nigelog Posted July 24, 2008 Report Share Posted July 24, 2008 I removed top end to find source of rattle (bent push rod) and while checking conrod this piston was revealed. I am wondering is this a stock item or has it been machined specifically (for what purpose). The numbers are AE 16945 413 IL82 GI and top is marked STD 5LL. I have tried looking up web for catalogues to no avail as I would like to replace rings. Any Ideas as to where I can source these. Quote Link to comment Share on other sites More sharing options...
nigelog Posted July 24, 2008 Author Report Share Posted July 24, 2008 Turns out it is a B25 piston (same bore different gudgeon pin height). Any ideas how the different pin would affect compression/clearances, or how they might have got around the difference. Any input appreciated. Rgds Nigel Quote Link to comment Share on other sites More sharing options...
beamish owners club Posted August 5, 2008 Report Share Posted August 5, 2008 Hi Nigel, it will depend on whether the gudgeon pin is closer to the crown on the B25 piston than the C15 or lower. Did you find / can you see a spacer or thicker gasket under the barrel to lift it? Quote Link to comment Share on other sites More sharing options...
peterb Posted August 6, 2008 Report Share Posted August 6, 2008 Hi Nigel, I was wondering if the bent pushrod was caused by the piston hitting a valve? Maybe the B25 piston has a far higher crown than the C15, in relation to the gudgeon pin centre. Do you have an old C15 piston to compare with? If not, it's worth checking valve to piston crown clearence using a bit of plastercine on the piston valve cut-outs to determine the valve clearence when assembled. Also worth checking for volume in the combustion chamber using thick oil from a measuring jug poured down the plug hole when at TDC with the valves closed, then compare this to the swept volume, eg: 246cc to determine the compression ratio, you should have something lower than 9:1. You may be able to turn the piston crown down a little if too high, check for crown thickness first. Bye, PeterB. Quote Link to comment Share on other sites More sharing options...
nigelog Posted August 6, 2008 Author Report Share Posted August 6, 2008 Hi thanks for the replies. There was no spacer under the barrel as it appears (from memory) that comparison with the C15 piston showed it to have a lower crown, lowering compression. Piston, bore and rings are very low mileage by their looks and will be kept. I will check the swept capacity at rebuild. Damage went further than a pushrod ( which looks as if bent by man when head last fitted). There is another problem listed in another thread with regard to the lower oilway from oil pump to timing bush bearing. I am intending cutting a channel in the ali casing to align feed to some degree. Then its rebuild time. (see other thread for details). Thanks again, rgds Nigel Quote Link to comment Share on other sites More sharing options...
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