1971 A65 OIF - Thunderbolt or Lightning head?

[adriancw]

Hopefully a quick question for the experts...   Sorry if this has been asked before - I cannot find a posting but did a search...

I was thinking it might be nice to have a single carb on an 1971 A65 OIF.   But it seems the part number is different for this than from earlier years of Thunderbolt (heads with a single carb).

I seem to recall reading that the studs in the later model head are bigger... Or maybe a different length, on the later 1971 - 1972 (final) A65 models heads, the Lightning, Firebird Scrambler and Thunderbolt - is that correct?

I guess I'm asking: Is there a reason that it is NOT possible to install an earlier model head from a Thunderbolt to a 1971/1972 Lightning?

Cheers,  Adrian

[idie]

The Thunderbolt head will fit the Lightning. You will need to bore the bolt holes to the larger size. Easy to do as the head is alloy. You will need the earlier rocker cover as the finned one  has wider spacing. When I did my friends Lightning we used one of the pair of carbs, rejetting to suit. It ran very well.

[JulianS]

Remember that the 1971/72 oil in frame models use the rocker cover as mounting for the engine head steady. The OIF item has extra ribbing inside to strengthen it and an extra threaded boss to take the 5/16 UNF fixing bolts.

If you use the earlier rocker cover you will need to consider how to mount the head steady.

[idie]

It so long ago that I did the head That I cannot remember how I fitted the head steady. I know I made one up that fitted as the pre-oil in frame type to under the front of the head but where I fitted the other end escapes me. My friend sold the bike last year so I cannot look at it.