pushrods

[rattlesnake]

78 440HP. How important is it for the pushrods to spin with the lifters? I have some that do and some that don't. I see no problems with pushrod cups or lifter cups. Will this create problems down the road?

Ray

[72cudamaan]

78 440HP. How important is it for the pushrods to spin with the lifters? I have some that do and some that don't. I see no problems with pushrod cups or lifter cups. Will this create problems down the road?

Ray

Don't see any problem with that.

[Chryco Psycho]

The pushrod usually spins with the lifter , if the lifter is not rotating the lifter / cam  is probably going away /grinding the lobe off , what oil are you using

[Strawdawg]

Yep,  you have a problem.  Sounds like time for a new cam and lifters

Steve

[72cudamaan]

Yep,  you have a problem.  Sounds like time for a new cam and lifters

Steve

Why is that necessarily a problem? I've seen many motors where the pushrod doesn't spin constantly. What would be the purpose
of it spinning in the first place?

[Strawdawg]

Why is that necessarily a problem? I've seen many motors where the pushrod doesn't spin constantly. What would be the purpose
of it spinning in the first place?

The pushrod spins because the lifter spins.  If the lifter does not spin, then it rapidly eats the bottom out of the lifter and scrubs off the top of the cam lobe.

The cam lobe has a taper across it from front to rear.  Normally, half the lobes are tapered down toward the rear of the engine and half toward the front.  The lifters are convex on the bottom and are offset to one side of the lobe when you look down thru the lifter bore.  This combination of taper and lifter offset causes a swiping motion that should make the lifter rotate.  This rotation minimizes the friction on the bottom of the lifter and soon wipes the cam and lifter.

Neil asked about the oil because the oil should have a friction reducing agent like zddp in it that further reduces the potential wear as this is a metal to metal contact unlike the bearings and crank which are hydro-statically separated by the oil film.  This is the reason we are either paranoid, or near paranoid in breaking in the cam.  Initially, the cam and lifters are not mated to each other very well and still valve springs wreak havoc.

[72cudamaan]

Thanks for the narrative.     But the pushrod does not necessarily spin with the lifter.  The amount of preload can be a determining factor( as well as the oil I suppose). I already knew the rest of the story.

[Strawdawg]

Thanks for the narrative.     But the pushrod does not necessarily spin with the lifter.  The amount of preload can be a determining factor( as well as the oil I suppose). I already knew the rest of the story.

sorry for wasting your time! 

the force of the lifter against the push rod accompanied by the rotation induces a rotation to the pushrod.  As long as preload exists, this should be the resultant action.  If the lifter spins and the pushrod does not, then the cam/lifter should be okay...not sure about the life of the pushrod and the rocker arm, but I will skip the narrative on that

I do agree,however, if the lifter is rotating properly, I would not worry about the lack, thereof, in the pushrod....at least not too much.....

[rattlesnake]

thanks guys for the response. all the lifters properly it is only the three pushrods that do not while cranking. they very well ma spin while runnin. new cam and lifters. iam using valvoline racing oil.

[Strawdawg]

thanks guys for the response. all the lifters properly it is only the three pushrods that do not while cranking. they very well ma spin while runnin. new cam and lifters. iam using valvoline racing oil.

No, I would not worry if they are not spinning while cranking.  That is far more likely.

I would only be concerned if they don't spin while running

[dodj]

sorry for wasting your time! 

but I will skip the narrative on that

Please narrate away. I'm not as smart as Andy. 

[blown motor]