DiscoClax Posted February 29, 2008 Share Posted February 29, 2008 I've run into a little glitch... Ahem. My vacuum advance unit (ie. diaphragm) failed some time ago on my '94 D1 3.9 V8 dizzy (3-pin, with ign module on side) - low comp, no cats, UN spec engine (I think the dizzy might be ERR4753, my chassis is MA082904). So I've been burning fuel at an even more impressive rate... Today I received in the post a used 3.9ltr D1 dizzy off eBay, complete and in excellent condition. But it's a 2-pin type (without ign module) - type 35DM8, ERR5207 Questions:- 1. Can I use the 2-pin vacuum advance capsule on my existing 3-pin dizzy? Will it fit, work as intended, etc? 2. Failing that, what do I need to do to fit the 2-pin dizzy in place of the original 3-pin unit? What extra bits do I need and is it a worthwhile conversion? 3. How do I tell if the rotor and cap are "genuine". I understand genuine is the only way to go as pattern parts are junk, but not sure how to identify the right bits. Do they have LUCAS moulded in? Are the Bosch ones equivalent? Any help gratefully received. Quote Link to comment Share on other sites More sharing options...
DiscoClax Posted March 3, 2008 Author Share Posted March 3, 2008 Anyone...? Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted March 3, 2008 Share Posted March 3, 2008 I've run into a little glitch... Ahem. 1. Can I use the 2-pin vacuum advance capsule on my existing 3-pin dizzy? Will it fit, work as intended, etc? Yes .............. they are all about the same sort of advance value................IIRC something like 12 - 15 degrees.............. The actual value it not so important as long as its giving a significant advance at high manifold vacuum which equates to light throttle (cruise) ....... it important to light the pots earlier due to the decreased VE .................this improves fuel consumption. Ian Quote Link to comment Share on other sites More sharing options...
DiscoClax Posted March 4, 2008 Author Share Posted March 4, 2008 Yes .............. they are all about the same sort of advance value................IIRC something like 12 - 15 degrees..............The actual value it not so important as long as its giving a significant advance at high manifold vacuum which equates to light throttle (cruise) ....... it important to light the pots earlier due to the decreased VE .................this improves fuel consumption. Ian Cheers Ian for your feedback. The dashpots look to be of similar sizes so the amount of advance vs vacuum should be about the same. Was more worried about whether the part would actually fit and why there are two different part numbers listed for the vac adv unit depending on 2 or 3 pin. Maybe I'll just pull my finger out and whip 'em both out and see if they're physically the same or not. Was just being a bit lazy and hoping someone could save me the hassle. I suspect the connection to the base-plate and/or rod length/shape might be just different enough to not be interchangeable, hence the different p/n's. Quote Link to comment Share on other sites More sharing options...
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