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MG MGA - 3 Main B into A What water pump+carbs?

After reading all the posts regarding installing a 3 main B engine in an A, one thing I didn't notice was which water pump to use. The one from an A or from a B?
I would like to retain my A's fan, but if the B pump is better, I could go with an electric fan.

Another thought...
I have carbs for both my 1600 and the ones that came with the B engine. Which of those would be best for use with the 1800 engine?
Cleve

Just completed early 18b engine. Used b waterpump, and 1600 carbs. Cliff
cliff hughes

Thanks Cliff,
Any particular year model water pump? I notice there are more than one listed.
Cleve

Cliff,

Did you change the carb needles? I found that the A needles were to rich when I did mine.

David
David Honness

I've done a little bit of port work on the '72 5 main B engine in my A. I'm using H4 carbs from a 1600 with #5 needles. A little bit rich at idle, but okay through the rest of the rev range. If I remember correctly, I have a water pump from a '72 B and a single row pulley from a '66 B. I did have to move the lower lip on the duct panel forward 1/2" and shim the radiator forward to use the pulley driven fan.
Steve Mc

What is wrong with the A pump? It fits.
JohnB

"What is wrong with A pump? It fits." JohnB

I thought that the MGA pump will not fit the 1800 engine be it 3 main or 5 main. Also that the A pump would be too small (insuffient pumping ability to cool the 1800 engines. JohnB could you give us more details? If the A pump works and cools the car, it would be the ideal pump to use with 1800 engine as one could then retain the A pulleys and the original look.
James Johanski

Do not use the A pump! The impellor is too small and will not flow enough water.
the B pump is superior

CP
Colin Parkinson

The impeller has to be at least a close fit to the housing - use the correct pump or you will have a small impeller thrashing around in a large housing, not moving much water.

The 3 main MGB engine and pump works well in an MGA.
Bill Spohn

Bill, Is it true that the MGB three main pump has a longer nose than the MGA pump essentially making the entire engine/pump assembly longer and requiring the radiator be moved forward and possible down to clear both the fan and the bonnet. If this is so and done, is one still able to use the hand crank?
The reason I ask this is I am contemplating the substitution of a 3 main 1800 cc engine in an A. IRetain the tach drive and have the car at least look original. The 1800 casting marks could be altered, to help achieve the original look. If the MGB 3main engine is indeed longer, could the nose of the pump be shortened?
James Johanski

When I installed my 3 main in my A I used the B water pump that came with it but I had to move the rad ahead about half an inch. I also used the A fan. There is just enough space to fit the belt between the fan and the rad. The only advantage to using the B carbs is you don't have the problem of leaking float bowl seals. performance is the same.
Kris Sorensen

Hi Cleve

The 3 bearing 'B' pump is different to all the 'A' and 5 bearing engine pumps, as mentioned it is too long and requires moving the rad forward. I had pump shortened by the company who made pumps for Unipart, this was a one off and as I am using a 5 bearing engine it is surplus and I am willing to sell it, are you interested? Contact me by email - terrydrinkwater@btconnect.com

Regards

Terry
Terry Drinkwater

You can move the rad about 1/2" forward, and a corresponding amount down and still use the hand crank.

If you want nice spacers yu can order them from George Folchi, as it's a standard mod required for fitting a Judon. But you need to modify the holes in the rad bulkead to drop the rad or you can't close the bonnet.
dominic clancy

This thread was discussed between 02/07/2007 and 05/07/2007

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