Loctiting valve chests

[ivanj]

On my drawings it specifies Loctite to fix the valve chests into the cylinder castings. Now I know that there is high temp Loctite but it is quite expensive. Has anyone used the standard 603 for this job?

The steam tables suggest that the temperature of steam at 80 psi is about 160 deg C which is close to the limit for 603.

Is this a good way to fix valve chests anyway?

Ivan

[spurley]

Hi Ivan

What type of engine are you building? I am not too sure why Loctite would be needed if the valve chests are bolted or held on by studs. It may be that the designer has opted to use it as a sealant but then better and more 'user friendly' mediums are available. Unless the engine is designed for very high speed operation and hence possible vibration I cannot see why Loctite is specified.

Are you sure it is not just for the fixings?

Cheers

Brian

[baggo]

Hi Ivan,

I presume we are talking piston valve cylinders? The 'usual' way of fitting the valve chest/liners is to make them a light press fit in the cylinder casting and then put a couple of grub screws from the back of the cylinder just to prevent any possible movement. They only need to be tight enough to prevent any steam leakage. Martin Evans used to recommend making the liners in two or even three parts to make the job easier. The liners can be made in one piece but you have to be careful not to make them too tight, otherwise they may crush where the ports are cut when they are pressed in.

There's no objection to using Loctite but as you suggest, it will have to be able to withstand the temperature. You could always put the grub screws in as before which will prevent any movement if the Loctite softens. The only problem I can forsee (and it would be bound to happen to me!) is that the Loctite may go off before you get the liner in all the way! Having a generous clearance and perhaps chilling the parts would help, as would making the liners in two parts fitted from each end.

John

[Shawki Shlemon]

I do not know why you need loctite for valve chest ,slide valves or piston type . but loctite no 630 or later equivalent stands temperatures up to 230 degrees C . I use it for securing piston rods to pistons .

[districtgrandmaste]

I've just noticed this thread so maybe I'm too late but I think the designer was specifing Loctite gasket sealer. I have had a bottle for ages and smear the gunge onto steam chests and cylinder covers. It's so much easier than hallite gaskets that clever people use! The only trouble is getting it off if you need to get inside the chest later!