Block plugs for a 300

Discussion in 'Small Block Tech' started by 33chifox, Sep 30, 2023.

  1. 33chifox

    33chifox Well-Known Member

    I bought a set of plugs for a 300 from TA last year and I have a ton left over, which is probably not right. I put in the six freeze plugs, three on each side, and I have the rear cam plug and two little screw in ones set aside. I have rover heads that have all their plugs in, am I missing something? I can't seem to find where else I may need to put in plugs.
  2. TrunkMonkey

    TrunkMonkey Well-Known Member

    The kit should have two cam hole plugs, smaller one for the 300 and the next size up for the 340. So, that would explain one extra plug.

    I then you should had two front and two rear blck plugs for the oil/lifter galleries. The two front would account for two extras.

    How many plugs do you have left over, and can you provide diameters with caliper?

    Then folks should be able to let you know what you have left over and if you missed anything.
    33chifox likes this.
  3. 33chifox

    33chifox Well-Known Member

    Okay so here are the measurements:
    2x 0.655 screw in, one 0.408 and the other 0.272 inches tall
    1x 1.797 tap in
    2x 0.625 tap in
    2x 0.592 tap in
    1x 1.922 tap in
    2x0.53 screw in

    The 0.53's and the 1.797 seem like perfect fits for the rear, so the rest is what I'm missing spots for, which is seven left over
  4. TrunkMonkey

    TrunkMonkey Well-Known Member

    Front of block there is a medium plug that fits above the cam tunnel.
    (in the "arch")
    two small plugs for the lifter/oil galleries front.

    Did you install cam and timing cover?

    I am guessing some of those plugs in the kit may be for the heads, you can check the number and size to account for any of those.

    Once you account for all the 4 gallery plugs, the heads, the rear cam plug, and the one extra. That will leave the 1.922 plug unused on your engine (340 rear cam plug)

    The oil gallery plugs may be threaded or tap in. Some blocks may be mixed threaded and tap in.

    The two different depth plugs are used where the oil passage comes in so the plug does not block the passage.

    The shorter threaded plug goes in the front passenger gallery, and the longer plug goes in the front driver's side gallery.

    Check and see what plugs are in the heads diameter and number and see if that accounts for any leftovers.
    33chifox likes this.
  5. 33chifox

    33chifox Well-Known Member

    Thank you, this helps a ton, can't believe I missed the front plugs, guess I have quite a bit of teardown and rebuild to do today. Why is there a hole in the arch the first place?
  6. 33chifox

    33chifox Well-Known Member

    Well it looks like TA did not include the front big plug, will need to buy that. Also, since the two little plug holes are not threaded, i can't use the included short and tall threaded plugs, but will use the tap in ones. Question though, the tap in plugs are 0.290" deep, while the passage starts 0.240" into the hole, that's an issue isn't it? The end of the plug is rounded but I don't think that will make it okay.
    TrunkMonkey likes this.
  7. TrunkMonkey

    TrunkMonkey Well-Known Member

    Verify, but the passenger side plug needs to be less depth when installed, so it doesn't interfere with oiling of the drilled passage feeding the gallery.

    Wait until someone who can verify what "tap in" plug should be installed in each front gallery , so you don't risk putting the plugs in incorrectly and starving the passages if oil flow.

    The oil mods done on big block
    Buick engines, address the issue with the threaded front gallery plugs.

    Bottom line, if you are not sure if what to have,ask and get clarification before you press on with running you build

    Better to get understanding, than breaking anything.
    33chifox likes this.
  8. 33chifox

    33chifox Well-Known Member

    Right, I'm not putting anything together yet, Maybe TA had the wrong set put together, which would explain the missing medium plug, so when I call tomorrow I'll update here.
    TrunkMonkey likes this.
  9. 33chifox

    33chifox Well-Known Member

    Okay so update, the medium sized hole does not get plugged, i was just told by a TA tech it's a vent hole. I'm buying the two small plugs that I'm missing from a member here and I should be set since the heads are all plugged, the cam and two small plugs next to it are also in.
  10. Super Bald Menace

    Super Bald Menace Frame off oil changes

    340 used same cam as 215 and 300. Shouldn't the rear cam plug be the same size?

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