MSD Cap build-up

[Rwillia4]

The car started missing at first I thought is was fuel related because of the dark soot and occationally 4' flame coming out of the exhaust but I check the FI mapping and it wasn't doing anything crazy. Then I started checking the ignition system. I swapped the coil (had a spare) then I looked at the cap (in this order mostly because the cap is a PITA to get off with the TWM rail system. I think this might be the problem, I'm planning on getting another cap. The rotor looks OK but I'll change that also.

I have under 2000 miles on this cap. Does this look normal?
To me it looks like a lot of buildup for 2K. Additioanlly, it looks like it is not firing while the rotor is in the middle of the post. Can this be changed?

Details: ignition MSD 6D, Distributor MSD, FAST Brain

[Blas]

Ozone & moisture buildup...even in a vented cap....solve this problem and you'll be rich.
Been all kinds of ideas to minimize this from drilling additional vent holes to a continuous vacuum purge connection added to the cap.
Just be sure your center connector on the rotor is touching the carbon button...The spark will jump to the contacts as soon as it has enough energy to do so, it won't wait to be centered on the post.

[FWB]

it does seem a bit off.....as far as mileage i normally get about 3000 mi from a cap.
actually it looks better than mine usually do.
like blas said the center electrode is usually the pain you get from these caps. just bend the rotor tang up to be assured of a good contact. i found caps to be a bit sloppy of a fit on the housing.

msd told me to drill a small hole in mine, oriented to the rear of the cap

[Clois Harlan]

Originally Posted by FWB

it does seem a bit off.....as far as mileage i normally get about 3000 mi from a cap.
actually it looks better than mine usually do.
like blas said the center electrode is usually the pain you get from these caps. just bend the rotor tang up to be assured of a good contact. i found caps to be a bit sloppy of a fit on the housing.

msd told me to drill a small hole in mine, oriented to the rear of the cap

Same duration for me. About 3000 miles and then buy another. $25 is about the cheapest thing you buy on a Cobra.


Clois

[Blas]

The newer red vented caps seem to have more problems than the older black caps did. I know they changes cap material and added a vent on the top of the cap. But I immediately noticed that my Escort radar detector's Laser alert goes crazy with the new red cap. And I believe it interfers with my garage dood opener. Never had those problems with the old style black cap. I actually went back and forth with the caps so I know the red cap is the problem...

[Robert McLinden]

My first red cap only lasted 10000 miles or so, then the center button fell out.

[kiwi408]

Hi Sorry to go off topic but the comment on the radar detector false alert on laser caught my attention.I have a Bel detector that false alerts on laser but only in my Cobra, not any other vehicle.I used to think it was because my IGN box was inside the cockpit on top of the trans tunnel,now I have fuel injected the car and the IGN box is on top of the passenger footwell under the hood,about 3 ft away,and the ECU is now where the IGN box used to be.Still false alarms so is it a field of some sort that is causing the interference or something else altogether? Thanks Greg

[Barnsnake]

The buildup on the posts doesn't look too bad, but you may want to do a search on "rotor phasing". It's possible that the small buildup in conjunction with bad phasing could cause your misfire.

[Rwillia4]

Thanks for all the input. The buildup is all on the lower edge of the post which makes me thing the rotor is not lined up with post and below it. I'll look up phasing.

thanks again

[RICK LAKE]

Rwillia4 Your cap looks OK. I been through the 1,000 minute cap and less.
This is the best info I have and seen to this date
Center piles fall out of or burnt up in the MSD caps
Burn holes in the rotors
Phazing being out causing all kinds of spark issues
Coils getting weak from heat, vibration, low voltage, and oil filled coils that are mounted on motors in a horizontal location.
For caps and rotors, some of the guys have gone to a cheap cap with a brass center terminal and rotor. It's a SBC I think. If you search CC and FE forumn there are a couple of threads about this with part numbers.
Phazing the distributor, I also have a FAST system with a crank sensor and cam sensor. Need correct phazing to the ECU to know where #1 cylinder is. To get this perfect, get old cap and grind out cap in top with dremel tool and open #1 terminal torward the middle. You want the rotor end to be centered on the cap post and terminal in the cap. You can also run the motor with this open window to check spark and see if you have any other problems. I wouldn't run this on the street because of getting dirt and other debrie in there.
The other thing is which coil are you running?? Are you running a ballast resistor for power. Some coils plug direct to MSD module and some don't.
MSD said "they don't recommend that you mount certain coils on motor or in horizontal location. I think an "E" coil it doesn't matter, oil filled is different. Msd has problems with caps and rotors, I would keep a spare kit along with a spare 6AL in the car with tools to fix on the side of the road. I carry a new distributor, MSD 6al module, and "e" coil with tools. Have used cap and rotor once in 15 years and lent out these parts to another FE owner at SCCA 31.
Good luck Rick L. PS have the remember that there is 20 degrees of steady spark to the terminal at lower rpms. I believe that over 3,000 rpms this is dropped because of rotor speed in the distributor. Also this causes alot of heat in the coil too. Same thing with sequential fuel injection with the old FAST system. Goes from Sequential to batch fire over certain RPM because there is no power differents you will feel.

[STEVE-O]

I replaced mine after about 6K miles and it didnt appear to have as much corrosion as yours is showing there.
A fellow cobra owner gave me the suggestion to seal the front part of the distributor where the wire from the control box enters, with silicon. Lots of dirt and moisture enters thru here. The cap is still vented at the top to release any other buildup of gases.
It may just be that where you are located its more humid and it needs to be changed more often as opposed to here in the dryer NE.

[glassdriver72]

I had mis-firing issues this past summer. Everyone said it was fuel related, probably an incorrect float level. Took the carb apart twice, and then had it rebuilt. Same problem. 4th person to look at it said that's an electrical problem, not fuel. We pulled the MSD vented cap and at least a teaspoon of water came out.


Proves always check the simple things first.

[SwiftDB4]

Agree with all the prior posts. MSD quality is definitely lacking. Check phasing as noted. Mine was OK, but I noticed like yours that the rotor was under the cap contacts! I cut off rotor tip and added another tip on top of original to raise the contact to proper height. You would think MSD could do better than that. Does anyone know if there is an alternative cap for the smaller diameter 351W distributor?

[Blas]

Would be interesting to know if this problem has been there since day 1 on the car or if it just started when you replaced the cap... If it just started and ran correctly before, you may have another issue lurking somewhere... I would assume that the caps all come from the identical forming press design molds so the alignment of the contacts and the depth of the contacts are uniform across the manufacturing process. Same holds true for the rotor. No possibility you replaced the rotor with the wrong part? No carbon burn marks around the center carbon post that I can see on the photo. Did you bend up the contact on the rotor a little to insure good continuous contact with the caps center button? I remember reading about a problem with some caps sitting too low and the gap was then too big at the 8 outer contact posts. Any rust or corrosion on the distributor internals? Are the Magnetic pickup wires secure and not too close to a plug wire... did you make any modification to the routing of the wires between the distributor and the MSD box to maybe clean it up since you were working on it? Good ground on the MSD box? Good secure power supply connections on the box? The ignition is usually wired as the switch for an MSD box...they are notorious for spreading power issues...

[601HP]

Originally Posted by Blas

The newer red vented caps seem to have more problems than the older black caps did. I know they changes cap material and added a vent on the top of the cap. But I immediately noticed that my Escort radar detector's Laser alert goes crazy with the new red cap. And I believe it interfers with my garage dood opener. Never had those problems with the old style black cap. I actually went back and forth with the caps so I know the red cap is the problem...

The cap is still available in black. #84333.

I get some of the build up on the posts. I use a Dremel tool with the soft wire wheel. The build up comes off in seconds and the post looks good!

David

[Blas]

REALLY....I looked around any you are correct...Thanks, that made my day..

[Rwillia4]

Blas, for me this is my first cap and rotor and I haven't touched them b/c the are a pain to get to with the TWM fuel rail in the way. The rotor looks to be in great condition at the center point and on the edge. No wires moved and insid ethe housing looks clean with no carbon or other crap other than on the cap post.
I've never had a problem that I could tell and this came on pretty fast (within 20 miles after a cold morning start). It began to miss on multiple cylinders at highway speeds, it felt like a way rich condition (it was because the plugs weren't firing). When I punched it, it would come back to life, kinda, sometimes it bogged down other times it worked. This again made me think it was fuel. I'm tempted to clean the current one and give it another try as I wait for the new cap and rotor to come in just to make sure this is in fact the problem. I know it is not lack of fuel!

[Rick Parker]

Rwilla4:
I recently had an episode that entailed replacing a distributor with a different one (mechanical tach drive type) that caused me to question the integrity and condition of various components of my ignition system that had worked flawlessly before the replacement. You've heard the phrase "It was the last thing I checked" (?) In my case, it was a new Ford Motorsport distributor that I had purchased about 5 years ago. Without going into detail as to what I chased, I say to you: check the air gap between the field coil and reluctor. Set it about .025. The cap looks fine. Besure the part number for the cap and rotor match and are specifically for the distributor part number being used. Sometimes that can get mismatched unintentionally.

[601HP]

Originally Posted by Blas

REALLY....I looked around any you are correct...Thanks, that made my day..

If you'd like, look in my Photos section. There are several images of my engine with the black cap. Click to enlarge. I installed that cap in 2009.

David

[Rwillia4]

So I did a little touch up on the cap, I think I made the contacts clean enough to be somewhere between new and where it was in teh photo above. I put everything back together and it started up fine. Within a minute it gets crappy, you can hear the change in the exhaust and it idles poorly. Fuel pressure is at 45psi. FAST is remapped with a good file that I know works. I have replaced the coil and cleaned the cap. What is next the MSD distributor or the MSD box? or am I going the wrong direction and it is something else?
When I had it on the road last week as this problem started and I nursed it home, it would "clean out" when you stepped on it sometimes other times it would bog down, it was inconsistant.

I didn't screw with the distributor or the MSD box nor have they gotten wet or have there been any changes to the electrical system.