If somebody could measure the secondary resistance on an MGA HA12 coil it
would be interesting to compare.
Turns out the Lucas coil which I thought was an HA12 is actually a smaller
diameter LP12. It along with an assortment of 5 spare generics reads under 4
ohms primary and under 10K secondary. The LA12 I'm looking at using is 3.8
ohms primary and 48K secondary.
Thanks to Paul, I now know where the LA12 originally came from - a friend's
1098 sprite - and since they are listed interchangeable for 1 liter motors,
it should be OK on the 1600.
Mike
----- Original Message -----
From: "Paul Hunt" <paul.hunt1@blueyonder.co.uk>
To: "Mike L" <renoman@sympatico.ca>; "mgs" <mgs@autox.team.net>
Sent: Tuesday, September 20, 2005 10:01 AM
Subject: Re: coils
> 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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