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MSD cap/rotor uneven wear

andrewwoz

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Hey guys, so I pulled the cap on my MSD distributor and the tang on the rotor is a little burnt up on one end, as are one side of all the posts in the cap. I am thinking an adjustable rotor/phasing the rotor would fix it but just wondering if it could be something else. Also, the rotor/shaft also seems to have a bit of play (not getting into the mechanical advance)


I wanted to check the rotor location when firing and I believe I did it correctly but tell me if I'm wrong. Base timing is set at 20 deg so I rotated the engine to 20deg on the balancer on the #1 cyl comp stroke. I then made a mark on the distributor body (black marker) to mark the location of the #1 cylinder post on the cap. The tang is at the far end of where the post on the cap would be and once the mechanical advance is added gets even further away.

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That play does not look right in the video.
The way you checked rotor phasing appears to be right.
 
Don't see anything that is burned up.
Static position of rotor tip & segment can be misleading. Has to line up when centri mech advances AND vac adv operates.
 
Here's the question:
How many miles do you have on it?

Yes it sounds like the rotor is phases a bit too far advanced but I the arc damage shown is not terrible.
Scrape (don't file) off the burnt stuff.
 
Here's the question:
How many miles do you have on it?

Yes it sounds like the rotor is phases a bit too far advanced but I the arc damage shown is not terrible.
Scrape (don't file) off the burnt stuff.

I have put around 3000 miles on the car but this setup was on it when I bought it, not certain how many miles the p/o put on the MSD stuff.
 
I have put around 3000 miles on the car but this setup was on it when I bought it, not certain how many miles the p/o put on the MSD stuff.
Are you having problems? I see nothing wrong with any of your photos.
 
Are you having problems? I see nothing wrong with any of your photos.

Glad to hear the wear looks normal, what about the slop in the rotor in the video?

And not having any major issues, car runs pretty well, it just feels slower than I expected it to for the setup but this is my first big block car so maybe my expectations were too high. I expected it to spin the tires if I just mash the gas while rolling in 1st at say 3000rpm but it doesn't. Its a 69 super bee with a 440HP lower end, trickflow 240 heads, comp magnum 305h cam([email protected]", .525 lift), rpm performer intake, 2" headers, 3" exhaust, 850 brawler carb, 4 speed with 3.55 gears and 255/70-15 cooper cobras in the rear.
 
It should be pretty powerful and I would expect it to spin the tires even rolling at 20 mph in 1st.
Could just be tuning?
Do the throttle plates open all the way when the pedal is to the floor?
 
Verified throttle plates do open all the way. I have been working on tuning it with a wideband/data logger, it started off very rich, cruising in the mid 12s, WOT low 11s. I have the cruise up in the high 13s now and the WOT is still rich but around 11.7. Jetting is currently at 70/82 (down from 76/84) I think I need to try an 80 in the secondary. Timing is 20 initial, 34 with advance that comes all in by about 2800rpm, no vacuum advance unfortunately.

A few other notes

-compression checked out at 160-170psi on all cylinders. I did 10 revolutions to get there, not sure if that is too many, Ive read conflicting opinions on that.

-I have at least 1 lifter that gets a bit noisey (#8 exhaust) from time to time and other lifters seem to bleed down quickly, maybe I am not getting as much lift as I should be?

-Yesterday I switched from 20w50 to 10w30 VR1 oil as my oil pressure at hot idle was 55psi+, anything above idle was 76-80psi which I was told seems a bit high. When draining the 20/50 I noticed I was down a little less than quart, I probably put about 500 miles on it since the last oil change, some of that being "spirited". I never notice any smoke and the compression test lead me to believe the rings are in good shape but I have a leakdown tester coming to further investigate. With the 10/30 after a 20 minute drive idle PSI was at about 40 (900rpm) and the gauge (autometer mechanical) reacted to RPM opposed to staying pegged at 76-80 above idle. The oil consumption seems high to me, I am wondering if I am pulling excessive oil through the PCV and/or breather which is connected to the air filter base, would that kill some power?
 
Hey guys, so I pulled the cap on my MSD distributor and the tang on the rotor is a little burnt up on one end, as are one side of all the posts in the cap. I am thinking an adjustable rotor/phasing the rotor would fix it but just wondering if it could be something else. Also, the rotor/shaft also seems to have a bit of play (not getting into the mechanical advance)


I wanted to check the rotor location when firing and I believe I did it correctly but tell me if I'm wrong. Base timing is set at 20 deg so I rotated the engine to 20deg on the balancer on the #1 cyl comp stroke. I then made a mark on the distributor body (black marker) to mark the location of the #1 cylinder post on the cap. The tang is at the far end of where the post on the cap would be and once the mechanical advance is added gets even further away.

View attachment 1458933
View attachment 1458935
View attachment 1458936View attachment 1458937

IMO....The leading edge (direction of rotation) of the totor terminal's arc mark is normal. The trailing edge of the rotor terminal shows the result of the arc mark or burning is due to the physical spark as the rotor interrupts the spark voltage as the rotor moves to the next cylinder to be fired. This spplies to BOTH the rotor and the cap's terminal.....this is entirely normal and is to be expected......due to the higher voltage being switched....just a benefit of s MSD ignition system.....just my opinion of course...
BOB RENTON
 
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