Whilst it will almost certainly work, and not do any damage as such, it
*will* have different characteristics. The much higher resistance of the LA
12 primary could mean it is much finer wire, which will tend to limit HT
current and spark energy. Or it could be due to a much larger number of
turns which will give a higher potential (ho ho) HT voltage and greater
spark energy. It seems to have been used on many Brit cars like the 1098
Sprite, Mini, Reliants (for which both are quoted as suitable), Lotus
Europa. But a Jag XK120/140 site says not to use the shorter LA12 in place
of the HA12. This *may* be because with the shorter dwell time of the Jag
the LA12 loses spark energy at higher revs, but I'm only guessing.
Shouldn't be a problem on the MGB though. A Moggie 1000 site says the HA12
is a higher powered coil than the LA12. Do they both have the same primary
reading i.e. about 3 ohms?
PaulH.
----- Original Message -----
> MGA coil is supposed to be a Lucas HA 12 and I have a spare LA 12
available.
> Difference seems to be the hi tension ohm reading is 48K on the LA 12
versus
> 8K ohms on the HA 12.
>
> Are they interchangeable?
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