Increasing Spark Plug Gap?
OpelGT.com is the premier Opel GT Forum on the internet. Registered Users do not see the above ads.
Results 1 to 18 of 18
Like Tree1Likes
  • 1 Post By Viny Charb

Thread: Increasing Spark Plug Gap?

  1. #1
    Destiny is to Fly My location ronskydivepops's Avatar
    Join Date
    Mar 2005
    Location
    Sanford, Florida
    Posts
    224
    Downloads
    0
    Uploads
    0

    CoolIncreasing Spark Plug Gap?

    I've just installed a pertronix ignition and flamethrower coil. Just wondering if increasing the spark plug gap will help. It's now set at .30 with new plugs. Compression is low (around 140) Just hoping to help burn off a bit of the oil that's blows by the rings, at least until I get my new engine built!! Thanks for any help

  2. Remove Advertisements
    OpelGT.com
    Advertisements
     

  3. #2
    Cunning Linguist Site Supporter My location tekenaar's Avatar
    Join Date
    Mar 2002
    Location
    Plano, TX 75074
    Posts
    5,297
    Real Name
    Otto
    Downloads
    0
    Uploads
    0

    ExclamationPertronix plug gap

    Quote Originally Posted by ronskydivepops
    I've just installed a pertronix ignition and flamethrower coil. Just wondering if increasing the spark plug gap will help. It's now set at .30 with new plugs. Compression is low (around 140) Just hoping to help burn off a bit of the oil that's blows by the rings, at least until I get my new engine built!! Thanks for any help
    Due to the increased timing accuracy and reliability of the Pertronix trigger, even using a stock coil, I increase the gap to 1mm (.040" for the metrically challenged) and make the following modification to the standard Bosch W7BC plugs (99¢) I use:

    Last edited by tekenaar; 03-05-2006 at 05:46 PM.


    1960: '61 Rekord PII 1.7 3S 3.9 '69 Kadett LS 'sprint' 1.9 3A 3.18
    1970: '70 GT 1.9 4S 3.44 '72 GT 2.2SSD 5S 3.44 '72 GT 2.4FI 5S 3.44P
    1970: '73 GT 1.9FI 4S 3.44 '75 1900 1.9FI 4S 3.44
    1980: '85 Bitter SC 3.9FI 5S 3.44P
    2000: '09 Solstice GXP Coupe 2.0 SIDI VVT "Stage 2" Turbo 5S 3.73P


    "De inimico non tantum loquaris male, sed cogites."

  4. #3
    Hoosier Opeler Site Supporter My location rrossjr's Avatar
    Join Date
    Mar 2004
    Location
    indiana
    Posts
    1,512
    Real Name
    Ron
    Downloads
    2
    Uploads
    0
    Quote Originally Posted by tekenaar
    ... and make the following modification to the standard Bosch W7BC plugs (99¢)
    Otto, can you explain what you mean about improved flame front?
    Ron in Indy

  5. Remove Advertisements
    OpelGT.com
    Advertisements
     

  6. #4
    1000 Post Club My location baronbors's Avatar
    Join Date
    Dec 2002
    Location
    League City Texas
    Posts
    1,126
    Downloads
    0
    Uploads
    0
    Quote Originally Posted by rrossjr
    Otto, can you explain what you mean about improved flame front?
    Ron in Indy
    I'm guessing more exposed spark: ergo- more better combustion?

    Texas Opel Preservation Society

  7. #5
    7,000 Post Club My location wrench459's Avatar
    Join Date
    Jul 2005
    Location
    Milner, GA.
    Posts
    11,260
    Real Name
    Dan
    Downloads
    12
    Uploads
    0
    by opening up the plug gap there will be more load on the secondary..coil,rotor,cap,wires,plugs
    as the plugs get worn in a typical car the firing voltage goes higher and the burn time gets shorter "keep this in mind"
    ok time for a short story...when I was working for a Chrysler dealer back in the 80's
    customer would come in for a Tune-up we would pull out the worn spark plugs (over .045 gap)
    and install fresh plugs gaped at the factory spec .035 I might be wrong with the numbers been awhile lol
    anyway MANY of the customers came back with a lost fuel mileage problem after the tune-up
    regaped the plugs to .040 problem solved

    are the plugs getting oil fouled if so the oil rings may be frozen try some upper intake cleaner
    because 140 psi compression aint that bad

    Go for it and see what happens with the bigger gap

  8. #6
    5,000 Post Club My location namba209 (R.I.P.)'s Avatar
    Join Date
    Aug 2002
    Location
    Imperial Beach, CA South of San Diego
    Posts
    5,893
    Downloads
    0
    Uploads
    0
    One of the tricks I used on my racing motorcycles way back in the 60s-70s, was to get a K-Mart brand, non Ford use 8 cylinder coil. There were many reasons, the prime being that brand coil would jump a 2 inch gap between electrodes during a test of coils conducted by a motorcycle magazine. They also had an idea that using an 8 cylinder coil, the time for coil saturation would be greater since we were only firing 1 or 2 plugs instead of 8 at the same RPM, and because of that, the coil would work nicely when the RPMs went into the 5 digit range. I would gap my plugs at .080" and never had a misfire. Using that ignition setup, along with a lot of other engine mods, I was able to get my Honda SL-90 from 55 MPH using a 15-47 final drive, to 70 MPH using a 13-70 final drive, with the RPMs up into the 14-16000 range. Also, I only had to change the points at the end of the racing season, and only because it seemed like the thing to do, they were not pitted or burned, just a little tarnished after a year of racing. HTH.
    Ron
    72 GT 3.4L V-6/T-5/ZF posi - almost done - Just need AC installed.
    75 Chevy monza 5.7L/TH350/Auburn 3.08 posi - Next

  9. #7
    Cunning Linguist Site Supporter My location tekenaar's Avatar
    Join Date
    Mar 2002
    Location
    Plano, TX 75074
    Posts
    5,297
    Real Name
    Otto
    Downloads
    0
    Uploads
    0

    Flame front . . .

    Quote Originally Posted by rrossjr
    Otto, can you explain what you mean about improved flame front?
    Ron in Indy
    Rather than being partially shrouded by the ground terminal, it exposes more of the spark to the combustion chamber and 'lights off' the compressed mixture somewhat better . . . old Smoky Yunick trick from the '50s.
    Last edited by tekenaar; 03-06-2006 at 02:13 AM.


    1960: '61 Rekord PII 1.7 3S 3.9 '69 Kadett LS 'sprint' 1.9 3A 3.18
    1970: '70 GT 1.9 4S 3.44 '72 GT 2.2SSD 5S 3.44 '72 GT 2.4FI 5S 3.44P
    1970: '73 GT 1.9FI 4S 3.44 '75 1900 1.9FI 4S 3.44
    1980: '85 Bitter SC 3.9FI 5S 3.44P
    2000: '09 Solstice GXP Coupe 2.0 SIDI VVT "Stage 2" Turbo 5S 3.73P


    "De inimico non tantum loquaris male, sed cogites."

  10. #8
    1000 Post Club My location baronbors's Avatar
    Join Date
    Dec 2002
    Location
    League City Texas
    Posts
    1,126
    Downloads
    0
    Uploads
    0
    YUH UH YUH UH- I was right- I win. I did win-didn't I?

    Texas Opel Preservation Society

  11. #9
    Member My location bosco's Avatar
    Join Date
    Nov 2003
    Location
    Las Vegas, NV
    Posts
    456
    Downloads
    0
    Uploads
    0
    how does one do that unshrouding??? with a file???

    .
    Next stop the Twilight Zone.....

    1973 Opel GT

    Previously:
    1971 Opel GT
    1973 Opel Manta
    1977 Datsun 280Z
    1993 Nissan 300ZX

  12. #10
    Cunning Linguist Site Supporter My location tekenaar's Avatar
    Join Date
    Mar 2002
    Location
    Plano, TX 75074
    Posts
    5,297
    Real Name
    Otto
    Downloads
    0
    Uploads
    0

    ExclamationPlug prepping

    Quote Originally Posted by bosco
    how does one do that unshrouding??? with a file???

    .
    I open the gap somewhat and then cut the ground strap, !!! VERY CAREFULLY !!! , with an angle grinder and finish with a hand file, again . . . carefully! I usually round off the new corners too and then gap to 1mm (.040").


    1960: '61 Rekord PII 1.7 3S 3.9 '69 Kadett LS 'sprint' 1.9 3A 3.18
    1970: '70 GT 1.9 4S 3.44 '72 GT 2.2SSD 5S 3.44 '72 GT 2.4FI 5S 3.44P
    1970: '73 GT 1.9FI 4S 3.44 '75 1900 1.9FI 4S 3.44
    1980: '85 Bitter SC 3.9FI 5S 3.44P
    2000: '09 Solstice GXP Coupe 2.0 SIDI VVT "Stage 2" Turbo 5S 3.73P


    "De inimico non tantum loquaris male, sed cogites."

  13. #11
    Member My location bosco's Avatar
    Join Date
    Nov 2003
    Location
    Las Vegas, NV
    Posts
    456
    Downloads
    0
    Uploads
    0
    Thanks Otto...

    so it would probably be helpful for my set-up too...
    early 1.9 with flat top pistons, solid lifters, crane ignition, stock type coil (red label bosch i think), sprint manifold.......and the same .040" would also be appropriate??
    Next stop the Twilight Zone.....

    1973 Opel GT

    Previously:
    1971 Opel GT
    1973 Opel Manta
    1977 Datsun 280Z
    1993 Nissan 300ZX

  14. #12
    Cunning Linguist Site Supporter My location tekenaar's Avatar
    Join Date
    Mar 2002
    Location
    Plano, TX 75074
    Posts
    5,297
    Real Name
    Otto
    Downloads
    0
    Uploads
    0
    Quote Originally Posted by bosco
    Thanks Otto...

    so it would probably be helpful for my set-up too...
    early 1.9 with flat top pistons, solid lifters, crane ignition, stock type coil (red label bosch i think), sprint manifold.......and the same .040" would also be appropriate??
    Right on, Bro!


    1960: '61 Rekord PII 1.7 3S 3.9 '69 Kadett LS 'sprint' 1.9 3A 3.18
    1970: '70 GT 1.9 4S 3.44 '72 GT 2.2SSD 5S 3.44 '72 GT 2.4FI 5S 3.44P
    1970: '73 GT 1.9FI 4S 3.44 '75 1900 1.9FI 4S 3.44
    1980: '85 Bitter SC 3.9FI 5S 3.44P
    2000: '09 Solstice GXP Coupe 2.0 SIDI VVT "Stage 2" Turbo 5S 3.73P


    "De inimico non tantum loquaris male, sed cogites."

  15. #13
    Member My location bosco's Avatar
    Join Date
    Nov 2003
    Location
    Las Vegas, NV
    Posts
    456
    Downloads
    0
    Uploads
    0
    Groovy....
    Next stop the Twilight Zone.....

    1973 Opel GT

    Previously:
    1971 Opel GT
    1973 Opel Manta
    1977 Datsun 280Z
    1993 Nissan 300ZX

  16. #14
    former opel racer My location jeff denton's Avatar
    Join Date
    Nov 2002
    Location
    near some glaciers
    Posts
    2,736
    Real Name
    Jeff "Oh-Oh" Denton
    Downloads
    0
    Uploads
    0
    That's a neat tip, Otto. I think I'll play with that. Have you ever tried indexing the plugs, I wonder where the ground strap should point to get the most benefit of the theory...

  17. #15
    Old Opeler My location GTJIM's Avatar
    Join Date
    Jun 2003
    Location
    New Zealand
    Posts
    5,565
    Downloads
    0
    Uploads
    0

    "J" gaps

    At one time spark plugs were available with the cut back side electrode - the theory being that the spark was more exposed to the combustion chamber and the sharp edge of the side electrode lowered the voltage requirement to fire the plug because electrons will depart from a sharp edge easier than from a flat surface.
    Indexing the plugs so the "open" side of the gap faces into the combustion chamber is another theoretical way of getting quicker and better flame travel through the combustion chamber. Though with the 'squish' type chamber the mixture is moved towards the flame front rather than the flame front having to travel.
    GTJim
    Opel Owner since last Century!

    Copyright © 2000-2009
    J D Henry
    All Rights Reserved

  18. #16
    BDD
    BDD is offline
    Member
    Join Date
    Mar 2003
    Location
    Wisconsin
    Posts
    1,176
    Downloads
    0
    Uploads
    0
    The sharp corners would be better for sparks to depart from. Pointed electrodes are best for that.

  19. #17
    Über Genius My location First opel 1981's Avatar
    Join Date
    Apr 2003
    Location
    Portland, Oregon
    Posts
    6,540
    Downloads
    0
    Uploads
    0

    Adding to an old thread

    I was reading this thread and thought I might want to follow some tech advice in here.

    I took my relatively new plugs and checked the gaps. They went from 25-32.

    I regapped them to .035" and then used a dremel to, very carefully (I have 10X magnifying goggles I use), grind the ground strap back to about 1/3 of the electrode showing when I looked straight inline with the electrode.

    It makes sense to do this as it exposes a considerable larger portion of metal for the electrode jump the spark to.
    Opel GTs are not GM products
    ̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶— ̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶ ̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶ ̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—
    Humans are not an endangered species!
    ̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶— ̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶ ̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶ ̶̶̶—̶̶̶̶̶̶̶—̶̶̶̶̶̶̶—

  20. #18
    1000 Post Club Viny Charb's Avatar
    Join Date
    Oct 2007
    Location
    Ontario Canada
    Posts
    1,280
    Downloads
    0
    Uploads
    0
    Cool little spark plug trick.
    First opel 1981 likes this.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

    Similar Threads

    1. SSD Manifold
      By nobody in forum Opel Engine Performance Modifications
      Replies: 10
      Last Post: 04-12-2006, 05:44 PM
    2. No Spark to distributer cap
      By crliwa in forum 1B - Ignition System
      Replies: 10
      Last Post: 07-26-2005, 11:48 PM
    3. Performance Spark Plug Wires
      By soybean in forum Opel Engine Performance Modifications
      Replies: 2
      Last Post: 09-09-2004, 01:40 AM
    4. Plug Gap?
      By greensmurf20 in forum 1B - Ignition System
      Replies: 2
      Last Post: 09-05-2004, 01:32 PM
    5. spark plug / ignition question
      By GT_Pheel in forum 1B - Ignition System
      Replies: 6
      Last Post: 04-30-2004, 08:53 AM

    Bookmarks

    Posting Permissions

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