dougbgt6 Posted October 27, 2015 Report Share Posted October 27, 2015 Well done James, dogged determination will get you there! Link to comment Share on other sites More sharing options...
jamesdennison Posted November 2, 2015 Author Report Share Posted November 2, 2015 Got the head back. Valves have been re-lapped. I spoke to the gaffer and he's told me that they had been done first time around. He's put them on a vacuum test and got ok results but not as good as he'd have liked. He said that the results got better when he tapped the springs so he suspects weak springs could be a factor in the low compression. I can spin the springs around with finger pressure, so I think he could be right. Should I be getting standard springs (Canley's probably) or is there an upgrade (that will actually make a difference without causing other issues!) that I should be looking at? Link to comment Share on other sites More sharing options...
SpitFire6 Posted November 2, 2015 Report Share Posted November 2, 2015 Hi, Link to comment Share on other sites More sharing options...
SpitFire6 Posted November 2, 2015 Report Share Posted November 2, 2015 Hi, So fault likely found; low tension valve springs? A new one for me. I think standard springs will be a big upgrade to your present setup. Cheers, Iain. 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 3, 2015 Report Share Posted November 3, 2015 There were some higher rated springs on the old forum which came from a jag xj and very cheap compared to std triumph , you should have two springs to maintain the hysterisis and inlet and exhaust have different collet collars a one peice and two peice, pete from Link to comment Share on other sites More sharing options...
Darren Groves Posted November 3, 2015 Report Share Posted November 3, 2015 you should have two springs to maintain the hysterisis and inlet and exhaust have different collet collars a one peice and two peice, I've googled hysterisis and I still don't understand what it means.... Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 3, 2015 Report Share Posted November 3, 2015 Its the relationship between spring rate opening and closing loads we used to plot a graph of load vs travel opening and closing is quite different .... well something like that . pete Link to comment Share on other sites More sharing options...
jamesdennison Posted November 3, 2015 Author Report Share Posted November 3, 2015 You lost me there a bit Pete, you should go on QI Hysteresis is the time-based dependence of a system's output on present and past inputs. The dependence arises because the history affects the value of an internal state. To predict its future outputs, either its internal state or its history must be known. However! I only have one spring per valve - see pic. I can see that Rimmers catalogue for Triumph 2000 shows two springs so this lends further weight the argument that the springs are weak and not closing the valves as they should. I've had the car 15 years and it is a real bitsa (GT6 chassis, 2000 "ME" Engine, spitfire tub) so can be difficult to know the origins of constituent parts which were assembled by the previous owner. Head has number 218225 stamped on it if that means anything to anyone I can also see that a couple of the collars have cracked. Not a cheap business this. Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 3, 2015 Report Share Posted November 3, 2015 Even my 64 1600 had the double springs I cant spell hysteeerisiss anyway any clutch maker tests for this or should do we only tested against a spec the compression load vs deflection creates a curved graph chart On release its not a reversed copy but quite different Its important to know how springs perform with regard to the load to open the valve and the load required to maintain sealing under compression. Adding smaller and lighter springs will inside t1he main will, reduce valve bounce and much more Im sure Jd will have some input into the physics of all this diatribe think only herald had singles Link to comment Share on other sites More sharing options...
dougbgt6 Posted November 3, 2015 Report Share Posted November 3, 2015 I thought hysteresis was a medical condition! Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 3, 2015 Report Share Posted November 3, 2015 Can you get pills for it or is this a rub on jobby ?.. Link to comment Share on other sites More sharing options...
jamesdennison Posted November 3, 2015 Author Report Share Posted November 3, 2015 Nothing wrong with your spelling Pete. Page 21 onwards http://www.racingsprings.com/Multimedia/www.RacingSprings.com/Files/kb/kb513103.pdf (still no idea what it is though) I've e-mailed Chris Wittor to quote me for the right bits as 2000's are his speciality. Happy Birthday by the way. Reckon I'll owe you a pint or two at a future TSSC event. Link to comment Share on other sites More sharing options...
dougbgt6 Posted November 3, 2015 Report Share Posted November 3, 2015 To my surprise there is a medical meaning! hysteresis/hys·te·re·sis/ (his″tĕ-re´sis) [Gr.] 1. a time lag in the occurrence of two associated phenomena, as between cause and effect. 2. in cardiac pacemaker terminology, the number of pulses per minute below the programmed pacing rate that the heart must drop in order to cause initiation of pacing. Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 3, 2015 Report Share Posted November 3, 2015 See ..... I said something like that And its now 29 pages of techy followed by a pacemaker pete Link to comment Share on other sites More sharing options...
Andy Moss Posted November 7, 2015 Report Share Posted November 7, 2015 Are you sure it was the stud that slipped. Sometimes the nuts are made from cheese and the thread strips inside them instead. Are you sure it's not just the nut, as this happened a couple of times for me. Cant remember if I replaced both stud and nut when they failed. Link to comment Share on other sites More sharing options...
jamesdennison Posted November 8, 2015 Author Report Share Posted November 8, 2015 Are you sure it was the stud that slipped. Sometimes the nuts are made from cheese and the thread strips inside them instead. Are you sure it's not just the nut, as this happened a couple of times for me. Cant remember if I replaced both stud and nut when they failed. Difficult to tell after the event. I couldn't get the nut off, and by trying (in vice) I stripped the stud threads. It happened a second time on another stud at just 40 ft/lb so I've ordered new studs, nuts and washers from another supplier. Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 8, 2015 Report Share Posted November 8, 2015 the HD nuts have are generally deeper section, they are often not marked like bolt heads std nuts are ok upto 38/41 any more and they give way, sounds like you have std nuts !!! ( must rephrase that ) as the stronger nut is heat treated they are generally black oiled finish Pete Link to comment Share on other sites More sharing options...
jamesdennison Posted November 8, 2015 Author Report Share Posted November 8, 2015 These were specifically bought as head nuts at the same time I bought everything else. They were the usual shiny material. Sounds like duff nuts. Link to comment Share on other sites More sharing options...
jamesdennison Posted November 14, 2015 Author Report Share Posted November 14, 2015 Head back on with new springs, studs & nuts. 1 2 3 4 5 6 152 160 142 60 142 162 I am gutted. This is pretty much identical to the first set of results before I did anything to the head. I'm probably a couple of hours work or so from being able to start her up and I guess it is possible that the new valves need to be bedded in with a bit of running .... but given that it has been cylinder 4 all along that has been causing the problems it seems more likely in my mind that this is a piston problem - do you agree Pete? I know from past experience with this car that the sump cannot be removed with the engine in situ - the engine is out of a 2000 and sits on a gt6 chassis. I had to get thrust washers fitted a few years ago and the mechanic (old school, worked on these when they were new) tried, but not enough clearance so that was an engine out job. I would really like to do as much as possible myself and I'm toying with getting / borrowing an engine hoist. There isn't enough room in my garage to swing the engine clear, but I could wheel the car into the drive and do it there. At that point am I looking at getting the lump into a machine shop or is changing the piston rings (assuming this is the problem!) a DIY job? Link to comment Share on other sites More sharing options...
dougbgt6 Posted November 14, 2015 Report Share Posted November 14, 2015 Changing the rings is easy once the pistons are out although, they are easily broken. Getting the pistons back in a bit more difficult, you need a special tool or skill with two screwdrivers and a third hand. If you have a hoist and facilities it is quicker to take the engine out rather than mess about trying to get the sump off in the car, which was probably more your mechanic's concern. Getting the sump off the GT6 with the engine in the car is difficult, you have to disconnect one engine mount and jack the engine up which allows you to wiggle the sump out. I understand the 2000 sump is different, it's sold as a different item, however I can't see why it can't be fiddled out. If you do take the engine out you're into "Does it need a re-bore, new pistons and a crank regrind?" territory. When I had my engine done the work shop gave me back all the bits and I put it back together, quite straight forward (apart from the piston rings!) and that saved me money. Link to comment Share on other sites More sharing options...
jamesdennison Posted November 14, 2015 Author Report Share Posted November 14, 2015 I still have a nagging doubt - surely I should have seen evidence of piston related problems when I looked in the cylinder bore? or is this not always the case? Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 14, 2015 Report Share Posted November 14, 2015 You can get the sump off its a right faf of engine heigth , angles , and oil pump all getting in the right place and it falls off, we changed the crank in car on the Vit6....blasted heavy any rebuild get a decent piston ring clamp, its too easy to snap one on entry to the bore, after all the other work pulling a piston may show the culprit I would expect better than 60 even with no rings , a good squirt of thick oil down no 4 should improve the ring sealling , you are not having much luck here, with a duff valve seat repair and constant head on head off its looking deeper seated and may we return to the rythmical puffs from the breather you spotted early on the trouble with classics is they have a mind of their own, when you cure the cause the problem still exists...happens a lot Dont get fed up, strong tea and walk away for a bit Link to comment Share on other sites More sharing options...
jamesdennison Posted November 14, 2015 Author Report Share Posted November 14, 2015 With lots of oil down the bore I'm getting 95 on no.4 ...... that really is suggesting piston rings isn't it. Just been looking at rebuild / short engine prices on-line. I don't really want to be spending that sort of money in one go if I can avoid it. I thoroughly enjoy tinkering and I'm not in a rush so seriously thinking about getting hold of a second hand engine hoist and doing this properly and replacing other internals if they need it. Any advice on specialist tools I may need? (piston ring compressor - check) and is there anything that really does need to go to the machine shop? Link to comment Share on other sites More sharing options...
dougbgt6 Posted November 14, 2015 Report Share Posted November 14, 2015 Don't despair! Really, it's a straightforward job. Hoists can be hired. I suspect you may need a re-bore but you might be lucky, your crank on the other hand may be OK (How was your oil pressure?). Get hold of a micrometer to check the crank. Engines from the club shop are around £2.5k but if you do the work you can get away with considerably less. Get it stripped down and take the block to a machine shop, a re-bore will cost hundreds not thousands. Link to comment Share on other sites More sharing options...
jamesdennison Posted November 14, 2015 Author Report Share Posted November 14, 2015 Don't have an oil pressure gauge so no idea on oil pressure. Thinking back, when the car started misbehaving I had oil leaking out of the rocker cover. I can't entertain £2.5k. Canley's have a short engine for £825. Also considering a s/h unit but my car is a real bitsa (told I have a toledo gearbox) so I'd rather stick with this engine. I'll get a second hand hoist on ebay and sell it on afterwards. I guess the head needs to come off yet again! Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now