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Thread: Spark Plug Numbers

  1. #11

    Default Final Word: 2407?

    My brush truck livery 67 M715 was just delivered Saturday, and ohhhhh I am in love. Man, what a beautiful expression of utility. Love it.

    Anyway, she is at the muffler shop now, and I have a carb kit coming to me via ebay, but regarding plugs, is the 2407 the final word on plugs? I have read several threads, and given heat range and length, and price too, sounds like this is the plug to buy?

    Can someone weigh in on this, who has run these plugs, and confirm they are the way to go?

    Thanks fellas. RB

  2. #12
    Join Date
    Feb 2004
    Location
    Silver Lake Sand Dunes MI
    Posts
    1,490

    Default

    Quote Originally Posted by ColoradoSpringsRob View Post
    My brush truck livery 67 M715 was just delivered Saturday, and ohhhhh I am in love. Man, what a beautiful expression of utility. Love it.

    Anyway, she is at the muffler shop now, and I have a carb kit coming to me via ebay, but regarding plugs, is the 2407 the final word on plugs? I have read several threads, and given heat range and length, and price too, sounds like this is the plug to buy?

    Can someone weigh in on this, who has run these plugs, and confirm they are the way to go?

    Thanks fellas. RB
    Yes. the 2407 is the proper plug to run. I run them in both my trucks and the shorter plug makes installing the waterproof cap much easier than with the taller 2344's
    Dave
    Delta Team Decals: http://www.deltateamdecals.com/

  3. #13

    Default

    I am running civi lines from a distributor. The plugs that came in mine were an Ac 303. I had them switched over to the 41-803. Man what a difference. It immediately went from 20 mph to 50mph. Might even go higher, I just keep running out of road to see. Hole is tapered. ( the ac 303, were definitely not what should have been in there. 1/4 to short, and non tapered head.)

  4. #14
    Join Date
    Jan 2011
    Location
    Fernandina Beach, FL
    Posts
    3,689

    Default

    Quote Originally Posted by Ec4fish View Post
    I am running civi lines from a distributor....Hole is tapered. ...
    If you are saying that the plug that you are using is for a tapered hole in the head, that is not correct. The Jeep 230 CID engine head is for a plug with a gasket.

    Sorry if I misunderstood what you were saying.

  5. #15

    Default

    Don, I wouldn’t know a tapered hole from a hole in the ground. I have a mechanic helping me. When the plugs were pulled, he told me I had the wrong new plugs, because they were tapered and too long. I asked him to inspect the holes to see if they were tapered (because of this thread we are posting on.) He found two things: that the holes were tapered, according to him. That the plugs installed by the last person working on this, used a plug to short in the threaded area, by at least a quarter inch. This pulled plug was also not tapered.
    After using a thread chaser, to clean the carbon, the new plugs were gapped to .030, and installed. It ran like a champ. Before the new plugs, top speed was 35, at best, and slow on the pick-up. With the newer plugs, 50 mph, and much better acceleration.
    I would like to get Nailhead to weigh in on how his is running. If the plugs are too hot for this vehicle, and I should find something else. I used his plug numbers, because I had civi leads off the distributor. I was not looking to replace the distributor, also.

  6. #16
    Join Date
    Jan 2011
    Location
    Fernandina Beach, FL
    Posts
    3,689

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    This is what we mean when we say, "Tapered Plug". Note the pencil is pointing to the seat and it is tapered meaning that it uses no gasket, rather the taper to seal the plug to the head.


    And the next Champion plug is a representative of what our original military plugs looked like albeit silver instead of the normal black. Notice that it has a flat seat and uses a metal gasket.
    Attached Images Attached Images

  7. #17

    Default

    Gotcha, thanks for the lesson. The new ones did have a crush washer. Not sure if there was a taper behind it, but I guess it doesn’t matter. They work, now I just have to worry about the heat you mentioned.

  8. #18

    Default

    That spark plug bore really is deceptive in its appearance, looking like it has a tapered seat in it. You could get away with running tapered-seat plugs in a crunch, but they come loose pretty quickly.

    After Mr. Cavey's patient admonitions, I switched to flat-seat plugs and they work great, obviously.

  9. #19
    Join Date
    Jan 2011
    Location
    Fernandina Beach, FL
    Posts
    3,689

    Default

    Quote Originally Posted by Nailhead View Post
    That spark plug bore really is deceptive in its appearance, looking like it has a tapered seat in it. You could get away with running tapered-seat plugs in a crunch, but they come loose pretty quickly.

    After Mr. Cavey's patient admonitions, I switched to flat-seat plugs and they work great, obviously.
    Admonitions! I hope not, if so, I'm Sorry.

    BTW, a plug with a washer will never have a taper seat. It is one of the other. Our trucks like the crush washer, which are technically made for one time use. But... many of us (yes, me too...) have been known to use them more than once.

  10. #20

    Default

    Quote Originally Posted by Don Cavey View Post
    Admonitions! I hope not, if so, I'm Sorry.

    BTW, a plug with a washer will never have a taper seat. It is one of the other. Our trucks like the crush washer, which are technically made for one time use. But... many of us (yes, me too...) have been known to use them more than once.
    Absolutely no apologies necessary, Don-- I thank you for your guidance!

    The seat I was describing was in the head, not on the plug: the plug hole is chamfered, and that's what threw me initially.

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