Ken:
The numbers on the advance units are very hard to see. They are on
the face towards the distributor (if I remember correctly) and may need some
emery cloth cleaning to become visible. They are there.
Kelvin.
> -----Original Message-----
> From: Ken Waringa [mailto:kwaringa@dynsys.com]
> Sent: Monday, January 28, 2002 9:00 AM
> To: Dodd, Kelvin; MG
> Subject: RE: Distributor choices
>
>
> Kelvin and all. I looked at the vacuum advances from both
> distributors, but
> could find no numbers or identification markings on them. I
> reconfirmed
> that both are 25D4 distributors, the only outside difference is one is
> marked 40897 A and the other is marked 40897 E. The internal
> centrifugal
> advances are different though. The one with the A is marked
> 10 degrees and
> the one with the E is marked 16 degrees. The mechanical stop for the
> centrifugal advance is clearly different as well.
>
> If anyone could advise which of these distributors would be
> best on a stock
> street car. I plan to use the HIF carbs on the car.
>
> Thanks,
>
> Ken
>
> -----Original Message-----
> From: Dodd, Kelvin [mailto:doddk@mossmotors.com]
> Sent: Wednesday, January 23, 2002 2:14 PM
> To: 'Ken Waringa'; MG
> Subject: RE: Distributor choices
>
> 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 as the superceded replacement.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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