris Offline
enthusiast

Registered: 03/31/05
Posts: 253
Loc: Colorado front range
Good advice, I just called the vendor (who is selling the pump dramatically discounted) and the guy told me it would have to be regulated for my purposes, unless maybe I was running a -8 or 1/2" fuel pickup and line. The restriction of the line at low RPM would would jack the pressure such that at idle and low RPM the needles would never seat. And, complete overkill for my setup generally.

I asked about ratings and he said they pay no attention to them, they go by the manufacturing specifications to see if a given pump could even be in the ball park, then test every pump and tweak to get what they need. He also said they see a huge variance from pump to pump on any given model.

His other additional comment that I found interesting was that with all the electric pump retro fit solutions, hardly anyone does mechanical fuel pumps for hi po streetable anything any more unless they're restricted by a racing class.

Good ol' physics F=AP, or whatever the equivalent equation for fluid is.

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#2456135 - 02/23/18 11:22 AM Re: MP P4876074 SB Mech Fuel Pump [Re: BcudaChris]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 34402
Loc: Lincoln Nebraska
Yes even my parts house "airtex" 318 replacement mech pump was overpowering my eddy 1406 (boosters dripping at higher speeds). I forget what the psi was but it was high (way more than what I would think would be needed for a DD replacement pump app)
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#2456255 - 02/23/18 02:52 PM Re: MP P4876074 SB Mech Fuel Pump [Re: BcudaChris]
BcudaChris Offline
enthusiast

Registered: 03/31/05
Posts: 253
Loc: Colorado front range
Yeah, my previous setup was a 625 AFB and I switched from a Carter Super Pump (the FP and carb were both late '80's vintage) to the Airtex. I pulled my cheesy Puroltor parts house dial regulator thinking it was no longer necessary. Boy was I wrong.

Anyhow, at this point, I've ended up going with an FBO modded Quick Fuel branded Holley pump that theoretically shouldn't require a regulator. We'll see.

At this point, I'm thinking not needing a regulator is a fantasy, and I'll have a return once I run my 3/8 line so no need to run a dead head regulator.

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#2457373 - 02/25/18 01:56 PM Re: MP P4876074 SB Mech Fuel Pump [Re: BcudaChris]
Mattax Offline
pro stock

Registered: 02/28/10
Posts: 1201
Loc: Phila. Pa.
Late to the party. Its been around a while but I couldnt get info on it either.

I bought the p4529368 pump and had it tested by Ryan Brown. The MP catalog had its pressure rating at 9.5 psi but it turned out to be a much more civilized 7 psi. That's a 1/2 psi less than the M6270 Carter "competition" pump was rated, and tested at.

Only problem with the MP p4529368 pump is interference with the '70 and up water pumps with passenger side inlet. Wish someone wouldf make a an aluminum driver side pump again.
http://www.heritech.org/cuda/fueldelv.html#Pump%20Fit%20Issues

I've had good luck with Holley's 110 mechanical pump on my 340.

PS. The other time (besides idling) those high cutoff pressures really bite you is when lifting off the gas at mid to higher rpm.

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#2457896 - 02/26/18 12:21 PM Re: MP P4876074 SB Mech Fuel Pump [Re: BcudaChris]
BcudaChris Offline
enthusiast

Registered: 03/31/05
Posts: 253
Loc: Colorado front range
Totally makes sense on overpressure while lifting when deep in the powerband. Certainly a problem in an autox or OT situation.

The p4529368 pump was in the running for me, but lack of availability and the fit problem were the hangups with that one. The other was the Edelbrock pump, it has a higher flow rating than the QuickFuel, but is probably over-rated.

The Quick Fuel I went with has been tested (FBO) at 104GPH at 4000, and has had the inlet/outlet upsized to 3/8 NPT and had AN fittings installed. That should be plenty for me, and the price was right. Don at FBO also told me no regulator necessary for that one. I'll give it a shot.

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#2457954 - 02/26/18 02:20 PM Re: MP P4876074 SB Mech Fuel Pump [Re: BcudaChris]
autoxcuda Offline
Too Many Posts

Registered: 01/20/03
Posts: 26051
Loc: So Cal
Originally Posted By BcudaChris
Totally makes sense on overpressure while lifting when deep in the powerband. Certainly a problem in an autox or OT situation.
...snip....


Troy had this same problem smallest 3 pc Holley pump with the dual Hemi Super Stock Holley 1850’s in his crosssram 472 Hemi with manual valve body. He added a regulator to solve his drivability issue. It wasn’t lifting in high throttle. It was just getting off the freeway and coming to a brisk stop.

This might be possible cause for issue in more situations than just autox and one track.


Edited by autoxcuda (02/26/18 02:27 PM)
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#2457983 - 02/26/18 03:07 PM Re: MP P4876074 SB Mech Fuel Pump [Re: autoxcuda]
BcudaChris Offline
enthusiast

Registered: 03/31/05
Posts: 253
Loc: Colorado front range
Totally, I had problems in the situation you describe with an airtex pump. Reinstalling the cheesy purolator regulator took care of it.

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