Pegleg, thanks for the reminder, but I think I will go ahead and use the eccentric, and I think, the mechanical fuel pump.   If it does not work out, I can always block it off and go to the electrical pump. 

Jan  Urbanczyk  Major USMC Ret.

                                                                 Bowie Maryland

I always wondered about the reasoning behind the Shaller 1/4 speed cam. Did anyone ever measure the HP loss/difference between cam speeds?

How about double speed/oversize cams? Could the shallower angle reduce wear/friction loss enough to be a viable option?

6 VOLTS/POS. GRD. NW INDIANA

All I can add to that is nobody goes quicker or faster unblown than you do. Might be a good idea to pay attention!

Jan, just remember to use a spacer in place of the eccentric and your mechanical fuel pump won't work very well without it!

Frank/Rebop

Bristol, In ( by Elkhart) 

John.  I did remember someone actually doing this cam design but didn’t have a name to put with it.  Thanks for the name and the details on the ignition and oiling.

Even with nothing but the cam gear in place and the eccentric removed on the Y camshaft, there is still an amount of imbalance present.  As John brought up earlier, this has to do with the stacking of the lobes at the front of the camshaft due to the firing order.  This is not unique to just the Y as almost all engines exhibit this to some degree on one end of the camshaft or the other.  The Y Block when first introduced was one of the few efforts made to address this before being dropped as an item that didn’t justify the cost in doing it.

 

I’m simply balancing the camshafts because I can.  And it's cheap on my end.  Worth the effort?  Undoubtedly not on a driver but in a performance application, I’m just going for anything that can have a potential benefit whether it's a measurable gain or not.

Lorena, Texas (South of Waco)

Frank:

I saw a dragster run at the Nationals with one, I seem to recall it was named the "Shaller Cam Special".  That's all I remember, so it wasn't very impressive.

When they first came out, an Engineering student buddy of mine said that if the valve action was the same in both a single lobe and dual lobe cam, there would be no difference in valve float, component stresses, and wear.

John in Selma, IN

John - "The Hoosier Hurricane"

     Can you imagine how difficult it must be to phase all those lobes exactly 180 degrees apart and absolutely symetrical. Somehow the idea was ( I think) that lower cam speed would allow more RPM before valve float. The valve/tappet/ spring still cycled the same number of times at any given RPM, I could never see the point. I don't think anyone accepted them, i never actually saw one in an engine, Did anybody ever see one run?

Frank/Rebop

Bristol, In ( by Elkhart) 

Dennis,

        NO! There isn't enough constants there to calculate anything. All you could do would be balance the steel and iron bits and then try and keep the damn thing full. I run a stick which is alot easier to understand

       All kidding aside, that's my point about the cam, the imbalance isn't really worth getting excited about. As you said, crankshaft and rotating weight is a different issue. Being a motorcycle nut I've been exposed to a number of engine configurations, none of which are as smooth as a V8 or V12. I am intriqued by some of the methods and factors involved with attempting to balance them, I think Ted is too, with his balancing business.i

Frank/Rebop

Bristol, In ( by Elkhart) 

Frank,

Are you asking the maximum amount of imbalance specified for a camshaft?  There is no specification.  On a lot of parts, geometic features and their tolerances controls the shape, and by default controls the balance.  Putting a balance spec on a product drawing, only means the manufacturing process will then require a balancing machine to measure the imbalance, a method may then be required to correct (add or remove material), a subsequent check for verification, and then additional correction, if necessary.   

I never recall a balance specification for a camshaft, including 427 race engines, both pushrod or SOHC.  Nor on newer engine designs, where NVH (Noise Vibration Harshness) would be more critical for customer satisfaction.  The fact that the camshaft is at half engine speed, and component radius is not as great as a crank or flywheel, indicates the amount of imbalance that may occur is not an issue. If it were, camshafts would be measured and corrected for imbalance.  However, if one elects to balance a camshaft, that is acceptable too.      

Incidently another factor in the balance of a camshaft "system" is the amount of chain contact / no contact on the camshaft sprocket.

Now would you like to discuss torque converter balancing, where the internal and external components rotate at different speeds, in and out of phase with each other?  Effects of fluid temperature, and the amount of fluid during balancing.  LOL       

Regards,

Dennis

   

This thread has addressed the imbalance in the cam, and I think, started with the counterweight to balance the fuel pump eccentric.  What happens if you don't install the eccentric to start with?

Jan  Urbanczyk  Major USMC Ret.

                                                                 Bowie Maryland

Since in another thread we have talked about a new head design, why not design a dual over head cam at the same time.  Maybe I don't really know enough about this subject, but it seems like that would be a way to dampen some of the inherent vibration of the firing order. Or would that make it worse?   'Course this would be far from stock configuration.

Jan  Urbanczyk  Major USMC Ret.

                                                                 Bowie Maryland