My 56 shop manual shows a counterweight on the camshaft,but none of the several 292's I've taken apart have had this counterweight.Have they all been removed or were they never in there to begin with?

 

Paul,

Boonville,MO

Per the 1956 Thunderbird parts Illustrated manual, there was either a counterweight or a spacer

54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

My shop  manual shows the counterweight and the spacer.All of them I've ever worked on had the spacer only.I only recently noticed the picture of the counterweight in my manual.

 

Paul,

Boonville,MO

The cam shaft counterweight balances the mass of the the fuel "cam" that is off center from the cam but rotates with it.    Since the cam runs at half speed in relation to the crank and the mass of the fuel pump eccentric along with its center of gravity  doesn't make for that much unbalance,  it seems to be OK.  It was one of the things that seems to have been eliminated or changed along about the model year change from '56 to '57 although it is unlikely that FoMoCo was as tidy about the date of the change as that implies. 5 or 6 million Y's since '56 would have shown if this was wrong. But all other things being equal it couldn't hurt to have the counterweight there if you are running the stock fuel pump eccentric and plan to run at very high speeds.  Ted Eaton may be able to shed some light on the effect of the counterweight on transmission of vibration from the assembled engine to the car.  Ted ??

Doug T

The Highlands, Louisville, Ky.

Here's the picture in the manual - it does say "or"





54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Paul,

That is a different picture than what's in my 56 manual.Mine does not show the "or" and the spacer below it.I did find the picture you show in one of the Ford parts supplier catalogs today.Ford must have changed the picture after my manual was printed.Anyway,I guess it's OK to put this engine together without a counterweight.

 

Paul,

Boonville,MO

Paul:

If you want a counterweight, I have some used ones.  Cheap.  feistritzer1[at]msn.com

John

John - "The Hoosier Hurricane"

John,

I appreciate the offer,but obviously it's something that isn't needed,so I'll pass.This must be another example of the people at Ford wanting to be sure these engines were as good as  they possibly be and then finding out later the counterweight wasn't necessary.

 

Paul,

Boonville,MO

Doug.  You said it well.  The lack of the counterweight doesn’t have much effect on a daily driver and was simply left out likely for cost reasons.  And for the Y engines, it does appear to be a running change that took place during the ’56 model year as I’ve seen ’56 engines both with and without the counterweight.  This counterweight reappeared on the Hi-Po 289 though so apparently Ford thought enough of the benefits of it to bring it back for that particular application.

 

The benefits from the use of this counterweight are two fold with the first being the obvious in that there is a reduction in harmonics or vibration with the fuel pump lobe being counterbalanced.  Even at half the speed of the crankshaft, this can end up being a significant amount of imbalance at the camshaft but the amount actually transmitted to the crankshaft is small if any as the chain can absorb a lot of this.  Could explain why chain stretch can be extreme on some of these engines though.  The other advantage from its use would be a reduction in wear on the #1 cam bearing as a result of imbalance and reducing any potential flexing or bending of the camshaft at speed.  The pressure submitted by the fuel pump arm is also a factor on the front camshaft bearing wear but simply compounds or adds to any out of balance issues that are present.

 

I will typically use the counterweight on a Y rebuild if I’ve got one handy, but don’t get overly concerned about leaving it off if I don’t have one.  Have put too many FE's together to give a counterweight for the fuel pump lobe any additional thought for a daily driver.

 

For my race engines, I actually go to the trouble of balancing the camshaft so I’m already cognizant of how important something as simple as a counterweight to counteract the effect of the fuel pump lobe can be.  Because I normally use an electric fuel pump, I do away with the fuel pump lobe altogether but the camshaft is still out of balance at this point and must be corrected.  This imbalance is due to the unequal spacing of the lobes around the perimeter of the camshaft.  The drive end of the camshaft is brought back to a zero state of imbalance reasonably easy at the timing gear but the back end of it gets much more complicated.  Hope this helps.

Lorena, Texas (South of Waco)

Ted,

Reading your posting on camshaft balancing, and having been involved a fair amount with rotating static and dynamic balancing of components.  You peaked my curiosity, and I have a few questions. 

I assume you corrected in two planes (dynamic).  How did you cradle the camshaft in the balancing machine?  How much unbalance (oz-in) was measured and how much unbalance was it able to be corrected to?        

One of my engineeering books from Balance Engineering Corp. briefly discusses camshaft unbalance.  It indicates this produces no primary unbalance, but can produce half-order disturbances typically in the range of 1/2 oz-in.

Production tolerances on dynamically balancing crankshafts range around 1/4 - 1/2 oz-in.  Other contributing factors that may effect balance include the component straightness (runout) and the difference in support as sitting in the balance machine and in the engine (cradled on bearings).

I'll see if I can find anything else out about this subject.

Regards,

Dennis