I am trying to determine what engine is in a Proteus recreation believed to be from a XJ6 1972. It is a 2 SU carb. DOHC 6 cylinder with no electronic aids. The motor number on the bellhousing flange is CS594. Any ideas?
Thanks,
Scott in CA

 

Another number found on the bellhousing which agrees with the VIN plate is 8L41420 for the Proteus.
Thanks,
Scott in CA

 

you can also find the engine number cast on the right bottom side of the block, at the top edge where it meets with the oil pan near the oil filter and starter.

 

Based on Jag-lover website, the 8L41420 engine number agrees with it being a 4.2 Liter XJ6. I guess what I would like to know is what series is this engine.
Thanks, Scott in CA

 

The "8L" indicates a later long-stud 4.2 litre block. The first long-stud blocks were prefixed "7L". The later block was supposed to be stronger, but really the biggest problem with either is cracking between the bores that eventually leads to head gasket failure.

 

My guess is 1975-1977.

I think all the S1's had 7L motors

Rob

 

Yes, your pretty much there, but the 8Ls continued beyond 1977 because my 1980 XJ6 had one. I'm not sure if 8L applies right to the end, or they used another code for the "slotted" blocks.