600 EW induction pipe fitting

[geomellish]

Trying to sort out a overheating problem, I have removed the induction pipe from my 1926 600 - it seemed a bit loose and impossible to completely tighten and I wondered whether it was causing too lean a mixture.

I attach a photo - it seems to consist of a cork washer (into the cylinder head), a metal stepped ring and the union nut. It looks like previous owners have tried various gunks to seal it. I have a 1927 parts list, which looks a little different.

Does anyone know what the correct arrangement might be? Possibly the stepped ring is inverted? The parts list has a ' stud fixing pipe to crankcase' which mine does not have nor any trace of on the pipe or crankcase. I can't for the life of me work out what mechanically might be holding the induction pipe firmly clamped and in place.

Many thanks, George




[Attachments converted to linked images. 12Dec21 -Doug, Admin]

[eddie]

George,
            Could I suggest you replace the cork packing with a tight fitting Viton 'O' ring? I have used this method for the same application on a veteran 2¾ and it has proved very effective. Another likely place for a leak to occur is up inside the muff. The manifold tube inside the muff would have got virtually no protection from any plating, and after 90 years, could be suffering from pin holes.

 Regards,
               Eddie.

[geomellish]

Thanks Eddie, I will look into both. 

However I still can't really understand what is holding the inlet manifold to the cylinder head given that there is no  flange on the manifold...

[eddie]

George,
            Normally, the inlet manifold has one fixed flange and one floating flange. This makes it possible to remove the manifold without disturbing the cylinders - the end with the floating flange can be pushed fully into the port, then pulled back to engage the other inlet port. With the nut on the fixed end fully tightened, the other nut can be tightened until the packing forms a good seal. As I have said, this system makes removal easier and also makes allowance for any expansion as the engine warms up - from cold, the engine will expand as it warms up but the inlet manifold will shrink as it tends to freeze due to the partial vacuum formed within.

  Regards,
               Eddie.

[eddie]

George,
            From the illustrations I have, it seems there are some detail changes depending on the year. The early models look as if they have an alloy block cast around the junction in the manifold, whereas the '28 &'29 models look as if they have a plain tubular manifold - is it possible you have a mismatch of years for the engine and manifold? - this could be the reason you cannot find any means of support for the manifold.

  Regards,
                Eddie.

[geomellish]

Eddie,

A mismatch is possible. My engine number is EH337, fairly early 1927?  The jacketted manifold has straight pipes at each end, no flange.  The 'exhaust' outlet of the jacket is three holes, rather than a small pipe.

I attach photos of both to see if any further light can be shed...

Regards, George






[Attachments converted to linked images. 12Dec21 -Doug, Admin]

[Doug]

However I still can't really understand what is holding the inlet manifold to the cylinder head given that there is no  flange on the manifold...

It is just the compression of the packing material that holds the manifold in place. It actually tightens up quite rigid, yet still allows for some expansion and contraction.

You have the flange shown the correct way. The broad face of the flange is towards the packing and the shoulder passes through the gland nut. This helps keep the pipe centered in the gland nut. You could solder one flange and leave the other end loose as Eddie says. Or you could just leave both ends loose to allow more adjustment/centering when fitting. Once tightened, it is not going anywhere.

The jacketed manifold is interesting, lacking the exhaust 'tail pipe'. Not seen that before. My F28 has the type shown in the parts list. Unfortunately I am missing the pipes to and from the jacket, but in my local climate the absence is not significant. 

-Doug

[geomellish]

Thank you Doug and Eddie - I have secured the pipe much more satisfactorily using viton O rings, and copper crush washers at each end.  But overheating not yet cured...

[eddie]

George,
             It might be worth experimenting with larger tappet clearances - say 2 thou larger. Our modern unleaded fuel (I'll refrain from calling it petrol) tends to burn hotter than proper petrol, so it is likely the valves are expanding more, resulting in reduced clearance (which again makes an engine run even hotter).

  Regards,
                Eddie.