Porting the intake manifold
Today I opened out the ports on the intake manifold to match the heads. To do this I first checked that the gasket matched the heads, which it did. I then used the gasket as a template on the intake manifold and scribed inside the gasket openings.
I then used a powerfile with a carborundum band and various files to open out to the scribe line and blend back into the port. An example below:
I am pleased with the results and it took only a couple of hours though especially in this weather its a sweaty job! The finished manifold.
Bleeding the intake manifold
I then had to make the bleed vents for the rear end of the manifold. I think I explained this before but it's to let trapped air out at the end of the heads. The water system flows up to the rear of the block on each side and then back through each head separately (as there is no cross-over waterway on the Performer RPM manifold) , if there is air trapped at the rear it can cause overheating, this is especially likely on a GTD because the engine is angled down with its rear in the air - air caught at the back has nowhere to go. The bleed allows it to escape to the header tank.
I checked the actual position of the waterway on the head (there is one both ends because not only do some manifolds support a rear cross-over but the heads are symmetrical so they can be fitted either side) and marked it on the gasket. I transferred this to the manifold and drilled the holes to take a 3/8 UNF tap size. I am going to use -3 bore hose fittings.
I then had to go round to my neighbour to use his mill. The outside of the manifold has a patina finish (intentional) and would not be a good seal on a crush washer. I milled the are round the hole on both sides and fitted the 'bulkhead' adaptors. For good measure I used PTFE tape on the threads.
I then made up the hoses in a T form to allow one hose to go back to the header tank, I will have to make the final hose after engine installation as its difficult to estimate the length needed and it mustn't kink downwards at any point but just have gentle climb.
The problem with the baffle in one of the valve covers is solved in my mind, I shall use some high strength epoxy resin (Super Steel) which will stop the rattle, the plate is never going to come off - this avoids me wrecking the whole baffle in efforts to remove it!