Ken:
Someone out there please double check me, cos I've got a 5pm
deadline and can't spend any more time on this.
The records I have show the 40897 dizzy as being original fitment on
62-67 MGB definitely not for the 74 cars you have. Lucas shows a 41288 unit
as the superceded replacement. The first 5 digits give the part number, the
suffix is not used for identification.
Any unit with the same 5 digits should be identical, given the
vagaries of production line, later modification and divine intervention.
Based on dubious years of swapping bits, I'm banking that both your
engines got dizzy swaps from the original rare bird 41491 to the much more
available earlier unit.
If you get me the part numbers off the vacuum advance units which
may be 54411230 with the following legend 5.13.10 underneath I can be of
more use.
The problem is what carbies are you using? HIFies, or HS?
It sounds like you may have a common case of mix and match, and you are
asking the right questions to figure out what combination will work the
best. First we gotta figger what you really have.
all the best
Kelvin.
> I've written before about our engine rebuild session
> currently going on.
> I'm rebuilding an engine for my 74 MGB. I also have a 74 MGB
> parts car.
> The two cars are less than 1000 apart in serial number, with
> what I believe
> to be original engines. Looking at the 2 distributors, they
> are both 40897,
> 25D4 distributors. I took them apart to clean then and find one has a
> letter A and one has the letter E (I think) after the 40897. Looking
> further one has 10 degrees on the centrifugal advance and the
> other has 16
> degrees. I looked at Paul Tegler's site, but don't really
> understand all
> the info contained in the distributor chart.
>
> My question is which distributor would be best for normal
> street driving?
> Obviously one will advance 10 degrees on the centrifugal
> advance and the
> other 16 degrees, but what does this get me in terms of
> performance and
> street drivability? I'm rebuilding the engine stock and
> intend to use the
> stock carbs.
>
> Thanks,
>
> Ken
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