Inlet manifold

Whilst the carbs were being processed I removed the inlet manifold from the spare assemblage..

Manifold as fitted

Removing the manifold

Manifold detached

I set about cleaning the manifold and degreasing. The heat shield is pretty much beyond use but the manifold should clean up OK.- a bit of brass wheel work and it was looking a lot better.

... and cleaned.

There was the inevitable build up of corrosion around the base of the studs so I removed them with a stud extractor. I could then clean the studs properly in the wire wheel and assess the state of the manifold.

Stud removed from manifold- coarser thread goes into the manifold and the finer thread passes through the carb and is secured with a nut.

Distorted and warped manifolds seem to feature in the forum reports and these obviously lead to air leaks. I checked mine for flatness with a straight edge. Surprisingly it was pretty good- everywhere that is except around the stud holes. Here the tension on the studs had pulled the aluminium up into a slight rise before the stud base. I did try to photograph it, but its hard to hold the manifold, straight edge and camera at the same time so the light gap isn't that clear. Although it was on both sides, you can just see it on the left below...

 

If I had a milling machine or a fly cutter I could maybe re-flat the whole surface but since my problems seemed very localised and obviously explicable I simply removed the "humps" round the stud holes with a countersink to recess the holes. This is fine as long as you leave a lot of gasket around the countersink to seal, and in this case there was no danger of leakage.

Cleaned flanges- stud holes countersunk

 A final polish, including the heat insulators which also had the occasional lump and bump (removed with gasket scraper) and the manifold was ready for reassembly.

Everything clean and ready for reassembly.

 I used Loctite on the studs- not so much because they retain any fluid or even take much of a turning force but primarily to keep water out of the threads and hopefully reduce corrosion in future.

I used Loctite medium strength on the studs to try and keep water out of the threads.

I will fit a new fibre washer under the brass coolant plug when I reassemble this manifold onto the car. In the meantime I had cleaned the steady plate/cable guide plate and sprayed this with VHT heat resistant aluminium paint.