How to Install New Pistons on Old Connecting Rods?

[Coolvibes]

I was practicing the soon to be lost art of reading, with the book, "How to Rebuild a Mopar Small Block". The author said that the connecting rods would need to be heated and then a special press used to press the pin out from the rod and piston. Is that true?

Prior to reading, I was planning to install new pistons at home, without the use of heat and a hydraulic press. Please advise.

 

[Professor Fate]

Depends on if your rods are for floating or pressed pins.

 

[RustyRatRod]

I've pressed lots of pistons both ways. Cold and hot.

 

[krazykuda]

With press fit pins, you have to be careful on the temp of the rod... If you overheat the rod where it turns blue, it rearranges the microstructure of the metal and weakens it... Between 470° - 510° F the rod will turn a light tan/brown color and is ok, above 510° it will turn blue...

 

[Coolvibes]

Depends on if your rods are for floating or pressed pins.

I don't know the difference, but I think there is some kind of clip at the end of the pin. Can you explain until I can post a pic?

 

[1WildRT]

As mentioned Floating pins don't require heat... 340's have floating pins...

 

[gzig5]

I was practicing the soon to be lost art of reading, with the book, "How to Rebuild a Mopar Small Block". The author said that the connecting rods would need to be heated and then a special press used to press the pin out from the rod and piston. Is that true?

Prior to reading, I was planning to install new pistons at home, without the use of heat and a hydraulic press. Please advise.

Let’s start with which engine you are working with. LA or Magnum and size? They are not all the same. From my poor memory the 340 and 273 use floating pins so no heat needed. 360 are pressed and need heat. 318 I’m not sure but I want to say floating too.

 

[1WildRT]

I don't know the difference, but I think there is some kind of clip at the end of the pin. Can you explain until I can post a pic?

Sounds like floaters.. Must be a 340?

 

[RustyRatRod]

I don't know the difference, but I think there is some kind of clip at the end of the pin. Can you explain until I can post a pic?

Lets do this the other way around. You post a pic and we'll tell you what you have.

 

[perfacar]

273, 318, 340 had full float pins and bushed rods.

 

[A56]

Floating wrist pin locks

 

[66fs]

273, 318, 340 had full float pins and bushed rods.

318 could be either. We were lucky, and know mostly older engines.

 

[rustycowll69]

With press fit pins, you have to be careful on the temp of the rod... If you overheat the rod where it turns blue, it rearranges the microstructure of the metal and weakens it... Between 470° - 510° F the rod will turn a light tan/brown color and is ok, above 510° it will turn blue...

If you are worried about overheating a rod end, you may benefit from "welding crayons" which only melt at certain temps.

 

[AJ/FormS]

Years ago, for a short time, I was a tear-down specialist in an engine-shop, specializing in Circle-track Chevys. One of my jobs was to cold-press the pins out. We had a fixture that cradled the pistons, but most of the pistons broke when I pushed the big red button, which was Ok cuz those pistons were never gonna be reused.
So to prevent injury, the fixture was to used with a shield between the operator and the piston.
Yeah right.
Picture me holding the rod in one hand, so it wouldn't fall on the floor, the shield balancing on the bed-rail, and me with the other hand pushing the go button. Key-raack, the pin takes off like a bullet straight into the waiting pail below, while the piston is left flopping around, sometimes broken, sometimes split, rarely not damaged in some way; but never did anything shoot back at me, so piss off shield.
That job was filler work, while I was between jobs. There had been talk of one of the assemblers moving away, and I was "in-training". But that fell thru, so I moved on. I did however learn how to run some of the equipment, and that looked good on my resume.

 

[Coolvibes]

Sorry, forgot to take the pics, but the engine is a 273 from my 1965 Dart.

 

[66fs]

Sorry, forgot to take the pics, but the engine is a 273 from my 1965 Dart.

Then you have floating pins in bronze bushed rods. Just pull the retaining clips and use your thumb to push the pin out. Reverse to install the pin.

 

[rustycowll69]

Then you have floating pins in bronze bushed rods. Just pull the retaining clips and use your thumb to push the pin out. Reverse to install the pin.

I believe you need to take note of which way the piston is facing on each rod, so they can be reassembled correctly. This will ensure pin offset is correct, & valve reliefs, if any, will be oriented correctly. Also the rod big end "spit hole" should face the cam.

 

[Coolvibes]

Attached are pics of one of the pistons. I guess after removal of the clip, I will use my finger to push out the pin. Yes, I will pay close attention to the orientation of the rod and piston, so I assemble them correctly. Thanks for the suggestion.

Tomorrow or Thu I have to go pick up the bored engine block, reworked heads with bronze guides, hardened valve seats, new springs, and parts (rings and bearings) from the machine shop for $1,900; engine disassembled. Surprised by the high cost of this engine rebuild.