Exhaust manifold work
Finally got some time to look at one of the things that’s been annoying me for a while on my car – the pretty badly made exhaust manifold (or headers in US-speak).
The Spitfire is running a 4 into 1 tubular manifold, this may actually not be the best choice for a 1500 engine but it came with the engine and it’s all I have at the moment. I did have a 4-2-1 version, but I’ve moved house and garage a few times and it seems to have gone AWOL.
I plan to get another 4-2-1 and test them out back to back on a rolling road some day.
Anyway, the main thing that annoys me about this manifold is its construction. You can see from the below photo (hopefully) that the pipe has been fitted inside the manifold face and then welded round the outside, it’s strong but leaves a huge lip restricting airflow.
Lip obstructing exhaust gas flow
I started cleaning this up with a carbide cutting tool and cartridge rolls on a Dremel. Here it is after a few minutes, the freshly cut away parts make it clearer to see the problem.
Starting to cut away the excess material
After a couple of hours grinding and cutting it looks much more reasonable, it’s still not finished but I think another hour or so making it perfect and I’ll move onto the remaining 3. I also plan to reface the mating surface and generally clean up the rest of the pipe.
Once all that’s done I need to find a better way of fitting and removing it, there’s not really enough space for a 4 into 1 manifold on a right hand drive spitfire and to say it’s a bit of a job getting it on and off would be a huge understatement!
