mahatma Posted May 28, 2004 Share Posted May 28, 2004 Rover k series, Accralite forged pistons; Just for clarification, could someone please tell me where the gaps on the piston rings should be. I looked in the Rover build manual and it only gives details for 4 rings ... but I have 5 (2 compression, 1 corrugated oil ring, 2 thin oil rings). Looking on to the top of the piston from above, with the front of the engine to the left and the rear of the engine to the right, what position should the ring gaps be in (maybe describe by using the position of the hand of the clock) ? I seem to be having excessive oil usage with my Scholar EVO2 conversion ... having spoken to Scholar this morning, they haven't seen this problem before but I want to make sure that I haven't done anything wrong upon assembly. Could badly positioned rings be the cause of excessive oil consumption (cloud of smoke under heavyish load) ? Scholar want the block back for checking but clearly this involves pulling the engine and stripping most of the kit off ... and sending it back down to them - which I don't want to do un-necessarily Thanks Andy p.s. The head is sound (new VHPD - freshly modified by DVA with all new oil seals etc). Link to comment Share on other sites More sharing options...
Jason Plato Posted May 28, 2004 Share Posted May 28, 2004 You normally put the rings in so that the gaps are at 10-2-7 on the clock face ( the gaps are 60 degrees apart so that the oil and gases would have to travell the maximum distance to bypass , with the thrust face of the piston at 12 o'clock . the rover manual states " position compression ring gap @ 120 degrees to each other away from the trust side , and oil control ring gap and spring gap at 30 degrees on opposite side of gudgeon pin axis " Did you check the piston clearance during assembly ? Have you checked the cylinder compressions ? Dave Edited by - Dave Jackson on 28 May 2004 13:13:29 Link to comment Share on other sites More sharing options...
prs Posted May 28, 2004 Share Posted May 28, 2004 Hmmmm, always thought that ring gap should be positioned on the side of the piston away from the thrust Phil S7 SVN Link to comment Share on other sites More sharing options...
Jason Plato Posted May 28, 2004 Share Posted May 28, 2004 Yes - thats what I have written PRS ? Link to comment Share on other sites More sharing options...
mahatma Posted May 28, 2004 Author Share Posted May 28, 2004 I didn't check the piston clearance upon assembly, I now wish that I had ! This shouldn't normally be a problem though should it ? Scholar do lots of these conversion and haven't had a problem yet and the Accralites are supplied in QED engines without problems (that I've heard of). I haven't yet measured the dynamic compression. Dave, the passage you quote from the Rover manual suggests that only 4 rings are used ... the compression rings are no problem but what about the other oil ring ? If the oil control ring gap and the spring gap are at 180° to each other, where does the gap for the 2nd oil control ring live ? I did use the pistons and rings without re-honing the liners after my problems with the very high compression head (few hundred miles of use) ... I wonder if I should have used new rings and re-honed. There was a little scuffing observed on the thrust face of the liners when the pistons were removed from the bores. Andy Link to comment Share on other sites More sharing options...
oilyhands Posted May 28, 2004 Share Posted May 28, 2004 As long as the gap in the thin oil rings is well away from the gap in the sprung ring the position isnt critical since they are not compression rings. would tend to have the gaps well away from the thrust and trail sides. Try to think of the oil control rings as a single compound ring.. Oily Link to comment Share on other sites More sharing options...
Tony Martyr Posted May 28, 2004 Share Posted May 28, 2004 I think your problems of oil consumption are due to poor ring bedding on a polished bore rather than the position of ring gaps. Link to comment Share on other sites More sharing options...
prs Posted May 28, 2004 Share Posted May 28, 2004 Dave, looking at your description again surely if the thrust face is at 12oclock and the ring gap is at 10 and 2 oclock these ring gaps are going to be on the thrust side of the piston, I wrote my original post as you were editing to include the bit about the rover manual states, anyway no offence intended. I eventually used Mech Repairs for a mapping session following your posting some weeks ago as Emerald were so fully booked. They were excellent and extremely thorough. Phil Link to comment Share on other sites More sharing options...
mahatma Posted May 28, 2004 Author Share Posted May 28, 2004 Thanks guys, In peoples' experience, for the sake of a new set of rings and a head-gasket, is it worth me honing the bores and trying again with fresh rings ... then if it still doesn't work, get the block off to Scholar for checking ? I'm not looking for definitive answers, rather guidence based on experience. It is a lot more effort and expense to get the block sent off (not that I'm bothered about the effort) for checking than doing a hone and re-ring myself ... also seems odd to have to problem in the first place when all other experience suggests that oil consumption is generally better with these liners. Andy prs, where are Mech Repairs based ? Edited by - mahatma on 28 May 2004 18:21:05 Link to comment Share on other sites More sharing options...
prs Posted May 28, 2004 Share Posted May 28, 2004 Andy, there in Cheltenham 01242 243385 www.mechrepairs.co.uk £300-500 for full mapping. FWIW when I re-built my engine back in the spring I kept the original pistons but re-ringed them. I used new liners but honed them with a flexi-honer, strange looking thing with wires and balls on the end but it gave a superb finish. I then ran it in on Mineral Oil for 500 miles and picked some roads with good long hills to load the engine in order to bed the rings in. Now back on fully syn and so far have done 1500mls with no oil consumption. It does very much sound like you may have glazed bores as Tony mentions. Phil Link to comment Share on other sites More sharing options...
mahatma Posted May 28, 2004 Author Share Posted May 28, 2004 For the cost of it, as I already have a flex-hone tool (but didn't use it ☹️) I think I'll try a new set of rings and then if the problem persists, I'll pull the engine out and get it down to Scholar. I'm getting quite good at taking the engine apart now ... just can't seem to get it back together properly ! Opinions on this approach are very welcome ... Andy Link to comment Share on other sites More sharing options...
Myles Posted May 28, 2004 Share Posted May 28, 2004 Hmm, bit late now, but a local who built his engine over the winter with a Scholar liner conversion (not sure if EVO2 or different) sent his pistons along at the same time so that they were bored to match... Keep BC free and open for ALL. Membership No. 43xx Alcester Racing 7's Equipe - 🙆🏻™ Alcester-Racing-Sevens.com Link to comment Share on other sites More sharing options...
mahatma Posted May 28, 2004 Author Share Posted May 28, 2004 Thanks Myles, I forgot to mention this, my pistons went down with the block and bearing ladder for the EVO2 conversion. Andy Link to comment Share on other sites More sharing options...
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