Lotus Elan

Twin Cam Head dissection

PostPost by: Certified Lotus » Fri Jan 29, 2016 2:53 pm

A couple of months ago I started a topic on the water cooling and oil passage ways of the Lotus Twin Cam head.
(lotus-twincam-f39/section-view-cut-away-drawing-head-t35733.html#p244188)

Several individuals had some interesting information consisting of a photocopy of a head cut away (Rohan) and an actual twin cam head that was cut to show the casting details (Nick). Those examples raised more questions and once I realized the aluminum head cutaway was a new casting I recognized I needed to find a way to slice apart an older cast head.

So the search began for a used head that I could cut apart. Nick Stagg (AVRO) from the UK kindly offered one of his for shipping costs only. Once I received it the next plan was where to cut it.

image.jpeg and
Twin cam head

image.jpeg and
Twin cam head side view


Deciding where I wanted to cut the head to show the water cooling passages and oil passages took a bit of thought, but then it was off to my local machine shop to get the milling done.

image.jpeg and
CNC machine milling

image.jpeg and
Another pass on CNC


Now I need to bead blast the machined parts and photograph them. Stay tuned for an update!
Glen
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PostPost by: Certified Lotus » Sat Jan 30, 2016 10:45 pm

This "project" of having a dissected twin cam head is not a high priority for me as I'm in the midst of rebuilding an S4 and I'm the Co-Chairman of LOG36 in Princeton (August 5 to 7, 2016) in addition to holding down my real full time job, but I do try to stay involved in my side projects that are Lotus related :mrgreen:

Early this morning I brought out the twin cam head pieces I had cut and machined looking at them from various angles and thinking about what I was going to do next, developing a plan in my head about the finished result.

Couple of main items; need to file down all the cut edges as they are razor sharp, will media blast the entire head to clean it to a nice finish, will install valves and springs in a couple of areas, paint the water jacket and oil ways a contrasting color to show those areas as a highlight.

Anyway, its a work in progress. Here are a few shots of the stage the pieces are in at the moment.

dsc07634.jpg and
TC Head sliced but not apart

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TC Head divided

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TC Head Section view 1

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TC Head Section view 2

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TC Head Section view 3

dsc07639.jpg and
TC Head Section view 4

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TC Head Section View 5

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TC Head Section View 6


Will update when I Find the time to media blast it, When I can fit it into my schedule!
Last edited by Certified Lotus on Thu Feb 04, 2016 12:37 pm, edited 3 times in total.
Glen
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65 Elan S2 - 26/4055
72 Europa - 74/2358R
69 Elan S4 - 45/7941
64 Elan S1 - 26/0379
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PostPost by: rgh0 » Sat Jan 30, 2016 11:00 pm

Great work. Some more straight on shots of each section with a tape measure against them for dimensions would be good when you have the time.

Incidentally do you know why the head was scrapped? It does not look excessively soft or corroded

cheers
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PostPost by: Certified Lotus » Sat Jan 30, 2016 11:41 pm

Thanks Rohan. Will absolutely show a scale in the final photos for reference. The head was skimmed one too many times, that is why it was scrapped.
Glen
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72 Europa - 74/2358R
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PostPost by: rgh0 » Sat Jan 30, 2016 11:44 pm

How thick was the head? The first photo appears to show around 4 and 9/16 inch ( corrected my typo)

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Rohan
Last edited by rgh0 on Sun Jan 31, 2016 9:27 am, edited 1 time in total.
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PostPost by: gjz30075 » Sun Jan 31, 2016 12:10 am

I see someone entering the LOG artwork contest :-)
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PostPost by: Mick6186 » Sun Jan 31, 2016 8:55 am

Rohan,
One of us should have gone to specsavers. Looks like 4.5 to me!
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PostPost by: rgh0 » Sun Jan 31, 2016 9:26 am

Problem is Fat Finger Disease rather than my eyes this time :lol:

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PostPost by: Bud English » Sun Jan 31, 2016 4:49 pm

...and the tolerance on a tape measure is plus or minus a furlong per fortnight. :lol:
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PostPost by: Certified Lotus » Mon Feb 15, 2016 7:49 pm

Its a holiday here in the States (Presidents Day) and its snowing. I had a spare hour or so this morning so I got the media blaster pressurized and cleaned up the TC dissected head a bit.

Thought about how I want to configure the head for a static display and decided it would be cool to have some valves, valve guides, springs and retainers in the head. I have old intake and exhaust valves, but I didn't save the springs and retainers from my rebuilt engine.

Anyone have two pairs of old valve springs, retainers and clips they don't want? If so I would be grateful if you could mail them to me ;-)

Some photos of todays work:
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dsc07741.jpg and

dsc07742.jpg and

dsc07743.jpg and

dsc07744.jpg and

dsc07745.jpg and

dsc07746.jpg and

dsc07747.jpg and


The reason the head was scraped is as stated by Nick: "If my memory is correct it had suffered frost damage. If you look at the rear waterways on the head face and the back face it had been welded. When heads freeze this is one of the places they usually crack. The head also had its cam caps missing and had the head face machined a little more than I felt acceptable. Perhaps some might think it worth repairing but it would have been expensive and having frozen there would have been doubts about its long term reliability".
Glen
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PostPost by: Certified Lotus » Sat Apr 23, 2016 7:49 pm

I found a spare couple of hours to work on my dissected head. Did a more thorough media blast of the entire head and then installed a pair of intake and exhaust valves, springs and keepers as well as a pair of spark plugs. It's starting to take shape in the way that I want it. I'm thinking I should add another pair of valves to complete the one side of the head. Then I will prime the water way jacket for prep of the final color.
image.jpeg and

image.jpeg and

image.jpeg and
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65 Elan S2 - 26/4055
72 Europa - 74/2358R
69 Elan S4 - 45/7941
64 Elan S1 - 26/0379
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07 Exige S - Wicked Road/Track Car
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PostPost by: adigra » Sat Apr 23, 2016 7:57 pm

Really love this. Fantastic effort and it will make a great display. If I may suggest, adding half a camshaft to one side would be pretty interesting, especially if set so it's opening the valves, so you really get the idea of how it works.
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PostPost by: Certified Lotus » Sun Apr 24, 2016 1:30 am

Adigra, glad you like my project. You have a good idea, but unfortunately I don't have a cam to cut or the bearings and caps. If someone wants to donate to my project I would greatly appreciate it. Would also like a weber carb to deconstruct and attach to the head. If anyone has one to donate :D
Glen
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65 Elan S2 - 26/4055
72 Europa - 74/2358R
69 Elan S4 - 45/7941
64 Elan S1 - 26/0379
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PostPost by: Certified Lotus » Tue May 03, 2016 12:41 pm

I'm at the stage where I've started to primer coat the water way passages in the head. The big question is do I paint these blue or red? I've looked up a number of engine cutaway's and it looks like blue is the color of choice. I'm wondering what others on this forum suggest?
image.jpeg and
Twin Cam head cutaway
Glen
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65 Elan S2 - 26/4055
72 Europa - 74/2358R
69 Elan S4 - 45/7941
64 Elan S1 - 26/0379
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PostPost by: pharriso » Tue May 03, 2016 12:51 pm

Certified Lotus wrote:I'm at the stage where I've started to primer coat the water way passages in the head. The big question is do I paint these blue or red? I've looked up a number of engine cutaway's and it looks like blue is the color of choice. I'm wondering what others on this forum suggest?
image.jpeg


I would suggest Blue for waterways & a different color (Red?) for Oilways
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