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Hi there,
I have recently purchased a david brown 880 white version. I have a fair bit of experiance with rebuilding tractors and I am currently training to be an engineer at college. My question is – I have purchased an engine rebuild kit for this 880 but I could only get one with unfinished liners! Do you have any idea
how to (finish them off?)Any help id be greatfull
Matthew
Hi Matthew,
If they are the dry liners, then when the liners are squeezed in (sometimes this takes some force) the diameter of the bore will change slightly. Therefore they need to be finnished to the correct size, and then honed.
To do this you need a honing machine. The best job is to take it to an engine machine shop as they have a proper machine to do the job. The machine also leaves the correct hone (diagonal) grooves in the bore.
You can get honing tools which fit to an electric drill, but these are definately not to be recommended – in fact DO NOT DO IT. These tools do not leave a perfect bore.
The reason for the honing marks is to trap oil in the grooves of the liner, which lubricates the rings, without allowing excess oil consumption – so it is a controlled lubrication system.
During the honing process, the bore diameter must be checked regularly for roundness and eveness up and down the bore. This is measured with a bore comparitor (the bore comparitor doesn’t take a measurement as such, but indicates the deviation from a set measurement).
So, you will need to go to the engine reconditioning shop. Maybe they will
show you the process. The picture below shows the cross-hatched hone marks in some cylinder liners.
Steve.
