Conversion from generator to alternator, 1940 La Salle

[Jay Friedman]

I do the same as 49er.  My 1949 Cadillac has 6v, points and a generator and I frequently drive it both around town and on long trips. 

I make sure it performs well on 6v by keeping the wires in good shape, all the grounds clean and have added a ground strap directly to the starter end plate. 

I've never had problems with points and condenser ignition, though, of course, I have to replace them every so often.  Point are cheap, particularly since I bought a NOS box of 10 Delco point sets. 

I've never had battery problems but to be sure I only buy 6v batteries with at least 600 cold cranking amps.  I do agree that an alternator charges better, but a generator and external regulator are adequate.  To improve them a bit I substituted a 1952 45 ampere, 6 volt generator and regulator for the stock 1949 40 amp set-up. 

[Caddy Wizard]

Jay's points are correct.  Points, generators, etc work fine within original design limitations, if well maintained.

[kkarrer]

Ok.  I knew this discussion was going to open up a can of worms.  Here's the real test for changing or not changing/upgrading older systems...if before you and your wife go on a trip in the vintage car, you feel the need to throw a bunch of extra parts into the trunk...brushes, relays, fuel pump, condenser, points, etc. then you might want to consider an alternator (neatly tucked into a generator body) or some of the other things that have previously been mentioned.  Of course you may already know a good divorce lawyer or you just may not desire her company on the next outing...41 years of marriage have made me a bit pragmatic regarding this stuff.  Everyone has to do their own benefit/cost analysis.  The best we can do when it comes to these conversion conversations is to provide the information and to remind the mechanic to keep the work professional and workmanlike and as well-disguised as possible.
Ken Karrer
CenTex Reg. Dir.
1941 6227D
1955 convertible coupe
1956 Biarritz

[Scot Minesinger]

On the changing the pulley to a different diameter to spin the generator more at lower rpm, I would not do it.  The factory was sophisticated enough back then to engineer the right size pulley.  The reasons I would not do it primarily are:

1.  The belt may slip and squeal due to a heavy load, this happens when you change a std 62 amp alternator on a 1970 Cadillac to a 100 amp in same housing so it looks authentic.  The smaller diameter would have less belt surface area compounded with a higher load.

2.  If the revised pulley spins the generator faster at low speed idle it will spin it faster at high speed too when it is usually not a problem.  This may wear out the generator prematurely.  This was mentioned on another post too.

Then there is the matter of finding a pulley that is the right diameter, belt width groove and shaft connection, unless you own (or have access to) a lathe, not too easy.  The diameter modification must be carefully engineered as well, no guessing.

[bcroe]

Here is another factor on increasing a belt driven load.  My small block V8s through 1980 used
the lower arrangement, and stopping belt slippage was an issue.  In 81 they went to the upper
figure.  Note that the belt wraps farther around the alternator pulley.  In addition note that the
driving pulley is a step up in diameter fro the ones behind it.  This means that the alternator
pulley can also be larger in diameter for the same rpm, giving more contact & less pull. 

81 was a definite improvement, and I managed to upgrade 4 cars just by changing pulleys.  The
only catch was changing the power steering pump to a single grove, which I did by swapping
out the pump to 81+.  Problem with THAT was the metric fitting on the pump pressure line, but
English fitting on my earlier power steering pumps.  I was able to swap the pump rear fitting. 
Bruce Roe