Lotus Elan

Twin cam head

PostPost by: 74Twincam » Fri Jun 08, 2018 2:56 am

You bet-
I literally went round and round for years agonizing over trying to get my old head to work, but once I met Tony I finally got it sorted. He was recommended to me from a friend who required a head and a block for his formula car, and his experience was quite the same-top shelf.

Keep us posted, hope you get it back on the road again soon!
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PostPost by: vstibbard » Sun Jun 10, 2018 6:03 am

I've known the bloke who's working on Ken's head for over 30 years, he's been around Lotus cars for many years, owned Elan's and prepared very competitive Lotus Cortina's here in Australia, his background was a professional member of race teams here in Australia and NZ in 80's 90's. He knows his stuff, and is trying to help Ken out by not wasting good money after bad!

Ken's head is soft, the washers on the head bolts in one case had pulled that far into the head that it was lower then normal face, a number of the head bolts have serious rusting, the source it seems was within the head as the head gasket sealing did not indicated water passing, it was pressure tested due this issue initially NOT because of the washers/soft head. What the pressure test found is that one chamber has water pissing out of pin holes before its even up to temperature.

So rather than wasting Ken's money his first recommendations as find another serviceable head. Ken, you're in good hands, he's also trying to find head for you to avoid you spending 7K+ by time a new heads landed.

Vaughan

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PostPost by: reb53 » Sun Jun 10, 2018 6:31 am

About 5 years ago my son bought a, ( possibly), soft head and made inquiries as to whether or not it could be re-treated.
Below is the email he got from a local company.
Other projects took precedence and he never made use of their services, so I cannot vouch for them in any way whatsoever.
However, at the prices mentioned it'd have to be worth a try wouldn't it ?
Especially if the head is pretty much regarded as worthless.

Ralph.

"Yes we can do this, generally without too much drama. We have done plenty of lotus/ford twincams over the years and I don’t remember any major headaches with any of them.
You don’t necessarily need to remove all inserts etc, the most important thing is that any copper based metal parts must be removed. This would normally be parts like bronze valve guides, brass frost plugs, copper washers, etc.
If the seats and guides are steel or iron, they can stay in (check with a magnet if in doubt). If you do leave the seats in place then they will possibly fall out during the heat treat anyway. The guides normally stay put ok.

Heat treatment of aluminium castings is quite a severe process so it's not without some risk, however these are a reasonably robust casting and as I said earlier we have done plenty without issue.
The main concern with heat treating aluminium is distortion/bending. We take all precautions we can to minimise any distortion but there is still risk. From memory the Lotus TC has the cam tunnels machined directly into the head so this means you can't tolerate much distortion before significant machining will be required to reclaim it. Most commonly with a nice robust head like this you will get away with just a simple skim on the top and bottom faces and everything is good, but please consider in the worst case you may have to go to the extent of some type of straightening operation or possibly line boring the cam tunnels.

Cost will work out about $100.00 + freight + GST and it will take about 4 days.


Regards,
Adam Walmsley
Heat Treatment Quality Engineer
This email is covered by the Heat Treatments Ltd Disclaimer at:
http://www.heat-treat.co.nz/disclaimer.htm
Heat Treatments Limited
PO Box 57025
Owairaka
Auckland
New Zealand
http://www.heat-treat.co.nz
PH: 0064 9 621 0020 Ext.252
DDI: 0064 9 621 0432
FX: 0064 9 621 0019
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PostPost by: group5 » Sun Jun 10, 2018 6:55 am

Hi Ken

I am contemplating buying a new head for my newly purchased Elan +2 and if the old head is OK I would be willing to sell it. If you are interested my email address is [email protected]
I am in Western Australia.

Regards
Bevan

PS if the text " target="_blank appears after my email address ignore it.
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PostPost by: matevick » Sun Jun 10, 2018 7:46 am

Ralph
Thanks for the info, the whole thing is a mystery of opinions as what to do with a soft head.
and
Vaughan
I agree, I trust the guy who is working on my car totally and I know he will not steer me wrong.
Regards
Ken
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PostPost by: rgh0 » Sun Jun 10, 2018 9:37 am

vstibbard wrote:I've known the bloke who's working on Ken's head for over 30 years, he's been around Lotus cars for many years, owned Elan's and prepared very competitive Lotus Cortina's here in Australia, his background was a professional member of race teams here in Australia and NZ in 80's 90's. He knows his stuff, and is trying to help Ken out by not wasting good money after bad!

Ken's head is soft, the washers on the head bolts in one case had pulled that far into the head that it was lower then normal face, a number of the head bolts have serious rusting, the source it seems was within the head as the head gasket sealing did not indicated water passing, it was pressure tested due this issue initially NOT because of the washers/soft head. What the pressure test found is that one chamber has water pissing out of pin holes before its even up to temperature.

So rather than wasting Ken's money his first recommendations as find another serviceable head. Ken, you're in good hands, he's also trying to find head for you to avoid you spending 7K+ by time a new heads landed.

Vaughan

V


HI Vaughan
I agree based on that information its best to find a replacement second hand or new head. Personally I would would still get it hardness tested over the top and bottom surfaces to confirm it is generally to soft. I also hardness test any used head I get these days before buying it or doing any work on it to make sure I am not wasting my money or time

cheers
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PostPost by: Davidb » Sun Jun 10, 2018 7:10 pm

Is there a concern that with a 'soft head' the valve seats will drop out?
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PostPost by: Chrispy » Sun Jun 10, 2018 10:25 pm

Davidb wrote:Is there a concern that with a 'soft head' the valve seats will drop out?


I've never heard of that occurring before, I would expect distortion of the head resulting in blown out head gasket is the typical result.
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PostPost by: rgh0 » Sun Jun 10, 2018 10:48 pm

Chrispy wrote:
Davidb wrote:Is there a concern that with a 'soft head' the valve seats will drop out?


I've never heard of that occurring before, I would expect distortion of the head resulting in blown out head gasket is the typical result.



Loss of head bolt tension due to them sinking into the top of head is the main problem and this leads to the head gasket failing. The head gasket can also fail due to the fire ring sinking into the bottom surface of the head.

The interference fit of the valve seats and guides may also become loose with the head material creeping and this may cause them to move especially during an overheating event caused by the head gasket failing.

cheers
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PostPost by: 2cams70 » Mon Jun 11, 2018 12:58 pm

So what are the opinions about the suggestion of having the hardness restored by heat treating? From a bit of googling on that New Zealand company it can be seen that they are no backyard operation and that Adam Walmsley is no snake oil salesman.
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PostPost by: rgh0 » Mon Jun 11, 2018 1:05 pm

It certainly can be done as it basically repeats the original heat treatment after casting that dissipates overtime time with excessive temperatures in the alloy.

The issues like they say are potential distortion of the head. It probably should be bolted down to a couple of heavy steel plates top and bottom.

The guides and seat inserts will probably come loose and potentially move during the heat treatment so best to remove them and replace after heat treating.

I have a good Weber head that is a little to soft I would like to try it on one day

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PostPost by: 2cams70 » Mon Jun 11, 2018 1:21 pm

For $100 it seems to be a real bargain even including shipping costs (maybe they dropped off a 0). Most heads are likely to need new guides, seats, etc. and the added cost of the heat treatment still makes it an economic repair.
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PostPost by: 74Twincam » Mon Jun 11, 2018 11:45 pm

I'll second a few items mentioned above since I went through all the same steps when trying to sort my soft head (end eventually determining happily that a new one was worth it "to Me")-

Getting the head hardness tested first will allow you to quantify the heat treatment process, should you decide to do it. You would be able to compare before and after and then know for sure as to what you get for a result. I went with a local metallurgical test lab who was able to use certified equipment.

A torque plate is certainly recommended, as what you are doing is not entirely "heat treating" as you are quenching to restore the original temper of the aluminum. The aluminum has softened over repeated (over) heat cycling and soaking to the right temperature, then quenching, will provide the desired hardness. Using the torque plate will help minimize the potential for damage (warp) and also potentially minimize secondary machining required.

The difficulty for me when I was trying to do the same was finding a local shop to do the metallurgy correctly, and then to find a shop that had the capability to align bore the cam carriers. That smaller diameter and length was outside of most shops capability here in Colorado.

I found that after getting my head hardness tested, it was so soft that it didn't register on the lowest end of the scale and mine was determined to be too far gone for repair. If your are able to find a suitable repair, or used replacement, bravo! IF you find you are ultimately stuck, I stand by my recommendation for Tony Ingram. It may be worth the phone call to learn about the other options.

I certainly wish you luck on the repairs, it sounds like you have some solid mates there to help out and some qualified shops to rely upon.

Cheers!
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PostPost by: matevick » Mon Jun 18, 2018 5:38 am

To All,
To finish the story, unable to find a good used head so went with SAS in the UK.
Thanks for all the people who responded.
Ken
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PostPost by: 1owner69Elan » Mon Jun 18, 2018 8:03 pm

I think you will be quite pleased with the SAS head.

I didn't have a soft head problem but wanted to replace my original Stromberg head with a Weber one.

I ordered a "street ported" version from SAS in 2015. In conjunction with a stroked engine (1700cc), Weber 40's (not 45's), Tony Ingram recommended high lift/short duration cams, and all orchestrated by master builder Dave Vegher, the SAS head configuration produces a tractable street engine with 181 hp and a broad, flat torque curve (143 lb-ft) all below 7000 rpm (I posted a dyno curve earlier). These new heads with better machining, material, breathing, seem to more readily allow for higher performance.

As delivered:

img_5135.jpg and
img_5137.jpg and


In situ:

img_8846-2.jpg and



It took a few months to take delivery of the SAS head, as the street version is a "special order". As I understand it most of their heads are for race applications.
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