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MG TD TF 1500 - New Item at FTFU

Doug Pelton sent an email to the TABC group showing a new product he's now carrying. Press fit, no soldering and only $7.20. I think it's brilliant!




Gene Gillam

Installation



Gene Gillam

Looks great. Only question - how much does it reduce the exit? Is it an insignificant amount? Bud
Bud Krueger

I'm guessing the size of the outlet is 5 to 10 times the size of the carb's jet openings at full throttle.
MAndrus

Mike, I'm thinking about the inlet side of the fuel pump. The pump isn't continuously feeding the jets. When called upon, it's filling the float bowls. Bud
Bud Krueger

"m thinking Bud may have a valid point.
MG LaVerne

Looks pretty nice. As I just finished making my own for $2 worth of materials and half an hour of time, I won't be getting one ... but in 20 years maybe :)
Geoffrey M Baker

But the bowls are only filling at the rate the jets are emptying them.
Steve Simmons

I wrote Doug irt the concerns voiced on the forum...here's his response:

The tapered fitting has .15" ID, plenty large enough.

In addition, it's a new filter and won't be gummed up like the one you're taking out of the tank...if that partially worked, this will fully work.


Gene Gillam

I'm an EE, not a whatever kind would handle such hydraulics. But, my gut feeling says that a .15" ID passage would make the pump think it's pulling through a rather clogged filter. Anybody happen to know the i.d. of the bare fitting? Bud
Bud Krueger

I installed two of these in my 52 TDC (two fuel lines) about 6 months ago. The car runs just fine with no issues from cold start to running at high rpm's. My original fuel screens were completely rotted and these screen filters were real easy to install since no solving is involved. Can't tell any difference in the operation of my two fuel pumps from before. I highly recommend them. JMHO. Tim
Tim Debes

Bud, the bowls will only be filled to replace the fuel going through the jets. So yes, it is continuously feeding the jets.

Tim
TD12524
TW Burchfield

Steve Simmons, sorry, I didn't see your post before I commented. Wasn't trying to be redundant.

Tim
TW Burchfield

I'm a huge fan of the department of redundancy department. :)
Steve Simmons

A piece of me wants to just say, "fuggedaboutit", but I'm just too stubborn. I readily admit to not being an expert on SU fuel pumps, but I have learned some things over time. For one thing, the pump is not continuously pumping. It senses the pressure in the outlet line. When the pressure reaches an upper level the pump is turned off. When the pressure drops to a lower level the pump is cycled to actuate (the familiar click). The diaphragm goes through its cycle and expects to bring in a designed volume of fluid. This volume is a function of the diaphragm's action and the cross-section of the fuel line. If the fuel line is restricted the pump will not transfer the amount of fluid that it's designed to transfer. As a result the pump will have to pump more often than would be expected in order to supply the volume of fluid necessary to close the needle valves and turn off the pump. Watch your ammeter when the engine is idling. You can expect to see it flicker about every 5-7 seconds when the pump cycles. I've got a full tank right now or I'd go and measure to diameter of the opening in the tank output.

I get a lot of practice at apologizing when I'm wrong, so feel free to shoot me down. Bud
Bud Krueger

Bud, proof of the pudding is in the taste...or in this case, usage experience. Tim has used them and recommends them...FTFU provides quality items. What difference does it make if your pump has to tick 5 times instead of 4 times to get the gas in the bowl?
Gene Gillam

25% shorter lifespan. It's an interesting point. My question would be what other restrictions are there in the fuel line? If at any point the line narrows to 0.15 ID its not a problem...
Geoffrey M Baker

They may well be fine. I'm just curious as to what sort of restriction it represents. Bud
Bud Krueger

Pumps, bowls and jets aside.... I'm thinking: at 60 mph (and assuming a reasonable 20 MPG) the rate of flow needs to be only 3 gallons per hour. At closer to 30 MPG, you'll need only about 2 gallons per hour.

I'm fairly certain 3 gallons will flow very nicely thought this new filter in somewhat less than one hour. Perhaps just a few minutes in fact.

.....
MAndrus

Bud,
I’m a CE, long retired to be sure, but fluid mechanics is one of the few things that haven’t changed since I was in school way more than half a century ago. I’m not about to analyze the flow in exact detail, but I think the added constriction in the fuel line can be put in the category of minor losses, which usually result from abrupt changes in magnitude or direction of velocity. It’s a minor loss compared with the total energy required to overcome the friction in the pipe and to lift the fuel from the tank to the carbs. Fluid pressure and velocity in the fuel system are fairly low. The increase in velocity as the fuel accelerates thorough the rather short constriction causes only a slight loss of energy. Interestingly, a bigger loss of energy occurs downstream of the constriction because of the production of turbulence resulting from the abrupt increase in pipe diameter. At any rate, I don’t think it’s a big loss that’s gonna make the pump work significantly harder.
Joe
Joe Olson


Top of tank, 32". Top of carb bowls, 28". If the pump wasn't higher than the bowls, gasoline would flow to the carbs by gravity from a very topped-up tank.

The fuel pumps in our cars are doing very little work until we have a near empty tank.
MAndrus

The pump delivers a set amount of fuel every time it cycles, so for a given flow rate it clicks the same amount of times.
Fuel is delivered on the spring driven stroke.
The only problem is pump stall on the suction ie powered stroke which will damage your windings through overheat.
By the way I was given an SU pump AUA154 is this suitable far a TF. I am not doing the lying on my back with a mirror trick!
Ray TF 2884
Ray Lee

Thanks Joe. Bud
Bud Krueger

I would strongly suspect that the pump is built to pump more fuel at all times than the engine can possibly use, and that the carburetor float bowls are the control mechanism intended to limit fuel delivery to the actual needs of the engine. So a minor restriction in the fuel line should have no effect on overall performance. A supercharged engine or the MKII might be a different matter.
Geoffrey M Baker

The fuel pump doesn't decide how much fuel to pump, the engine does. The engine requirement for fuel from the tank will remain the same no mater what filter is in place. Now whether the filter is large enough to fulfill that requirement is another story. If the guy selling the new type filter and others are using it and say it supplies the required amount of fuel then I am satisfied it will. After all the seller is a parts supplier to many people on this forum and has his professional reputation to think of.

Tim
TD12524
TW Burchfield

This thread was discussed between 14/08/2015 and 16/08/2015

MG TD TF 1500 index

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