2.7 with new MSD 8524 and coil - missing badly

[Orange911S]

Over the weekend I completed the MSD upgrade from Wayne's article 24.
This was brought on by a no start issue and feedback from the forum was that this was a coil or CD box. In Wayne's article he suggests re-timing, which I have not done yet.

I drove Sunday night and it ran pretty well. Since then, I have noticed less power at low RPMs with some slight misses and it got worse over the last couple of days. This morning on the five mile trip to work I had a stall at a stop light and backfire when pulling away.

From those who have done these changes, is this typical? Do I need to change the distributor to a non-resistance version? I have not done anything to the plugs. They are about 2500 miles old. Also, the plug wires are not changed out.

Any suggestions on where to start?
Thanks.

[Bob Kontak]

Recheck your connections. Coil primaries, etc.

Tell us in detail how and where you grounded the unit. This is really really important.

Right now, the last thing I would suspect is the hardware and the first would be installation.

Timing maybe, but for now, reach in there and see if you can twist the dist by hand. Maybe it's loose and you just bumped it?

[mreid]

How are you triggering the MSD? Do you still have points (upgrade to pertronics would be great)? An msd box will stress old wires, caps, and rotors so make sure yours are up to the task.

[T77911S]

points are fine. more reliable. i ran my 77 for 10 yrs and i think i changed the points once.
the gap is not critical, but do make sure they open and close completely. i would check it.
the bushing can wear down and the points wont open.

i do not know what the 8524 is. i looked it up and a distributor came up. did you replace coil too. i dont knos this unit so i dont know how it should be wired. does it have a dedicated wire that runs to the battery? were did you connect it? does it have a dedicated pair to the coil? is the coil still grounded? bob's questions on grounds. marks question on triggering.

what about timing? advance working?

plug wires OK? check for arcs and sparks at night with all the lights off and engine running.
if you have a multimeter ohm them out. cap and rotor good? how do the plugs look?
the wire form the dist to the CD came get brittle and crack and short out.

outside of that it sounds like fuel or an air leak.

[pors1968]

After a tune up and wiring check i would check gas filter and fuel pump pressure.

[Orange911S]

I got the model number wrong. Sorry for the mis-info.

The MSD is connected to the starter hot wire and the ground from the MSD is to the back of the aluminum panel. I could use some insights if someone thinks this should be a better ground.

I am confident of the connections to the coil and used the plug from the factory perma tune for the white and red wires, so I am hopeful those are not the issue.

I just drove it home and had a couple of misses, but nothing major.

There is nothing like a little "bucking" at high speed to create a loss of confidence.

I am still new to this and appreciate the insights and advice.

[rsscotty]

You can run into problems like you describe if you try to use parts of the factory wiring harness. It is best, if not mandatory to use the MSD harness by itself. Read their install instructions and use the proper spark plug wires, and resistor plugs.
The current way it is running sounds erratic, which is most likely EMI interference.

[snbush67]

The ground could be better if connected directly to the chassis. Also clean the coil connections. Maybe open up the gaps on the plugs a bit.

Check for vacuum leaks, also check for any plugs or hoses that may have came loose when you were installing the MSD.

[Bob Kontak]

Originally Posted by snbush67

The ground could be better if connected directly to the chassis.

There are lugs welded into the driver's inner fender for mounting parts. Use one of these along with those washers with teeth.

Do not discount the importance of the ground. Remove it from the list of possible causes. Grounded to the panel, it's suspect.

[Orange911S]

OK, I will start with an improved ground connection and double check the hose connections. The coil is new and the connections are clean.

I'll post more as I sleuth this one.

[wwest]

Originally Posted by Orange911S

OK, I will start with an improved ground connection and double check the hose connections. The coil is new and the connections are clean.

I'll post more as I sleuth this one.

I would have NEVER even tried to drive the car before checking the timing, too much opportunity for permanent damage.

Magnetic pickup is much more reliable and accurate.

Points major shortcoming is unavoidable rubbing block wear.

As a minimum, if you haven't done so already, NEW points, then time.

Plus the condenser will have a much greater spark delay with CDI vs with a ~1 ohm ignition coil primary.

[dicklague]

As mentioned make sure you have a very good ground.

ALSO make sure you have a very good power lead. I had trouble with my Daytona-Sensors CD-1 install because I connected the power line to the big red wire that goes to the starter, but I connected it AFTER the 14 pin connector. It backfired and quit running a few times. I cleaned the connector and all was well. Later I connected the new power wired downstream of the connector and installed a 20 amp fuse in the line. Everything was fine then.

Point here is the MSD puts out at least 2X what the bosch did so you need to be sure that the wiring is right.

If the above does not do it, look at the points and timing.

[dicklague]

as a follow up make sure the signal going into the MSD is good. If your point gap is too small the running can get erratic and sometime just quit when the rubbing block wears away and the gap get minor on non-existant......I have learned this over many times. That was the major reason I switched to Hall effect Pertronix.

I have an MSD tester that I bought on eBay that simulates the points output. You can dial up different RPMs. I use it with a spark testing gap. this video explains it well. How to test for spark on your MSD 6 Series - YouTube

Maybe someone has one near you. I wish I were closer to Walnut Creek, I would be happy to help you out, and test the MSD and the spark input and wiring.

I have spent a lot of time getting to know the early 911 ignition system and upgrading it. I have a 2.7 MFI motor that I have running great. I have acquired some good test equipment. At least you will know the MSD is working well. Just too bad you are not closer.


here is the plug tool that you can hook to the coil output

[Orange911S]

I have not had time to address this issue over the last couple of days, but plan on looking through connections first thing in the morning - starting with the ground.

I appreciate all of the insights.

Jeff

[wwest]

LQQK, the CDI is quite obviously firing the spark plugs!

Put in NEW points and condenser, set 70% dwell.....

Check the TIMING.

Then fiddle-futz around with the wiring and connections.

[snbush67]

+ 1, I am a fiddle-futz pro.....this stratagey allways works for me, its allways the last thing you check so just go there first!

[john walker's workshop]

check the rotor. msd will burn out the resistor rotors. it's pretty obvious when it's toast. use an echlin with no resistor.

[Bob Kontak]

Originally Posted by Orange911S

I'll post more as I sleuth this one.

Don't sleuth. Just do.

JW comes up with stuff that lots of us don't know enough about. Check your rotor.

The ground may or may not be problematic. Nail it and put it to bed.

Check your points, check your timing. Buy tools if needed.

[wwest]

Originally Posted by john walker's workshop

check the rotor. msd will burn out the resistor rotors. it's pretty obvious when it's toast. use an echlin with no resistor.

Will that still happen with the proper resistive HV wires and resistor spark plugs?

[Bob Kontak]

Originally Posted by wwest

Will that still happen with the proper resistive HV wires and resistor spark plugs?

Sounds like it's an eyeball check. Worth the effort if a three minute job.

Whether or not it could happen.