I'll leave the techy bits to Tim but gas flowing inproves the breathing still further - more efficient - more power. Rootes did an SU manifold on the Hunter range - it won't be as good as Tim's masterpiece for Harvey but it will do the job without chopping holes in the inner wing:I
This sounds like a a big advert for Tim:I but he can also modify your standard inlet manifold to take an SU.
Here's a Hunter engine with SU - but it might be an alloy head which has different porting and stud centres to yours.
Will, i have skimmed 2mm off without problems although you do have to slot the holes in the tappet cover afterwards
Standard heads/manifolds are not as good as they could be, so porting them makes them more efficient at getting things in and out, which = more torque/bhp/bmep, better B.S.F.C (more bhp per pint of fuel), improved economy and less thermal losses. Cooler running if the exhaust gasses get out faster and less pumping losses
Standard manifolds should be seperated from each other as the inlet gets way too much heat and power suffers.
S.U can be fitted on the STD manifold with a sidedraught conversion.
"You,re only supposed to blow the bloody SLIDING doors off"
Not sure if it's the same as mine but will need a few things from your Commer engine swapping over to make it go in. If it is an ally head engine then the exhaust will need a bit of fettling but easy enough. You will need to ditch that air filter as it doesn't look like it will fit in the engine bay but a nice K&N should do the job.