never seen one of these...

[VOETOM]

That is like the VariCam minus the spring. Dad ran one for a long time before he switched to Rhoads lifters. Mr. Rhoads invented both, we were told.

 

[pishta]

That is like the VariCam minus the spring. Dad ran one for a long time before he switched to Rhoads lifters. Mr. Rhoads invented both, we were told.

OK, I see the the adjustment mechanism now. But I dont know what that eccentric is for or that hair spring? Now we got oil pressure activate VVT tech. I think Triumph had a vacuum operated VVT that was sun gear (planetary gear, brain fart) operated?

 

[VOETOM]

You dial in the advance or retard you want and as the engine speed increases, the drag overcomes the spring and the cam timing changes. Dad used to run a bigger cam and ran the timing advanced and as you raced, it retarded back to where you set it. It obviously is dependent very much on valve spring tension and anything that loads the cam. These used to cost more than camshafts in the late 50s and 60s so they never likely sold as well but they were a brilliant design that as you just said, were technology we are just now seeing.
His Rhoads lifters accomplish the same thing, sort of, using a different way to get there.

 

[pishta]

I get it, sort of a distributor mechanical advance so the faster it spun, the more or less advance it would give itself? Interesting.....

 

[VOETOM]

In a way, sort of. You set the total advance and retard you want and then install and run some good numbers!
Tom

 

[mvh]

I still think, so long as you have the timing cover off already, it's a hell of a lot easier to install a new chain and sprocket set, then to jerry rig some kind of tensioner (which probably will not last as long as a good chain set).

 

[AJ/FormS]

OK, I see the the adjustment mechanism now. But I dont know what that eccentric is for or that hair spring? Now we got oil pressure activate VVT tech. I think Triumph had a vacuum operated VVT that was sun gear (planetary gear, brain fart) operated?
View attachment 1715176999

Years ago,I wanted to try one of those, on my SBM.

 

[VOETOM]

I suspect the spring gets weak and the advance-retard rate changes but Dad's never failed to the point where it hurt the engine in any way.

Remember that ignition timing changes with the cam timing so that was likely something fun to play with and monitor. I think Dad's used to make a tenth or so on his older 14 second big heavy Pontiacs so they did their jobs at the time.

 

[VOETOM]

Here you go, Dad found his instructions.

 

[pishta]

I think the eccentric is the RPM advance adjustment. Looks like you turn that to adjust the tension on the spring and that would raise your RPM advance window. Like putting heavier springs in your distributor.


( I wrote this hours ago before the instructions were posted, just never sent it)
PS> note the mention of a silent chain being used instead of a double tooth loud "truck chain" as the varicam absorbs the shock that wears out silent chains.