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Any Lotus Twin Cam experts?


Scarface GTti
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These are the differences:

 

1) It has short camshafts. The end bearing cap before the half moon seals at the end of the head are not there. In fact there isn`t even the holes to bolt the end cap on if you wanted to.

2) The cast inlet trumpets are about an inch and a half longer.

3) It doesn`t have the cast "box" on the base of the end inlet trumpet that passes oil in and out of the head to the block.

 

This isn`t a butchered head, this is factory standard. Any help greatly appreciated.

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It's like the thread was made for you :D

 

This whole forum was made for me, wasn't it? :D I hassled you and Chismo enough about it!

 

Seriousy, though, if it was a V8 then I'd ba able to answer off the top of my head. The Twin Cam was bit before my time. Plenty of people still about that I can ask though.

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Digsy, now found out that it is a pre-production head. The rumour is that three were made and that was it. Confirmation of numbers made or any further info would be great. If there were only three, then i`ve found them. We have one, QED have one and a fella in California have one. it would be nice to know for sure.

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Glad to hear you are getting sorted out. Where did you turn up that information?

 

If only three were made it might be difficult for me to turn up anything as I would have to fins someone who actually worked on the project and could remember what went on. You must have a pretty good source of info already.

 

Are there any numbers or identification marks stamped or cast into the head?

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There is 7915 and WM9043. WM stands for William Mills who cast the Lotus heads.

This is some info someone given to me from an Elan forum:

 

"The absence of the Lotus part number that was also cast into the heads again suggests its an early development head before the Elan and its parts numbers were finalised.

 

Vegantune did at one time make twin cam heads for Caterham in 78/79 after Lotus stopped making them. The supply was negotiated between Lotus, Caterham and Vegantune, William Mills cast 50 heads but could do no more due to lack of capacity. The foundrys Vegantune tried after William Mills were not available to do the casting did not make many successful heads due to porosity ( see page 201 of Wilkins book) and the program stopped."

 

QED are the source of the other information that i have found out.

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"The absence of the Lotus part number that was also cast into the heads again suggests its an early development head before the Elan and its parts numbers were finalised.

Definately nothing that looks like a Lotus part number on there, but I'd take the above statement with a pinch of sale because we usually put numbers on major castings like the head and block right from the prototype stage. I suppose it's possible though.

 

Anyway, I'll do some digging when I get back to the office.

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Right. Here's the word from my man who knows about these things:

"It's not an early head from the first days of the Twincam, it appears to be an early "mark 2" or "sandcast" head which would date it from about 1967 or thereabouts. A photo from the inlet port side and or the rear of the head would allow me to confirm this. William Mills was the foundry which cast the mark 2 heads, the mark 1 heads were die cast by Birmal. The missing rear cap studs are interesting, but the provision of the cast features as on "normal" heads suggests the machining op was simply omitted, possibly as an experiment to see if the rear caps were necessary, although that said it would have been much easier to use a std machined head without the caps fitted.... The head normally has a number stamped on the rear face, below the core plug. The number for a series production head destined for a Lotus normally starts LP, Cortina and Escort heads often had no number. Are the caps numbered? Normally they would have a one or two letter code (also stamped on the machined gasket face of the head to link the caps to the head as a machined set) and then numbers 1 through to 10 with adjacent stamps on the head to control position. If this head was machined as a test I would guess they would be numbered 1 to 8. It could be an experimental head cast before the introduction of the mark 2 head I guess, but it would be hard to prove, and probably not of any additional value over a std head of similar condition.

The block looks like a std 6015 round cap block from the mid sixties, which would tie in with the date for the head. Does it have a large L cast inbetween the engine mount bolt holes on the other side? If so it is a Lotus block, if not it's origins are rather more Dagenham orientated. Is the flywheel held onto the crank with 4 or six bolts?"

Oh, and I have to slap you for resting the head upside down on the valve stems too :D

Hope this helps. If you can take extra piccies where he suggests he'd be more than happy to add some more details.

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Cool.

 

I bumped into the guy in the corridor again today and he asked me how you were getting on. He seems to be well up for helping you out in identifying the lump.

 

I'm going to be out of the office for the next two weeks (back again on 28th Jan) so you have plenty of time to get more info collected. Of course if you can post it up before the end of the week I'll send it right along.

 

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To be honest it would be much easier for me if you could post them up on the web like you did before. You can't e-mail them to me at work because of our over-zealous spam filter, and if you e-mail them to me at home then I just have to e-mail them into myself at work and I run into the same problem.

 

If you post them on the web I can download them straight onto my work PC wthout any issues.

 

Cheers,

 

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