Close



Results 1 to 9 of 9
  1. #1
    FEP Power Member fgross2006's Avatar
    Join Date
    Sep 2014
    Location
    Freeport NY
    Posts
    1,531

    Default crusty cap and rotor

    I have been having an intermittent RPM droppage at red lights that I've been trying to diagnose. This started after I dropped in a crate rebuilt motor last August. Didn't have the problem with the old motor.

    At first I thought I was losing fuel pressure so I dropped a Walbro fuel pump in but that didn't solve the issue.

    I pulled the stock Motorcraft ignition coil the other day and put a high performance Accel in. I saw a nice boost in power but the car did have one RPM drop episode after putting it in.

    Today I pulled the cap, rotor and wires. I had stock motorcraft cap and rotor and MSD 8.8 mm wire set. I had put new Motorcraft platinum plugs in when the motor was dropped in.

    I put in stock Motorcraft cap and rotor and Ford racing 9 mm wire set.

    This is what the cap and rotor looked like when I pulled them. I didn't change them last August when the motor was swapped but I cleaned them with sandpaper and re used them. This is what they look like after 6 or 7 months. Not a daily driver so its not been run everyday.

    What caused this kind of crustation in the cap and breakdown of the rotor and is the cause or the symptom?

    For the record, after changing the cap, rotor and wires I drove the car a mile to bring to operating temp and ran code scan. Ran all 11's. No codes at all.

    Name:  20170320_150308.jpg
Views: 74
Size:  133.9 KB

    Name:  20170320_160736.jpg
Views: 74
Size:  81.5 KB

    Name:  20170320_160856.jpg
Views: 74
Size:  65.4 KB

  2. #2
    FEP Super Member JTurbo's Avatar
    Join Date
    Jan 2006
    Location
    Western MA
    Posts
    5,609

    Default

    Just guessing - moisture in the cap during long periods of storage????

    Glad the swap was simple and fixed the problem.

  3. #3
    FEP Power Member fgross2006's Avatar
    Join Date
    Sep 2014
    Location
    Freeport NY
    Posts
    1,531

    Default

    Quote Originally Posted by JTurbo View Post
    Just guessing - moisture in the cap during long periods of storage????

    Glad the swap was simple and fixed the problem.
    Im not sure if the problem is solved. I have to drive a few days to see if it comes back.

    The stock Ford distributor sits loose so I don't see how to keep moisture out. Very poor design.

    The had no codes last week either before I changed everything so it just means the ECM isn't complaining or not detecting what is causing the RPM droppage.

  4. #4

    Default

    Crap aluminum is the cause of "crustation". Brass materials within ignition components is MUCH better.
    Mike
    1986 Mustang convertible ---> BUILD THREAD
    1983 Mercury Cougar LS
    1986 Ford Thunderbird ELAN
    1966 Ford Fairlane sedan
    1966 Ford Fairlane GT
    1981 Mercury Marquis Brougham
    1980 Capri RS Turbo
    1971 Mustang
    1974 Pontiac LeMans

  5. #5
    FEP Power Member fgross2006's Avatar
    Join Date
    Sep 2014
    Location
    Freeport NY
    Posts
    1,531

    Default

    Quote Originally Posted by Walking-Tall View Post
    Crap aluminum is the cause of "crustation". Brass materials within ignition components is MUCH better.
    in my old motor I had an MSD cap and rotor and the white crust buildup was worse than with a stock motorcraft. The MSD was so bad that if I cleaned the contacts and tried driving again it would last 2 days at most before the car had no spark and the cap was fouled again. I briefly considered re using the MSD cap but when I looked at it closely I saw big pit marks in the contacts.

    General consensus, whats the best quality cap and rotor out there?

  6. #6
    FEP Super Member mustangxtreme's Avatar
    Join Date
    Feb 2009
    Location
    Snohomish, Wa
    Posts
    3,954

    Default

    You want a cap and rotor that have brass contacts.
    Dave

    If common sense was common wouldn't it just be sense?

    1983 Capri L T top 5.0 efi aod
    1983 Capri RS Turbo
    1981 Black Magic 400 c6
    93 F-250 351 5sp 4x4

  7. #7

  8. #8
    FEP Supporter BMW Rider's Avatar
    Join Date
    Oct 2014
    Location
    Calgary, Alberta, Canada
    Posts
    575

    Default

    That's pretty normal build up on those contacts. You can scrape them clean as long as the aluminum is not too eroded. If the contact is eroded too much, the gap gets excessive and reduces your spark output. Basically that gap being too large is like a badly worn plug as the spark has to jump the gap. Too wide and it take more voltage to do so leaving less for the actual plug. Normal wear item that should be inspected and or replaced at similar intervals to the spark plugs.

  9. #9

    Default

    Check for leaks in the shaft seal. If your distributor has excessive endplay it will chew the hell out of any cap and rotor. It also leads to misfires and hard starts, etc. if it gets really bad you'll get oil deposits in the cap and oil down in the distributor internals that have to be cleaned frequently to make the motor run. Granted mine had 400K when I saw this problem for the first time.

    And agreed - the MSD caps are far from ideal on a stock dizzy. The problem seems to be both in material selection vs tolerances between the cap and rotor. I somewhat attribute it to endplay on a factory distributors as I've not seen similar problems on an MSD replacement dizzy ever.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •