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| UK 907 Distributor without vacuum advance | Rate Topic |
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| Posted: 01-12-2021 04:59 pm |
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1st Post |
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JPJH Member
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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 06:12 pm |
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2nd Post |
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redracer Member
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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 06:18 pm |
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3rd Post |
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Esprit2 Member
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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 -- 1974-75 -- 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 03-16-2021 08:41 pm by Esprit2 |
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| Posted: 01-12-2021 11:22 pm |
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4th Post |
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JPJH Member
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Thanks both for your feedback, just what I was looking for.
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| Posted: 01-12-2021 11:22 pm |
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5th Post |
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JPJH Member
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Thanks both for your feedback, just what I was looking for.
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| Posted: 01-13-2021 02:44 am |
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6th Post |
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discogodfather Member 
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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 07:52 pm |
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7th Post |
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Esprit2 Member
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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 07:07 pm by Esprit2 |
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| Posted: 03-10-2021 07:34 pm |
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8th Post |
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Distributorguy Member
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Esprit2 wrote: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. Sorry this is a load of crap. You have 60 degrees of dwell time. There's no way you can cross fire a 4 cylinder unless its a vacuum distributor and its WAY out of phase (meaning the thumb knob is cranked all the way CW until its tight, which allows the rotor to approach the next terminal.) The next issue with your argument is that you're limited to your functional spark plug gap. That limits actual HT voltage to well under 25kV. More like 12kV in most cars, no matter what the sticker on the coil says. To answer the initial question, yes you can just remove the vac unit, but you need to also get the breaker plate position correct before you weld or screw it together. Again, back to my phasing comment above - it can make or break how the engine runs!!! JHPS can get your distributor rebuilt minus the vac unit, with a better than original timing curve for best overall performance.
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| Posted: 03-12-2021 06:59 am |
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9th Post |
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discogodfather Member
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Distributorguy wrote:Sorry this is a load of crap. No one has ever said that Tim Engel was full of crap. It just hasn't happened yet, in human history.
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| Posted: 03-13-2021 02:32 am |
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10th Post |
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Tom Bradley Member
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Both Tim and "Distributorguy" have good points, except for the "load of crap" part. IF everything in the HV circuit is good and the timing is mostly correct, then the voltage is limited to the breakdown voltage of the spark plug gap. In that case, either size is OK. HOWEVER, if there is any problem, such a a loose connection, bad plug, too-large gap, etc. then the coil, being an inductor, will build up the voltage until there is a path to ground. With the smaller stock distributor cap, the path could more easily be places you do not want, such as punching a pinhole through the cap. This is even more likely to happen with a coil with a higher voltage rating. The larger distributor caps were designed to handle higher voltages. That was the whole intent of the design. So these will be more tolerant of problems, which, as most of us know, will happen, probably sooner than later in these cars. The materials used in the larger caps are also often better quality than the cheap thermoplastic and aluminum conductors available nowadays in the smaller caps. Last edited on 03-13-2021 02:33 am by Tom Bradley |
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