MSD ? or...

[500gls]

hi my 911 '73 has a faulty cd bosch box.
I have informed but it's pretty expensive to get it rebuilt.
A friend metioned that a MSD unit works quite well.

So my question is : wich one do I need and do I get any problems with the tach ?


Thanks,

bas

[Zithlord]

MSD is not original, but regarded as ok even if not. I works very well. You can order it off Pelican where you will easily see what modell you need. You also need the tach adapter also found at pelican.

John

[TEC69E]

I've got a Bosch 3-pin CDI for your car. In perfect condition.

PM me if your interested in buying.

[TEC69E]

I run an MSD as well, and I'll say that if you go MSD you should also replace the coil with the proper MSD coil which adds to the cost ($50). Also I still haven't plugged in my tach (just got the car running this weekend) but past experience tells me that I/you may also need the tach adapter ($?). Bottom-line, while the MSD is a great alternative, costs will likely be more than just replacing your Bosch unit . . . and you will also need to modify the wiring to mate to the MSD.

So my initial intention was to run the Bosch CDI (to maintain factory/original) in my new motor, but I was advised against it because my motor is twin-plugged with a Mag Distributor, and the MSD was actually a better solution in this case (for me).

So I have two Bosch 3-pin CDI's and two Bosch black (correct) coils that are sitting in a box which I will sell for the same fair price that I purchased them for.

Regards,

[super9064]

I know the MSD claims to be better, but is it? Any non biased dyno testing done? I never understood the whole hotter spark thing, it seems to me either the gas ignites doesn't.

[Mr9146]

MSD is fantastic ... good clean spark (like a welder). My car actually ran smoother at idle and low RPM with the MSD, but I didn't notice a whole heap of difference in the upper reaches of the tach.

MSDs are readily available at your local NAPA or Kragen, too, which makes getting parts and service for them that much easier. They're a snap to install, too.

That said, however, originality is king with these cars.

[Mr9146]

I know the MSD claims to be better, but is it? Any non biased dyno testing done? I never understood the whole hotter spark thing, it seems to me either the gas ignites doesn't.

It's not about HOTTER ... it's about MORE. MSD = multiple spark discharge. You get multiple sparks per ignition cycle.

[super9064]

It's not about HOTTER ... it's about MORE. MSD = multiple spark discharge. You get multiple sparks per ignition cycle.

So, what's the science behind this, a highly combustible fuel, in a gas form does not need multiple sparks once the fuel is ignited, its self propagating. I understand twin plugs, two flame fronts converging. I don't doubt your car is running better but could it be that you replaced a faulty CD box with one that works 100%? Did any one sleep at a Holiday inn last night? I'm very curious how this works.

[Mudi]

The MSD works as noted above with Multiple Spark Discharge, but only in the lower rev ranges. Above 3000 it reverts to a single spark discharge. Makes it ideal for cars that like to foul plugs in low load, low speed driving.. I've been very happy with mine..

[super9064]

The MSD works as noted above with Multiple Spark Discharge, but only in the lower rev ranges. Above 3000 it reverts to a single spark discharge. Makes it ideal for cars that like to foul plugs in low load, low speed driving.. I've been very happy with mine..

I think I see how this works, does it allow you to use a plug with a different temperature range, so the plug does not foul? The MSD burns off any carbon build up, preventing erratic idle, and missing at speed.