Thread: Torque Converter recommendation - '78 Chevy / Jaguar XJS

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Welcome to CHR, Steve:

I’ve always liked Jags and the Chevy V8 swap seems like a natural. You now can tune up for less than $100 bucks versus the $500 plus from your local Rover/Jaguar dealer.

Your cam specs are spot of for a Howard’s 117091-14 or the GM #3896962 which was used in the 350HP 350 quite successfully. I’m in agreement with Roger but would shade toward the 2,400RPM, reason being that while the wide lobe separation (114 degree) has some real advantages (nice idle, good vacuum) it also pushes the overall torque curve higher. You’re working with a 4,000 pound car and it does take a bit to get her moving from a dead stop and at 2,400 you’re coming onto the torque curve that will pull strong for another 3,000RPM. Both Hughes (Part #HUP-GM20) and B&M (Part #20412) have 2,400 stall speed offerings – either would be a good fit for this application.

That said, with the 3.31 gears and assuming a stock tire size – 70 series 15 - once you get rolling and nail the pedal you’ll be very pleased between 2,000 and 6,000RPM. Won’t be a barn burner from dead stop but will certainly be respectable. If you stomp hard and force a 3rd to 1st downshift at 35 you will hear a real squeal of tires and you will get a glimpse of God when she shifts from second to third at about 90MPH - from 45 - 120 MPH your Jag will flat fly.

Fun project – hope you stick around and let us know how you progress. Pictures are always appreciated.

Regards,
Glenn