Register now to get rid of these ads!

Hot Rods Whats My Gap?

Discussion in 'The Hokey Ass Message Board' started by Joe Romano, Jul 31, 2015.

  1. Here's another one.
    I have a SB 350 from a 74 Camaro, nothing special in it, still has the original size pistons, cam & crank. It does have a 4brl, Edelbrock 600 CFM carb. (1406).
    And MDS ignition.
    So the question is, what's the plug gap? (AC Delco R45)
    I've read on line it should be 45K.
    What say you....
    Thanks again, Joe
     
  2. Special Ed
    Joined: Nov 1, 2007
    Posts: 6,741

    Special Ed
    Member

    Thickness of a matchbook cover.
     
  3. Larry T
    Joined: Nov 24, 2004
    Posts: 7,661

    Larry T
    Member

    What sort of ignition? Something with a 6AL box will set probably set at a different gap than a plain distributor and coil. I'm assuming (I know) you're talking MSD.
     
  4. squirrel
    Joined: Sep 23, 2004
    Posts: 48,683

    squirrel
    Member

    in the other thread today about what to set the plug gap with an MSD ignition, the answer was .045"
     

  5. Ole don
    Joined: Dec 16, 2005
    Posts: 2,915

    Ole don
    Member

    Mess with the plugs until it runs right. That is your new gap.
     
  6. .045 will be fine.
     
  7. derpr
    Joined: Mar 11, 2007
    Posts: 257

    derpr
    Member

    .030 or .035. Sounds right to me. For something with points.
     
  8. Blue Coupe
    Joined: Oct 11, 2009
    Posts: 58

    Blue Coupe
    Member

    Happened to have my repair manual out, I so looked it up in "the book". Four barrel carb engines had R-44T plugs gapped at .035. 1975 engines went to electronic type distributors, plugs went to R-44TX and gaps jumped out to .060. In 1976 the plug went up in heat range to R-45 & R-46TX and plug gaps decreased to .045. So there you go.
     
  9. onetrickpony
    Joined: Sep 21, 2010
    Posts: 502

    onetrickpony
    Member
    from Texas

    .035 with points, .045 with HEI has always worked best for me.
     
  10. Larry T
    Joined: Nov 24, 2004
    Posts: 7,661

    Larry T
    Member

    Stock specs don't always work with aftermarket parts. With a standard style ignition, I'd run .030/.035. With an ignition box, I'd open the gap some - something like .045.

    But the truth is that you probably won't tell much difference in the way the engine runs unless the gap is way to tight or way to wide.
     
  11. And again I thank you all for your support.
    Match book cover......really?!
    I'm dumb, but I ain't stupid!
    I'll go with the consensus of 45K
    Yes MSD, no points.

    PS: match book cover reads 15K
    Stupid is, as stupid does......f.g.
     
  12. Larry T
    Joined: Nov 24, 2004
    Posts: 7,661

    Larry T
    Member

    Joe,
    You might be surprised what you can do with a match book cover and the cellophane off a pack of cigarettes.
     
    Special Ed likes this.
  13. Special Ed
    Joined: Nov 1, 2007
    Posts: 6,741

    Special Ed
    Member

    That's a very thin matchbook cover. If it reads .15, then simply fold it twice, and PRESTO!, you have now created a tool in which to set your spark plug and/or points gap to .45. It's not stupid, it's what mechanical-minded folks have used for at least the past 70 years. Don't knock it 'til you've tried it ... ;) and please don't call me stupid, moron ... :rolleyes:
     
    Last edited: Aug 1, 2015

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.