Thanks Harry
Wagon is supposed to take priority

we will see how the young fella goes.
Found this on the YT web site, might pop the head off and have a look
Cheers
Gazza
Iron Heads
iron cylinder head
The Holden Blue and Black cylinder 12 port style head forms a good basis for performance engine build ups however the factory version is unreliable and prone to cracking.
Yella Terra redesigned the Holden 12 port head with improved water flow and superior quality material to resist cracking in both mild and high stress applications.
The Yella Terra 12 port has a greatly improved port design over the original GM head, delivering a 35% flow increase over the stock head with significant scope for further flow improvement through individual hand porting by professional head shops.
All Yella Terra 12 port iron heads are fitted with valve seat inserts making them perfectly suited to unleaded or LP Gas fuels. The heads feature huge 1.740" intake and 1.550 exhaust valves and performance double valve springs.
There is a choice of standard 56cc combustion chamber size and a large volume 68cc 'turbo' chamber for low compression supercharged and turbo charged applications.
Member : Holden Car Club WA.
:ASRF Member
: Secretary FB/EK holden Club of WA.