Austin Healey 3000- head configuration

[ajayjayalath]

Hi everyone, I am just curious and wondering what the correct casting number for a 62 BT7 - tricarb cylinder head should be. It is my understanding that the casting number on the block should read AEC 881 as opposed to AEC 335.

I have two cylinder heads, one with a casting number of AEC 721 and another AEC 960. To my understanding the AEC 721 corresponds to the 100-6 model.

What are the common differences of the two cylinder heads?

Some additional information would be of great help.

Thank you,

Ajay

 

[Healey Nut]

My 62 Tri-carb with side shift has the AEC881 block and all the numbers were confirmed by my BMHIT certificate .

 

[John Turney]

My understanding (FWIW) is that AEC 721 heads were those before the thermo-electric choke was added (July 1959), and the AEC 960 is for those heads and after. July 1959 is early 3000 timeframe.

 

[BoyRacer]

AEC 721 are 100-6 heads. AEC 960 are 3000 heads. I believe the combustion chamber volume, valve sizes, etc. are identical. The only differences are minor changes around the boss where the water temp bulb screws in and the drilling for the thermo electric choke in 1959.

 

[ajayjayalath]

Thanks everyone, much appreciated!

 

[donnercm]

Do you have a need for your 721 head? I have a 100-6 and recently had to replace the 721 due to a bad valve guide bore with a 960 due to availability, PM me if you are interested in selling it.

 

[Patrick67BJ8]

AEC 721 are 100-6 heads. AEC 960 are 3000 heads. I believe the combustion chamber volume, valve sizes, etc. are identical. The only differences are minor changes around the boss where the water temp bulb screws in and the drilling for the thermo electric choke in 1959.

The sparkplug hole is different.

 

[dcarlg]

Do BT7 tri carbs and BJ8's share the same cylinder head and block?
Thanks, Douglas

 

[BoyRacer]

Patrick, Please explain about the spark plug hole difference.

 

[dougie]

Patrick, Please explain about the spark plug hole difference.

Richard this might be helpful: https://www.myaustinhealey.com/aec960-healey-cylinder-head.html

 

[steveg]

Andrea on this forum has been using extra-long reach NGK LFR5 & 6 plugs. The threads protrude into the 960 combustion chamber by 1/8" which I have measured on a friend's spare head.
Having some extras, I made one into a cheapo tap for cleaning the carbon out of the last few threads.
Picture shows this as well as the two .060" index washers required for the exact reach.