There is a recurring discussion on the lists regarding installing narrow
belts for alternators, providing some sort of torsional vibration dampener,
and the pro's and con's of removing the fan. I recently offered some parts
for sale on eBay that caused a number of questions, and I thought I'd share
what I know about this subject.
There are apparently two commercially available kits. One is from England
(I don't know the vendor) that includes the crank and water pump pulleys.
One is from British Frame and Engine (626-443-0939) and contains a water
pump pulley, a crank pulley with a torsional vibration damper that was
dyno-developed, a fan belt, and a new timing cover seal to fit the new
pulley. Price $380. The only tricky part in its installation is the need to
mark the pulley for timing, because it comes with no marks. It is the
highest quality approach I know of.
The third approach has been around for a long time and is the subject of
this message. It is not quite as good because it requires a little
machining, the damper is not tuned quite as well, and the Woodruff key in
the crank does not engage very far into the pulley. However, it's pretty
cheap. I have had one on my car for six years of racing and it has caused
no problems, but for racing I will eventually switch over to the BFE kit.
This low-buck approach uses an MGB crank pulley -- I think there are two
models -- but the one you want is 4-5/8" diameter. The portion that
contains the seal surface is the wrong length and diameter, so the engine
side of the pulley must be machined off until the pulley bore is 11/16"
deep. Then you take a TR4 pulley and cut off an 11/16" piece of the engine
side of that pulley, creating a spacer that goes on the crank first and
provides a seal surface. So then you put on the new spacer, put on the
altered MGB pulley, and secure with the heaviest washer you can find and a
5/8" fine thread bolt, 1-1/2" long or so, with red Loctite.
After doing this you can't use the fan, of course, but it doesn't do much
anyway, and you must make or buy a water pump pulley suitable for a narrow
belt. If you're going to run an alternator, this takes care of the narrow
belt adaptation problem. If you're going to stay with the Lucas generator,
you have to make a new pulley for it.
If you try this and run into problems, send me a question and I'll try to
help. If these instructions are too murky, let me know and I'll sketch it
up and put it on a website after the Mid Ohio race weekend.
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