TEA 20 80 mm, change to 85 mm ?

doug larson · Nov 30, 2014

Hello,

In the process of overhauling a TEA 20 currently with 80 mm pistons. Any problem switching to 85 mm sleeves / pistons ? I thought I had seen earlier discussions on this, but can't seem to find the details.
Also, what company has the best source of quality overhaul parts in the US?

Thanks,

Doug

Charles in Aus. · Nov 30, 2014

Not too sure , but I think that the conversion requires the cylinder liner seats in the block to be machined to take the larger liners .

2tractors · Dec 1, 2014

Makes you wonder if you could bore to the 87mm.

doug larson · Dec 1, 2014

I

From a previous post that I found it looks like Bareco # EK 1 kit will work when going from 80 to 85mm.
Has anybody used this kit? And would anybody know who the Bareco dealer would be in the Midwest, USA?

Thanks.

Richard L · Dec 1, 2014

This may help you a little. For more precise info I suggest contacting John (UK) directly at his email enclosed.
Changing 80 to 85 mm engines

Charles in Aus. · Dec 1, 2014

(quoted from post at 13:53:30 12/01/14) Makes you wonder if you could bore to the 87mm.

There is a kit to do just that but it is made for the 85 mm model .

Bill Brox · Dec 11, 2014

This is also what I have heard in general about all 80 to 85 med mer Conversions. In addition Ferguson used to deliver a steel plate and an extra head gasket to reduce the compression since so much increase in cylinder volume will increase the compression signifcantly.
I also think Ferguson offered longer push rods for it, since the head came to a higher position.

Bill

Charles in Aus. · Dec 12, 2014

Bill , that steel plate and extra head gasket was for the Kerosene or TVO conversion to the petrol engine .
The plate increased volume but decreased compression so that the kerosene based fuel could burn a little better .
The 80mm to 85 mm conversion was also carried out when converting to this fuel .

Grandfatherjim · Dec 16, 2014

The Triumph TR3 engine started out with 83 mm pistons and it moved up to 87 when they introduced the TR4, so this is a common conversion and they [i:9c25e74eed]supposedly[/i:9c25e74eed] drop right in. If you can find out that they do, then to source them you can try The Roadster Factory, Victoria British, or Moss Motors, or possibly British Parts Northwest (and there are others). Since there is competition the prices are reasonable.

I don''t know about the seats being the same though. My guess is they are, but best to research.

Bill Brox · Dec 17, 2014

(quoted from post at 23:53:07 12/11/14) Bill , that steel plate and extra head gasket was for the Kerosene or TVO conversion to the petrol engine .
The plate increased volume but decreased compression so that the kerosene based fuel could burn a little better .
The 80mm to 85 mm conversion was also carried out when converting to this fuel .

Yes, you are so right, and I was equally wrong. Man, how could I forget that, I knew it. But anyway, I have done my homework this time, and the 80 mm engine has a 5.77:1 compressioni ratio, and given it has the cylinder volume it has, increasing it to 85 mm with the same headgasket and head it should give about 6.5:1 in compression ratio, and the 87 mm engine I think had to compression ratios, and the highest of those I think was 6.6 or something like that. So, I Guess 6.5:1 sounds like a healthy compression and it should give more than the standard 28.2 horsepower the 85 mm engine had from the factory.

I am sorry I had not done my homework in my first post.

Bareco should be able to answer if their kit needs a block machining or not. But, if you just buy new 85 mm sleeves for a standard 85 mm engine, and try to put them in the 80 mm block, then you need to machine the block.

Bill

TEA 20 80 mm, change to 85 mm ?

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