I have a 5/16" lift exhaust camshaft C.2237 (with a casting # MC20889-B) from a 3.4 L engine fitted to a 1954 120 fhc. This cam has a badly scored lobe that probably won’t survive much use. I have compared it to a 3/8" lift exhaust cam C.13801 (casting # MC 20889-1) from a 4.2L engine in an E-type, and the two cams seem to be dimensionally similar, if not identical, aside from the lift.
I would like to keep the 3.4 L engine stock/“original,” but I am having a hard time finding a replacement C.2237. Is it possible to fit a set of cams from a later XK engine to the 3.4 L head? If so, what problems might be encountered?
Thanks,
Jake
Once Jaguar changed from the 1/4"’ lift on the early XK120 to the 3/8" lift, the early cam lobes were the same. Differences came in with whether there were oil holes on the bottom of the lobes or not. Most all of the early cams had the threads at the rear for tach drives or slingers. Along about 1969, the lobes changed to a quieter design but the lift remained the same. If you have a 2 bolt exhaust cam, you should be able to use it in your car without any problems. The later cams will work good also but you will have to set the valve clearances accordingly for the cam, not the car.
1 Like
Most of that was as I remembered, but I wanted to confirm it with you.
I think if you use a more common 3/8 lift cam you might have to chamfer the tappet guides a bit. 5/16 cams can be found locally (U S ) but I wouldn’t bother. The lower lift type have slightly less duration, something like 10/50 vs 15/57.
Thank you all for getting back so quickly. It looks like I should be able to use a later camshaft set, as long as I check for interference with the tappet guides and observe the cam-correct valve clearances. Now, can anyone recommend a trusted source (Offline) for the later cams?
Thanks again,
Jake
The only tappet guides you will have interference with are the ones on the very early XK120 and MK7. You can tell these as the upper outside edge is tapered and they sit higher than the later ones.
I have a pair from a series 3 XJ6, lying in my rafters, free for the shipping.