Roger K Posted January 1, 2021 Report Share Posted January 1, 2021 This is a pretty good summary of how to measure a crank and its bearings. https://blog.k1technologies.com/how-to-check-bearing-clearances Some will think buying this kit might be excessive, and expensive - but my set of micrometers were bought secondhand for a reasonable price. I would buy secondhand best-quality instruments every time over cheap new ones. It helps if they've recently had a calibration check, but if you're taking anything to a friendly machine shop they might do a comparison for you just as a check. Moore & Wright used to be excellent quality, not sure if they still are though. Mitutoyo are good also. It's a difficult call - if you are just building one engine and not likely to do any more, it doesn't make sense. If you take your first measurement and the crank is out of spec or the cylinder bore is oval, there's no point in doing any more because you now know you will need the machine shop anyway. If you're building engines on a regular basis, they are worth buying and should last you a lifetime. Mine have now done several Ford V8s, Jag sixes, old Land Rover engines etc. - the only problem is when you get to bigger engines you need bigger micrometers. My usual routine is to get the machine shop to do whatever basic machining work is required, and a chemiclean, and then do the assembly myself, including selective bearing assembly. Happy New Year, and above all, enjoy it! Note - For bearing shells, this article discusses mixing bearing shell sizes with tolerance undersize bearings to get exact figures. Whilst these bearing sizes are commonly available for Ford and Chevy V8s, I have no idea if you will find these for the Triumph engine. You could at least measure replacement sets for selective assembly to get as close as you reasonably can. I know this will look like overkill for a simple refresh, so I'm not suggesting you do all this - just showing you what the gold standard would be. You can decide how far you want to go! Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 1, 2021 Report Share Posted January 1, 2021 to get the correct dimension spec we need the engine number to eliminate all the variations over the years /evolution Pete Link to comment Share on other sites More sharing options...
AidanT Posted January 1, 2021 Author Report Share Posted January 1, 2021 14 minutes ago, Pete Lewis said: to get the correct dimension spec we need the engine number to eliminate all the variations over the years /evolution Pete Engine number is HC52156HE Link to comment Share on other sites More sharing options...
AidanT Posted January 1, 2021 Author Report Share Posted January 1, 2021 From front to rear these are the average measurements 2.309 2.316 2.313 2.310 I'm not sure how accurate my micrometer is, it's a cheap one from maybe 10 years ago Aidan Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 1, 2021 Report Share Posted January 1, 2021 spec 2.3120 to 2.3115" get it double checked by the MC shop but that looking like a grind is needed as some are below spec Pete Link to comment Share on other sites More sharing options...
Iain T Posted January 1, 2021 Report Share Posted January 1, 2021 It really does reinforce what I said re good quality instruments and having them calibrated. Your reading variations do show the crank needs a regrind but as Pete says you can't trust the actual value. When you are making decisions on close tolerance parts you must have the correct equipment. As Roger said buying good quality equipment is better than new cheap rubbish but then it MUST be calibrated. Most very good sets come with calibrated bars but to be sure on second hand equipment you should these bars (or rings for bore gauges) checked by a good machine shop. Iain Link to comment Share on other sites More sharing options...
daverclasper Posted January 1, 2021 Report Share Posted January 1, 2021 On 30/12/2020 at 20:42, johny said: Yes it was a bit fiddly and I had to release the engine mounts to jack the engine up which as you can imagine would have been easier with a hoist from above. Obviously working on your back isnt ideal and also maintaining the cleanliness of everything is a problem but its doable. Id done the BE years ago at about 40k miles from new during the resto and then heard a slight rumbling when revving the engine at stationary after approx another 30k. I wouldnt have noticed the noise if I hadnt had the car such a long time and know it so well. All the mains are accessible but the hardest is the front which is covered by the bridge piece that is also bolted to the front plate. I had to carefully separate the bridge piece from the front plate without damaging the gasket then put it back in place with sealant. The BE unsurprisingly still had life in them but the mains were just going through to the copper (this is one of the advantages of a multi metal type of bearing) and had been caught just at the right time. However as I say all were replaced with the cheaper single metal bearings which have their own advantages apart from cost. I also changed the thrust bearings and splashed out on the bigger capacity oil pump for good measure🤑 The only thing I regret is not having replaced the bridge piece at the same time as its threaded holes have since needed further work... Thanks for that Johny, much appreciated. I'm hoping not, but may be something I have to do. Dave Link to comment Share on other sites More sharing options...
johny Posted January 1, 2021 Report Share Posted January 1, 2021 Obviously recommended to do them before any damage occurs but this can be difficult to judge. I did read somewhere that the Triumph six crank can last indefinitely without regrinds if the bigends are changed every 40k and mains every 70k or something like that. I know some seem to do more than that but it fits in well with my experience and considering the annual mileage many cars do these days plus the relative ease/cost of the job compared with a regrind I think its quite a good idea. Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 1, 2021 Report Share Posted January 1, 2021 we changed the crank and shells in car with the Vit6 1600 for a reground balanced assy yes back breaking and needs a hoist of sorts to take the anchor weight of the crank its a monster , while you fits shells and couple of mains then release the rope it easy to slip new shells in apart from the weight of the crank getting the sump off takes the longest faf but its quite doable ( but i was 15 years younger) Pete Link to comment Share on other sites More sharing options...
AidanT Posted January 11, 2021 Author Report Share Posted January 11, 2021 Piston Ring questions On number three the second ring is well not locked up but certainly doesn't rotate around the piston - why would this be? Is it ok to remove all the rings now as they will be replaced or are they still needed? What about the third seal rings- do they need replacement? Should I just remove them all to clean the piston sides? Thanks Aidan Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 11, 2021 Report Share Posted January 11, 2021 the restriction is crud in the piston groves old idea was to use a broken ring segment to scrape the groove clean as you are rebuilding there is no point in re using old rings i would take them all off and give the piston/grooves a good clean ready for new ones ...but if you end up with a rebore then all this is hogwash as all will be NEW Pete Link to comment Share on other sites More sharing options...
AidanT Posted January 11, 2021 Author Report Share Posted January 11, 2021 The Pete What about that third ring/seal - will far need replacing with just a hone? Aidan Link to comment Share on other sites More sharing options...
Nigel Clark Posted January 11, 2021 Report Share Posted January 11, 2021 Replace all the rings at the same time, including the third oil control rings. They are sold as a full set anyway. Nigel Link to comment Share on other sites More sharing options...
Roger K Posted January 11, 2021 Report Share Posted January 11, 2021 I know it's an additional expense, but a simple set of piston ring pliers makes life a lot less stressful. They don't cost much and changing the rings can be a fiddle without. I have a second set of rings the same size to hand because it's a right pain waiting for a replacement if you are unlucky, or cack-handed enough to break one. A good piston ring compressor is essential as cheap, single clamp ones make it a lot easier to break the rings on insertion. I am a big fan of tapered ring compressors, but as with the spare set of rings I assemble a lot of small block Ford V8s so they get enough use to justify the cost. MED make them for Mini engines, but I don't know if they are available for the Triumph 6 size - probably, somewhere. This vid shows the pliers, too. Roger 1 Link to comment Share on other sites More sharing options...
Iain T Posted January 11, 2021 Report Share Posted January 11, 2021 2 hours ago, Pete Lewis said: but if you end up with a rebore then all this is hogwash as all will be NEW Aidan, I really do suggest measuring or getting the machine shop to measure and review everything as you may be wasting energy. I know it's all good fun and valuable lessons but it doesn't really get you further along. Iain Link to comment Share on other sites More sharing options...
AidanT Posted January 11, 2021 Author Report Share Posted January 11, 2021 12 minutes ago, Iain T said: Aidan, I really do suggest measuring or getting the machine shop to measure and review everything as you may be wasting energy. I know it's all good fun and valuable lessons but it doesn't really get you further along. Iain Hi Iain I'm just cleaning everything up before it goes off the the machine shop. Just wanted to know if it was best or ok to remove all the rings TBH, I will probably get them to refit the crank, bearings pistons and rings, as I have no real way of measuring what is needed accurately 1 Link to comment Share on other sites More sharing options...
Iain T Posted January 11, 2021 Report Share Posted January 11, 2021 M 35 minutes ago, AidanT said: I'm just cleaning everything up before it goes off the the machine shop. Make sure you get a pass from the local constabulary, I hear they are using 'stingers' now. The world's gone bonkers! Iain Link to comment Share on other sites More sharing options...
AidanT Posted January 11, 2021 Author Report Share Posted January 11, 2021 Another question all Rear crank oil seal - replace ? Or leave well alone Aidan Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 11, 2021 Report Share Posted January 11, 2021 as you are going to all the trouble to make a good job the seal has to be replaced why would you not want to ??? quite cheap compared to any other work Pete 1 Link to comment Share on other sites More sharing options...
AidanT Posted January 15, 2021 Author Report Share Posted January 15, 2021 Totally odd question now What's the best colour VHT paint do you think best I will be using POR15 but have spent all week trying to decide on the best colour ? Views please! Aidan Link to comment Share on other sites More sharing options...
AidanT Posted January 16, 2021 Author Report Share Posted January 16, 2021 A more specific question Does the rocker cover need VHT paint? Thx Aidan Link to comment Share on other sites More sharing options...
Nigel Clark Posted January 16, 2021 Report Share Posted January 16, 2021 19 minutes ago, AidanT said: A more specific question Does the rocker cover need VHT paint? Thx Aidan No, engine paint sold in Halfords, motor factors etc will easily cope with the temp of the rocker box. Nigel Link to comment Share on other sites More sharing options...
Colin Lindsay Posted January 16, 2021 Report Share Posted January 16, 2021 Interesting video, Roger, but the sad thing is that whilst I like the ring pliers (quite a few identical brands for sale online, between £5 and £10) he makes the use of the old clamp-type piston ring compressors look too easy to justify buying the other tool! He should have broken something to make them more desirable... The price I've found at present is MED £35 + VAT, ARP are about £40, assuming I can find the size I need for, say, Herald 1200 +030 oversize (I'll have to measure then go looking!). Med seems to supply only 1275 engines at present, and I'd guess that 1147 Triumphs are way down the list. I bought a boxed set of Sealey piston ring compressors at Stafford for £1 a few years back and have been keeping them for this engine... so might be the cheaper option, provided I don't break anything... Link to comment Share on other sites More sharing options...
rogerguzzi Posted January 16, 2021 Report Share Posted January 16, 2021 Hello All I made a piston introducer but then I have a big lathe you just need a big piece of tube! It is nice to use. Roger Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 16, 2021 Report Share Posted January 16, 2021 when someone borrowed my ring clamp and didnt return it (you only realise when you cant find it) i used some shim stock rolled around the piston and a couple of jubilee clips to clamp it up , Pete Link to comment Share on other sites More sharing options...
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