Is it possible to machine a normal head to super spec?

58A - 71E · Post by **58A - 71E** » Mon Dec 07, 2009 10:16 pm

Anyone know and what is entailed?

Had a quick read of the Harry Pellow book ABC and 912s and think the only difference is the intake ports - can anyone confirm and what the difference actually is? (1957.5- 1963 heads - the Late A early B heads)

Thanks

john fletcher · Post by **john fletcher** » Tue Dec 08, 2009 12:35 pm

James,
They are the same. The higher compression was achieved with different pistons. Cam is also different.
John

58A - 71E · Post by **58A - 71E** » Tue Dec 08, 2009 2:02 pm

Hi John
Pellow suggests oval intake became circular with Super head - and that manifolds are different diameter for fitting with Super Zeniths?

john fletcher · Post by **john fletcher** » Tue Dec 08, 2009 7:02 pm

Hi James,
The Parts List just shows just one manifold for the Normal and Super but two Zeniths, PO3 for N and PO2 for S. Jets were also different but the main difference was the venturi increased from 24mm to 28mm.
However you can never be absolutely sure unless you have the parts on view.
John

cubist · Post by **cubist** » Tue Dec 08, 2009 8:05 pm

A bit of match-porting will go a long way to improving what you can get out of the std heads. You could go to the cost of machining for bigger valves?

Dakota · Post by **Dakota** » Thu Dec 10, 2009 9:04 pm

Hi
as already stated I believe the heads are the same , the later ones have a pair of webs cast into the valve chest , I think your mild confusion is over the C inlet manifolds that flare out internally to mate up with the larger ports they used in the heads (this is the opposite to convention which has the inlet tract tapering down to the valve to keep the mixture speed up) The C and SC had the same port size and as for the inlet manifolds employed for C's to me they look the same as the earlier ones from the outside and I think they are the same castings. Super Zeniths have different jets and larger bore chokes but the basic carb is the same oh and weirdly unimogs used those Zeniths too..