Roger K

Doug, the heater valve on the MkIII threads into the union shown in the diagram as part 6. That union has one hose fitting cut off (in effect) and the mini-type heater valve threaded directly into it in its place. That's the thread I was asking about, not the thread for the actual banjo fitting. It's not shown in that diagram. Sorry for the confusion! Roger

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!

There are, but I haven't been able to find one that gives the thread size for the heater valve...

Is anyone able to tell me the tapping thread size for the heater valve for a GT6 MkIII, where it threads into the 3-way banjo fitting on the intake manifold? I'm guessing BSP of some size... Thanks Roger

I meant a bore micrometer, not an external one. You could use three strips of Plastigage (three separate readings), one at either end of the shell and one centrally. Not as accurate as a gauge but should give you an idea. I'd be aiming for somewhere between 0.001" and 0.0015" as an ideal, might accept 0.002" if not too fussy. I'm sure someone on here will know the factory tolerances. That said, frankly I'd be fitting new good quality shells. I wouldn't want to do it all again if the oil pressure's low.

That's true, but given the amount of work to get to them again I'd want to at least get an idea of the wear on them. Just because they're not pitted, and still show a smooth lead indium surface, doesn't mean they're not worn. If you don't have the micrometers to measure, you could at least get an idea of bearing clearance with a pack of Plastigage to give a rough idea. Again it comes down to what you want - a simple refresh or an engine rebuild. And if replacing, you would need to get them back in the original positions.

Believe me, it's bad enough at 65. Not so much the memory, more the arthritis and joints that just won't do what they did. Not sure for how much longer I'll be able to move the car trailer around unhitched - and I've still got to get the engine and 'box back into the XK140DHC yet. The crane will lift it, but there's a lot of heavy jiggling to do...

That makes sense. I was trying to work out how it had got bent - strange place to get accident damage.

Ah, thanks - easy enough to check, and to modify if necessary.

I had a similar experience with Ivor Searle's. They do a collection/delivery service (I'm only 20mins from Soham), and about 7 or 8 years ago they did a Jensen Interceptor block for me - a cast iron 440 (7.3) Chrysler V8. The guy just picked it up, walked over to the van and laid it in carefully. Made me feel about 4' tall with sand in my eyes...

Thanks Pete. I've just noticed that the 3.63 diff I bought has a bent plate, which is slightly loose on the bolts. I'm planning to replace the pinion oil seal anyway as it's leaking, so thought I'd swap the front plate off an older 3.89 (split pin) diff I have which is in great nick. I'll watch the bolts - I'm wondering if someone's fitted normal ones, which is why it's a bit loose - or more likely the bolts have backed off and the taper's not engaging. I'm assuming careful removal of the big nyloc after centre punching alignment holes and reassembling to the same position after changing the seal is OK?It's what I used to do on my E46 BMWs...

- is the diff mounting plate at the front of the diff the same for all Spit/GT6, regardless of split pin/collapsible spacer type? Thanks Roger

Two people's easy for a bare block - a hoist would be overkill, really.

I would really want two people to lift a bare six block these days. It’s heavier and longer than a four and dropping it, or it slipping, could easily damage the block or you. Mw wife has been known to help lug the odd block around...

Using a dial gauge properly (not the way described, but taking the middle of two positions), is very accurate, and far more reliable if the head is still on, for cam timing purposes.

I've spent a fortune on fast-road components on the other cars - I want to keep the GT6 pretty well standard, as it can't compete anyway and that's not why I own it. Essential non-changeable items for my purposes are anything external - so that's carbs, exhaust etc. which limits things quite a bit. A nice cam that is a bit nicer than stock wouldn't hurt, though. From what you say, Clive, I take it the earlier stock cam is better than the later one?

Would those in the know recommend a PH1 profile for an otherwise standard late stepped-block GT6 engine (sorry to hijack)?

The correct method for using a dial gauge is to set the dial gauge before tdc at an arbitrary position, well 'on the ramp', and note the reading. Move the crank over until it reads exactly the same amount on the other side. Halve the value and set your pointer there - that is tdc. You will never get a decent result trying to read tdc directly off the dial gauge. Much easier, and more reproducible, than using piston stops in my experience, although of course that is a perfectly valid method. It's also the only way I know to get peak position on a cam lobe, as well.

More persuasion. You're at the end of the Woodruff key, which is probably raised a little bit stopping it from coming off. With a bit more effort the key will shift position slightly (the groove is 'C' shaped usually) and the sprocket will come off.

Interested to know how that is more accurate than using a dial gauge?

My diff is out already, and it is incredibly easy to do with the rear casing off. Took me about 10 mins all in. I wouldn't want to trust to gravity and sticky oil, to be honest, but that's a personal choice. Having just done the job on the clean, degreased rear casing off the diff, there is a lot of swarf produced which would stick to any oil left around the new drain plug hole. I just wouldn't want to take the risk, but that's not to say you shouldn't. We don't even have dwarfs in the UK any more. They're called something completely different (and much longer) now, but I can't remember what that is offhand.

Snake? Or worm? You decide... Just checked, and apparently it's a legless lizard.

Snake? Or worm? You decide...

No snakes of any kind here in the Fens in good ol' East Anglia, thank heaven. The only thing that threatens working underneath the car is the water table. Did the job this afternoon - rear casing came off easily, 27/64" tapping bit in the pillar drill, 1/4NPT taper reamer, 1/4NPT taper tap. Job's a good 'un. I bought a 1/4NPT magnetic drain plug for a Harley from arh customs: https://www.arhcustom.co.uk/product/doss-magnetic-drain-plug-1-4-inch-18-n-p-t-allen-style-for-2000-2016-softail-oil-tank-transmission-2001-2016-dyna-flt-transmission-2007-2016-softail-dyna-flt-primary-2004-2016-xl-primary-models-arm044205/37398 ...which does the job very nicely. Using the tapered reamer meant I could set the hole so that the head of the plug is flush with the casing. Roger

Looks like your oil pump is for a KC/KD engine, if it has that style of pick up. Much clearer image here: https://www.canleyclassics.com/?catalogue=triumph-gt6-mkiii&diagram=triumph-gt6-mkiii-oil-pump The parts suppliers seem to list only one pump, with a hemispherical filter basket, for all 6 cylinders now including TR6 etc.