That takes me back. I used to work in the aftermarket division of Wellworthy, the main manufacturer of these pistons. The main idea behind the offset pin is to reduce noise when the piston reaches tdc and moves across the bore. Great video.
Interesting video as always Joe, if I may, a few comments. 1, taking the bores out to +30 was common practice, bus companies were notoriously tight with their cash and if they could save a few bob they would, the blocks would be painted black for standard and dark green for +30 bores. 2, To carry on from that, pistons would not only be obtained directly from Gardners but they would have also been sourced from other suppliers, Wellworthy and Hepolite springs to mind. Bearing in mind that on an LW the piston had to be removed by taking it down past the crankshaft and replaced in the same way. Gardner pistons had relieved skirts and were (relatively) easy to fit. The other pistons didn’t and consequently, especially the +30 pistons were much more of a fiddle due to the limited clearance between the crankshaft and crankcase. LX / LXB pistons weren’t affected as they were removed by taking them up through the bore, the conrods were 4 bolt big ends and were shaped so that the bottom end of the rod had clearance to allow this. 3, We had to be aware, when fitting a block and pistons that all the pistons had to be the same. Stores being stores, weren’t above dishing out a set of mismatched pistons in the rather vain hope that no one would notice. As for the horizontal engines I was given to understand by a Gardner work’s engine builder that the gudgeon pins on the horizontal engine pistons were offset 30 thou compared to the vertical engine pistons to allow for the fact that the things were on their side so to speak.
Joe, as always, very interesting. Would the offset gudgeon pin have been designed to try to ease wear on the thrust side of the cylinder, and was this process unique to Gardner? Thanks again. J
Still never heard anything about timing chains, I used a piece of string around 2 timing case studs, to line up with the pop marks on the chain sprockets, this was the Gardner way apparently.
How much weight difference in a set would you allow, and would you grind off a little to make them even. If so where, a bit off the skirt, only guessing and curious
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