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Help! FJ40 SBC tune-up spark plugs, distributor questions?

Discussion in '40- & 55-Series Tech' started by ARC1, Aug 13, 2009.

  1. ARC1

    ARC1 New Member

    Messages:
    585
    Location:
    Orange County, CA
    I can't find spark plugs for my SBC!:bang: I just fixed (I think) my Edelbrock carb by wiring full 12V power to the electric choke (from wiper circuit). I wanted to change out the spark plugs, because I suspected it's been running rich with the electric choke constantly closed.
    [​IMG]
    ~ looks pretty black, sooty, not too oily. Too rich? Need hotter plugs? Gap?

    [​IMG]
    According to my stampings, this is a '65 327cid SBC, but the plugs Autozone gave me don't seem to match and needed 13/16" socket. The old plug installed is 5/8" socket. (don't know if thread and distance are same.. rats, should have checked that) But, the wells for the plugs seem a little small. Someone here suggested one of the POs may have changed out the headers, so spark plugs may not be spec?

    How do I find this spark plug? or the best alternative? The only one that came up on cross-reference at A-Zone was this Motorcraft, which threads in nicely, but sticks out farther. In fact, I couldn't tighten it down, because my 5/8" socket wasn't deep enough.
    [​IMG]

    This is my distributor. Is it HEI? (how can you tell?) So, I don't need to worry about points, or dwell? Any idea what this random disconnected nearby wire is?
    [​IMG]
    So, the old Bosch Super plug looks gap'd around 0.035. If I have an HEI Distributor, I was going to gap 0.040 to 0.045? Does a bigger gap affect timing? Does that need adjusting? I'm assuming it's been rebuilt, so the original spec timing criteria don't apply anymore?

    As always.. THANKS! :cheers::beer:
  2. RMC73FJ40

    RMC73FJ40 Regular Member

    Messages:
    149
    Location:
    Lawrenceville, GA
    If you're running 5/8 plugs then it's probably not 1965 heads on there. Maybe take a look at a plug like this for starters:

    ACDelco R44TS - ACDelco Conventional Resistor Spark plugs – SummitRacing.com

    I would gap around .040

    The wire you're pointing at should be the tach wire. I believe it'll be written on the top of the distributor.

    Do your heads have mounting hold holes (front and rear) for accessories in them?
  3. cmiller114

    cmiller114 New Member

    Messages:
    298
    Location:
    Enola, PA.
    Sparkplugs.com - Application Search Results

    You are confusing yourself! The Bosch plugs you pulled are 13/16.....the new plug is 5/8. You have a 1st generation small block chevy.....any plugs on the list above will work. Gap 35 or 40, it's not critical unless you are mega horsepower and gap certainly won't affect timing.
    HEI distibutor has coil built in to cap.....like yours.
    I agree...looks like tach lead....trace it back.
    Check out distibutor cap, rotor and plug wires very carefully...they look a little old and tired to me.
    You will find that most guys at box stores like Autozone don't have a clue......not all but most. You are better off figuring out what you need and ordering it from Summit or Jegs. IMHO
  4. pb4ugo

    pb4ugo SILVER Star

    X2, Try r44ts or r45ts AC plugs. I prefer a gap of .045. Run them for a while then pull a couple to see how they look. The lower the # the cooler the plug & vice versa.
  5. ARC1

    ARC1 New Member

    Messages:
    585
    Location:
    Orange County, CA
    lol.. that's for sure! :lol:

    Hmm.. I originally got 8 Bosch Plat plugs 13/16 and a 13/16 socket. Wouldn't fit on the current plugs. Returned everything and just got the 5/8 socket, which fits and removed this Bosch Super plug. Tested it, and it fits perfect in the 5/8 socket. I took it to A-zone, and as mentioned.. they were clueless. First one I went to, the guy insisted that based on my year/engine info, I need the 13/16 plugs, and that I should go to NAPA (maybe the 1 good piece of info he gave me). The 24hr A-Zone, was able to cross-reference this Bosch Super with a Motorcraft plug. It threads in, but it's too long for my socket. I'm thinking of returning the Motorcraft, and maybe trying the ones you guys suggest from Summit or JEGS.

    Regarding that green tach wire.. makes sense. I have no tach on my panel, but was considering installing one. So the tach hooks up here? or the wire goes to the distributor? It does say "TACH" on the distributor, but this green wire does not appear to be coming from the distributor itself. I'll check more closely and try to trace it back. Maybe the other end heads towards my instrument panel and ends? ( I have dozens of cut end wires all over my rig! :confused: )

    I was also considering changing out the wires and distributor/rotor with new OEM brass-contact parts, but now I'm not all that confident in A-zone, so I'm wondering if I should just remove the parts and take them somewhere to make sure I get the correct replacement parts? Can any of you pros tell from the outside appearance and info I've already provided, a specific part number for a replacement OEM distributor/rotor/wires?

    :beer::beer::beer:
  6. CruisinFJ60

    CruisinFJ60 New Member

    Messages:
    6,140
    Location:
    Ft. Worthless, TEXAS!
    do NOT put bosche plugs in a chevy, they never seem to last long on really any year chevy for whatever reason. go with A/C Delco.

    and just cause the block is 1 thing doesnt mean the heads arnt another.

    could help you later down the line to run the numbers on the heads.

    i had an old 70 chevy LWB p/u and it supposedly had a 350 then once i ran the numbers i found it was a 327 block and 305 heads. she ran really nice but still wasnt what it supposedly was. and just looking at em its not likely you can tell between the 3. (305 / 327 / 350)
  7. ARC1

    ARC1 New Member

    Messages:
    585
    Location:
    Orange County, CA
    Ok.. i've seen AC Delco mentioned a few times now..

    I'll go with AC Delco plugs. Is there a downside to using a hotter plug, like the R45TS ?

    I'll look at my HEI AC Delco distributor, and maybe carefully dissect it a bit, to see if I
    can figure out exactly what replacements parts to order online.
  8. ARC1

    ARC1 New Member

    Messages:
    585
    Location:
    Orange County, CA
    my rig is idling better, but still sputters and occasionally quits.
    I've sprayed out the edelbrock carb (but did not disassemble), put fuel filters on either side of the fuel pump, changed air filter, wired 12V to the electric choke, and will replace plugs tomorrow.

    Wondering if I need to change the distributor cap & rotors? It's a Delco-Remy HEI, and I pulled off a plug with difficulty, and the contacts look brass. Looks old.. How much difference do new cap/rotors make? Will the new plugs/cap/rotor/wires make any noticeable change? How can I tell if the coil needs replacing? Will it fix my idle problem? I think I may need some kind of carb adjustment, or rebuild. Also, it's kind of hit-or-miss finding parts. The '65 SBC 327cid engine has a traditional points distributor, so I'm not quite sure what is compatible with this upgraded, but old, Delco-Remy HEI part. Any recs on brands? I see these MSD ignition set-ups?
    THANKS..
  9. 4x4Poet

    4x4Poet New Member

    Messages:
    309
    Do a Summit search on the Bosch plug part number and see if compatible plugs from other brands also come up.
  10. cmiller114

    cmiller114 New Member

    Messages:
    298
    Location:
    Enola, PA.
    OK.....buy AC delco R44ts or Champion RJ18YC. DO NOT experiment with hotter plugs! Danger.
    Install plugs. Let the motor idle up to operating temperature don't rev it. Shut down, pull a plug and post up pic (nice pics BTW). Take the pic on a slight angle so we can see down into the plug from the bottom. Reinstall the plug, start motor and rev it up to about 3000 and hold it. With the motor running at appx 3000 shut off the ignition.....pull plug and post up pics.
    Yes...Cap, rotor, coil, wires can all make a big difference. Pull the cap off and post up a pic of the contacts inside the cap and the single contact on the rotor. Inspect the wires.....check every inch for cracking, burn marks or stiff spots.
    I have a MSD Streetfire HEI with less than 1000 miles on it......you can try it...if you like it $100 plus the ride. You will need new wires. I also have a known good Edelbrock 600 with tuning kit from same motor $150 plus the ride.
  11. pb4ugo

    pb4ugo SILVER Star

    IMO, Champion is a lawnmower plug.:) Stay genuine GM & use AC plugs.

  12. RMC73FJ40

    RMC73FJ40 Regular Member

    Messages:
    149
    Location:
    Lawrenceville, GA
  13. ARC1

    ARC1 New Member

    Messages:
    585
    Location:
    Orange County, CA
    Thanks guys.. ok, I'll swap out everything. That Summit kit looks convenient. I'm paranoid about parts not fitting, because it's actually a 327cid small-block, not 350. But, the header has been changed, which I assume wouldn't change the drive gear insertion? So, this kit should work I assume? I already picked up the Delco plugs at my local NAPA. Looking at the Summit cap pic, those terminals look aluminum? not brass? Is that ok? I'm new to this stuff, and Summit, so don't know their quality.

    I was originally planning on just doing the wires, cap-n-rotor, maybe the coil. Not sure about the steel drive gear? Is this easy to exchange? I thought I read somewhere that it can be tricky, and requires making sure your at TDC or something like that? Also, if I exchange out any parts of this ignition system, do I need to check and readjust timing? I don't have a light, and I also read that there are no clear timing guidelines in an engine this old that has likely been rebuilt.

    I'll post pics. I like the plug experiment idea. I don't have a tach meter, so maybe that would be a nice thing to add, if I can figure out how to wire it to the distributor. or.. get a hand-held tach/dwell/volt meter.

    Thanks again.. :beer::beer::beer::beer::beer:
    Last edited: Aug 14, 2009
  14. RMC73FJ40

    RMC73FJ40 Regular Member

    Messages:
    149
    Location:
    Lawrenceville, GA
    Yes.....everything should fit fine. My advice would be to bump the engine over until the rotor button points either directly to the front or rear. When you remove the distributor pay attention to where the button is pointing.....probably about 15 degrees off of where you want it. Align the new distributor like that, drop it in and it should be pointing either to the front or rear depending on how you initially lined it up. Typically the distributor can only go in right....or 180 out unless you turn the oil pump drive shaft. You'll see it's easy.

    As for for timing.....it may be off a little. Do you have a vacuum gauge? If not mark the location of the vacuum advance with chalk or something for a reference for approximate timing. I stick a pencil in the vacuum advance and mark the location on the valve cover before I remove it. I also love digital cameras for this. You can also set it by ear......rotate until you hear a miss one way and note position...then back the other way until it misses and set it in the middle.

    If you'll check your block numbers we can figure out what engine you have. They are on the block on the top of the flat portion where the bell housing bolts and behind the head (I think on the drivers side). Should be something like 3970010 or the like. If you happen to remove a valve cover we can also look up what heads are on it.

    If you need any help shoot me a PM. We just finished the LT-1 in my son's 73 FJ40.
  15. JJS

    JJS New Member

    Messages:
    2,323
    Location:
    Washington
    The tach lead connector on an electronic HEI is right next to the hot wire for the module (red). I don't know what the hell that is in your picture.

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