How to / DIY > Engines

JP2 big end bolts

<< < (2/2)

Seedyh:
Many thanks for your replies.  The con rod bolt instruction is in the Lister JP/JK/JS manual admittedly a much later book than the engine which is from an early Ruston loco.  The heads have an annular ring machined to fit over the liner rims and uses copper rings/shims to set bumping clearance.  One piston is a replacement and has the normal ring set up the other one is probably original with the tapered scraper ring.  The liners are chromed and in very good condition with no perceptible ridge at the top.
The big end shells are being reused as in good condition.

cobbadog:
Hi Bob, the ring sets provided for tractor engines when rebuilding offer the tapered ring to be fitted to the top position and in way that the narrow or thinnest side of the ring faces up to avoid any lip on the bore. Some kits that are supplied with the new liners do not have this taper ring at all. I purchased a made to measure set of 6 rings to fit an old McDonald Crude Oil Engine from 1945. I was not boring it out and only honing it. The ring set when made and after asking me if the engine is being bore or had been. I replied no just a hone then they made a tapered ring for the top and had it clearly marked with a description that said this side up.
I have heard of it for car engines too.

Diesel Engineering:
 A couple of attachments showing piston rings and big end fitting. Maybe of some help.

mobile_bob:
cobbadog

thanks for the info

goes to show and old dog can learn a new trick or three!

everything i was ever taught was to remove the lip/groove at the top of the cylinder, then hone, and then put in the rings with the taper down.  but then again, i was taught nearly 50 years ago, and mainly on mid and heavy diesel engines.

one higher compression engines, i wonder how they keep the ring flutter down?  one would think that the higher compressions and higher pressures from ignition would lift the rings?  but maybe that is not the case on lower compression engines?  maybe even on higher compression engines, if the rings are made stiffer or have added expanders?

interesting indeed,  i could see how a stepped ring would be advantageous if you had a ridge/lip/groove at the top of a cylinder,  having a step would keep the ring from contacting that and being damaged.

i suspect there is a compromise being made, in order to not have to remove the ridge/lip/groove and being able to just give the bore a quick scuffing to remove the glaze and put the engine back together again and get it back in service without having to tear down for rebore or resleeving the engine. i suspect the lifespan is shorter than going with a complete overhaul. 

but what do i know?
i have been wrong before, just ask my wife!  :)

bob g

cobbadog:
Bob, no doubt you would have forgotten more than I would ever know. But over the last 12 or so years with doing engine rebuilds on old vintage tractors, stationary engines and mowers I too have been advised of some new tricks put into action by those who have followed us through on the journey of engines and their ways of bringing us unstuck.
The old McDonald had a lot of issues from lip to an unusual ring size both in diameter and thickness. These were made to measure over in Ne Zealand. These guys also advised about the taper as did the ring set for a grey fergy rebuild. Ring 'flutter' can be controlled by machining the ring groove out to next size up or by adding a spacer similar to the old style oil ring which had a top n botton thin ring with the thicker ring with grooves in it in between.

Navigation

[0] Message Index

[*] Previous page