Intake plug connection

[AntietamClassicCycle]

#8 on Table 2A of the workshop manual. The stub that threads into the head, rubber manifold elbow clamps onto it. How is this supposed to be secured into the head? Any sort of thread locker or sealant? Mine will turn (along with the manifold and carburetor) once the engine is up to full operating temperature.

[72degrees]

They can be inclined to work loose. Not that easy to tighten them well with just the two 'notches' to work with (once the rubber elbow is off).

A drop of Loctite and getting a bit brutal with a hammer and drift to snug it up eventually worked.

[EVguru]

I've only ever had this problem with the early cast manifolds coming, or where the early type have been converted to the latter stubs.

If the stubs are coming loose with the engine hot, then the obvious suggestion is to tighten them in that condition!

I would make a proper tightening tool. Easy for me with my facilities, but I can suggest something that should be possible for most people.
Take a cheap socket and cut a pair of notches to hold a piece of key (square) stock that fits the tightening slots.

Threadlocker can be used, but make sure it's rated for the temperature it's likely to see in a cylinder head application.

[AntietamClassicCycle]

I've only ever had this problem with the early cast manifolds coming, or where the early type have been converted to the latter stubs.

If the stubs are coming loose with the engine hot, then the obvious suggestion is to tighten them in that condition!

I would make a proper tightening tool. Easy for me with my facilities, but I can suggest something that should be possible for most people.
Take a cheap socket and cut a pair of notches to hold a piece of key (square) stock that fits the tightening slots.

Threadlocker can be used, but make sure it's rated for the temperature it's likely to see in a cylinder head application.

I agree they need to be tightened with the engine at operating temp, but that's easier said than done. Will endeavor to do it that way though.

I had the same idea for a tightening tool, easy to do here at the shop.

Loctite 272 should suffice - it's for threaded fasteners up to 1.5" in diameter and temps up to 450 degrees F.

Thanks!

[72degrees]

I've only ever had this problem with the early cast manifolds coming, or where the early type have been converted to the latter stubs.

That makes sense. Mine ('76 heads) definitely has converted stubs. I had a bit of trouble with it after pinching a head from the spare '77 Strada engine under the bench (a quick fix for a stripped exhaust thread) and converting that to a stub suitable for the PHBH28. It started to work loose on the Dijon trip but got me home when I resorted to thread lock and percussive maintenance. It hasn't shifted since.