Hi all,my 66 Hornet has a single carb head on, it runs fine, it was like that when bought.I am thinking of changing to a twin carb head, I believe the correct part number for 66 is 68-700, could anyone tell me if a head with the number 68-701 would fit ,or are all A65 heads interchangable, looking to buy one , many thanks Gordon.
Hi Gordon, the casting number is always 1 digit out, so the 68-701 casting number is the same
As the 68-700 parts book number (the finished part number).
Hi Gordon,
For 1966 Hornet you need part number 68-834, twin carb head , also fitted to the Lightning. You probably have part number 68-704, single carb Thunderbolt head. I believe the head used in 1967 is okay.
The heads for other years are not readily interchangeable. As the years progressed: the two smaller diameter rear cylinder head bolts changed to match the front (there is a machining solution). The rocker cover studs and gasket profile changed, you need a matching rocker cover. The head steady moved to the rocker cover.
With a will to change to other years it can be done but be prepared for some issues.
Best wishes...
All the casting numbers for these heads are 68-701 although I believe the ones used on the later spitfire are different.
I've attached an image from the 66 parts manual, the later part number is 68-834 but as I say this is the finished number and not the number on the casting. The change between these two numbers might just be the change from 5/16 to 3/8 studs but this isn't a difficult job to alter successfully.
Rocker cover for ANY head beginning 68- will all fit each other whether they be finned or otherwise, OIF heads began 71- and do require a different rocker box.
Thankyou