Rosie's return to glory

[378S2]

Lovely to see - solid progress. Are you going to pull the bottom end apart and change the rings? I see SJ have plenty of options for them.

[TorqueHorse]

I used coppereze on all the threaded mechanical fasteners, because getting them off the first time was hard enough.

they are designed not to be undone. The nut is a special locknut that jams in the thread when you try to undo it.

Right! I was actually talking about the tiny little eyeglass size screws (5 and 10 from the diagram I added) I think the leaking oil had hardened over the years to lock them in place. I needed to dremel one of them out.

[TorqueHorse]

Some great work going on here.
It has been decades since I lapped valves, seriously tedious but rewarding at the same time

Thanks @Par, I sure hope so!

Lovely to see - solid progress. Are you going to pull the bottom end apart and change the rings?...

Thanks @378S2. Funny story about that. No...because I couldn't get the woodruff key out for the life of me (which holds the toothed pully on the crankshaft). After a couple days of trying, I figured it was probably for the best on this go around. Provided this reassembly goes well, I'll go to a machine shop to get the key out the next time, since I'll probably want a rebore by that point too, with new pistons and rings.
But d@^^n you, if I'm not re-reading the service manual now and seeing that I don't need to remove the crankshaft in order to take the pistons out! Grrrr, now I'm going to have to look at what SJ has. I really need to stop posting here, or I'll never finish

[HJ2]

Great work and an inspiration for my next job, when Steel Blue is finished: Engine revision
Thanks and keep those updates + pictures coming!

[378S2]

Sorry Matt - I mean you no harm!

[TorqueHorse]

Haha - no worries! That's your role in all this; I need the fresh eyes and perspectives. I'm just embarrassed at myself for not figuring that one out.
Keep 'em coming

[378S2]

You’ll need to get the crank out to re-bore it though won’t you?

But I want to distance myself from any sense of peer pressure you are feeling to do more to your engine than it needs. Also go on, strip it down further you know you want to and I want to see what it takes!

[Simon_P]

I want to see what it takes!

about £2k and the parts to do it properly like graded bearings aren't available.

If you have to do it follow the mamual. You are unlikely to need a rebore, a hone and new rings in spec. The crank is treated so there is no regrind tolerance or bearings. That doesn't mean you can't, it means don't do it unless it is outside the spec.

If it aint broke don't fix it.

[378S2]

Mmm... I feel like Simon is the person to listen to!

I am interested in the parts list that make up the 2k - what sort of things do you end up changing apart from the obvious gaskets & seals etc.?

[Simon_P]

That's all consumables, seals, gaskets, bearings (£60 a pair), belts, pump, paint including the yellow for the engine number, new clutch, crank balanced and polished, clutch and flywheel balanced to crank. Oil cooler hoses, rings. I balanced the pistons and rods to +- 0.1g (a bit obsesive) and did all of the work myself so no labour cost. You soon get there!
Advice to anyone is to follow the manual to the letter and realise that there was a massive leap in engineering between that old twincam/mini engine you rebuilt and this. This one is designed not to wear out so you are unlikely to need a rebore and new pistons, and you only need to check that the bearings are in spec.

[TorqueHorse]

...an inspiration for my next job, when Steel Blue is finished: Engine revision

thanks @HJ2! And that sounds fun; can't wait to see that one too

This one is designed not to wear out so you are unlikely to need a rebore and new pistons...

Thanks for the advice @Simon_P! I'll post what I find after pulling the pistons.

In the meantime, the top of the block seemed to checkout at least.


Everything stayed in it's own hole, and the only place that got close was between cylinders 2&3. And that was with just the weight of the glass in place.


Finished cleaning and repacking the last of the HVL's last night!

Just the intake valves left to lap and then the head can go to the machine shop to clean and check for true (and skim if needed).

While the head is out next week, then I can work on getting 378S2's money shot of my pistons and rings (hopefully out).

[Simon_P]

When you see the bearings look at them with a forgiving eye they may not be pretty but they are likley to be better than the Aluminium replacements that are not graded and don't have the 2 holes required. If they check out with plastigauge they are good to use again. There is a reason that one pair is the same price as a whole set of aftermarket bearings! Follow the manual!

[TorqueHorse]

Well, the good news first.
The valves are done and after a final wash in the dishwasher, it is all clean.


And I got my level and feeler gauges in the mail. The head is dead flat; even tighter than factory limits


Bad news
Pistons are pretty much pfft.


And a bit of cylinder scoring too in 1 and 4. Can't catch a fingernail in them, so I'm going to try and hone out.


The dims of the cylinders and pistons seemed to match the relative previous leakdown results too. (Just showing the largest value out of all the measurements per cylinder. Gap is supposed to be less than 0.08)
Cylinder 1: 79.98; Piston 1: 79.75 = Δ 0.23
Cylinder 2: 79.97; Piston 2: 79.87 = Δ0.1
Cylinder 3: 79.96; Piston 3: 79.92 = Δ 0.04
Cylinder 4: 79.98; Piston 4: 79.64 = Δ0.34

Goodish news is that all cylinders still seem in spec enough to hone without a rebore <80.03 (and just new, original size pistons should still fit). Plus the compression and leakdown tests were still good as-is, so I'm pretty hopeful. Got my flex hone in the mail and I'm in the middle of removing the camshaft and then I'll see how it works. Oh, and I found out you don't need to remove the Woodruff key in order to remove the toothed sprocket, to get access to the camshaft. Still need to check the bearings, piston pins, and cylinders post hone before I make my replacement purchases, fingers crossed.

[378S2]

What causes the pistons to wear like that? Obviously contacting the sides but what causes them to do it? Is it a heat thing, an oil thing, a bearing thing?

Glad you can rebuild, looks like it’ll come up to good as new.

Love the photo of the dishwasher, I showed it to my wife and we want to know if you put the dishes in as well?

[Simon_P]

That's pretty much how pistons wear - They aren't round when cold and there is a specific place to measure them.
Narrowest there, I'll guess that at normal operating temperature they are nearer round, and too hot they become wider there due to the non uniform thickness. Also note that its rotating about the little end and the longer portion of the skirt.
Don't think in terms of engine temperature the pistons are next to the flame and cooled by a rich mixture under load and oil jets from underneath (turbo). It could also be the block overheating reducing reducing the tolerance - so all manner of things.

Torquehorse. The three on the left don't look too bad I assume that you are measuring them in the righ place - what do you get if you measure just above/below the wear patch?

Your bore measurements don't look quite right - they are smaller than the new grades!

Id check the oil jet for the piston on the right and also that the hole in the bearing shell was in the righ place. Aftermarket bearings don't have the hole so you have to make one.

If you are looking for pistons don't forget that the Lotus ones are forged and different from the N/A

It doesn't need to look pretty!

I can smell your diswasher from memory!

[TorqueHorse]

What causes the pistons to wear like that?...

Given this car hadn't really been run in over 20 years, I can't tell if it was a contributing factor to why it hadn't been run (like how Simon_P explains), or if it was a result of trying to 'just run it and see' with a clogged coolant system and varnished oil. But, with the coddled throttle, blown turbo, and bypassed elec. waterpump, and all the varnished oil everywhere getting addressed, I'm hoping that this resto will eliminate whatever root cause led to the scoring.

Love the photo of the dishwasher...[did] you put the dishes in as well?

Benefit of being the dishwasher in the house is I get to load it how I like But no, no dishes were put in at the same time, and I did another cycle with it empty before loading again. And maybe I waited until the wife was out of the house to do it? Let's just keep it between us though to be safe.

Your bore measurements don't look quite right - they are smaller than the new grades!

Right? I pretty much spent all yesterday doing the measurements, multiple times per bore and pistons with the same set of gear, and figured if its wrong, at least it is consistently wrong, and that the relative measures are the most important takeaway.

Id check the oil jet for the piston on the right and also that the hole in the bearing shell was in the righ place. Aftermarket bearings don't have the hole so you have to make one.

If you are looking for pistons don't forget that the Lotus ones are forged and different from the N/A

Thx, will do.

I can smell your diswasher from memory!

[Simon_P]

Simon_P wrote:
Your bore measurements don't look quite right - they are smaller than the new grades!

Right? I pretty much spent all yesterday doing the measurements, multiple times per bore and pistons with the same set of gear, and figured if its wrong, at least it is consistently wrong, and that the relative measures are the most important takeaway.

What are you measuring with? and where are you measuring.

[TorqueHorse]

Hey,
I've got a telescopic gauge set to 'capture' the bore diameter, and then I read that with a caliper. The same caliper is also deep enough to measure the piston at it's described measure point in the manual too (30mm from the crown). For the cylinder bores, I have a string hanging down in the cylinder marked at the 3 different depths to take the measures at (12, 55, and 95mm). I'm taking each in both the thrust and axial directions, and I do each one a couple times to make sure it is consistent. I just put the calipers on a ruler I have and it seemed to read right too.

...But, of course a quick internet search shows that the level of precision on both the telescopic gauge and the calipers I have isn't where I need it to be, so oh well.

[Simon_P]

I seem to remember a similar situation several times before - hence the suggestion to measure above and below the wear patch on th pistons to give a relative measure, same with the bores at the top - On the basis that those were the original dimensions so the wear relative to those is x. I never managed to get on well with a bore gauge and I'm sure it was user error.

[378S2]

Have you been watching LEC on Facebook?

https://www.facebook.com/groups/1841457 ... 664634096/