aluminum pushrod question.

[dbanana]

I have read with great interest the threads on valve adjustment, but I am wondering ,what is the advantage of using aluminum pushrods? I have a '56 pan engine with solid lifters and solid aluminum pushrods. What brand of solid aluminum pushrods would you recommend ?

[steve_wood]

Last time I checked, http://www.nosparts.com" onclick="window.open(this.href);return false; had the OEM pushrods (which are steel).

[Cotten]

Dbanana!

If there really is any advantage, it is only one of weight.
I know of no producer of solid rods, as they are all tubing.

Did you just mean yours were for 'solid conversions"?

If we can find a source for modern steel tubing "solid conversion" rods with Pan tops on them, they would be my choice in spite of any extra weight, as it alleviates the expansion problem.

There was a time when S&S offered the whole conversion kit. Perhaps they still do?

....Cotten

[kitabel]

Aluminum is so much less rigid than steel that it must be much, much thicker to get the same stiffness, which removes any weight advantage.

[Cotten]

For a panhead or shovelhead, they expand at a rate closer to that of the aluminum heads than steel would (which has more slop when the engine is hot - the top ends grows faster than the pushrods). For an iron engine like an XL or knuck, steel expansion is closer.
Aluminum pushrods have been sold for 50 years based on "saving weight".
It does, in the same way that making them out of cardboard saves weight. It's not a useful product, because the single most important factor for a H-D pushrod isn't weight, it's bending resistance (especially since they're so long, and the angles are bad on everything after 1947).
Aluminum is so much less rigid than steel that it must be much, much thicker to get the same stiffness, which removes any weight advantage.
Steel is the best choice for hydraulics.

Kitable!

Have you held the pushrods in your hands?
This one is a full 55g less than OEM.

ALRODWT.jpg

That's nearly a half-pound off the valvetrain.... !
No serious "Go-faster" would consider anything else, and just accept the downside of carefull adjustments.

And don't look now,
but the cast iron cylinders are the major portion of the vertical expansion, along with the aluminum cases and heads.
Steel rods' expansion comes closer to the added total of the different metal's expansions, and that's why steel is friendlier to deal with than aluminum for a solid conversion.

With hydraulics, the expansion issue is taken care of, and either or any metal is accomodated, automatically.
I'll bet that's why they were invented.

....Cotten

[dbanana]

steve_wood, ,thanks...that site looks like an excellent source for parts...but I can only find aluminum pushrods listed for panheads.

cotton , solid as in not adjustable. I have the conversion with solid adjustable tappets and non adjustable aluminum (tube) pushrods.

I like how responsive the engine is with the solid lifters, and I sure don't mind adjusting them.
I don't care about the weight.....but where do I get steel pushrods ?

Also , what is the opinion on the best brand of aluminum pushrod ?

thanks,

[Cotten]

Dbanana!

The response of lighter pushrods is a bit subjective at street speeds, but if beating your buddy to the next street light, or seriously beating the clock, is important to you, then you will easily deal with the trial-and-error curve on adjusting them, as well as their sound.

Once you have a grasp on them (literally), they sing a pleasing song.

And I doubt that any one brand is substantially superior to another, but I have been out of that scene for years and years.
And that is why we must ask our other Forum members to chime in on both steel and aluminum brand options.

And Kitable!

We heard you the first time, you do not have to shout.
That's why I captured your complete quote into my reply.

I agree that "stiffness" is important, as flex soaks up horsepower at the pushrods just like it does at the connecting rods.
But a half a pound off the valve train!
That's quite a shortcut to 'getting with the program'!

Steel-shotpeening, "polishing", and re-peening the aluminum rods is yet another step toward solving the stiffness concern.
If a pushrod bends and stays that way, something else did it.

....Cotten

[Panshovevo]

Aluminum is so much less rigid than steel that it must be much, much thicker to get the same stiffness, which removes any weight advantage.

Pure 1100 aluminum, that may be the case. Not necessarily true for the alloys.

[RUBONE]

Having used many different aluminum pushrods over the years (street racing made my heart go fast!) I have found that the current examples all pretty much suck. And despite the weight savings, if you have ever looked at aluminum pushrods after some use and abuse they have wear marks where they have flexed out to, and rubbed on, the covers. Short term, no big deal. Long term, I have seen them worn halfway through. Steel is the best for longevity, not just expansion. Flex is a big factor.
Robbie

[Cotten]

Robbie!

Yes, fat aluminum rods definitely have clearance issues.
But wearing half-way through was a maintenance issue!

For some reason so many folks thought they should be set loose-as-a-goose.
Set tight, they were within limits, inspite of flex.

Please understand that I am not trying to defend aluminum pushrods for anyone but the rabid hotdog.

The question remains: does any manufacturer still offer a steel pushrod alternative for "solids"?

There's a time and a place for everything.

....Cotten

[mbskeam]

looky here....

https://www.hydra-glide.net/phpBB3/view ... f=5&t=6462

http://www.caimag.com/forum/f22/colony- ... -4557.html

http://www.caimag.com/forum/f44/4130-pu ... -4581.html

these are still going strong......

[kitabel]

Not necessarily true for the alloys.

Absolutely, always.

[Panshovevo]

Not necessarily true for the alloys.

Absolutely, always.

Hmmm...We did some research years ago when a 'friend', on a mad quest to make his high performance modified Pitts S-1S aerobatic biplane as light as possible, decided to replace all the steel bolts in the airframe with aircraft grade aluminum hardware. In order to achieve equivalent tensile strength, we would have had to go to larger diameter bolts, but even so, and not even considering the weight of material removed to accept the larger bolts, the total weight of the aluminum bolts was approx 3/4 the weight of the steel bolts.
I realize that tensile strength and rigidity aren't the same thing, but I believe there is a correlation.
We didn't do it, because most of the holes couldn't be enlarged enough to accept the aluminum bolts due to wall thickness or interference with other components.

Story time...

The friend finally gave up on the Pitts and bought a monoplane, then developed a chronic case of vertigo and had to quit flying.
I didn't feel too bad for him, as he damn near killed me once.
I had been competing in the Sportsman category at International Aerobatic Club competitions, never got competitive, but got bored with the relatively simple maneuvers, and moved up to the Intermediate category.
The mandatory sequence for Intermediate that year included a maneuver which started with flying inverted for approximately 10 seconds, enough time for one negative G to push much of your blood to your head, lowering your blood pressure, then pulling down to an inside loop, which caused a fast switch to multiple positive Gs.
Every time I tried it, when I reached about the 7 oclock position and 7 positive Gs, I would gray out (lose vision) temporarily from the G force reversal. I tried every tactic I had learned in the Embry-Riddle Flight Physiology course, which included a trip to McDill AF base for altitude chamber training and the same G force technics they teach fighter pilots. Nothing worked.
I asked the above mentioned Pitts pilot, who had many years of experience on me, how he would handle it. I don't remember exactly what he told me, I do remember that it went against all I had been taught.
I figured that since what I knew wasn't working, why not try it, and I did.

I reached the 7 oclock position.
The next thing I knew, I was waking up, without a clue of where I was or what I was doing, with the sound of an engine faintly in my ears, and an unidentifiable object in my hand.
The engine was on my airplane, and in my hand was the control stick.
Fortunately, I was flying a Vans Aircraft RV-4, a relatively stable and forgiving platform that will almost fly itself. If that happened in the Pitts I have now, which is rigged for maximum instability (to increase maneuverability), I most likely would have bored a hole in the ground. That was the last time I asked him for advice, as it occurred to me that he was a friend of my wife's ex-husband.

[james]

From October 2009 a thread on steel vs aluminum push rods.
Must be that time of year again.
I had a set of 4130 steel push rods made by mbskeam.
I sent him my aluminum pushrod ends and he used them to make my steel pushrods.
Nice job too.
Don't know if he is still making them.

Jim

[Hog54]

I never had a problem with aluminum pushrods.I adjusted them 15 years ago and that was the last time I seen them.