Lotus Elan

Short block long stroke engine

PostPost by: 2cams70 » Sun Oct 03, 2021 10:39 pm

ill_will wrote:That's a good list of things to check, thanks. The kit I have has 3 hex head bolts which have been machined slightly (a kind of anti-countersink, if that makes sense) which should give a bit of extra clearance to the pulley.

I'm interested to hear you are against a gasket - in the case of a Burton cover I'd agree, as you'd end up with a slight misalignment between outer and central faces if you keep the o-ring arrangement, but in the case of a 'normal' cover it doesn't seem like too bad a solution to me. I had a look and 0.15mm gasket paper is available, so the front cover wouldn't be offset by much. What's your thinking behind your comment?


The more gaskets you have across an interface the more chance you have of gaskets compressing, things moving about, flanges bending and bolts loosening over time. It's bad practice to have more gaskets than you actually need across the sealing interfaces. Lotus was correct - you don't need a gasket between the backplate and front cover. Correctly chosen sealant is much better especially these days with everything that's available. Some people prefer to use an anaerobic sealant here but I personally prefer Threebond 1215 RTV. The adhesion is much better than anaerobic and it's flexibility means it copes much better with any joint movement than anaerobic. Apply exactly as per the instructions on the box however and don't use too much.

Yes Burton supplies cap screws for the water pump cartridge that have had the heads chamfered for more clearance. In my case this still wasn't enough for sufficient clearance. The 5/16" cap screw in particular fouled the inside of the water pump pulley. I had to replace with low profile button head screws.

Pictures tell a thousand words so attached below for reference. Note this pulley was the original one for this engine and used with the original timing cover assembly previously.
Attachments
IMG_2742[1].JPG and
IMG_2743[1].JPG and
IMG_2745[1].JPG and
1970 Ford Escort Twin Cam
1972 Ford Escort GT1600 Twin Cam
1980 Ford Escort 2.0 Ghia
Peugeot 505 GTI Wagons (5spdx1) (Autox1)
2022 Ford Fiesta ST.
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PostPost by: ill_will » Mon Oct 04, 2021 7:31 pm

2cams70 wrote:Pictures tell a thousand words so attached below for reference. Note this pulley was the original one for this engine and used with the original timing cover assembly previously.


Those pictures are great thanks. I didn't press on the pulley carrier/boss (or whatever it is called?) and it isn't on as far as yours, so thanks for the tip. It also made me realise that since I was originally going to fit an electric water pump I hadn't seen the W/P pulley for a long time - I replaced the pump with an alloy plug with o-ring arrangement to seal. One to have a dig about for!
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PostPost by: ill_will » Mon Oct 04, 2021 7:48 pm

Had a chance over the weekend to re-measure the bores, twice. The results were consistent with the previous measurements, which was reassuring at least.

Process was: calibrate the 3-4" mic against 3" gauge bar, then also check against 4" gauge bar. Both correct to nearest ten thou of an inch. Set mic to 3.2870" and lock in place. Zero bore gauge to nearest 0.01mm against the mic, which takes a bit of practice as you are holding the two tips against the fairly small circular surfaces of the mic, whilst trying to perturb it laterally and vertically, to get the minimum reading. I'd guess it is within 0.005mm. I have seen a suggestion to hold the mic in a vice - I found it easier to lay it on the workbench with a small piece of wood offsetting slightly from the surface, and then you have something to brace against with your fingers to make small movements of the bore gauge.

I measured in both the thrust direction and co-linear with the crank axis, in both cases about 1" down from the top and maybe 1.5" up from the bottom. I understand that the bores should be close to cylindrical, but don't know if there is a convention for where to take the readings? I vaguely remember that the pistons have some taper (don't have them to hand to check this, so I might be misremembering) and if so the position to measure is critical, but don't think that is the case here.

Summarising, thrust direction only (the perpendicular direction was similar):

#1 +0.010mm (+ = oversize nominal 3.287", which includes 0.0030" clearance)
#2 +0.025mm
#3 +0.025mm
#4 +0.030mm
(all +/- approx 0.005mm)

Per the suggestion above I've approached Dave Bean in the US, who provided the pistons, to ask if they have a contact at JE Pistons for asking how acceptable this is. I'll keep you posted.
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PostPost by: ill_will » Mon Oct 04, 2021 8:51 pm

Had a chance to trial build up the jackshaft, to check alignment of the new bearings. I shortened the jackshaft by grinding off the end portion, refacing the end on the lathe and rotating the rear bearing to block off the oil supply.

Building up with a little assembly oil the fit is very nice. End float was at the lower-middle of the range (spec 0.063 to 0.190mm) at approx 0.09mm.

Engine16.jpg and


I also test assembled the crank in the new shells - feels nice and smooth. The main aim at this stage was to check for clearance between crank, block and jackshaft. There was plenty of clearance - more than 2mm. Let's hope with the rods in it is a similar story.

Engine17.jpg and


(This was all done before the front cover test fit posted above.)
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PostPost by: Craven » Mon Oct 04, 2021 10:47 pm

Simple practical test of clearances in plane bearings is the use of Plastigauge,
Check bores using a piston ring and feeler gauges on gap.
P1020718.JPG and
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PostPost by: ill_will » Sat Dec 04, 2021 8:47 pm

Other priorities have meant not much has got done on this for a while. I need to give the 182 Trophy a service which, along with the Christmas deadline my g.f. has imposed on me to get the kitchen finished, has pushed the engine build to the bottom of the queue.

I had shipped the conrods back to Gosnays to have them crack tested and the courier company lost them. A month later I'd given up hope and started researching replacements when Gosnays got in touch out of the blue to say they had just turned up - which is great news.

I had previously measured the con rod (larger) bearing housing diameters with a two-point dial bore gauge and was concerned they were slightly oversize, up to +0.01 to +0.015mm was what I'd measured. We have a very good Mitutoyo 3-point bore mic at work so I took them in and measured them there. Interestingly they came up slightly smaller than with the 2-point bore gauge, so I have now concluded that the 2-point method gives slightly larger measurements which I assume must be due to two factors: a) 3-points giving an averaging effect + more enforced concentricity vs the 2-point, and b) the design of the 3-point mic, which relies on a line contact at each of the three measurement points, rather than a single 'point' in the case of the 2-point gauge: the line contact approach would measure to the peaks of the surface whilst the point method could feasibly measure to the troughs. Both were checked against calibration gauge(s) so I don't think it was that. Interested if anyone has any other experience of this?

For completeness and in case anyone else on here measures with a 2-point bore gauge and is concerned, here are the full set of measurements:

2 point meas --> 3 point meas
#1 52.918 --> 52.906 (all mm)
#2 52.918 --> 52.907
#3 52.923 --> 52.914
#4 52.913 --> 52.905

spec is 52.896 - 52.908 mm, so #3 is very slightly over, the rest ok. The 2 point measurement technique appears to over-read by approx 10 microns.

I will try to remeasure the cylinder bores using the 3-point bore mic and post the results up here too - based on the 2-point measurements I did before I suspected them of being slightly oversize by around 0.025mm, which is roughly the same as the ratio of the diameter to what I saw here. Fingers crossed
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PostPost by: ill_will » Sun Feb 27, 2022 11:02 pm

A little progress on this.

Made up a front cover positioning tool from some scrap on the mill at work.

IMG_20220225_182944_copy_1728x2304.jpg and
IMG_20220225_183003_copy_1728x2304.jpg and


Also needed to deepen the oil gallery plug relief on the reverse of the front cover back plate by 3mm or so.
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PostPost by: ill_will » Sun Feb 27, 2022 11:16 pm

With the cover spacer tool I found the cover could be centred on the crankshaft and then the single bolt that holds the back part of the cover onto the block tightened up. Note to self - when doing the real build remember the slinger!

Then pressed on the water pump pulley boss to align the belt between main pulley and water pump. Alignment of the belt meant the boss was maybe 0.060" clear of the casting, so pretty tight.

IMG_20220225_184546_copy_1728x2304.jpg and

IMG_20220225_190046_copy_1728x2304.jpg and


Checked clearance with the pulley on the boss and the larger of the three bolts is very close (using the supplied turned down cap head.) With a washer fitted it clashes. Without washer it is ok.

IMG_20220225_185146_copy_2304x1728.jpg and
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PostPost by: promotor » Mon Feb 28, 2022 5:52 am

ill_will wrote:A little progress on this.

Made up a front cover positioning tool from some scrap on the mill at work.

IMG_20220225_182944_copy_1728x2304.jpg
IMG_20220225_183003_copy_1728x2304.jpg


Also needed to deepen the oil gallery plug relief on the reverse of the front cover back plate by 3mm or so.


If you needed to deepen the hole my secondary thought to "the hole isn't deep enough" would be to check the oil gallery plug. Some suppliers don't actually know what thread the gallery plugs are and therefore supply one they guess to be correct. The large ones are 1/4" NPTF and the small ones are 1/8" NPTF.
I'd check the gallery plugs tooth pitch. Found this out at my expense after believing that suppliers know what they are supplying.
If I recall, the incorrect ones sit out further due to a mismatch of threads.
Last edited by promotor on Mon Feb 28, 2022 8:37 am, edited 1 time in total.
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PostPost by: 2cams70 » Mon Feb 28, 2022 6:38 am

I've been through the Burton front cover saga myself and posted at length about it previously. There's quite a few points to check and not just those you have listed.

One thing you need to watch is that the front pulley offsets are slightly different between twin cams and ordinary crossflow engines. Burton's supply pulleys with the wrong offset for a twin cam. QED supply pulleys having the correct offset.
1970 Ford Escort Twin Cam
1972 Ford Escort GT1600 Twin Cam
1980 Ford Escort 2.0 Ghia
Peugeot 505 GTI Wagons (5spdx1) (Autox1)
2022 Ford Fiesta ST.
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PostPost by: ill_will » Mon Feb 28, 2022 8:11 am

Made a start getting the pistons built up, to check clearances. The first issue I've spotted is the gudgeon pin to con rod little end fit. New bushes were fitted and they were honed, but they appear to be too tight still.

I found a few posts suggesting putting the rods in hot water and rechecking but they will not push in by hand, and I had to lightly drift them to get them out again. I suspect it might be possible to lightly drift them in, but this feels very wrong to me. Any thoughts?

The pistons are JE and the fit of the pins to the pistons is a very close running fit, i.e. push in with both thumbs, which I understand is ok.

IMG_20220227_191616_copy_2304x1728.jpg and
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PostPost by: rgh0 » Mon Feb 28, 2022 8:31 am

The pins should float freely on the rod small end bearing with close to zero clearance, they should not need to be pushed in and certainly not drifted out, the clearance is specified in the manual at 0.0003 to 0.0004 of inch. The pins are a finger push fit into the JE pistons as you have experienced.

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PostPost by: RichardHawkins » Mon Feb 28, 2022 7:13 pm

I agree with promotor, NPT & BSP are often confused and the differences can be difficult to distinguish. I met a man in my industrial life who was adamant that the two systems are the same! This seemed to be based on his ability to force the two together in one particular size.

I think the block has NTP threads as it is a Ford (American company) item whilst other parts (head?) which were made in the UK may be BSP.

Always worth checking,

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PostPost by: rgh0 » Mon Feb 28, 2022 7:35 pm

Yes all the Ford castings use NPT all the Lotus castings use BSP

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PostPost by: ill_will » Mon Feb 28, 2022 8:30 pm

Thanks guys, I'll check. I got the plugs from QED so I hope they are the correct ones.

I read that at least one other person had the same issue and had to take a few mm off the bottom of the hole, but don't know if that was the casting or the plugs at fault.

A DMG 5 axis monoblock was a bit overkill but we have them at work.
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