4 replies to this topic

[MiniElliott]

Hi, in the near future I will need my pistons fitting to my con rods. They are the press fit type.

My question is, how should I fit them ? 

My machine shop said that the pins need to be pressed in, however I have seen a couple of other techniques.

 

1. The technique shown in this video

 

 

 

From 13m

 

I would create a jig to do this.

 

or

 

2. the technique using heat on the small end of the con rod

 

http://www.theminifo...ons-to-conrods/

 

I would create a jig for both methods but what are peoples opinion ?

 

Thanks

Edited by MiniElliott, 29 December 2013 - 10:07 PM.

[welshdan]

what I do....

 

pins in the freezer overnight.

 

put the rod in the vice.

 

heat the rod with blowtorch until the little end is cherry red.

 

with heatproof gloves on and quickly!!!....line up the piston, push the pin in and centralise with your hand.

 

you only really get one go at this without risking damaging the piston skirt trying to move it later. you have to be quick, you have about 2-3 seconds until the pin cannot be moved any more in the little end.

 

if doing it this way, you will certainly get a sweat on! I always do!!

Edited by welshdan, 29 December 2013 - 10:20 PM.

[Guess-Works.com]

You don't need a jig.... in fact it'll probably be a hindrance...

 

I've lost count of the number of pistons I've fitted to rods using heat... IMO the simplest and least chance of deforming the piston.

[ACDodd]

Not cherry red straw colour at the most cherry red destroys the temper of the rod. By heating to cherry red you are effectively annealing the steel and reducing its hardness. By only heating to straw colour you maintain the temper of the steel. You also introduce a stress raiser at the point where annealed steel meets the original material.

Agree no need for a jig to put them on, but a jig to remove them is required to avoid damage to piston and rod.

Ac

Edited by ACDodd, 29 December 2013 - 10:32 PM.

[dklawson]

My way of fitting the pistons to the rods is to let the machine shop do it.  They already will have the engine parts and they have the tools.  It is a tiny increment to the expense of building the engine for them to handle this step.