I've only been driving my 3-main B for a year or so, but it seems to
me--from memory, rather than direct comparison--that the early engine
is a bit "rougher" and vibrates more above 3300 rpm or so than a
5-main. At least mine seems to.
I've read a number of period road tests which mention this to some
extent-- that the new 5-main engine was smoother than the 3,
especially at engine speeds above 4500 rpm. Later articles about
rebuilding 3-mains mention the importance of balancing components as
part of the rebuild.
If what I notice has to do with some peculiarity of my engine, the
question is--what's causing it? Imbalance in parts is possible, I
guess. Vibration damper gone bad? High speed ignition problem (I'm
using Pertronix module)? Cam wear? Got any ideas? Is high speed
roughness a characteristic of 1600 MGA engines?
On the bright side, it adds to what the Brits call "rortiness".
Period charm. (I once bought a couple of used Brooklands article
reprint books on Morgans. The previous owner had gone through them
with a highlighter and marked out all the references to "rorty".
Can't get more British than that.
Chris Attias
'64 MGB
'84 Alfa Romeo GTV-6
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