Nick Jones
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Everything posted by Nick Jones
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Nah.... probably using it for medical purposes..... :P I'd be inclined to work on the devil you know - at least you know it doesn't howl like a banshee! And while you're in there, have a good look at the cupped thrust washers on the little gears - the fibre ones just vanish and the yellow metal ones get eaten by GL5 oils - either way you get a big clunk..... Nick
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2.5 grunt plus low first gear does break 3.27 diffs...... plenty have proven this........ just a matter of time Tim...... (having watched an appreciated your Prescott video :)) Nick
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You should check the ring gaps on all compression rings by pushing them down the bore about half way with a ringless piston and then measuring the gap with feeler gauges. There will probably be a bit of paper with your pistons telling you what the gap should be. The one from my County brand ones says 0.003 - 0.004" per inch of piston diameter...... so 0.009 - 0.012" gap. Too small is the bigger risk as if the gaps close right up when the engine is hot the rings will break. If you get a huge gap it suggests the rings are the wrong size for the bore (std rings in +0.020 bore say) Did you ever determine what caused the original failure? Any pics of the wreckage? Cheers Nick
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99176 wrote:Much better to measure piston heights using micrometer depth gauge at centre of piston. Deck heights are a subject in themselves. I'll come clean what I run when everyone else 'fesses up'. I'm sure this is true but I don't have one. I'm getting more consistent results now I'm turning the engine over a couple of times before measuring and measuring in the centre of the piston. Measuring all pots with the same rod/piston combo (with dti in centre of piston)shows that the crank throws are equal within 0.05mm (0.002"). Hopefully will get the best combination sorted over the weekend. Looks like eventual deck height will be around 0.005". I like squish - not that there's squish area worth a damn on the 2.5 head - 2.0 L much better! Nick
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Hardened seats needed for exhaust valves only. Inlet seats just need re-cutting as lightly as possible to clean them up. Exhaust valves might need upgrading for unleaded but probably ok as are. Standard guides are fine. Nick
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If you are planning a full rebuild of the 2.5 it doesn't matter all that much which engine you start with as the major bits are the same on all. Therefore no reason to pay over the odds just because it's claimed to be ex-TR6 or whatever. My recipe, based on a 2.5 PI MG prefix engine Rebore +0.020" and new pistons (because it needed it) Crank ground 0.010" (because it needed it) Crank and flywheel balanced (Vitesse flywheel) Rods and pistons all weight matched to 0.5g Assembled with attention to even deck heights, 308778 PI 132bhp cam (good used) with new followers Toleranced oil pump Head (based on original PI head) Home porting job as per http://sideways-technologies.co.uk/forums/index.php/topic/6080-nicks-diy-head/ New manganese bronze guides and SS valves with unleaded inserts on the exhausts. Skimmed for 10.5:1 CR (will be mostly running on lpg - advise less for petrol! - though this will depend on cam choice) EFI and 3D distributorless ignition controlled by Megasquirt MS2 (already in the car and running the old engine, a smokey, rattly old ruin) TR6 twin-downpipe exhaust manifold Hoping for a torquey, docile and economical 140 - 145 bhp. Assembling bottom end at present. Nick
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Certainly should have springs. The carbs cannot correctly meter the mixture without them - will tend to make the engine run leaner as the piston can rise higher at a given flow rate reducing the vacuum over the jets. Size needed depends on whether you have the ball bearing dashpots (late cars only) which uses the big springs of the plain bush daspots which uses the smaller springs. There are also (at least) 2 different spring weights (red or yellow) - you need to get the right ones. You should probably check to see what needles are fitted. Cheers Nick
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Chris's progressive springs are good. They do ideally need a bit more damping than the standard dampers give IMO. Nick
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I've had a couple of those - I think it's a factory spare. Nick
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I'm inclined to agree with Bill. Having done a certain amount of digging around in various 6 cylinder water jackets recently I can certainly vouch for the large amounts of muck that lurk in there. You might find that the black muck is slightly magnetic (Fe3O4 is magnetite) - which would prove it's just ancient deposits disturbed in the water jacket. I did find some magnetic black powder in one of the blocks I've been working on - which was also from a car that had been stood a long time. Probably worth flushing the cooling system again before doing anything drastic. Nick
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Richard_B wrote:When in doubt, whip it out ::) I agree.... it is so damn heavy though. They seem to be breeding in my garage and they stay right where they are if you bump into them...... Nick
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Possible, but not a lot of fun or perhaps the way to get the best result. You'll need to raise the engine quite a bit and/or remove the rack to gain access to the front end. You may need to dunk the piston in hot water before you can push the gudgeon pin out (even after removing the circlips!). One other thing that would bother me is you will need to hone that cylinder before refitting piston (good used?) and new rings and just how you'll get the honing dust out of the engine..... Also - how has the piston damage occurred? Standard engine? Was it pinking horribly? Matching valve damage? Nick
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Alec, Where did the 0.065" come from? I gave 0.0065" (false precision!) as the lowest deck height with highest being near-flush. Rods are the originals. I'll have a go at evening things up a little more by swapping parts around. Piston measurements were a quick and dirty vernier between the top of the pin bore and the crown, just for comparison purposes. There are variations, but they are very small. Measured the recesses in my other block today and they are even less at 0.30 - 0.32mm. That's not been messed with since it last ran though it is a factory rebuild so may have been decked before. Having looked at and measured the new gasket I think it'll be fine. Once I've figured the best piston/rod/bore combinations for most even deck height I'll build it up. Nick
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Thanks Andy - nice link that. Will have a better look later. Nick
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piman wrote:Hello Nick, ideally you want to match the piston heights, to even out the compression. Alec Yes, this is the plan - to try mix and match and find the most even combination. Pistons all measure the same so it's all in the rods and crank throws.
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Got my block back from the machinist. Has had "a very light tickle across the top to true it up" - which could be true as the engine number is still clearly visible. However, block recesses now measure at 0.35mm (0.014") which doesn't seem like much...... I've seen figures of anything between 0.025" and 0.038" being quoted as the correct, or at least acceptable depth. Anyone know what the book figure is and what the minimum you can get away with is? On a related subject, deck height is less than expected. This is slightly complicated by the pistons not being level in the bores (another story!) but two are more or less flush and the lowest is 0.0065" down. I always understood that they are about 0.025" down from the factory. This all seems to point to it having had at least 0.020" off but I'd not expect to see the engine no anymore (or only the ghost of it)? Cheers Nick
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Oil seals are specified by inside diameter (Shaft size) x outside diameter (housing bore) x thickness (less critical, typically 6 - 8mm) So by measuring the diameter of the crankshaft nose were the seal runs and the diameter of the housing you should get a pretty good idea. Of course, the numbers you get may not be a standard general engineering size quite a lot of the automotive ones are not. If you get the choice, a double lip seal usually seals better and Viton will last better in the hot, hostile conditions of the engine. Hope this helps Nick
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Oh yes....... 🙂 Nick
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It is a nice bit of road. We actually went that way on the RBRR 2008, not because we were lost but because we wanted to! I think it's more fun going up though (yowling 6 pot and yipping tyres ;D) and we went down it that time as we were going north. Nick
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Really lovely 🙂 Just to add to your gearbox choices...... you should seriously consider a Toyota W series, the W58 being the pick of the bunch ratio wise. Dellow (in Oz) and Conversion Components (in NZ) both do kits for the TR6 which would get you a bell housing and clutch sorted. I also suspect that if you can find a bell housing for a 2WD petrol Hilux (late 80s early 90s maybe) with 21R petrol engine and W series box, you'd be able to make that fit just by modifying the backplate. The W58 will fit with chopping anything but you may need to bend the inner chassis flanges downwards a bit. Good ratios, nice change and should be unbustable with a Triumph lump. If you do talk to either Dellow or CC I'd be very interested to hear what they want for the bell housings as I got so bored with waiting for them to answer my emails I made my own...... James Beaumont (Jango) has one in his GT6. Pretty sure that's a CC kit as a friend of his imports them to the UK. Returning to the type 9, there's a company called HI-Gear Engineering here in the UK who make a T9 conversion for the TR5&6 using a specially cast bellhousing rather than an adapter plate. http://hi-gearengineering.co.uk/content/view/18/33/ This might use the short input shaft? Though if you've already got the other kit it's probably cheaper/easier to swap the input shaft. Cheers Nick
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Hmm, might have to do a recce "shed to the med" run next year to stay in practice :) Nick
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Good god man, haven't you finished yet?! :P Best get an MoT booked to spur you on..... ;):P Nick (You are making the rest of us look very idle)
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Looks superb! You could get some brushing synthetic mixed to match the colour easy enough and invest a couple of hours with a brush on the floors - would finish it off nicely :) Nick
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The engine is certainly very heavy..... approx 180kgs. Nick
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Jason wrote:Could the fuel issues be down to the contents of the tank being sloshed around a damn sight more than usual? Could be a factor in some cases. Mine gets thrown about fairly often which may help to keep things clean..... :P Another reason to use them properly on a regular basis :) Nick