Javelin/Jupiter Internal Balance Pipe

[Mike Allfrey]

Good Evening All,

Has anyone tried machining an aluminium internal carburettor balance pipe? This question has arisen because most internal balance pipe connectors, Part Number 50628, that are now encountered are damaged through mutilation or rust. It could be that an internal balance pipe machined from aluminium would expand, during warm up, at the same rate as the crankcase set. It could have a better fit at the sealing 'O' rings and, maybe, be easier to dent for crankshaft web clearance.

Part of my idle pondering during COVID-19 restrictions, which in Melbourne have eased somewhat.

Stay well,

Mike A.

[Forumadmin]

I think the answer is probably 'No' . I would also think that worldwide there are sufficient good originals.

[Srenner]

Interesting thought to use aluminum and for the right reasons, but I have at least 6 spare steel ones in excellent condition.

[Keith Clements]

Rather than turning aly you could use pipe and swage the hump.
The right alloy should be used to prevent fracture especially if it has to be formed to miss the crank.

[David Kemp]

How would you replace the pipe? They look fixed in to me.

[PJGD]

The internal induction balance pipe is a ⅝" diameter steel tube, 5 ⅝" long with swaged ends that is trapped between the two halves of the crankcase during assembly, and with o-seals at either end. It is seen in the center of this Jowett partial cross-section drawing of the engine. Installing this item so that it is leak-free is essential, otherwise the engine has to come apart again.

Induction Balance Pipe Installation.png

[Mike Allfrey]

Thanks Folks.

As I said, idle ponderings. However, it is my belief that the original seals were square section rings, not the more common 'O' rings used now. That could make assembly easier, with the connecting pipe having the rings mounted on the pipe prior to assembly. I wonder how the factory assembled these components? I seem to remember that, back in 1963, the Payen gasket set contained square section rubber rings.

Most of the connector pipes that I have come across have been brutally savaged with sharp jawed pliers. I have repaired a couple with silver solder.

On the engine being worked on at present, I intend to, with an artist's fine brush, apply Loctite 569 at the balance pipe where the balance pipes fit into the crankcase halves. This is because the 569 wicks-in between the pipe and the aluminium. The reason for this action is because the head gasket surfaces of the crankcase have been machined, thus losing the pipes' flared protrusion.

This machining is a bit alarming because the liners do not require spacer washers, just shims to achieve suitable protrusion, It is my intention to use the latest New Zealand head gaskets (the thicker ones) with 0.010-in. liner protrusion, with 14 lb. ft. applied at a bare cylinder head. So far, two head gaskets have failed at 0.008-in. protrusion, and I have no desire to go there yet again!

All the best, and stay well,

Mike A.