Valve adjustment and compression and/or leakdown test before you condemn your engine. When mine was running right it was decently quick, about even with my turbo 300D, and this is at 4700 feet elevation.

If you can get the parts together to do a four speed swap it would be good. The automatics are ok when they work right, but getting them tuned right is becoming a lost art. About six months ago I talked to a member in California who had the appropriate four speed and parts. Vegestar. I don't know if he still has that stuff for sale, but it's worth a try.

BTW, my 114 is for sale. The short block is good but it will probably need a cylinder head. PM for details.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.