Cooper S distributor

[Gary Schulz]

I am sorting through miscellaneous parts and was wondering if this is the correct distributor for a 1275S? It is labelled 23D4 41372

20201107_101653.jpg

[Aginley]

I thought 40819 ?

[251 ENG]

It's not cooper s its marina

[jay weinstein]

Hi Gary....the distributor in my 67 S is a 40819 dated 11/67. I'm sure it's
original to my car.

[LarryLebel]

http://www.starchak.ca/tech/pdfs/lucas.pdf

Marcel's distributor data base also says Marina.

[Gary Schulz]

It's not cooper s its marina

I would have thought a Marina would have a vacuum advance? This one has no vacuum advance on it...

[Gary Schulz]

http://www.starchak.ca/tech/pdfs/lucas.pdf

Marcel's distributor data base also says Marina.

Wow that is a very complete list of distributors! I need to compare specs then to the S -unit. I presume the only difference is weights and springs then?

[iain1967s]

Late Mk3 S also used that distributor I think.

At least, it was listed as the replacement part according to MiniSpares, not sure about factory fitment - nothing in Parnell either.

I could certainly imagine BL getting toward the end of Mk3 S production when stock was running low, and throwing Marina distributor just because they had them on hand and it’s “close though”...

[Gary Schulz]

I think once I get the distributor dialed in on the SUN machine I can make it match whatever advance curve is needed for my 1275S. I compared the 41372 curve to the 40819 curve data in the table and to be honest, I am not sure what they mean. Seems like they only list maximum advance at a given RPM and then list two other RPM ranges that are below the idle speed of the engine. Not sure how to interpret the meaning of those three data points except the maximum RPM/Advance

[LarryLebel]

The spec might be for distributor rpm.

[Gary Schulz]

The spec might be for distributor rpm.

Yes, of course!

[TECH396]

I think once I get the distributor dialed in on the SUN machine I can make it match whatever advance curve is needed for my 1275S. I compared the 41372 curve to the 40819 curve data in the table and to be honest, I am not sure what they mean. Seems like they only list maximum advance at a given RPM and then list two other RPM ranges that are below the idle speed of the engine. Not sure how to interpret the meaning of those three data points except the maximum RPM/Advance

Gary. Distributor RPM is half, or 50% of engine RPM

[CooperTune]

Back when I first started this journey late 60s early 70s J.C. Whitney sold those dizzies for $12.00 with a quick fit point plate. All needed was a Lucas point plate with the pin for the 32 oz. points and re curve. Steve (CTR)

[Spider]

I think once I get the distributor dialed in on the SUN machine I can make it match whatever advance curve is needed for my 1275S. I compared the 41372 curve to the 40819 curve data in the table and to be honest, I am not sure what they mean. Seems like they only list maximum advance at a given RPM and then list two other RPM ranges that are below the idle speed of the engine. Not sure how to interpret the meaning of those three data points except the maximum RPM/Advance

If you plot out the Curves on Paper, you'll see the story, here's a couple of curves I have to hand;-



Most Distributors have a Primary or Initial Advance and then a Secondary 'curve'. This is done as most engines need a quick advance up to Peak Torque, then a reduced Rate after that. They do that in the Distributor by fitting a lighter spring on the Primary that's under tension as fitted and the other spring is heavier and has measure amount of slack, so it only comes in to play once the weights have moved out a measured amount.

[LuisM]

f this is the correct distributor for a 1275S? I

As said by Simon this is a Morris Marina distributor , they had no vacuum advance , not even the 45D fitted to later Marinas had vacuum advance .

Cheers
Luís

[Gary Schulz]

Well I am back to being confused with the data in that impressive table. It seems to suggest that maximum advance (40819 data) doesn't come on until you are at 7600 RPM on a 1275S ? I think I need a better source for curve data to suit the engine in question. Once I have it in hand then I can just recurve the distributor I have.

[Ronnie]

I hope this is of assistance details are from a Lucas data sheet (Service Engineering dated 1/02/72)
Part No 40819K
Model 23D4
Rotation Clockwise
ECM 749
Range 14-16
Spring set auto advance 54414766
Weights auto advance 54413073
Shaft & action plate 54416610
These link's may help regarding ECM > http://www.bobine.nl/jaguar/02-engine/o ... s-for-xks/
> http://mgaguru.com/mgtech/ignition/pdf/ ... s_dist.pdf

[Tds76]

My Haynes Mini Restoration Manual lists the following for Cooper MK3: 23D4, 40819 or 41033

And the following statement, 'All pre-1969 Minis were fitted with the 25D4 unit. All Coopers and 'S's were also fitted with the 25D4 distributor except the MkIII Cooper S'.

Not all that helpful in identifying the specific one for a Mk1 or 2.

Cheers, Paul.

[Ronnie]

My Haynes Mini Restoration Manual lists the following for Cooper MK3: 23D4, 40819 or 41033

And the following statement, 'All pre-1969 Minis were fitted with the 25D4 unit. All Coopers and 'S's were also fitted with the 25D4 distributor except the MkIII Cooper S'.

Not all that helpful in identifying the specific one for a Mk1 or 2.

Cheers, Paul.

All UK Cooper S models had NO vacuum advance hence the 23D4. The Haynes manual is correct the mini cooper and the smaller cars had the 25D4 with vacuum advance.
"Not all that helpful in identifying the specific one for a Mk1 or 2" = 40819, Mk3 = 41033

[Spider]

http://www.starchak.ca/tech/pdfs/lucas.pdf

Marcel's distributor data base also says Marina.

I'll suggest some caution if working from these Curves. I've no idea where they were compiled from, but I've found quite a few errors in it.



These are the MKI and MKII S Curves (From Lucas's Data);-