11 replies to this topic

[johnv]

I’m looking to replace a couple of exhaust valves on this head .. I measured them at 1.209 in 30.71mm but I can’t find them anywhere .. length 3.52in single groove collet .. where could I get these? Thanks

[nicklouse]

take them to your friendly engine builder and they will be able to supply and advise. ie replace them all and maybe replace guides and re cut seats. you may not be too far from Mr Dodd have a chat with him.

[Pigeonto]

That's got to be Mini Spares' AEG594 surely?

If they must be 30.71mm but come slightly bigger  it's no problem at all to make them smaller, what ever size you like but I think I'd leave them as are.

[ACDodd]

They are these, your ones have likely been cleaned a few times I there life and are now Little small.

https://www.minispar...|Back to search

Ac

[DeadSquare]

They are these, your ones have likely been cleaned a few times I there life and are now Little small.

https://www.minispar...|Back to search

Ac

Are those valves Nimonic?

[ACDodd]

Unlikely these will likely be plasma nitrided, which is better!

Ac

Edited by ACDodd, 18 November 2018 - 01:30 AM.

[johnv]

Thanks!

[johnv]

It is a 940 not a 163 though but I think it's quite an early one

[ACDodd]

Maybe it has thw wrong valves fitted, and it should have the normal 3.57" valves fitted.

Ac

[johnv]

They seem to fit I’ll try to post a pic

[carbon]

The shorter 'S' valves will fit in a 940 head, but be aware that the springs will go coil bound at lower lift.

 

If you're using high lift rockers or a radical cam profile then you will need to measure very carefully. If required the valve seats in a 940 head can be machined down to suit the shorter valves, but may you need to find a specialist machine shop for this.

[johnv]

Pics .. I measured the combustion chamber at 18cc .. this seems quite small? although with dished pistons it looks like I could achieve a 10:1 cr ok

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