No need to pull the head, just remove a spark plug and measure the
length of the (threaded) spark plug hole - counting threads would work.
'Incorrectly machined' heads will have a longer threaded hole.
3000 MkI registrar
richard mayor wrote:
> Chris - and the rest of the guys. This is the first I have heard of this spark
> plug depth issue. This is now on my radar!! So, I walked around my shop
> tonight and checked a couple of engines. The AEC 960 is the casting/part
> number on my original 3000 engine (circa 1959). It is also the same casting #
> on my BJ8 cylinder head. I looked at one of my 100-6 heads and the casting #
> is AEC 721. As far as I know, the only real difference between the 100-6 and
> 300 heads was the boss where the water temp bulb screwed into - hence a
> different casting #. The chamber volume is the same.
> I think that what you have discovered is a factory machining issue. You
> should not compare a BN1 and Sprite head with the AEC960. That's apples and
> oranges. You need to compare a BJ8 head with an earlier AEC 960 head. Having
> said that, I am not about to pull the head off my BJ8 motor to make any
> Westlake designs have nothing to do with the spark plug depth. Westlake is
> only responsible for the heart shaped designed of the combustion chamber.
> I would really like to hear from others on the list that can confirm this
> spark plug depth issue, because I am pretty sure that the castings are the
> same - just different machining practices. Then again, I could be wrong.
> Richard Mayor
> BN7L-466 Vintage Racer
> Portland, Oregon
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