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UK 907 Distributor without vacuum advance  Rate Topic 
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 Posted: 01-12-2021 05:59 pm
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JPJH
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I’m hoping someone can assist. I’m looking for a UK version of the Lucas distributor without Vacuum for a Dellorto installation.

I recall the club sells a converted one, but curious if anyone knows the Lucas part number or model for the UK part

Thanks!

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 Posted: 01-12-2021 07:12 pm
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redracer
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the vacuum for our dizzy is a RETARD; pull it out, plug the holes(silicone works) and bolt the top plate to the bottom(where the points & condenser are)

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 Posted: 01-12-2021 07:18 pm
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Esprit2
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The 23D4 & 43D4 have NO vacuum capsule.
The 25D4 & 45D4 DO have a vacuum capsule.

Despatch
Number
41488 -- 23D4 -- 1972-75 -- J-H & JGT
41488 -- 23D4 -- 1972-75 -- Elite, Eclat, Esprit

41634 -- 25D4 -- 1976 -- Jensen-Healey
41634 -- 25D4 -- 1976 -- Elite & Eclat
6° Vac Retard
Centrifugal Advance:
Nil. @ 1000
. 8° @ 2000
18° @ 4000
22° @ 5000
26° @ 6000

41584 -- 45D4 -- 197?-7? -- J-H
41584 -- 45D4 -- 197?-7? -- Elite, Eclat & Esprit
8° Vac Retard - Lotus Spec 1
8° Vac Retard - Lotus Spec 2
0° Vac Blanked Off - Lotus Spec 3
Centrifugal Advance:
Nil. @ 1000
. 3° @ 1500
10° @ 2000
16° @ 3000

41605 -- 45D4 -- 1975-76 -- J-H & JGT
41605 -- 45D4 -- 1974-78 -- Lotus Elite, Eclat
41605 -- 45D4 -- 1976-78 -- Lotus Esprit

41623 -- 45D4 -- 1978-83 -- Elite, Eclat S1 & S2.2
41623 -- 45D4 -- 1978-83 -- Esprit S2, S2.2 & Turbo
0° Vac Blanked Off - Lotus Spec 3
Centrifugal Advance:
Nil. @ 1000
. 8° @ 2000
16° @ 3000

41626 -- 45D4 -- 19??-?? -- Elite, Eclat & Esprit
8° Vac Retard - Lotus Spec 2
0° Vac Blanked Off - Lotus Spec 3
Centrifugal Advance:
Nil. @ 1000
. 8° @ 2000
18° @ 4000
22° @ 5000
26° @ 6000

In North America, contact Jeff Schlemmer at Advanced Distributors
http://advanceddistributors.com/wordpress1/

In the UK/ Europe, contact the Distributor Doctor
http://www.distributordoctor.com/

In either case, tell them what you want. Given any 23D4 or 43D4 distributor (no vacuum capsule), they can set it up to any advance curve you specify. They can also convert any 25D4 or 45D4 with a vacuum capsule, to a 23D4 or 42D4 without a vacuum capsule.

Regards,
Tim Engel

Last edited on 01-17-2021 08:44 pm by Esprit2

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 Posted: 01-13-2021 12:22 am
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JPJH
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Thanks both for your feedback, just what I was looking for.

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 Posted: 01-13-2021 12:22 am
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JPJH
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Thanks both for your feedback, just what I was looking for.

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 Posted: 01-13-2021 03:44 am
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discogodfather
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If you are not mechanically inclined or know the inside of a distributor the best way to go about this is to buy a used 23D/25D on ebay or elsewhere and then have it sent in to Greg or someone who does Lucas rebuilds. It doesn't matter if the dizzy has a vacuum unit or not. The ones that don't just have a metal plate in place of the vacuum unit, and ANY distributor with a vacuum unit can be easily removed in about 1 minute. Blocking the hole that is left is easy with some silicone.

Plenty of 23D and 25D modern "new" manufacture diszzys out there but they lack 2 important features:

1) They have NO INTERNAL OIL SEAL. Only Jensen Healey and Lotus have these special seals added and without them they dump oil all over the place as the dizzy shaft sits right inside the oil pump.

2) They have incorrect advance curves for the 907 engine. They work (I have tried them) but it isn't ideal. Unfortunately if you engine is tuned or modified a stock 907 advance isn't correct either.

I have rebuilt distributors and replaced oil seals, that is actually pretty easy. I also have made my own distributors by buying 23D housings from a British supplier and then swapping out the shaft and centrifugal advance into the new housing after machining an oil seal pocket into the new distributor housing. A bit of a Frankenstein but it works.

Number one problem will all distributors both new and old is the awful design around the clamping area where the thin sheet metal clamp exerts lots of pressure when you fix the distributor in place. Because these are die cast housings and can't have any areas that are thicker than a few mm, they chose to leave the area behind the clamping ring support-less (there is a 1mm gap). The metal fatigues and crushes over time and the distributor becomes loose and can pop out. The fix for this is to machine a small ring to fit behind it to fully support it, or to machine the entire housing down and fit a steel ring in place of the thin and easily broken aluminum lip ring.

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 Posted: 01-17-2021 08:52 pm
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Esprit2
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The 'heads' of the 23D4 & 25D4 are small in diameter, and that puts the spark plug terminals close together. If you upgrade to a higher voltage coil, then there's a very good chance that the extra voltage will just arc between the terminals inside the distributor cap. Those small distributors are simply not compatible with high-voltage coils... period.

If you're going to the trouble and expense of replacing the distributor, then consider upgrading to the later 43D4 or 45D4. They're larger in diameter, and can handle hotter coils.

Regards,
Tim Engel

Last edited on 01-18-2021 08:07 pm by Esprit2

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