Originally posted by Lee Nicolle
Healey 100s are 6cyl?
Yes that is what I was referring too. The 'big'. Healeys with the 3 litre 6.
Were the 4 cyl ones called 100 also? They are a bit shorter in the front I think.
When Donald Healey produced the Healey 100, first displaying it at the London Motor Show I think, Austin immediately became involved and it became the Austin-Healey 100.
The whole mechanical package was from the 4-cylinder 2.6-litre Austin A90 Atlantic. I'm not sure of the machinations of it all, but somewhere in the early phase the first gear was blanked off because of the extra torque from Healey's uprating of the engine and it was a 3-speed.
But the A90 was in the throes of being phased out anyway. So it was soon necessary to put the A90 Six/Wolesley 6/90/Morris Isis 6-cylinder engine into it, again with some extras for more power including a 12-port head at some stage. At this time the overall dimensions of the car didn't change and the car was known as the 100/6.
Boring the 2639cc engine out to 2912cc came about 1959. As far as I know, the only modification to make the engine fit was to use the Isis bellhousing to put the starter motor on the side where there was room for it. Of course, radiator changes would have taken place along with alterations for engine mounts and so on.
The overall size of the car changed when the prototype Austin-Healey 4000s were built, with 6" being grafted into the width of the car at the centreline. This car used the Princess R 4-litre Rolls-Royce six and had a different gearbox and rear end, a Salisbury rear if I recall.
Though it was a huge improvement over the 3000s, it was canned because of the Leyland takeover and the fact that BLMC then had 6-cylinder sports cars laid on, the GT6, the TR5/6, E-type and of course the magnificent MG C, which was probably the main one involved in the making of this decision.
The MG C engine was a 7-bearing version of the 2912cc engine, also used in the fabulously successful Austin 3-litre De Luxe...
With regard to engine bores, each cylinder of the early cars was over half an inch smaller than the Chev, so that's over two inches in block length assuming a similar gap between the pots. The V8 also has the extra inch or so of length to allow for the stagger between the banks, so that's over 3" that the Chev was longer. With the six, you would be looking at a full cylinder dimension saved, so I would doubt it would be any more than 5" longer than the V8.
Edited by Ray Bell, 21 November 2017 - 04:01.