MSD ISSUE... backfires w/no power at all

[johndglynn]

Did you pull the distributor out? Rotor came off OK, didn't take the dizzy out to get it in a vice?

Sure you have got the ignition timing all set up right?

[Rebel911]

I did not pull the distributor, just the cap and rotor. the rotor came of fine.
The timing was on when I pulled everything out.

[Rebel911]

after work today I am going to:

mod the rotor
drill holes in the cap (per MSD)
new grounding straps.

anything I missed?

[scarceller]

What way does that rotor spin in the SC clockwise or counter-clockwise? I ask because it's rather telling that the bad rotors are burnt on the right edge, most likely spark is occurring far before or after it should. Meaning the rotor may not be near the post at the time of spark. Could be timing is far advanced or retarded. Also keep in mind that maybe for some reason cyl #1 is firing correctly but somehow one (or more) of the others are not? That much damage on the rotor is most likely from the spark jumping a very large distance to the post. The question is why?

[john walker's workshop]

Originally Posted by scarceller

What way does that rotor spin in the SC clockwise or counter-clockwise? I ask because it's rather telling that the bad rotors are burnt on the right edge, most likely spark is occurring far before or after it should. Meaning the rotor may not be near the post at the time of spark. Could be timing is far advanced or retarded. Also keep in mind that maybe for some reason cyl #1 is firing correctly but somehow one (or more) of the others are not? That much damage on the rotor is most likely from the spark jumping a very large distance to the post. The question is why?

the resistor melted and it just happened to bubble out at the end. usually it exits out of the epoxy.

[scarceller]

Originally Posted by john walker's workshop

the resistor melted and it just happened to bubble out at the end. usually it exits out of the epoxy.

John,

Thanks for the simple answer. If this is the case then a rotor without the resistor or one with it modified should solve the issue. I'm interested how this turns out since soon I'm installing a MSD 6600 (pro unit) into my 84 Carrera.

Thanks.

[Rebel911]

Originally Posted by scarceller

What way does that rotor spin in the SC clockwise or counter-clockwise? I ask because it's rather telling that the bad rotors are burnt on the right edge, most likely spark is occurring far before or after it should. Meaning the rotor may not be near the post at the time of spark. Could be timing is far advanced or retarded. Also keep in mind that maybe for some reason cyl #1 is firing correctly but somehow one (or more) of the others are not? That much damage on the rotor is most likely from the spark jumping a very large distance to the post. The question is why?

I believe it spins Counter Clockwise.
I Checked all the wires for continuous spark with the timing light. Looked good for the most part. Every once in a while one of the wires would skip a spark.

Now, correct me if I am wrong, if it is spinning CCW and the damage is on the right side of the rotor as you look at it that tells me it is firing too early and I need to rotate the distributor cap clockwise back.

[Rebel911]

Originally Posted by scarceller

John,

Thanks for the simple answer. If this is the case then a rotor without the resistor or one with it modified should solve the issue. I'm interested how this turns out since soon I'm installing a MSD 6600 (pro unit) into my 84 Carrera.

Thanks.

I keep this post updated with pictures of the fix... just don't make fun of how dirty the engine bay is. She is a project in process.

[scarceller]

Originally Posted by Rebel911

I believe it spins Counter Clockwise.
I Checked all the wires for continuous spark with the timing light. Looked good for the most part. Every once in a while one of the wires would skip a spark.

Now, correct me if I am wrong, if it is spinning CCW and the damage is on the right side of the rotor as you look at it that tells me it is firing too early and I need to rotate the distributor cap clockwise back.

Correct, would mean firing early.

But first do the rotor mod as already pointed out by John, this is most likely your issue.

[RSWiser]

I went to the shop today, put in the new Niehoff rotor. Pushed it down firm.

Car started right up and rev good in neutral to 6000 rpm.

When in gear, driving, in all gears revs good to 3500 then cuts out, runs great at 3400rpm.

Any ideas.

[Walter_Middie]

What did you put in the MSD for a rev limiter? The default is around 3500 if you didn't put anything in it.

[RSWiser]

I currently have the 6000 rpm chip in the MSD.

Revs good in neutral.

Not in gear.

[scarceller]

In your first post you said plug gap is 0.42" this can't be you must mean 0.042" right? Just double checking, I doubt it would even run at 0.42" or for that matter not possible to even gap them at that value.

[RSWiser]

Yes .042 is correct.

[vash]

where did you ground the MSD unit? i missed it if you mentioned it......

[Rebel911]

Grounded to the fan shroud but I am going to run a 2 gauge grounding strap from that location to the frame.
I am uploading pics of the rotor mod now. they will be posted with in the hour.

[Eagledriver]

Double check your timing. I suspect you are way advanced. Engine runs fine until 3500 RPM when the advance goes so high that the spark cant make the jump from the rotor anymore. It's easy to mistake the 30 degree mark for the Z1 or 5 degree timing marks. When I had this problem it was because the magnetic pickup was hooked up backward. It gave me about 35 degrees of advance at idle.

The green wire should go to green and the purple to the shielding.

-Andy

[Rebel911]

Non-mod rotor 5.05 kilo ohms
modified rotor 0.0 ohms
the rotor mod:
(sorry pics are huge my normal host was down)

[Rebel911]

Well did everything:
new ground straps
new ground for battery
modded the rotor
drilled holes in the cap (per MSD)
checked wires

still idles good but as some as I let the clutch out if backfires and loses power.
I am going to close the gap down more on the plugs.
from .042" to .035"
any other ideas?

[john walker's workshop]

was your original bosch unit dead?