> I have a 25D Lucas distributor. The side markings say 40897,
> which should
> mean that it was for an MGB, I think.
I agree.
> Someone said that I should have a vacuum advance that says 2-6-3.
I don't know the magic numbers, but that doesn't match the information given
in the factory service manual. And 3 degrees (even distributor degrees)
seems awfully small.
> The DM2 distributor that was on the car when I bought it has a dead
> vacuum advance that's labeled 4-11-7.
That seems a lot more likely to be right. Have I mentioned that my local
independant parts house was able to have my original vacuum advance rebuilt
?
> I have a spare vacuum advance that I got off of Ebay (NOS)
> that the guy
> said was for a TR3 and it's marked 4-8-5.
Might be right, but that's not much advance.
> Can someone tell me what the mechanical advance inside the
> distributor is
> supposed to read?
Book shows max advance for a TR2 is 14-15 degrees. Might be different for a
3A, though.
> Is it the same for a TR3 as it is for an MGB?
Paul Tegler's site says your MGB dizzy should go to 20 degrees, so I'd guess
they're not the same.
> Are these distributors around?
Show up on eBay all the time. Of course, I wouldn't trust an eBay seller to
know what car it's actually for ... at best they might be able to read the
numbers off the unit for you. Fred Thomas claims to have a source for
rebuilt Lucas dizzys.
> Does the vacuum advance really make that much difference?
You should be able to see about 10%, maybe as much as 15%, better fuel
mileage with a working vacuum advance.
> My TR3 runs like a banshee, but only gets about 20 mpg.
IMO you're not likely to get a whole lot better on what they sell for
gasoline here in the People's Republik of California. Those 30 mpg claims
you see in the books were done with real petrol, measured in Imperial
Gallons. Our gallons are smaller, and our gasoline is deliberately "watered
down" to increase pollution and line farmer's pockets.
You could probably pick up a couple of mpg by tuning the carbs about 2 flats
lean of 'normal'. The tradeoff is reduced performance though.
Randall
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