Quote:
Originally Posted by Bill Hanlon
I am no 4 cylinder Pontiac expert, but I read your post and thought "If he can't find a Trophy 4 cam, why not use a V8 cam?" So then I Googled "can you use a Pontiac V8 camshaft in a Pontiac Tempest 4 cylinder engine?". The answer I got was ....
"Yes, you can use a standard Pontiac V8 camshaft in a 1961–1963 Pontiac Tempest 4-cylinder engine (the 194.5ci "Trophy 4"). Because Pontiac made the 4-cylinder by essentially cutting a 389 cubic-inch V8 in half, the cam dimensions match."
... but that was followed by ...
"However, there is a catch regarding engine rotation.
The 1961–1963 "Trophy 4" (Pushrod Engine)Compatibility: The camshafts for early V8s and the 4-cylinder share the same lobe spacing, base circle, and block-mounted design.
The Catch: Some early 4-cylinder Tempests used a unique "rope drive" flexible driveshaft that connected to a rear-mounted transaxle. These specific engines rotated backwards (counter-clockwise). If your 4-cylinder is a standard, front-mounted engine, a V8 cam will work. If your Tempest has the unique rear-mounted transaxle, a standard V8 cam will run your engine in reverse."
... REALLY? I thought ALL 4 cylinder Tempests used the flex driveshaft. And I've never heard that the half-a-V8 engine turned backwards.
Anyway, if the Trophy 4 does NOT rotate backwards and you can find specs for the cam you are looking for I'd bet that you could find a Pontiac V8 cam with similar specs.
My apologies if the Trophy 4 really does turn backwards.
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Bill, thanks for taking the time to respond the trophy 4 is indeed a half of a 389 but the problem arises due to the rod journals being 180 degrees apart and a v 8 s are 90 degrees so half the lobes will be in wrong spot. Yes the 61-63 tempest have a transaxle in the rear with a "rope drive" drive shaft which in reality a approximately a 5/8 steel shaft.