6-port head casting numbers?

[Steve P.]

Howdy fellow LBC fanatics,
I'm digging through a rather large pile of Healey parts trying to sort out things
to keep and things to sell. Does anyone know if there is any difference between
heads with different casting numbers on 6-port heads? Three heads I have
are AEC 960 and one is AEC 721. I can't see a difference but that doesn't mean there
isn't one. Thanks!
Steve :eagerness:

 

[red57]

The 721 is an early head without the cast area where the sensor for the electric choke/carb goes on some models - the 960 has this cast area, but if the car wasn't equipped with the electric choke carb set-up it is just flat on top & if it was equipped with the electric choke there will be a hole for the sensor and three tapped hols for the screws. Infinately easier to install the temp gauge capillary bulb on the earlier 721 without the cast area for the electric choke sensor. I don't know if there are any other differences.
Dave

 

[johnea]

On the 721 the spark plug sits flush in the combustion chamber. On the 960 the thread is deeper and that makes the spark plug recessed.

 

[BoyRacer]

The 721 head is a 100-6 head. The 960 is a 3000 head.

 

[kozelding]

So in my case, someone installed that 100-6 head onto a (29D) 3000 block. The engine _seems_ to run great with plenty of power, et cetera -- are there disadvantages (other than orginality) to this set-up?


I assume the 960 head was supposed to be an improvement of some sort....

 

[andrea]

I have installed on my 100 6 the (960) BJ8 head - I can confirm recessed spark with completely threaded hole ,
(For this reason I have find a long nose spark https://picasaweb.google.com/112770819864514987162/AHWORKSAndUPGRADEProject#6148861087075257842
BUT ALSO NGK LFR5A or LFR6 A_B_C can be used)
and a probably increase of compression ratio. my car love the 100 octanes fuel. otherwise dieseling at the cut off

 

[Steve P.]

Thanks for everyones insights into this!
Steve