Lotus Elan

Cylinder head work needed - Essex, UK

PostPost by: nigelrbfurness » Mon May 08, 2017 9:10 am

Good morning all.
I am near Dunmow, Essex and I need a twin-cam head resurfacing - a very fine finished skim suitable for a Cometic head gasket. The only place I can find near me, apart from Gosnays, is Thurston Engineering in Ongar. I have experience of Gosnay's work. Thurston don't have an email address on their website which is worrying in itself (this being 2017) so I wonder if any of you have any experience of this company or can recommend someone who will not automatically sandblast the head the minute I'm out of the door and despite labels attached to the head saying "DO NOT SANDBLAST" :D

Thanks!
Nigel F.
1970 S4SE/1760cc big valve/SA-AX block, L2s, 45DCOEs, 1978 Jensen GT, 1962 AH Sprite, Alfa-Romeo 159, 1966 Bristol Bus, 1947 AEC Regal bus.
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PostPost by: rgh0 » Mon May 08, 2017 9:39 am

Hi Nigel
Why do you want to fit a Cometic head gasket. IMHO I don't think the potential benefits match the problems of getting them to seal in most cases ?

cheers
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PostPost by: nigelrbfurness » Mon May 08, 2017 11:04 am

Seems to be all Burton are offering in an 85mm head gasket at the moment and their write up suggests they are better sealing than the standard head gasket, so it that's what I've ordered. I've no experience of Cometic head gaskets otherwise, but Burton have a good name so I assumed they wouldn't be selling something dud!
1970 S4SE/1760cc big valve/SA-AX block, L2s, 45DCOEs, 1978 Jensen GT, 1962 AH Sprite, Alfa-Romeo 159, 1966 Bristol Bus, 1947 AEC Regal bus.
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PostPost by: rgh0 » Mon May 08, 2017 11:11 am

I have never used Cometic MLS ( multiple layer steel) gaskets myself but I know of a number of people who have tried and struggled to get them to seal. I believe they are too rigid for the relatively flexible twin cam head

I personally use fibre composite gaskets from a small local supplier but companies like Ajusa make similar and you should be able to get an 85 mm gasket from them.

cheers
Rohan
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PostPost by: nigelrbfurness » Mon May 08, 2017 11:12 am

Oh dear. I'll drop Burton a line and see if they can change my order. Thanks!
1970 S4SE/1760cc big valve/SA-AX block, L2s, 45DCOEs, 1978 Jensen GT, 1962 AH Sprite, Alfa-Romeo 159, 1966 Bristol Bus, 1947 AEC Regal bus.
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PostPost by: William2 » Mon May 08, 2017 12:18 pm

Nigel, I used CTM Engineering at Dagenham (Tel 02085921180) to rebuild my engine. Excellent job. Speak to Charlie who runs it, he's knows twin cams inside out after 30 years.
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PostPost by: nigelrbfurness » Mon May 08, 2017 12:46 pm

Thanks - I'll get on to him right away.
1970 S4SE/1760cc big valve/SA-AX block, L2s, 45DCOEs, 1978 Jensen GT, 1962 AH Sprite, Alfa-Romeo 159, 1966 Bristol Bus, 1947 AEC Regal bus.
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PostPost by: Gray » Mon May 08, 2017 12:49 pm

CTM were recommended to me by Brian Buckland last week, so should be good.
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PostPost by: nigelrbfurness » Tue May 09, 2017 7:41 pm

Thank you everyone who contributed tot his thread, I'll take my cylinder head to CTM. Expanding on some other comments, my gaskets have arrived from various sources including the Cometic MLS head gasket. Everything I've read on the web shouts "DON'T USE IT!" and I cannot find a reference anywhere to anyone having successfully used one of these on a Lotus Twin Cam engine. This begs a puzzling question - why are they being made and supplied for the TC at all if they simply don't work?

However, a much more important question for me now is where am I going to get an 85mm composite or copper head gasket from? The only ones on offer seem to be either 84mm or 87.5mm. I can't imagine there being much chance of a good seal using a head gasket for too large a bore, whereas presumably to small a bore gasket will just burn away. I've never needed to study this problem before because this is the first time in ten years or so I've had to replace the head gasket and I don't recall supply problems with 85mm bores in the past. I've tried QED, Burton, some guy in Germany... et al. The guy at QED said (paraphrasing here) "we stock MLS gaskets for 85mm... but I wouldn't use one... :? "

So you see my quandary....!

Nigel F.
1970 S4SE/1760cc big valve/SA-AX block, L2s, 45DCOEs, 1978 Jensen GT, 1962 AH Sprite, Alfa-Romeo 159, 1966 Bristol Bus, 1947 AEC Regal bus.
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PostPost by: rgh0 » Wed May 10, 2017 10:53 am

I think the Cometic MLS gasket is made and works on the standard iron cross flow head and suppliers think because its dimensional similar it will work on a twin cam. Unfortunately with the less rigid alloy head it does not work on from what I have seen from others who have tried it. QED comments seem consistent with that!!!

I get my 85 mm bore gaskets composite fibre gaskets made locally by a small local specialist head gasket maker. I use these on 83.5 mm bore blocks so that when the fire ring is compressed it is still not protruding into the combustion space allowing for non centering of the gasket versus the bore which can be quite significant when you are offset boring the block to maximise the casting wall thickness.

There must be someone else in the world who makes 85 mm bore fibre composite gaskets???

cheers
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PostPost by: elan66 » Sun May 14, 2017 9:53 am

Hi Nigel,
took my zetec head to charlie at CTM to fit some newman cams and gas flow and port.Turned it around in under a fortnight (included a bank holiday) and for sensible money.Charlie has been tuning fords since they were new not classics.If you have a word with Charlie he will advise you on what gaskets to use or not use.He seems a top bloke,and will also check your head as a matter of course
regards
Paul
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PostPost by: nigelrbfurness » Sun May 14, 2017 1:12 pm

Thanks to everyone once again, this is sorted now I think. I've spoken to Charlie at CTM and will take the head down for him to look at this week hopefully. I have also managed to find a couple of 85mm Gaskets, for future reference the Payen No. is AH270. They can be found with a bit of diligence, though most reconditioners I've spoken to claim that an 87.5mm head gasket would be fine. However that just doesn't "sit right" with me so I'm pleased I've found some traditional gaskets in the correct size. Needless to say I bought a few lol. Now I just need to find the motivation to get on with the job!

Nigel F.
1970 S4SE/1760cc big valve/SA-AX block, L2s, 45DCOEs, 1978 Jensen GT, 1962 AH Sprite, Alfa-Romeo 159, 1966 Bristol Bus, 1947 AEC Regal bus.
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PostPost by: dougal9887 » Sun May 14, 2017 1:23 pm

I'm using a Cometic gasket without any problems (as yet!). 10.5:1 compression ratio. ARP studs.
Dougal.
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PostPost by: nigelrbfurness » Tue May 23, 2017 8:26 am

Just as a follow up to the head gasket problem and for interest, when I was cleaning the block surface I found that farthest bolt hole, inlet side number 4 cylinder, had a slight raised edge to it just at one side. I recall that the bolt in that hole felt tight as I undid it, however trying head bolts in it now the thread seems fine so I'm wondering if this ridge was there all the time and caused the gasket to fail by preventing the head from seating properly. Clearly, removal of said ridge is necessary but I am perplexed as to what caused it in the first place and why it was not noticed when the block was new in 1994. If the bolt had been over-tight to the point where the thread became stretched then it would be tight again now when I put a bolt in. This is only the second time the head has been off since the engine was built. The block surface is straight, no signs of warping.

Nigel F.
1970 S4SE/1760cc big valve/SA-AX block, L2s, 45DCOEs, 1978 Jensen GT, 1962 AH Sprite, Alfa-Romeo 159, 1966 Bristol Bus, 1947 AEC Regal bus.
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PostPost by: Plus2cabby » Tue May 23, 2017 9:12 pm

I have used CTM , and spent good money to rectify what they did.
Would not use again, indeed makes me shudder every time I see their advert in club lotus
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Mark
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