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MG MGB GT V8 Factory Originals Technical - Swirl pot fabrication

I know I have seen specs somewhere, but can't remember where and the Archives don't help. There is/was a firm north of LA that made these for MGB's.

What I am looking for is a swirl pot that goes in one of the battery wells. The original fuel pump feeds the pot. From there, a high pressure fuel pump feeds the engine. There also is at least one return line involved. The purpose of all this is to prevent surge to the FI if the gas tank is not full enough. Any help would be appreciated.


Stan Arendts

There has been lots of discussion about swirl pots in the last year or two. However, I don't recall references of the system you refer to here. My own swirl pot was welded into a new MGB tank. I took the pot from an old Ford Sierra tank and the modification was very quick - cheap and is completely reliable.Try the archives. I searched under "swirl" and came up with a lot of hits. As you refer to battery wells - in the plural - then I assume that you have an older MGB. It might well need a new tank by now anyway.

You can install swirl pot/surge tank in one of the wells, or you can bolt one on to the back of one of the wells.
Plumbing is:
- one hose surge tank - high pressure pump
- one return hose efi - surge tank
- one hose tank - low pres pump - surge tank
- one optional return hose surge tank - tank
Feeder tank - surge tank needs to be bit above the middle of surge tank. You could try a shutoff construction where the feed to the surge tank is blocked if it is full enough. You could also trust the low pressure fuel pump in shutting of if pressure rises when the surge tank gets full (later pumps do this).
Mount high pressure pump under surge tank.

Frank de Groot

I modified a 3 quart Briggs and Stratton fuel tank and put it in the left battery well using one of the drop in plastic liners. The high pressure pump, a junkyard take off frome a Ford pickup with dual tanks at $20, sits in the well below the tank. The diaphraghm in the stock pump was jellified by our modern gas, so I fitted a generic replacement, $30 at Autozone. Brazed 2 heavy washers to the top of the 3 qt tank, and another one on the filler neck, then drilled and tapped all 3 for 1/8" NPT, which also matches the bottom fitting. One of the top fittings became the fuel fill or feed from the main tank, the other became the return from the fuel rail pressure regulator, and the highest one, up on the neck became the return to the main tank. The bottom fitting became the feed for the high pressure pump. I used steel lines throughout, keeping sizes consistent with the other fuel system components, and ran them through plastic tubing or rubber hose where they crossed from one side of the car to the other, just in case the driveshaft happened to get loose and hit them. 3/16" line was used for the return to the main tank, and a short section of it was flattened with vise grips to restrict fuel flow but still allow the tank to vent. This line is connected to a short stub brazed into the main tank filler neck. Foam padding was used around the pump as well as above the tank.
Jim Blackwood


There is a book called Chevrolet TPI TBI Engine Swapping by Mike Knell that has a lot of info re: fuel injection and home made swirl pots that can be mounted anywhere on the car and also serve to keep a good supply of fuel ready for high pressure use. Published and distributed by JTR they have a website by same name.

Lots a valuable info for swappers.


I havent finally decide what to do about this yet but in the meantime I have a T peice that feeds to a Bosh high pressure fuel pump which in turn feeds the fuel rail that returns to the T peice. A very large fuel filter (half litre)sites above the T peice and acts a a reserviour. This is fed by the old 4 cylinder low pressure fuel pump. Not too sure how it will work though but I figure you can't use all that much fuel on a corner.
I expect I'll end up with a new tank eventually.

This thread was discussed between 08/01/2003 and 09/01/2003

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