On Thu, 09 Jan 1997 08:46:53 -0600 Jeff Fayne <fayne@ibm.net> writes:
>Barney Gaylord wrote:
>>
>> This should be easy. Somebody tell me the water pump impeller
>>diameter or engine block front cavity diameter for any 1965-1971
>>engine, models BG through GK.
>Here's what I measure on my 18GH pump:>
>impeller dia: 2.850"
>impeller height (end of impeller to pump face): 1.026"
>
>Hope this helps.
Yep! That's exactly it.
Hear ye, hear ye! Anything you may have noticed me write about
modifying the MGB water pump to fit the MGA engine is hereby retracted.
The MGB 3-main engine water pump is nearly identical to the MGA water
pump and will fit the MGA engine without modification. It also has the
same water chamber and impeller dimensions and therefore has no advantage
in pumping volume. The impeller is 2-3/8" diameter. This clearly
implies that the MGA water pump will also fit the MGB 3-main engine, and
my book says the MGA pump is a lot cheaper. Make of that whatever you
like.
The MGB 5-main engine water pumps all have 2-7/8" diameter impellers,
therefore will not mount up to a 3-main block without some serious
machining to the block. The cavity at the front of the block has a snail
chamber (ie. Archimedes spiral) surrounding the impeller. The cavity on
the 3-main block would have to be machined to duplicate the cavity on the
5-main block. To make that job even more difficult, the 5-main water
pump shaft is in a different location, a bit lower and a bit closer to
the pump inlet, so the larger impeller still clears the mounting screws.
Now I need to contact the guy who drew the diagram for the pump
modification to set him straight, or find out what he had in mind. Also
that drawing appeared in the July/August issue of MGA! magazine, the
newsletter publication of NAMGAR. It appeared under the by line of
technical editor Mike Ash with credit given to the original author. I
suppose Mike and the rest of the NAMGAR staff may be a little embarrassed
over this one. Or maybe they already know.
So to install a 5-main water pump on a 3-main block you will need a
5-main block as a pattern, and a very creative machinist.
Barney Gaylord
1059 MGA
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