"Les Rose" wrote in message
...
Those who have followed my posts will no doubt have sussed out that I'm
building a 998 for my Frogeye. Has anyone worked out how to fit an A+
Metro
distributor into a pre-A+ block? I have the different drive shaft and
forked
retainer, which Vizard in his book says I need, but he says nothing about
what to do with them (being the polite soul that he is). The original
dizzy
suffers points bounce at anything over 6,000.


Can't you find some points that will do better than that? Not all makers of
replacement points used the same strength spring and ISTR that an outfit
called Commercial Ignition (or some such) used to make ones that would run
to 8,000 or so. Finding them now might be a bit tricky though. . .

As for changing to an A+ Metro unit, are the advance curves the same?

Ron Robinson

"R. N. Robinson" wrote in
message ...

"Les Rose" wrote in message
...
Those who have followed my posts will no doubt have sussed out that I'm
building a 998 for my Frogeye. Has anyone worked out how to fit an A+
Metro
distributor into a pre-A+ block? I have the different drive shaft and
forked
retainer, which Vizard in his book says I need, but he says nothing
about
what to do with them (being the polite soul that he is). The original
dizzy
suffers points bounce at anything over 6,000.


Can't you find some points that will do better than that? Not all makers
of
replacement points used the same strength spring and ISTR that an outfit
called Commercial Ignition (or some such) used to make ones that would run
to 8,000 or so. Finding them now might be a bit tricky though. . .

As for changing to an A+ Metro unit, are the advance curves the same?

Ron Robinson

There are various reasons to change to the A+ dizzy. One is the stronger
points spring, another is the longer-lasting points (wiping action), then
there's the assymmetric cam which delays points bounce. Yes the advance
curve is different but I'll be changing that anyway to match the camshaft.
Actually most of these benefits are available just pre-A+, but it's the one
I happen to have. This engine is designed to rev to 7,000 - the standard
dizzy, as I know from having tried it, bounces at about 6,300. Also it's
worn out! So I might as well change to a better, later one if possible.

"Les Rose" wrote in message
...

There are various reasons to change to the A+ dizzy. One is the stronger
points spring, another is the longer-lasting points (wiping action), then
there's the assymmetric cam which delays points bounce. Yes the advance
curve is different but I'll be changing that anyway to match the camshaft.
Actually most of these benefits are available just pre-A+, but it's the
one
I happen to have. This engine is designed to rev to 7,000 - the standard
dizzy, as I know from having tried it, bounces at about 6,300. Also it's
worn out! So I might as well change to a better, later one if possible.


Ah, right. Must confess I'm not familiar with the A+ dizzy, but I know from
experience that the standard Lucas 4 cylinder unit from the late 50's /
early 60's will, when in good nick and fitted with a good set of points,
cope with over 8,000 rpm. It wasn't until the Formula 3 screamers started
running at over 10,000 rpm that Lucas had to go to something rather more
special - first a black box system that used to suddenly stop working for no
discernable reason, then a conventional distributor with lightweight points
that would, if you were lucky, last for just about one race. However if you
have the chance of something with wiping points then go for it, especially
if it is anything like the Ducellier ones where you can set the dwell angle
with the engine running.

Ron Robinson