Anti blowback valve XK150

Unbolted the tube from the starting carb to the inlet manifold, as I removed it some parts fell out and not sure where they are on the garage floor now. So there is a 4 bolt flange and an o-ring on the tube and I found a part with prongs that seems to fit in the manifold recess, I think I’m missing a spring and maybe some other part because the tube no longer fits securely in the manifold. Having trouble finding a drawing of this assy; can anyone enlighten me please?

Hi Graham,

I have one of these early manifolds off the car, but with the oval plate still in place. When I get home I will carefully dismantle and see how it all fits together for you.

Hi Graham,
Photo 1 - my blowback valve in place on manifold.
Held in with studs; noted that there should be spacers used to cover the unthreaded area of the stud. Two of mine have been lost and the previous owner replaced with larger nuts. As such someone has been playing inside before me… (like the chromed manifold bling?)

Photo 2 - There is a black plastic ring in the right side hole, but this turned out to be just a plastic washer.

Photo 3 - Various nuts and bolts holding the cover in place… damaged plastic washer on right side, and a rubber O ring also fell out… Home-made gasket

Did not see anything like the pieces you showed in your photos… Sorry I couldn’t help

My XK150, S834632 has none of that anti-blowback stuff. Just a direct port in bottom of intake manlfold. One port for the hisser and one for the brake booster. Just like the photo above from Jon.

Thanks Jon for going to the effort of dismantling it to see what is inside. As you say someone has been there before you so although similar it doesn’t really represent what I seem to have. But thanks a lot for the effort.

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