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Re: Another question on Negative Grounds

To: MarKap2032@aol.com
Subject: Re: Another question on Negative Grounds
From: Jim Boyd <gumby@joshuanet.com>
Date: Tue, 22 Oct 1996 21:31:49 -0700
MarKap2032@aol.com wrote:
> 
> I've been lurking on a variety of British Car lists for over a year.  I'm an
> active member of the MGCC-Western NY centre and I have a  variety of British
> cars which keep me occupied in the garage during the long western NY winters
> (which have now started).
> In the past I have converted MGAs and a TR3 to negative ground during a
> rebuild.  I know you need to switch coil wires, repolarize the generator etc.
>  Now I am working on a '67 MGBGT and I want to switch to negative ground so
> that my wife can enjoy  "period" sounds on a modern  CD while she uses this
> sportscar hatchback for her travels to every garden shop in upstate NY.
> I know that the electric tach on the MGB needs to be rewired and I have John
> Twist's instructions for that.  NOW , finally I get to my question for this
> esteemed group......The car seems to have an SU fuel pump (altho I doubt if
> it is the original one).  I know that many ,if not all, replacement SU pumps
> contain diodes which make them blow out if you switch polarity.  How can I
> tell if this fuel pump will work when I switch battery polarity (without
> blowing it out and saying,   "guess not").
> I don't want to remove the pump unless I absolutely have to and I'm not sure
> I'd be able to tell anything by looking.  Soooo, please accept my apology if
> this question has come up before but anyone out there have any advice?  The
> present pump works well so I'd rather not replace it unless it "must be
> done"....
> Thanks.    Mark in Webster--currently with a floorless, sill less, 1/2
> crossmemberless 67MGBGT.Mark:
There will be others who will know the answer for you!  When I switched 
my '67 BGT, I didn't even think about the fuel pump!  Yes, ignorance is 
bliss (and usually more expensive!!)

As I recall, muy fuel pump was isolated by a large rubber collar.  So I 
followed the instructions printed in the Moss catalogue.  When altering 
the tach, I burned out a diode (or something like that) during the 
re-soldering process.  In turn, I took the tach to a local electrical 
specialist and he correctly adapted it.

good luck!

Jim Boyd
Paradise, CA    '67 GT, '69 GT, '70 GT

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