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MG MGB GT V8 Factory Originals Technical - Which Fuel Pump?
|Guys, can anyone recommend a suitable fuel pump when using a 390 or 465 Holley and a mild street engine?|
|Yes, a Facit Red Top will give you a nice steady 5 lbs/sqin|
and feeds my 200 odd hp 3.9 with a 600 Holley.
|Same basic setup as my TR8. I use a cheap generic electric|
pump like the facet. I think the last one that I bought was
a Purolator. some are square. The Purolator is cylindrical
|I am using the standard SU that came with the 79MGB, it feeds through a regulator set at 2.5 and goes to a Carter 500cfm on a 3.5 Rover. It cruises all day at 70mph and around town has given no trouble.|
|MikeCook Atlanta Ga.USA|
|We were monitoring the fuel pressure when we set my GT up on a rolling road.|
At 5500 rpm the brand new SU pump couldnt cope and was registering 0 lbs/squin.
The Facit maintained 5lb/squin and the Holley doesnt need a regulator
at that pressure. A normal V8 wouldnt have a problem except under conditions
of very high load. If you are starting from square 1 though you might as well
fit a really good pump from the gitgo!
|BobP to Mike Cook|
|I think there are at least a few threads on this in the archives...|
I'm not too keen on Facet brand pumps. I had one die prematurely. Also,
I find them to be relatively loud. Incidentally, I think Facet is owned
by Puroleter. I've had better luck with a Mallory branded pump from my
I think someone (David?) recommended visiting the local junkyard and
grabbing a Honda pump. I like that idea! I'm sure you want a fuel pump
you can put on and forget about.
|Guys, I probably should have said that I am starting from scratch (have no pump at all...SU or anything) and don't want to go the expense of a regulator if a stock pump (Holley Red?)will suffice. What output do you reckon I might need? If I have this info I can probably pick up some local solid state unit here in Australia...Does a Honda really fit and if so which model?? |
I have the same set up on my 77"B" but have not a regulator in line . Cruising at 70MPH gives no problem but around town when I have to come to a fast stop then the engine dies on me. This is probably due to fuel starvation in the carburetor(Carter 500cfm).
I might switch to a Honda pump just to be sure on the road. Anyone knows what type of Honda?
|Werner Van Clapdurp Lynchburg Va email@example.com|
|The original question was "what pump for a mild street engine". Your test showed a failure of the SU to supply at 5500 revs. You must not have any cops in your area. The reason for the regulator (which I already had) on my machine was to stop the Carter 500 from flooding, since it was fitted, no problems. I also carry a Facit pump just in case because I had always read SU horror stories, but it is still in the box. Have SU specs been changed over the years?|
|My car was on a rolling road at high revs, simulating a heavy load.|
The same load would be found, say in continental Europe driving fast up through
the various mountain passes found there. We stay out of tunnels these days!
The SU fuel pump has never been able to handle a "big" Holley when its really
pulling fuel in. It will literallyfall right off in pressure as the demand goes
up. I am reliably informed that Holleys will take 5lbs/sqin
as they have good gaskets.
Facit RedTop at 5500 rpm - 5lbs/squin
SU 5500 rpm - 0lbs/squin
Sigma engineering, where we did the work is nationally reknowned for their
cylinder head work and racing Mk2 Jags. They use dual Facit
Red Tops for the "Classic" racing Jags. The jags by the way have to stay on 2inch SU'S
They however give over 300bhp at the wheels.
While I was at Sigma, I saw a road -going Connaught,an HWM,a
Lister-Jag,an Allard an Aston Martin engined Cobra type car
and a bucnch of racing Jags.
|bobp to Mike Cook|
|I have not experienced any form of fuel starvation even of late, travelling around Atlanta or in 5 0'clock jams with temps close to 100 degrees. I run a mechanical fan as well as the 2 electrics which are on a manual switch in case of emergencies, I have not had to use the back up yet. Could your problem be timing or carb set-up? Does your idle speed fluctuate from day to day with the change in outside temp/engine temp?|
|MikeCook to Werner|
|Mike, I bought the Carter new from Towery and was set to operate with the Rover 3.5|
I will check the timing. Can stretching of the timing chain have a negative influence on the timing?
I wished I had installed a roller chain instead of the original one.
|Werner in Lynchburg VA.|
|Mark, I'm using a Holley Red pump with a Holley 465. It's noisier than an SU because it's constantly running. A cheaper alternative is a Repco pump. It's a small box shape type.It's about half the price of a Holley & according to the label, is suitable for V8's. You can get them from Auto One or Repco. I don't think Facet pumps are available over the counter in Aust.You'd probably have to send o'seas for one.The Repco pump is rather noisy too.|
Regards, Barrie E
|Barrie Egerton Sydney firstname.lastname@example.org|
|If any of you guys want a good cheap, reliable, solid state pump from a junk yard, then the one to go for is from a Subaru Leone.|
I do not know the specs on these, but you should be able to pick one up for $5-$10 and a lot of budget racing guys use them. Probably the biggest problem is finding an old Subaru with one still in it. If any one knows the specs, please let me know. I think that these pumps are actually made by Mitsubishi.
I hope that this is of help.
Yeah, it was me pushing the Honda pump. The one to use is from the 1984 Accord (carbed, of course). They are cheap, quiet and work well. The unit is made by Mitsubishi and sells for about $45.00 at NAPA. It will mount easily in the stock pump location. No regulator is needed.
Bob and Denice Thompson from Statesville send their regards.
|I'm using a Holley fuel pump, too but would advise against it because of NOISE, NOISE, NOISE! Have heard that there's a very silent Mallory available or the Honda mentioned before.|
A question for HONDA FUEL PUMP USERS: does this pump really put out enough fuel to feed a Buick/Rover 215 at full tilt? Have a hard time understanding how it would unless Honday overbuilt it. There's such a big difference between the 4 cyl Honda's and the V8! How about a report on how it does at full throttle. Thanks...Mike
|Mike in Western Colorado|
|Does anyone have any experience of problems with pumps on E.F.I. systems? The standard Lucas/Bosch pump has difficulty in starting my car from cold(although it is o.k when running) I replaced it with a high pressure pump from Rimmers and initially it seemed o.k but now I have the same problem. I've checked for air leaks, and the pumpis o.k if I remove the resistor, does this mean I'm losing voltage somehere down the line ? HELP.|
!Mike Barnfather Blackpool
|mike barnfather 113414.2071@compuserve|
If you think the fuel pump is not pumping when it should, check the fuel pump relay. I encountered a similar problem on a Porsche 944. The relay provides(relatively) high amperage power to the unit and are triggered by low amp power from the ignition circuit. Having said that, I would place a pressure gauge in-line to check for pressure with the ignition switched on and engine not running (you should get line pressure). My guess is that the fuel pump is not the problem at all.
Has it always been giving you this problem? Was this EFI unit grafted from a particular Rover? Which EFI system do you have? I would suggest obtaining the factory shop manual for the donor vehicle and chase down the diagnostic path outlined for the EFI system. You could have a bad sensor or solenoid or any of a dozen items that enrichens the mixture and controls the idle when the engine is warming up.
Forest Hills, NY
72 rust never sleeps red BGT
|Pumps suitable for EFI are not good at pulling fuel from|
the tank. I would make sure that the pump has an adequate
The pump needs to:
be supplied with large lines,
have the fuel filter after the pump (high pressure filter),
be mounted below the fuel level
or have a low pressure pump feeding high pressure pump.
Most fuel injected vehicles have the pumps mounted in the
tanks. Many of those that don't (Merkur XR4Ti's and I
believe Ford pick-ups from the late 80's) have a low
pressure pump in the tank feeding the high pressure pump
under the vehicle.
This thread was discussed between 18/08/1999 and 09/09/1999
This thread is from the archive. The Live MG MGB GT V8 Factory Originals Technical BBS is active now.