Hello everyone:
I just finished a new 2.9liter motor for my '70 911. I put about 100miles on it running OEM Bosch/Porsche ignition before I replaced the Bosch CD unit with a MSD 6AL unit. The improvement was imediately noticed. Idle was much smoother and a flatspot at 3800rpm virtually disapeared. After about 40 miles of traval, I shut the car off. When I tried to start it again, I could not get the motor to catch. the closest I got was a lot of sputtering and back fires. When I checked the motor, I found that the Coil wire was fried, and the Distributor cap and Rotor were smoked as well. the Coil, points, and other components of the ignition system appeared to be fine. I managed to replace the items that were fried and still the car would not run. I re-installed the original Bosch unit and the car fired right up. The car ran so much better with the MSD 6AL for that 40 miles I want to go back to it but need help with the necessary parts to make sure the extra energy of the MSD CD unit work properly and don't cook again. What am I doing wrong and what specific parts do I need to install to resolve this proplem? For some back ground, the motor was built for street and track events. It started out as a '77 2.7liter case. I used Mahle pistons and barrels, Porsche Carrera 906 cams, the heads were heavilly ported and all the extensive machine work was performed by Ollie's in Orange, California. With the exception of the MSD 6AL, the ignition circuit is 100% OEM Points ignition, including distributor, wires, and coil. Any Ideas and advice that will help make the MSD work properly will be greatly appreciated. if you have ideas on part replacement, manufacturers and part numbers would be a real help.
Thanks, Jim

 

Sorry I can't help, but have you tried MSD tech support??

 

I have the MSD 6AL in my car and it works great!
I think MSD recommends (possibly requires) using an MSD coil with the MSD ignition. (Get the MSD High Vibration Coil, its the only one which allows mounting in any position including upside down)

 

Jim:

Would you please call me? This is rather complex,.....

FWIW, you must use an MSD coil since the Bosch coils have different impedances. I'm assuming that you used the correct trigger wires for points, from the MSD.

Lastly, grounding is VERY VERY important as the MSD draws almost double the current (they have an internal relay) but the power leads and grounding on MSD's is quite critical and is the major cause for troubles and failures.

 

Thank you to 11181 and especially to you Steve. I suspected that the coil was a problem, but it's always good to get some confirmation. Steve: I will call you Monday, I won't have time until then.
MSD Was really no help at all. Has any one else had that sort of feedback from them?
Thanks.
Jim.

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Jim Florance:
<strong> MSD Was really no help at all. Has any one else had that sort of feedback from them?
Thanks.
Jim.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">MSD Tech is about as helpful as a kick in the nuts. I had a few questions and they couldn't tell my even what type of distributor I had in my 930.

With Steve's help, I was going in no time.

 

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Jim Florance:
<strong>Thank you to 11181 and especially to you Steve. I suspected that the coil was a problem, but it's always good to get some confirmation. Steve: I will call you Monday, I won't have time until then.
MSD Was really no help at all. Has any one else had that sort of feedback from them?
Thanks.
Jim.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Hi Jim:

My pleasure, Sir. I'm happy to help anytime.

As much as I like MSD products, I've always been frustrated at how worthless their Tech Support is and how little they know about product applications beyond Detroit products. IMHO, they are better at selling their stuff, rather then resolving application issues.

 

A good number of Bosch coils kill MSD boxes. The killer numbers are listed in the MSD instructions. Your box is probably dead. If you replace it replace the coil too and you'll be OK.

 

Good, sound advice from Carlos,.....................

MSD ignition amplifiers are impedance matched to the coils.

One MUST use the appropriate MSD coil to keep the ignition box from drawing too much current and burning out, as well as getting the HP you want.

Not long ago, I proved the point to some other folks here at our dyno by running an engine with a MSD 6AL and a Bosch Blue coil. This made less power than stock. Installing an MSD Blaster High-Vibration coil restored the lost HP and even added more after the plug gaps were opened up to .040.

 

Based on Steve's previous recommendations regarding MSD, I installed a unit on my 76 Targa. Also used an MSD Blaster Coil and the new Pertronix II points eliminator. Everything works great. You do not need an adapter to run the tach. Use the signal directly from the distributor, not the signal supplied by the MSD unit. Good luck.

Howard

 

Just a follow up here... I ended up going with Pertronix pointless ignition, a larger power wire to the MSD 6AL device, and an MSD Blaster coil. For some time I still couldn't get the tach to work. To Remedy this, instead of getting the accessory capacitor and resister from MSD to get the Tach to read the square waveform, I had a quality Speedo shop modify the stock VDO Tach to read the MSD waveform directly. and bypassed the electronics panel on the driver's side engine compartment entirely by jumping directly to the black and purple wire that runs from the engine compartment to the tach. These modifications work perfectly, thanks for the help.
Jim Florance

 

I ran an MSD6 for years on my 1970 Mercedes 6.3 daily driver for years. MSD recommended the Bosch blue coil at that time, this was before the MSD brand coil was available. I used tight spark plug gaps, to avoid cross arcing in the cap. The spark voltage is so high that it WILL find an alternate spark pathway if the resistance of the wires or plugs is too high. If your distributor cap is a small diameter type use .025 - .030 plug gap. Avoid the German 7mm plug wires with the screw on ends. Don't run the engine with a plug wire off, the arcing will quickly destroy the cap, rotor or wire. Also realize that the spark duration may be 5 - 20 crankshaft degrees, depending on rpm. To keep the end on the rotor aligned with the brass plug wire post inside the cap may be difficult. It may still be producing sparks after the rotor tip has rotated past the post. This can produce big sparks inside the cap. This ionized air inside the cap leads to further arcing. Sometimes you have to drill 1/4" holes in the cap to let the ionized air out.
I don't think the MSD is picky about which coil you use. Better (higher ratio) coils will produce more sparks though. I ended up using an Accel coil, but I don't think it was any better than the OEM Bosch (non-blue) coil. I think you can test it using any old coil off a pre capicitor discharge American car, to see if your coil is bad. I also ran mine using late 60's OEM Ford and Chevy coils. I remember reading that the late 60's OEM Corvette coil worked well also.
The MSD6 was designed to work on an 8000 RPM+ V8 engine, a 6 cyl should not stress it. The Mercedes ran noticeably smoother with the MSD. The main advantage is that it will fire the mixture even if it is a little too rich or lean, similar to a dual plug motor. It will run OK with dirty or fouled plugs. I also connected an optional rheostat that allowed advancing the timing from inside the car.
Be careful not to let the plug wire shock you. The multiple sparks will not be good for your heart rhythm. A disconnected plug wire will arc about 15 2 inch sparks at idle.

 

Just a quick note about MSD's and coils:

MSD ignitions are impedance matched to their respective coils and if you use others (Bosch Blue coils for example), you will see a power loss.

Use an MSD with its matching coil and these ignitions will provide MUCH better drivability and better power than OEM components.

Lastly, wide plug gaps give much a better idle, less plug fouling and more HP. As suggested by ebaker, all the rest of the ignition parts must be up to snuff to handle the increased current & heat. We use & recommend Magnecor 8.5mm racing wires in all of these applications.

 

Bump.

 

Thanks, I've done most of these things now, with the exception of drilling the ventallation holes in the cap. I also switched to pertronix ignition rather than points. This, the magnacor wires and the MSD Blaster coil seem to reslolve all the problems. If anything else comes up, I'll post it.
Jim