This might be a stupid question, but what retains the camshaft in a Cadillac 331/365/390 to stop it floating forwards and backwards? Does it just rely on the double timing chain to limit the fore/aft movement, or does the distributor gear retain it? Just interested
Force of the oil pump drive and the taper of the cam lobes and lifters. Cam lobes are made slightly off center of the lifter bores. Lifters have a radius on the face. Causes the lifters to spin and force cam to the rear.
I only know about 331's but, the early 49's had a little spring in the end of the Cam. I'm guessing that is exactly what that was for. It was not present in the later 49-55 cam. Maybe it was deemed unnecessary? Don't really know anything more than that other than the fact that there was some other weird things that were different on the early 49's (i.e. Floating wrist pins and 2 bolt valve covers)..
I am so glad I came across this post, because i had the same question. I also have a question regarding the timing chain slack. how much is acceptable ?
How about acceptable timing chain slack on the 390. All parts are new for the timing set, but the chain seem to have a little too much slack. Cannot go any further until i get this figured out.
I can't speak for Cadillac in particular, but on most flat tappet camshafts the lobes are ground on a taper to help spin the lifters. This also causes the camshaft to thrust rearwards [due to valve spring resistance]and the back of the timing gear controls this rearward thrust. Roller cams don't have this lobe taper so the cam needs a front button, cam walk can be observed with a timing light.
I like them tight. But ,,OK up to 1/2" deflection mid way between installed gears. If new stuff. How are the main bearings and cam bearings?
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