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MG Midget and Sprite Technical - Spare Distributor

I just found a 25D Lucas Dizzy in a '73 at the junkyard.

It has new points an newer condenser and looks to be the perfect $12 spare for my Crane ignition

My midget is a '72 and this is from a '73 The #'s are 41400 49 70

How close will this be to my '72, or I should say how close to my currrent set up?
Fast Road cam, ported, custom exhaust,+.20 Hepolite pistons

When I get a chance, I'll send this one off to Jeff at Advanced Dist to work his majic, for now I just want an emergecy spare to get me home if my Crane quits
Phil Burke

Phil
$12...wow, ill give you $13 for it...hahaha

you got a great find...i cant imagine it will be that far off...esp as an emergancy back up

Id pull the alt as those arent real common like a chevy...in fact might be worth while to take the entire motor as a back up,,,there arent as many 1275s on ebay like there used to be

Prop
Prop

The 49 70 is the date of manufacture WW YY, so if this was made for production, it was probably for a 71. If for spares, then it could be anything prior to 49-70. 41400 is the specification number, and may well be the same as the one in your car. I do not have the specification numbers readily available. I came on one reference to a 41400 marked 49-72 which would be for 73 production. And now a listing showing 41400 as for 73-74 1275 - are you sure you read the date correctly? There was a change in compression from 8.8 to 8.0 "from 72 on".
But, it will certainly work.

FRM
FR Millmore

Phil it will get you home so who cares how close it is.
Just make sure you don't over advance it and you will be fine.

But why would your crane quit?
Onno Könemann

......But why would your crane quit?.....

Delivering babies is a full time job, making ignitions work is just a hobby.... OH, RIM SHOT PLEASE....hahahaha

Sorry, I ll get my coat AND MY HAT



On a serious note....

Wouldnt a 71 dissy be better on a 72-74 ,,,, IF all the smog and enviormental green stuff was removed ....granted I know im spilting "hairs of a hare" but would loseing. the enviro green stuff make the engine run faster then the advancing curve of the dissy would be set up for, although as fillmore makes note There is a .8 differance in compression ratio

...just curious.

Prop
Prop

I don't expect my Crane to go anywhere, but after an hour looking thru the scrapper only to find a 25D in realy nice shape, I couldn't help but liberate it from the rusting hulk of a yellow '73
Phil Burke

The engine must have been in as well.
1275's don't grow on trees and what looks bad externaly can be a good block crank and rods!
Go get them ;)
Onno Könemann

Phil. I have known the Crane/Allison points replacement systems to fail in use. Also, Luminition and Petronix systems to fail. Points will, also, but frequently give some warning. However, replacing the distributor on the side of the road, unless one also carries a timing light with one's spares, is not a really viable option in most cases.

There is a data table of Lucas distributors at the following site: http://www.starchak.ca/tech/pdfs/lucas.pdf which lists the Lucas 24D4 distributor to specification number 41400 as being used on the 73 Midget (Low Compression) and shows the following advance curve:

2100 (dizzy rpm) gives 18 degrees of advance
1350 rpm gives 12 degrees of advance
950 rpm gives 7.5 degrees of advance

and the vacuum system starts at 10", finishes at 15" and provides 5 degrees of advance.

All of these figures are as taken from a distributor test machine and crankshaft figures, both rpm and advance, are twice what is shown.

Thus, the 36 degrees of advance, at the crankshaft at 4200 engine rpms, even with zero static timing, may be somewhat more than your modified engine would tolerate. A trip to Jeff's is definitely in order.

Les
Les Bengtson

Jeff will be at Elkhart, so just take it with you and save shipping and talk to him in person.
Trevor Jessie

Changing the distr on the side of the road is easy!!
Just make sure you time it before and mark the position on the distr and block
Always perfect timing
Onno Könemann

This thread was discussed on 04/07/2011

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