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shibbyme
09-27-2003, 01:24 PM
I have an MSD-6AL with MSD-8350 distributor, supercoil wires & Blaster 2 coil. I installed MSD-8910 (I use the white trigger wire) and that got the tach running but it doesn't read the correct RPM's after about 2000 RPM. The car is a 1972 Mustang with a 351C engine. Any suggestions?

One other thing: I took the car in for dyno tuning Thursday. Every time the RPM reached around 5000 the engine lost power completely. We removed the 6AL and it still happened. I have the blue bushing and 2 blue springs in the distributor. Could the coil cause the dropout? Is this ignition setup too much for an older car?

Thanks for your help

msdtech2
09-29-2003, 02:42 PM
I would recommend trying a different tach and connect to the MSD tach output, we have found that some of the older tachs can read fine at lower RPM's than higher RPM's due to the calibration of the tach. If possible try an aftermarket tach.
On the timing situation you may have to play with the timing curve to see where you may get the best performance, it may need less timing at higher RPM's or vise versa, every engine could respond different to different timing curves.
Thanks,
msdtech2

shibbyme
09-30-2003, 05:16 AM
Since the car is old I really wanted to keep as much of the original as possible. That's why I was trying to get the original tach to work. Do you have any reccommendations for which tach to install? I would like to avoid the trial and error method.

As far as the fuel/ignition problem, I found out Holley carburetors are notorious for blowing out the power valves in a backfire. After I installed the 6AL with the old Accel distributor I did experience some backfire. The power valve failure would cause erratic fuel delivery, especially at higher RPM's. I have new ones on order and I'll let you know if that was the problem.

msdtech2
09-30-2003, 08:41 AM
I would recommend borrowing an aftermarket tach, like an Autometer to compare to make sure that it is a tach problem. Although Autometer is the mostly used with MSD Units, let me know on the power valve situation.
Thanks,
msdtech2

shibbyme
10-01-2003, 03:04 PM
I installed a new power valve but it made no difference. The engine still runs very rough. I'm frustrated and going broke trying to fix this. What started as a $200 purchase has now cost me over $1000.

Before I installed the 6AL everything was fine. Now it seems I have a problem that can't be fixed.

msdtech2
10-02-2003, 02:33 PM
I would recommend starting to look at plugs to see how the motor is running, if too rich or lean. Check timing make sure that it is steady, when timing is not steady, this could indicate EMI noise causing to be erratic. Check compression, do a leak down to see if there is no mechanical problem.
Thanks,
msdtech2

shibbyme
10-10-2003, 01:40 PM
EMI noise? Not sure what that is. How can it be checked? How can it be corrected?

Compression is good, fuel mixture is 12-13 at the tail pipe, no leakdown problems. I checked the resistance of all the plug wires and they are in the 40 ohm per foot range.

msdtech4
10-10-2003, 03:19 PM
shibbyme,

What is the voltage on the red of the MSD distributor while the motor is running? How man wires are coming out of the back of the tach? Did it originally trigger off of the plus or minus of the coil? When you are setting the timing in the motor what type of timing light are you using? Is it a dial or digital type timing light? I am jumping in on the thread with MSD tech2.

Thanks,

MSD tech4

shibbyme
10-12-2003, 06:32 PM
Voltage: 12.2v
Wires on tach: 2
Old Trigger: (+)
Timing Light: Actron CP7519, Dial type

msdtech4
10-13-2003, 10:00 AM
shibbyme,

The tach problem is a simple fix. The 8910 is not needed in this case, you will require a Chrysler dual ballast resister. Look at the instructions on page 8 figure 5 of the MSD 6 instructions, this is how your tach will need to be wired in order for it to function correctly. As for the timing the light you are using is not recommended at all. I highly recommend starting over with a non-adjustable timing light verify the timing both initial and total. The dial and digital type lights will more often then not give you a bad reading. So the timing you think you are at is probably not the case.

Thanks,

MSD tech4