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MG MGB Technical - Bosch Alternator Conversion

This is a follow up note on my recently completed Bosch alternator conversion. I used a NAPA 13-8133 rebuilt, and needed to change the fan belt to the next longer size (NAPA/Gates #7365). The only unforseen issue (which was identified by Bob M), was that the adjustment arm hit the alternator fan. (This made for an interesting squeal when I started it up!). All that was required was to grind down the sides of the adjustment bracket at the attachment point on the alternator. It works great, with a significant increase in overall brightness of the lights.
A very satisfying upgrade.


Peter VanSyckle '7 MGB
Peter Van Syckle

I avoided this with a bracket that was fabricated to reach over the top of the Delco - if you like, i will send a photo

rn
RN Lipow

I had an extra and just bent it into a slight 'z' shape and did the bolt on the alt from the reverse side. Yup, the fan did squeal a bit on start-up the first time!
Luis

Is the Bosch a bolt-on item for the most part? Is there an adapter needed to fit it? I'd love one of those photos!
Steve Simmons

Steve; Go to Bob's web site at;
http://hometown.aol.com/bobmunch/index1.html
Scroll down to his "My other pages" and click on
Bosch Alternator Conversion for MGBs -

Bob has the conversion very well covered. In fact he has so much information and so many
links to information it's a good site to bookmark for future reference. People like Bob and
Paul Hunt to name only two have web sites crammed with very useful MG information, and
the good part is the information is reliable and free. FWIW Clifton
Clifton Gordon

Quoted from Bob's site:

"The old Lucas units as used on 1968 - 1974 MGBs were designed to provide adequete battery charging and electrical system capacity. But very quickly, additional electrical accessories could eat up this marginal capacity if they were all on at once (as sometimes happens in cold climates at night) or newer, unanticipated accessories (Big Blast Stereos, etc) were added to a low (35 amp) amperage system."

Is the upgrade worth it for a car with no electric alterations? I don't even have a radio! I do notice the turn signals slowing down at idle and speeding up with engine revs, and the headlights have never been overly bright. The unit in my car is in good condition with only a few thousand miles on it since rebuild. Come to think of it, does a '65 have an alternator or generator?
Steve Simmons

Steve; Your car should have a generator, I had forgotten what year car you have. In your
case it would involve a little more than the Lucas alternator to Bosch alternator conversion.
For the record I have not converted to Bosch, I have about three spare Lucas and will run
through them before switching. I don't use a radio in either car but have electric cooling
fans on both cars. I have not experienced and problems keeping my batteries charged, but
I do not often drive at night.

I would think the Bosch may be a little hard to find in a few years, also the Lucas as used on
MG's may becomet scarce. The GM alternators will be around for a long time because there
are so many street rods. In this area there are probably 10 or 15 street rods for every MG.

Clifton
Clifton Gordon

Steve,
You may well not need to bother with a conversion in your case. In a case like yours, I would suggest that you simply spend the same time and less money to install a pair of relays into your headlight system. This, at least, might solve a dim dash light circuit. :-)

Bob Muenchausen

Pardon my ignorance, but how will relays help things?
Steve Simmons

A relay will allow the power to feed your headlights to feed them without having to go through several Luclar connectors and the headlight switches. Every connector and contact is a potiential bad connection and power eater. With a properly installed relay, the current going through your switch simple feeds the magnetic coil on the relay while the headlight's power gomes from a more direct source. This will also make your switches last longer because they will be carrying less of a load .If the relay eventually goes bad you toss it and plug in a new $5 relay, instead of buying a new $100 Lucas switch.
gerry masterman

Sounds like a good idea. I'll have to look into that.
Steve Simmons

This thread was discussed between 15/06/2002 and 17/06/2002

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.