Two cylinder manifolds

[ian Howell]

By their shape shall ye know them.

Looking back over quite a long time, I notice that the 'bridge' type two-cylinder manifolds come in - what appears to me to be - a very wide variety of formats.

Some come up and then forward, some have front or top exits for the water, some have two or four stud fixing to the cylinders and so on.

Has anyone actually catalogued all the varieties? It seems to me this could be useful a) to identify disembodied engines that are attached to them, and b) to correctly identify replacements if the one in use becomes unserviceable (usually internal corrosion).

There would also need to be accompanying photos, so not a five minute job I fear.

Any volunteers?

[Dhbangham]

Don't get excited, I am not volunteering at the moment, but I would like to let everyone know that we should keep all manifolds, however corroded the they are. I believe it will be possible to repair them in the near future. I am investingating the idea of buying a piece of equipment that “cold fuses” aluminium. This will allow any aluminium casting to be repaired without heat distortion. It has become a main stream technique in the aero industry and a “tradesman” version is now on offer for about £5000. A big investement to repair one manifold, but good value if there are lots to repair and all the other aluminum castings we have on our cars.

[Tony Fearn]

I saw on 'Chasing Classic Cars' on the TV that Wayne Carini used a product called 'JB Weld' to fix a leaking petrol tank.
Perhaps there's an aluminium version.
Has anyone used it?
Tony.

[Dhbangham]

Yes, I have used alumnium filled epoxy resin (JBWeld) to repair my current manifold. From memory, this is process I used:

a) Cut a 5/8th BSW thread or appropriate thread for your car, into the water outlet hole of cast iron cylinder head.
b) Turned up a 3/4 inch length of PTFE plastic rod with 5/8th BSW (matching) thread at one end and as large a hole as possible down the middle
c) Screwed this PTFE tube into the cylinder head (approx 1/2 inch). Leaving 1/4 spigot exposed.
This PFTE tube coming out of the cylinderhead creates an electricaly non conductive break between the cast iron and aluminum, so reducing galvanic corrosion in the future. PTFE is a cheap easy to machine material that copes with high temperatures (it is also called non stick plastic)
d) Then I used a die grinder to cut back the corroded manifold to bear metal.
f) I then packed the manifold cavity with high temperature aluminum filled epoxy resin (JBweld) Using another length of 5/8th PTFE down the middle of the cavity to create a core hole. I did try and make sure that this core hole would line up with the spigot on the cylinder head.
g) When the resin had hardened, I removed the PTFE core from the manifold leaving a clear waterway.
h) Flattened off the excess resin to make the gasket surface flat.
i) made sure the spigot and core hole lined up. adjusted as needed
j) fitted new gasket and tightened up.
k) I have not removed the manifold since this repair 5 years ago.

PS. I wrote an article on cold spay technology in an earlier post.

[ian Howell]

Great! Thanks for that info.

I had assumed that corrosion was likely /possible between water and mixture passages but your explanation makes it clear tat the most likely point is the head / manifold junction and your ideas about the PTFE sleeving make perfect sense.

Did you need to clean the manifold down to bare metal or does the resin 'stick' to any reasonably clean and solid surfaces?

Thanks again . I bet others are watching with interest (or possibly amusement?!).

[Dhbangham]

I think grinding to clean metal is advisable. Galvanic corrosion is a fickle thing. Using stainless steel is often the worst choice. I also did my best to reduce the electrical conduction between the components by wrapping the threads with plumbers tape ( ptfe). Before installing the nuts. Thanks for your comments