Lotus Elan

Front cover alignment

PostPost by: seniorchristo » Mon Jul 12, 2021 7:07 pm

Thanks for that Richard
I measured my old head gasket at .030". If my new gasket compresses to .043", I would think the proper cork gasket should work. My cork gasket is a foil sandwich and I was able to compress it with calipers to .045" without damage..
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PostPost by: rgh0 » Tue Jul 13, 2021 11:34 am

seniorchristo wrote:Thanks for that Richard
I measured my old head gasket at .030". If my new gasket compresses to .043", I would think the proper cork gasket should work. My cork gasket is a foil sandwich and I was able to compress it with calipers to .045" without damage..


0.090 to around 0.055 is probably OK going down to 0.045 is pushing it ... may work may not overtime

I am not sure what is considered a "proper" cork gasket. The world has changed in the last 60 years and if your using silicone sealants designed for a computer assembled metal to metal face on a cork gasket then your a long way away from "proper" already and if it works for you great. However I don't see cork gaskets ... proper or not... that are happy with more than 30% or 40% compression of original thickness long term regardless of the sealant used on them.

How thick is your head gasket uncompressed ? Is it a MLS gasket? How thick is it supposed to end up when fully compressed ( if MLS it does not compress much which is the problem as it is to stiff IMHO).

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PostPost by: seniorchristo » Tue Jul 13, 2021 12:56 pm

Hi Rohan

I don't know if my head gasket is "MLS" or not. I enclose below, the label from the package. Uncompressed, the gasket is about .048". I think it compresses to .043" based on the label. Visually it appears to be multiple layer stainless steel but the part number doesn't correspond with a similar MLS gasket from Burton. Burton advertises less "clamp force" is required. Does this mean using a different torque value?
The gasket I received was recommended by Quicksilver Racing and is also used by Marcovicci Wenz. Ideally I would source a thinner cork gasket but I wouldn't know who to contact. Or perhaps special order a thicker head gasket which looks to cost in the neighborhood of $200. :(
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PostPost by: 2cams70 » Tue Jul 13, 2021 1:09 pm

That gasket is CFM material - i.e "Compressed Fibre Material" and not MLS. It will be fine.
The pure cork gasket you have for the timing cover will be fine with that amount of compression.
Threebond 1215 works very well as a cork gasket dressing (minimal amount only) and is recommended as being able to be used as a dressing by Threebond themselves. The adhesion is tenacious but can be easily be removed with Acetone or better still CRC contact cleaner. Do not substitute other brands or grades of RTV for this purpose. They are nowhere near as good. See data sheet below

https://threebond-europe.com/products/tb1215/
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PostPost by: seniorchristo » Tue Jul 13, 2021 1:28 pm

Rohan and 2cams
Thank you so much for your help and the sharing of your knowledge. I think i now have enough information to proceed with the cover /plate installation.
Chris :)
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PostPost by: seniorchristo » Wed Jul 14, 2021 12:40 am

I got the plate and timing chest installed. Everything squared up fairly well. Next step is installing the head and timing the cams :)
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PostPost by: rgh0 » Wed Jul 14, 2021 10:16 am

seniorchristo wrote:Hi Rohan

I don't know if my head gasket is "MLS" or not. I enclose below, the label from the package. Uncompressed, the gasket is about .048". I think it compresses to .043" based on the label. Visually it appears to be multiple layer stainless steel but the part number doesn't correspond with a similar MLS gasket from Burton. Burton advertises less "clamp force" is required. Does this mean using a different torque value?
The gasket I received was recommended by Quicksilver Racing and is also used by Marcovicci Wenz. Ideally I would source a thinner cork gasket but I wouldn't know who to contact. Or perhaps special order a thicker head gasket which looks to cost in the neighborhood of $200. :(


If it is a compressed fibre gasket thats good. I believe this is the best technology for the Lotus twin cam head. However these gaskets normally compress at least 20% so I would expected it to end up around 0.8 mm / 0.032 inch thick once the head is torqued down if its 0.048 inch thick now uncompressed.

However you say it visually appears to be multiple stainless steel layers which is what a MLS gasket looks like ? The MLS gaskets compress very little so an expected final thickness of 0.043 inch versus a current 0.048 inch would not be unexpected. Have you got a MLS gasket with a CFM gasket label on it somehow? can you post a photo of the actual gasket

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PostPost by: seniorchristo » Wed Jul 14, 2021 6:38 pm

Rohan
I was mistaken. I'm convinced now it is compressed fiber. Wouldn't the 043 in the part number indicate .043" compressed thickness? With the front crankshaft seal centered the plate now sits s.008" above the head so the cork gasket will have to compress to.035" to match the cylinder head gasket
Chris :)
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PostPost by: Mazzini » Wed Jul 14, 2021 7:13 pm

Steve Taylor from Lotus Marques can help with different thickness timing chest gaskets.

https://lotusmarques.com/info/technical ... sket-guide
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PostPost by: rgh0 » Wed Jul 14, 2021 8:36 pm

seniorchristo wrote:Rohan
I was mistaken. I'm convinced now it is compressed fiber. Wouldn't the 043 in the part number indicate .043" compressed thickness? With the front crankshaft seal centered the plate now sits s.008" above the head so the cork gasket will have to compress to.035" to match the cylinder head gasket
Chris :)


I suspect it represents the nominal uncompressed thickness. If its a compressed fibre gasket it will compress about 20% of its thickness when correctly torqued down. Its that relatively long compression that enables the gasket to seal the head well with movements in the bolt loads from pressure and temperature effects during operation.

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PostPost by: seniorchristo » Wed Jul 14, 2021 9:22 pm

Thanks Mazzini
It looks like Lotus Marques might have what I need.
Chris :)
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PostPost by: fatboyoz » Thu Aug 04, 2022 8:52 pm

Good Morning 2 cams,
Can you please provide details of the front cover alignment tool. Measurements to be specific.
Regards and thanks,
Colin.






quote="2cams70"]1. +1 have a mandrel made up to ensure the seal aperture in the front cover stays concentric with the crankshaft. Although you may think you can get it right by using a telescopic gauge things start to move around once you start tightening bolts plus it makes things much, much easier. The mandrel will lock things in place to ensure the seal opening stays in alignment whilst still giving you freedom to rotate the cover slightly for best fit. I had my mandrel turned from a piece of plastic. There's no need for it to be steel. Easier and cheaper to have it made out of a block of hard plastic. I had mine made by a guy on Ebay for $A60 after I sketched up a drawing with dimensions. See picture.

2. The Lotus specification for maximum timing cover surface mismatch in height is .010". See extract from manual attached.

3. I highly recommend doing a trial build first and loosely fitting the head with all bolts together with the timing cover and it's backplate (no timing chain, no sprockets and no cork gasket but with backplate to block paper gasket fitted). By doing this you and easily determine by eye whether or not it is possible to assemble these components with the top face of the back plate and timing cover parallel with the deck surface of the head and also when in this position the sump face on the underside of the timing cover and backplate is parallel with the sump face of the block. Make sure you loosely fit all of the timing cover bolts too as it is possible that you may need to file some of the bolt holes in the cover and/or backplate in order to be able to rotate things enough so these surfaces are indeed parallel. Nothing is guaranteed when it comes to aftermarket cover assemblies! Yes you can use a straight edge on the block to check alignment but it's easier and nothing beats doing a trial build to fully determine whether everything is as it should be

When you are satisfied with the alignment nip up the single backplate to block bolt sufficiently to prevent the backplate from moving whilst you disassemble prior to final assembly.

4. I recommend you use a cork gasket that is pure cork (like the original one) rather than the commonly available ones that are a cork/synthetic rubber granule mix. Pure cork has much better compressibility than cork/rubber mix. The pure cork gaskets are a laminated construction and have aluminium foil faced with cork either side. I know QED supply them - unfortunately these still aren't quite as good as the original ones because the adhesive used to bond the foil to the cork isn't as good and can separate unlike the OEM cork gasket.

5. I recommend that before you fit the head for the final time that you give the cork gasket a thin coating of Threebond 1215 and fit the head bolts and three timing cover to head bolts nipping them up finger tight only and allow the Threebond to cure overnight before final tightening. This will allow the Threebond time to firmly adhere the cork gasket to the surfaces and will prevent the cork from any further extrusion both during final tightening and over time whilst the engine is in regular use. Tighten the 3 timing cover to head bolts to the lower end of the specified torque range - i.e 10ft/lb rather than 15 ft/lb of the (10-15ft/lb range). This will help prevent excessive stress on the cork gasket and the timing cover itself as the cork gasket being very soft offers no resistance to bolt loads so by tightening these bolts you are effectively trying to bend the front of the head over the block!

Threebond 1215 is great stuff. Do not substitute for other RTV silicones. Unlike other silicones it's sag grade so very thin and you can spread it easily with a finger over surfaces. It has a long tack-free time and being sag grade excess tends to spill over and flow onto interior surface and adhere rather than hang suspended in mid air ready to break off (still no excuse for using too much however!) Japanese OEMs use it.

There's probably a few other hints I could offer but these are the main ones[/quote]
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PostPost by: Hawksfield » Fri Aug 05, 2022 7:38 pm

Fatboyoz

See my post on how I made a simple front cover centraliser, worked fine for me :D
Been oil tight since last December 8)


viewtopic.php?f=39&t=51159&p=372397#p372397
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PostPost by: 2cams70 » Sat Aug 06, 2022 1:36 pm

fatboyoz wrote:Good Morning 2 cams,
Can you please provide details of the front cover alignment tool. Measurements to be specific.
Regards and thanks,


See attached
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PostPost by: fatboyoz » Sat Aug 06, 2022 7:52 pm

Thanks John.


quote="Hawksfield"]Fatboyoz

See my post on how I made a simple front cover centraliser, worked fine for me :D
Been oil tight since last December 8)


viewtopic.php?f=39&t=51159&p=372397#p372397[/quote]
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