Nick Moore Posted November 29, 2013 Author Share Posted November 29, 2013 A few months ago, I bought a GTT42 camshaft from GT. The torque curves his camshafts produce are impressive, and suited to 'fast road' engines like mine will hopefully be. Unfortunately, when it arrived from Andy Thompson in Perth, it was in two pieces 🙁 It was well packed and the tube it came in showed no sign of damage, so it must have been dropped somewhere between Perth and Brisbane, and shattered. Well, Andy very generously came to the party and sent me a GTT43 from his race car, along with twelve matched Newman cam followers. The photo shows how Andy packs his parcels. I'm keeping the block of wood as a souvenir. Mr Thompson, you are a champion.The camshaft and followers are in perfect, mint condition and have already been bedded in. That last bit is welcome news because I was nervous about running a brand new, untested engine at 2000rpm for 20 minutes, using an injection system that had also never run before. With a pre-loved camshaft, that trial of fire for my soldering and engine building skills won't be necessary! Quote Link to comment Share on other sites More sharing options...
andy thompson Posted November 29, 2013 Share Posted November 29, 2013 Really pxxxsed about Australia Post and that first cam - made sure the second offering was as bullet proof as possible. Glad its all in one piece - I have a cam swap coming up this holiday period - my 2100 EFI cam has partially munched a couple of exhaust cam lobes - my fault - ran too hard valve springs that I thought 7500rpm would need . Just shows even with a NOS cam ground and then tufrided with top quality followers over hard springs will still cause ruin..... Quote Link to comment Share on other sites More sharing options...
Nick Moore Posted November 30, 2013 Author Share Posted November 30, 2013 Two steps forward, one step backwards.I've been away working for the last six weeks, and have one weekend at home before heading north again until Christmas. That sort of schedule is why the GT6 rebuild has been so slow this year. I'd be grumpy, except a lot of geologists were laid off in 2013 and I know I'm lucky not to be driving a taxi. Anyhow, I shot out to the engine shop in the Herald yesterday and picked up my machined rods and pistons. The rods have been balanced end-for-end. One rod came from a different casting and was so different that Terry substituted another rod. They're beautiful!(BTW I used my macro lens and flash to try and show how good a job Terry has done. The lens has a shallow plane of focus, which is why some parts of the photos aren't in focus).The pistons have had their skirts modified to clear the crankshaft counterweights. Terry trimmed them with a Dremel and judging by the quality of work, drastically undercharged me for his time. I installed them without rings and used plasticene to check that they are well clear. Yep, another problem eliminated. And so to the most exciting part - fitting the rings and finally installing the pistons for the last time. And guess what? The rings don't fit. I've checked the ring thicknesses and they seem correct. They're a set of 1/16" (1.6mm) top and middle rings, and 5/32 (4mm) three-part oil control rings. The top and middle piston grooves are just slightly undersize, but the bottom groove is too narrow by about a mm.Terry and I discussed machining the ring grooves before working out that the pistons are designed to take standard Triumph ring packs, which are as thin as any modern high-performance ring (Triumph didn't cut corners with their choice of rings). Machining the ring grooves is a tricky job requiring a custom-made lathe jig to hold the pistons, and Terry wasn't keen. But the block has been bored for these specific pistons, so unless I buy another piston set, strip the engine and get it bored out further (and it's at 60 thou already), the best choice seems to be to modify the pistons further. Oh for parts that fit without repeated journeys to the machine shop Quote Link to comment Share on other sites More sharing options...
junkuser Posted November 30, 2013 Share Posted November 30, 2013 Sounds like top rings should be 1.5 mm and scraper 3 mm possibly, from what you say Nick.Could the supplier of the pistons not help you out with supplying or guiding you as to the correct rings to use?What are the actual sizes of the grooves?I apologist if I have missed something you have posted previously. Quote Link to comment Share on other sites More sharing options...
Nick Moore Posted November 30, 2013 Author Share Posted November 30, 2013 I'm currently waiting for a reply from the piston maker. If they have been machined for 1.5mm and 3mm rings by mistake, and there are ring packs available for a 76.2mm bore, then that would be the best solution. Back to Google-trawling. Quote Link to comment Share on other sites More sharing options...
Nick Moore Posted November 30, 2013 Author Share Posted November 30, 2013 Righto, the verdict is in - the pistons have been machined to metric thicknesses by mistake, as Mal suggested. So far the only metric 3" rings I've found are for a chainsaw - drive it like you Stihl it? Quote Link to comment Share on other sites More sharing options...
junkuser Posted November 30, 2013 Share Posted November 30, 2013 Would help you cut through traffic. Quote Link to comment Share on other sites More sharing options...
junkuser Posted November 30, 2013 Share Posted November 30, 2013 Seems a pity if these pistons have been made for ring sizes that are not readily available.Looking for ring sizes via Google seems fruitless, came up with "O" rings and other odd stuff.Maybe an engine re-conditioner would know or know where to look for ring specs.Parts these days are listed by make and model or part number only.Years back you could go to Repco and tell the bloke behind the counter the dimensions of a ring you wanted and he could tell you what engines used the size, usually off the top of his head. I feel that the piston manufacturer should either tell you which rings these pistons were made for or, if groove size was a mistake, re-machine them or replace. Sorry you are copping these problems Nick.Would be interesting to know how this happened. Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted November 30, 2013 Share Posted November 30, 2013 Quoted from Nick Moore Righto, the verdict is in - the pistons have been machined to metric thicknesses by mistake, as Mal suggested. So far the only metric 3" rings I've found are for a chainsaw - drive it like you Stihl it? A chainsaw with a 3" bore...... jeez, what kind of trees does that deal with (and what kind of hero hangs on to the blunt end) 😲The gods are definitely trying you on this one!Nick Quote Link to comment Share on other sites More sharing options...
ferny Posted December 1, 2013 Share Posted December 1, 2013 Quoted from junkuser I feel that the piston manufacturer should either tell you which rings these pistons were made for or, if groove size was a mistake, re-machine them or replace. Sorry you are copping these problems Nick.Would be interesting to know how this happened. Indeed, rather strange. If it's their mistake I'd be rather pissed off and have to cut them down to size... Quote Link to comment Share on other sites More sharing options...
GT6 M Posted December 1, 2013 Share Posted December 1, 2013 Nick, there may be another way oot for the top rings,As they may be ground doon, My marra All does this on the rings he makes to get final thickness.So if top 2 rings are just a wee bit oot, then this is a viable optionee.BUTT, the oil ring set up luks like the pistone will need either opening up,OR, ye can re use the old expander bit, IF it is thinner than the yan ye got noo.OR get the expnder bit, also reduced, OR try and get a smaller expander bit.Nick, there some v v BIGG chain saws aboot now a days, http://www.youtube.com/watch?feature=player_detailpage&v=u17ll043Ld8#t=8M Quote Link to comment Share on other sites More sharing options...
npanne Posted December 1, 2013 Share Posted December 1, 2013 Quoted from GT6 M Nick, there some v v BIGG chain saws aboot now a days, http://www.youtube.com/watch?feature=player_detailpage&v=u17ll043Ld8#t=8M Hahaha - V8 chainsaw? Why does that look like something invented for Top Gear? Quote Link to comment Share on other sites More sharing options...
junkuser Posted December 1, 2013 Share Posted December 1, 2013 Found this site when looking for listings of ring sizes via a Ducati forum Nick. Nothing there coincides with what you want exactly but further searching for motor bike ring sizes may get a result. Hopefully this site does not cover all bikes. http://www.jeproseal.com/ Quote Link to comment Share on other sites More sharing options...
Nick Moore Posted December 14, 2013 Author Share Posted December 14, 2013 The Ring Saga is nearly finished! Terry found that 30 thou overbore rings for a Hyundai G4EK (whatever that is) are an almost perfect fit. The Hyundai bore equates to 3.002", only 2 thou larger than my bores. The top and second rings are 1.5mm and the oil rings are 3mm, and they have the right radial depth. He was able to get one set of rings straight away, enough for four pistons. Once we'd confirmed that they do fit, we ordered two more sets. The ACL rings have been discontinued, so I will have a second set in case I decide to re-ring the engine one day.Some people have asked why I didn't just send the pistons back. Well, they were part of a very small batch and there probably aren't any more left. Also, each cylinder was machined to match its piston, and so substituting a new set would have involved more cylinder boring. And lastly, the pistons are beautifully made, just not to the correct specs. They're light, strong, and the wrist pins are slightly offset to reduce or eliminate piston knock when cold. It was definitely worth persevering with them.Pistons 1 to 4 have now been ringed - the last two will have to wait until the other ring sets arrive from interstate. Every ring was gapped to at least 12 thou. A piston was used to make sure the rings were square in the bores for measuring. The honing process causes cylinders to be slightly wider at the top, so the gap was measured 10mm down the bore, and again halfway down. I oiled the bores to make it easier to slide the rings in and out, so it'll no doubt blow a big cloud of smoke when it starts!Several of the pistons had slight marks on their sides, where they'd been bumped or held in a chuck during machining. As a result, the grooves had closed up slightly in a few places, meaning that although the rings would fit in the grooves, they weren't free to rotate. A few minutes with a points file cleaned up the grooves, and the rings will all spin freely.I also checked that the engine turned freely as each big end was torqued up. It got tight when #4 was tightened, and sure enough, even though I'd checked, the cap was on backwards. I'll check the others just to be sure...So that was my Saturday afternoon. Happily measuring, grinding and filing, measuring again and again, and then painstakingly assembling and fitting each piston. From time to time the smell of leather from the seats drifted past, mingling with the smells of oil and metal. Two more cylinders to go, and the bottom end will be finished. It's only taken a year! Quote Link to comment Share on other sites More sharing options...
junkuser Posted December 14, 2013 Share Posted December 14, 2013 Great news Nick.Christmas will be happier now.Looking forward to further progress reports.Mal. Quote Link to comment Share on other sites More sharing options...
ferny Posted December 14, 2013 Share Posted December 14, 2013 This might seem churlish or even dumb, but... if the pistons are so beautifully made how comes they've been damaged in the machining process? Quote Link to comment Share on other sites More sharing options...
Nick Moore Posted December 14, 2013 Author Share Posted December 14, 2013 Quoted from ferny This might seem churlish or even dumb, but... if the pistons are so beautifully made how comes they've been damaged in the machining process? Well, their skirts were originally too long and touched the crankshaft counterweights at BDC. Apparently that happens with some crank castings... so I had the skirts machined down slightly. The marks on a couple of the pistons were 120 degrees apart, which looks like chuck marks to me, so I assume the damage was done then. Easily fixed though. Quote Link to comment Share on other sites More sharing options...
Hughbert Posted December 14, 2013 Share Posted December 14, 2013 Looking good Nick those pistons do look as though they are very well made and I guess it takes a real engineer to understand that 😉 as for the damage some small witness marks are always going to be there with polished surfaces Well done to the engine builder finding a set of rings that will do the job just right plus a fantastic photo of the ring gap. Quote Link to comment Share on other sites More sharing options...
ferny Posted December 14, 2013 Share Posted December 14, 2013 Ahh, so it happened after manufacturer and when they were tinkered with? Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted December 14, 2013 Share Posted December 14, 2013 Hyundai G4EK seems to be pretty commonhttp://en.wikipedia.org/wiki/Hyundai_Alpha_engine.Even gets a chromed top ring as standard apparently!Getting closer to the first fire-up......Nick Quote Link to comment Share on other sites More sharing options...
thescrapman Posted December 14, 2013 Share Posted December 14, 2013 I would have thought they would have used rubber chuck jaws to prevent damage if they were clamping over the slots.CheersColin Quote Link to comment Share on other sites More sharing options...
Nick Moore Posted December 24, 2013 Author Share Posted December 24, 2013 Christmas arrived early for the GT6! The second pack of Hyundai rings arrived on Christmas Eve (each pack is for a four cylinder engine), so I spent the day fitting them and torquing up the big ends and mains. With that done, the vaselined oil pump and sump were bolted in place. After nearly a year of modifying and hunting for parts, the bottom end is finished and buttoned up!Bolting up the gearbox was straightforward. As always my index finger turned out to be accurate enough to centre the clutch. I'm amazed that everything aft of the engine fits together so well - none of it is Triumph. The gearbox is a Supra W58, mated to a custom cast bellhousing from Conversion Components in New Zealand designed to fit a Supra box in a TR6. The Conversion Components hybrid clutch is mounted on a lightweight steel TR6 Bastück flywheel (which is almost too pretty to fit in a car). And the alloy back plate is for a TR6. Even the starter motor is non-stock, a Nippon Denso conversion made here in Australia.A big bore head gasket is on its way from Chris Witor, but in the meantime I'll have a go at degreeing the camshaft. That should be fun.Oh, and the reason I've fitted a stock oil filter is that I don't want any debris ending up in an oil cooler. I'll run the engine in for 500 miles, change the oil and filter and only then plumb in a cooler. Quote Link to comment Share on other sites More sharing options...
junkuser Posted December 25, 2013 Share Posted December 25, 2013 Good to hear things are now working out well Nick.Enjoy today.Like the idea of a contemplation chair in the workshop. Quote Link to comment Share on other sites More sharing options...
Phwoar Posted December 25, 2013 Share Posted December 25, 2013 Good things come to those that wait! Merry Christmas. Quote Link to comment Share on other sites More sharing options...
Nick Moore Posted December 25, 2013 Author Share Posted December 25, 2013 I dragged my carcass back down to the garage after Christmas Dinner to work off an overdose of Pavlova and install the camshaft. This was my first attempt at decreeing in a camshaft, so if the valves tangle with the pistons, it's my fault. With a degreeing wheel, pointer and dial gauge, it seemed fairly straightforward.And now I think I'll go sit in the contemplation chair with a drink, and look at it. Merry Christmas everyone. Quote Link to comment Share on other sites More sharing options...
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