Electronic Distributors

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Todds Coupe

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What is the wisdom on installing an electronic, programable distributor on an E9? I am having difficulty balancing cold start and warm idle. All else seems to be working great. Cold start is rough, and accelerator needs to be nursed to keep him running until a little bit warm, once warm, idle is a bit irregular around 1100 or 1200. On cold start, chokes are completely closed, linkages adjusted and all moving freely, bushings etc. replaced, so I believe cold start mechanisms are good.

I recently changed the main jets to 120's and 130's, (it had 105's and then I put in 140's and 150's but it ran a bit rich) and he accelerates and runs better than I can ever remember, but cold start is rough. My wrencher suggests an electronic distributor might help smooth out all of the issues. All feedback is welcome.
 
I don't think your distributor is the issue here. Based on your description my guess is that you need the fast idle adjusted. You didnt say which carburetors you are using. On Webers there is a fast idle screw behind the choke adjustment pod (electric or water) that will allow you to increase the idle speed when the choke is on.

It is always worth checking the basics. What is the point gap, or better yet the dwell angle, make sure your timing is set where you expect it and then adjust for the cold start using the fast idle adjustment above.

If you want to check the distributor for bearing failure (a real reason to replace other than wanting to tune more easily, then hook up your timing light and check to see how much your timing mark jumps. If you have trouble getting a stable timing mark then you may have issues that would cause you to want to change the distributor.
 
Sounds like a vacuum leak that closes up when the engine warms. CHeck intake manifold and carb gaskets as well as top mounting screws. Does your cold start linkage high rpm/kickdown to low rpm work? 1100-1200 rpm is too high imho. Are your carbs synched?
 
Todds Coupe said:
What is the wisdom on installing an electronic, programable distributor on an E9? I am having difficulty balancing cold start and warm idle. All else seems to be working great. Cold start is rough, and accelerator needs to be nursed to keep him running until a little bit warm, once warm, idle is a bit irregular around 1100 or 1200. On cold start, chokes are completely closed, linkages adjusted and all moving freely, bushings etc. replaced, so I believe cold start mechanisms are good.

I recently changed the main jets to 120's and 130's, (it had 105's and then I put in 140's and 150's but it ran a bit rich) and he accelerates and runs better than I can ever remember, but cold start is rough. My wrencher suggests an electronic distributor might help smooth out all of the issues. All feedback is welcome.
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All the advice above is a good AND depending on your setup, you might also consider a mechanical advance distributor. The Mallory 46 series is a good one. Granted, i am running 40dcoe's and was tired of chasing down an elusive timing /idle issue (similar to yours) that stemmed partly from the vac connection in my manifold not being ideal for providing proper signal. The mech advance units take the fine tuning aspect out of the equation and simplify the number of variables. You get reliable, repeatable performance every start, every drive, albeit at the expense of optimal fuel economy and efficiency of a finely tuned vac system or an electronic one. But for me, its been a godsend. Set it and forget it. I started with the 46 series and MSD programmable ignition but got tired of the all too frequent faults it would randomly see. So i stripped that out and now just run the 46 with a standard coil. i have to set my idle a bit high to keep it consistently smooth (850 to 900) but its the compromise i made to get the car running optimally when driven normally and under heavy load.
 
You should evaluate whether your timing is stable before throwing a new diz into the mix. I'd connect a timing light and see whether/how much the timing jumps around at various rpms. Only then, if the timing is not steady, you can start to consider why/not. Consider that the diz is driven by a steel gear at the base, which engages with a brass gear on the cam. Is the brass gear worn, or the steel gear incorrectly engaging? Is there rotational play in the diz that's not attributable to the plate on which the points mount? Do the diz internals move freely or could they be gummed up causing sticking? Lots to consider here before dropping in an electronic diz and expecting it to cure your problems.... i.e., don't throw parts at the car in the hope that you'll get lucky.

The above also suggests checking timing chain tension and tensioner function.

Example: a friend got a factory rebuilt motor for his 2002 (this was decades ago) and the timing was absolutely rock steady, suggesting that there was no longer any stack-up of play from cam to spark.
 
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