34 replies to this topic

[Spider]

Heating the little end, when the manufacturer says otherwise, is a butchers method of fitting pins.

 

I was a little harsh there with my choice of words. This is the factory advice on heating Rods;-

 

 

And the factory advice on using the correct tooling for fitting Press Fit Pins;-

 

The factory tool works on a screw thread and they recommend using it with a torque wrench set to 16 ft/lb to check the minimum force needed to pull the Pin in.

[mini13]

any idea what that thread is on the factory tool? just wondering if its standard or something extra fine.

[ACDodd]

The A+ engines were assembled with heat from the factory. I agree heating will soften the rod if not done correctly. Too many YouTube videos showing a glowing red little end being fitted to a piston equal one ruined rod due to tempering causing a huge reduction in strength. But then, I ensure the fit is correct, the rod bore is parallel and round and the heating is controlled.

In 30 years of engine work I have still to have a pin slip in an interference fit rod even at 8000rpm.

Ac

Edited by ACDodd, 01 September 2022 - 12:29 PM.

[Spider]

Now I've had a little more time, here's the whole factory recommended procedure. This is A+ but even the Pre-A+ was the same;-

 

 

 

 

any idea what that thread is on the factory tool? just wondering if its standard or something extra fine.

 

Sorry, I don't.

I don't have the factory tool for doing these, I have instead a Con Rod Cradle that supports the Little End while the Pin is Pressed in. I can't recall the actual pressure numbers now, I worked it out a very long time ago, but when I press the Pins in, I check the pressure gauge on my Press while doing them and I know they need to be over 1100 PSI on that gauge. Interestingly, those that have been heated usually come in around the 600 - 800 mark, some even less.

The Factory had machines for doing these and that too worked in a similar way.
 

 

 

The A+ engines were assembled with heat from the factory.

 

 

Sorry to say, they definitely did not. They were pressed 'cold' and monitored. While there was different rods over the years, they were all made from one of the two materials they used, including A+ and as the little ends were all similar in dimensions they retained the same techniques, as also shown in the Factory Workshop manuals.

Here in Australia, we had press fit Pins in our locally built 998 engines from 1965 and again, the same technique was used in the factory and also recommended by the factory for repairs.

In my 46 years of tinkering with these engines, I've seen plenty that have gone for a walk, few have been from performance engines as they tended to use the correct assembly techniques.

[ACDodd]

Seen plenty go for a walk over here. Also seen plenty of factory engines with heated marking on the small ends.

Ac