How to: Piston / Rod swap, pressing pins - Uncle Tony

[RemCharger]

With the importance of pressing the wrist pin either in or out, it would seem better to use full floating wrist pins, secured with EITHER Spirolox retainers OR Waldes Tru-Arc retaining rings. I realize that in order to use retaining rings, the pistons would need to have the retaining ring groove machined in the pin bore, whose dimensions (width, diameter and location) would need to be determined ahead of time. Some people prefer a Spirolox ring or others prefer the Waldes Tru-Arc type (usually 2 per groove per side to prevent push out). The only special tools required are the appropriate snap ring tools.
Out of curiosity, what is the advantage or dis-advantage of either method, other than perhaps a slight weight difference, due to the retaining ring(s) weights. Personally, I would prefer the retaining ring method....comments?
BOB RENTON

You need to do some more research. It appears you don't understand what a full floating pin is.

 

[Nate S]

With the importance of pressing the wrist pin either in or out, it would seem better to use full floating wrist pins, secured with EITHER Spirolox retainers OR Waldes Tru-Arc retaining rings. I realize that in order to use retaining rings, the pistons would need to have the retaining ring groove machined in the pin bore, whose dimensions (width, diameter and location) would need to be determined ahead of time. Some people prefer a Spirolox ring or others prefer the Waldes Tru-Arc type (usually 2 per groove per side to prevent push out). The only special tools required are the appropriate snap ring tools.
Out of curiosity, what is the advantage or dis-advantage of either method, other than perhaps a slight weight difference, due to the retaining ring(s) weights. Personally, I would prefer the retaining ring method....comments?
BOB RENTON

If you’re in there frequently the full floaters are great. Easy to work with etc. If you have an engine that is to be left alone for 100000 miles, the lack of pin motion in the rod is one less place to have wear and trouble. It also has fewer parts and costs less. No other magic I know of.

 

[70bigblockdodge]

There is no noticable performance gain from pressed or floating. Floating has always had a problem at high RPM with snap rings, clips, distorting and coming out of its groove and raising havoc with cylinder walls. Spiro locks have pretty much solved that. Pressed pins are dead nuts reliable. If your tearing up pistons with big load nitrous engine or changing aluminum rods every 30-50 licks complicated pin removal will not work, so a floater becomes more practical.

 

[RJRENTON]

You need to do some more research. It appears you don't understand what a full floating pin is.

Perhaps you may be correct....my interpretation of a full floating wrist pin: the wrist pin is allowed to move AXIALLY, bounded by or limited to the space between the inboard retaining ring (at end of the pin) at each end of the wrist pin and the small end of the connecting rod (as the piston moves up/down) and any thermal expansion. I believe that this arrangement reduces the friction of the piston's pin and pin bosses in the piston and the connecting rod. If not, please enlighten me ......
BOB RENTON

 

[Lowcar]

I stand corrected, and have edited my post.
Dull red would not be above the critical temp, but probably is hot enough to change the properties, if the rod is originally hardened. By that I mean you would probably soften the steel.

obvious you have never worked with metal, heating does not soften the metal quite the opposite it hardens it but if not cooled very slowly and controlled it will be bridle and break very easily

 

[zyzzyx]

O.K., Here goes. Obviously you have never worked with air hardening tool steel! A2. Heat it to 1150F and let it
cool and it will be 55 Rockwell. If a connecting rod did have a slight heat treat on it, you could soften it by bringing
it over about 780F. You anneal steel by heating it and keeping the temperature from dropping too fast by covering
it with a insulation blanket like ceramic wool. The reason metal can get hard is because of the carbon content. If
it has no carbon such as certain grades of stainless steel, it will not harden. Heating a rod to 500F long enough to
slide a pin in it will do nothing to it.

 

[padam]

obvious you have never worked with metal, heating does not soften the metal quite the opposite it hardens it but if not cooled very slowly and controlled it will be bridle and break very easily

It would obviously depend on the grade and condition of the steel.

 

[RJRENTON]

obvious you have never worked with metal, heating does not soften the metal quite the opposite it hardens it but if not cooled very slowly and controlled it will be bridle and break very easily

Incorrect assumption....I have extensive knowledge and experience in theat treating, annealing, stress relieving, normalizing, quenching and tempering of various steels and their alloys, with particular emphasis on carbon content of the component involved. The effect heat has on the particular alloy depends on several aspects of what is trying to be achieved. The addage of "time and temperature" applies.....how hot and for how long as well as the rate of temperature change, both increasing and decreasing temps are the governing factors involved, as well as if the heat treating involves reducing, oxidizing or carburizing atmospheres during the process.
BOB RENTON

 

[zyzzyx]

That's exactly what I said! Thank you for putting it in technical jargon.

 

[RJRENTON]

That's exactly what I said! Thank you for putting it in technical jargon.

I appreciate your comment and support....
BOB RENTON

 

[Lowcar]

Incorrect assumption....I have extensive knowledge and experience in theat treating, annealing, stress relieving, normalizing, quenching and tempering of various steels and their alloys, with particular emphasis on carbon content of the component involved. The effect heat has on the particular alloy depends on several aspects of what is trying to be achieved. The addage of "time and temperature" applies.....how hot and for how long as well as the rate of temperature change, both increasing and decreasing temps are the governing factors involved, as well as if the heat treating involves reducing, oxidizing or carburizing atmospheres during the process.
BOB RENTON

i don't understand how i'm incorrect when this is the long version of what i said. i thought this thread was about overheating a stock connecting rod that was what my comment was based on yes i know different metals have different properties but it would take a book to discuss it all. we are on the same page thou

 

[RJRENTON]

i don't understand how i'm incorrect when this is the long version of what i said. i thought this thread was about overheating a stock connecting rod that was what my comment was based on yes i know different metals have different properties but it would take a book to discuss it all. we are on the same page thou

IF you meant to say the same thing, perhaps you should have been more explicit in your initial comment, stating specifics. Yes....different alloys require different heat treating methods. How hot is "overheating a stock connecting" in terms of temperature? Red hot, orange hot, or 1200° F or 2000° F checked with a Templ-Stik for how long? What is the alloy.....SAE 1045, 4140, 83xx, 86xx as each have different expansion characteristics. If the alloy is a high carbon alloy, high temperatures for prolonged periods of time, may tend to de-carborize the alloy, lowering its strength. A good definitive source of information is published by USS (United States Steel Corp), called The Making, Shaping and Treating of Steel. It goes into the hows and whys of steel production. Just a thought.....
BOB RENTON

 

[Danny Boy]

Thanks for all comments - getting back to one of my previous questions...

Regarding other member comments and Uncle Tony's method, it doesn't appear that a jig was used(required)

Question? How critical is it that the pin and rod be centered?

Uncle Tony appears to center the pin relative to the piston sides (same amount of pin sticking out each side of the piston)

Must the pin and rod be centered together with pin centered on piston?

In other words pin centered on both rod and piston?

Hope this makes sense - thanks again for comments.
Danny

 

[Lowcar]

again i repeat i thought this thread was about over heating a rod to get a piston pin on or off?I say the sky is blue you say no it isn't it's aqua, I say the grass is green you say no it isn't it's jade.

 

[RemCharger]

Thanks for all comments - getting back to one of my previous questions...




Must the pin and rod be centered together with pin centered on piston?

In other words pin centered on both rod and piston?

Hope this makes sense - thanks again for comments.
Danny

Yes I see this got derailed about heating, but to answer the question; the pin has to be centered in the rod. The piston slides back and forth on the pin, so there's no real centering on that.

 

[Danny Boy]

Yes I see this got derailed about heating, but to answer the question; the pin has to be centered in the rod. The piston slides back and forth on the pin, so there's no real centering on that.

RemCharger,

BINGO! Question answered!

"piston slides back and forth on the pin"

Since I'm in the learning stages of building an engine I should have remembered that the piston rocks/pivots on the rod...

Thanks all FBBO for being patient with me in quest to learn more about MOPARs and vehicle restoration.

Danny

 

[70bigblockdodge]

Don't forget about work hardening. It takes a long time in a regular car engine, but the heat cycles and stress of stretching a rod and smashing it under pressure over and over will work harden you connecting rods. Hell some of you guys should not even ever start you engine you will ruin your connecting rods.
Apparently some of you would try to stick a 10" slab and roll it through a strip mill at 450°f to make a .090 black iron coil.
I guess the annealing ovens should stay below 400°f also.
If you break a rod in a BB Chrysler it is because it is old and cycled too much, not because you put 200°f too much heat in it one time.
Most likely you will break the rod at the bolt head steps in the big end or the piston will break.
I'm sure it happened to your brother in laws uncle, but it is very rare.
If your beating a set of stock 1053 connecting rods that hard you asked for the problem.