Lotus Elan

Short block long stroke engine

PostPost by: ill_will » Sat Feb 10, 2024 12:14 pm

The gasket I returned to Cometic with 83.5mm bores Vs 84mm nominal, they claim is 'in tolerance' and have charged me a restocking fee. I've asked what the tolerances are. Seems odd that it isn't 0 to plus something I think.

The 85mm one is about 0.5mm over in both directions, but consistent at least.
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PostPost by: smo17003 » Sat Feb 10, 2024 1:28 pm

ill_will wrote:Does anyone have any advice on what to use to oil the bores if the engine might sit for a while before being run, but that doesn't affect bedding in the new rings when it is run-in? I've used ATF for the moment, but not sure if that's a good choice.


I have used a fogging oil on my S3's stored engine. It's intended for spraying into the inlet of a running engine before storage, but I've used it just spraying it in via the plug holes and the ports. Time will tell if it works. It's main use is for marine engines I believe.
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PostPost by: ill_will » Sun Feb 11, 2024 10:33 am

smo17003 wrote:I have used a fogging oil on my S3's stored engine. It's intended for spraying into the inlet of a running engine before storage, but I've used it just spraying it in via the plug holes and the ports. Time will tell if it works. It's main use is for marine engines I believe.


I'll look into that, it isn't something I've heard of before. thanks!
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PostPost by: 2cams70 » Sun Feb 11, 2024 12:40 pm

I’d just use engine oil. Give the engine bit of a squirt with oil down each bore and turn the engine over with a spanner on the pulley every 6-12 months. If you use WD 40 or other products not designed to lubricate an engine you risk starting up the engine dry with engine oil washed off between the piston and bore by these types products going past the rings. Engine oil is the best lubricant. That’s what’s designed to properly lubricate cylinder bores under combustion pressures not WD 40, transmission oil, etc. Many engine oils these days have an additive package that assists the oil to cling to cylinders better than older type oils. The cross hatch pattern on freshly honed bores will retain the oil. That's what it's designed to do. Plus if you rotate the engine occasionally there will be less risk of valve springs losing tension over time due to some being continually compressed.
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PostPost by: ill_will » Tue Feb 13, 2024 4:40 pm

Crank installed. Dave Bean recommends 70 ft lb vs 60 ft lb in the lotus manual.

IMG_20240211_185916.jpg and
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PostPost by: ill_will » Tue Feb 13, 2024 4:41 pm

It turns nicely once torqued. Assembly lube on the shells.
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PostPost by: ill_will » Tue Feb 13, 2024 4:45 pm

Next step was to install the pistons. Rings were gapped previously and the rods assembled. Ring alignment per the JE piston instructions.

I got one of those tapered sleeve type ring compressors and it was a real pleasure compared to the thin metal clamp type I have used before. Line up, then push with the thumbs and the piston is in. Sorry forgot to take a photo.
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PostPost by: ill_will » Tue Feb 13, 2024 4:49 pm

Forgot to note on the rings. The first ring (chromed steel) gaps needed to be opened up very slightly, which I did carefully with a file, always going towards the centre of the ring. The biggest hassle I had was deburring, ended up using a bit of 600ish grit with a piece of metal under it to knock the burrs off without rounding the corners. I made sure the ring could rotate freely in the groove, as with the burrs it couldn't.
The second (iron) and oil control were good, and no adjustments were needed.
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PostPost by: ill_will » Tue Feb 13, 2024 4:58 pm

Next step was the big end bolts, ARP 2000. Spec was 55 ftlb or stretch method preferred.

The stretch spec was 6.5 to 7 thou.

IMG_20240211_214127.jpg and


The stretch gauges available in the UK seemed pretty expensive for what they are, and not available without a DTI. I got a cone anvil 1" to 2" micrometer for a tenner, which did the job.

IMG_20240211_195638.jpg and
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PostPost by: ill_will » Tue Feb 13, 2024 5:08 pm

The unstretched lengths vary by about 5 thou so the lengths and locations were all recorded. They say to discard them if this length increases by more than a 0.001" when the bolt is removed.

With their special lube on threads and under the heads, the torque of 55 ftlb resulted in not quite enough stretch, so a little more was added by angle rotated method until in the middle of the target range. The micrometer is marked 0.001" increments but is good to approx 0.00025-0.0005" with care.

IMG_20240211_213539.jpg and


The micrometer fitted fine on either side by very slightly rotating the crank either way to give clearance to the anvil/frame.
Last edited by ill_will on Tue Feb 13, 2024 5:13 pm, edited 1 time in total.
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PostPost by: ill_will » Tue Feb 13, 2024 5:12 pm

Now ready for the front cover assembly to go on next.

IMG_20240211_213820.jpg and
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PostPost by: 2cams70 » Thu Feb 15, 2024 5:25 am

ill_will wrote:Crank installed. Dave Bean recommends 70 ft lb vs 60 ft lb in the lotus manual.

IMG_20240211_185916.jpg


Ford increased the torque spec. by 5 ft/ib for later engines when they switched to square main caps. Ideally you should use they same torque spec. as the factory used when they line bored the tunnels. 70 ft/lb is OK for your engine with the square caps but I would not use that spec. on engines with round main caps and originally machined tunnels. If you torque differently to what the factory did when they line bored the tunnels there is a risk they will become out of round.

I notice you have washers under the heads of the ARP big end bolts. You might wish to run that past ARP to be sure. Sometimes washers can be a hinderance rather than an asset. Washers are never used OEM. I once bought a kit of ARP flywheel bolts that included washers. Separate to the kit was a notice not to use the supplied washers under the bolts!

Edit: I see they mention the washers in the supplied instructions. I'm not sure why ARP say use washers when OEMs stopped using any form of washers on big end bolts at least 50+ years ago. Perhaps ARP can explain.
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