<<The MGB engine was improved by the addition of the extra
bearings in 1965, after a very short production time in this car, and it
subsequently became among the most rugged and simple British engines ever
built. The Triumph engine was increased in size steadily until it reached
a point where it became unreliable due to its design. >>
OK, let me stick my .02 in here again.
The B engine was arguably improved by the conversion to 5 mains, with the loss
of a little power and feel. It is indeed pretty rugged and simple, but I note
that you don't add 'advanced'. The head design of the pushrod B series is
sheer automotive dreck!
The design of the big TR engine (I know the quote above refers to the Spit
1500, not the 2 litre engines) is far superior in the head, at least, but
these engines are severely limited by bottom end design. It wasn't the
increase in size from 83 mm bore to (eventually) 87 mm that caused any
problems with the TR, it is the inherent limitation of the bottom end.
You can run a TR engine to 5500 RPM all day, given an engine in good order to
start with, and it will normally stay together. This is 500 RPM over factory
red line. I have done this on the race track with my 1955 TR-2, with the
_original_ unrebuilt motor, with no problems whatsoever. If you use 6000, the
life of the bottom end will be about a race season. If you use 6500, it will
be anywhere from a few minutes to a race or so, unless you use a billet crank.
It is a _big_ 3 main that won't rev relaibly without very major and expensive
modification. Note that none of this affects the street use of the engines. By
the way, guys like Hardy Prentice, who has been racing a TR3 in SCCA for
decades (I ran with him, well, behind him, at Westwood in the 70's) uses up to
7000 RPM in his car, meritting my amazement/admiration. Come to think of it,
when the race was over at Westwood, my car was still running and his had a 6
inch square hole in the side of his block where bored engine bits had exitted.
Oh well.
And that's probably more than you wanted to know about big TR engines. The
1500 Spit/Midget engine referred to by the previous poster is another story
again. Later.
Bill Spohn
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