3 1/2 engines vs. 3.4 engines

(PhilW) #1

In the '50’s the engines were 3.44 litre and had 3 1/2 cast into the side of the block. in the '60’s (and 70’s) the displacement was the same and they were called 3.4 engines. Did the blocks still carry the 3 1/2 on the side of the block or did they cast in 3.4 similar to the 3.8 on the early E’s or 4.2 on the later ones?

Just curious.


(Ed Nantes) #2

From memory , my 1950 Mk VII had " 3 1/2 litre"
Jaguar had rounded out the engine sizes since about 1936 to 1 1/2 , 2 1/2 and 3 1/2 litre, for simple marketing purposes.
The new twin cam had intended to be , I think , 3.2 litres [ in a preview perhaps of the XJ 40s dropping from 4.2 to 3.6 litres.] However Jaguar were embarrassed to find the new 3.2 litre XK engine as slower or less tractable than the old pushrod engine, so he capacity was increased.
It was said the 160 BHP achieved by the factory # 18008 SS 100 was taken as the starting point for the new engines.
Of course once the Mk VII and XK 120 got going there was no optional 4 cylinder or 2 1/2 litre options so they could just use “3.4”

(Rob Reilly) #3

I have a 150 block here V5144-8 which has 3-1/2 on it. So I suppose that could help pin down the date when they changed from 3-1/2 to 3.4 on the block casting.

(Morris Barnett) #4

V-4141-8 has 3.1/2 litre. July 10 1958. ots