I have been an ironhead man for many years and the noise coming from the valve train from one of those babies when hot sounds like a typewriter. My shovel also gets somewhat like that as it has solid lifters as well. Diss-similar metals, ie iron and aluminum expand due to heat at different rates and even though when cold everything seems snug, when the cylinders heat up and expand they basically get taller thereby making the aluminum pushrods sloppy since they don't expand nearly as fast or as great. So my question is why don't we use pushrods with similar makeup in composition as the iron cylinders to compensate for some of this expansion? Yes the shovel with aluminum heads will expand at a different rate, but for anyone who understands the concept of geometric tolerance and dimensioning, the "stack-up" for worst case should in theory be greatly reduced. In other words if the cylinder expands a certain distance when hot at a defined rate, would it not make sense for the pushrods to be made of a material that matches the same expansion rate as the cylinder? Has anyone ever tried this?

Just a thought.

randy

 

if you hold a empty gallon container in one hand and a full one in the other

then pick them up and down the full length of your reach

the empty jug is an alloy pushrod and the full jug is an iron pushrod

and the valve springs notice this BTW

 

Nicely done.

 

It what you are saying that the steel rods would be too heavy? I don't think that would be that big of a difference and since steel chrome molly pushrods exist although lightweight I would expect there expansion due to heat would be a lot closer to that of the iron rather than the aluminum which dissipates heat quite effectively. And for argument stake what would the valve springs have issue with given when they close the pushrods are going downward, if anything they would in theory close faster if this extra weight came into play.

Just wondering guys..

randy

randy

 

OK look at it this away -- for get the temp thing its a non issue

if the valve train is light the ability of the valve spring has just so many up and downs till it floats < well that is what they say = it does not float well maybe -- it slinkies and when it slinkies it does not have the ability to go up and down --- straight -- hence -> its doing the slinkie thing

so the heavier the valve train parts are the less RPMs the spring can handle and its a lot to take on the parts -- push rod /// alloy material verses steel verses titainum all have an RPM play no matter what the lift - but the more lift the greater RPM the tighter spring, the spring needs to be and the valve train weight is at play at all times -

the correct term is the speed of torque - the heavier all of it is the slower it can make power and the weight absorbs the speed of torque, so your machine is much slower then mine so to speak

 

Just a side note here. Many times the "lifter" noise is not all in the lifters but in the rockers if they are not shimmed properly. Something to check anyway.

 

now that makes a world of sense; thanks John

 

About the aluminium pushrods , check them. The most common are a set of pinky finger sized fat cheapies that tend to rub the upper inside of the pushrod tubes plus most are warped to some degree which makes them rattle a lot. The good ones are Andrews or another similar make about pencil sized in diameter.

 

Wouldn't it be easier just to put hydraulic units back in to get rid of the noise? Adjust them once and forget them.

 

If you adjust a solid lifter Shovel with aluminum pushrods to a "snug turn", warm, it will not start when it cools off.
I tried this back in the '70's, when I thought I knew everything about bikes, and women..........I was wrong on both counts....
Scott