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Thread: Gizzard's M38A1 Restoration

  1. #41
    Member Gizzard's Avatar
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    Quote Originally Posted by bmorgil View Post
    ....................So you are going to have all 4 bored to .060 over?
    Havent settled on a course of action. All I know now is that it has an existing sleeve at 30 in Cyl one and it will need new sleeve in cyl 2........ cyl 3 and 4 bored to 60 to remove gouge.



    Question for someone smarter than me. Can a f134 sleeve be safely bored to 60 over? Is there enough meat? (existing sleeve is bored 30 over)

    Is two different bore sizes a no-no? For example : sleeves at 30 and remaining two cyls 60? Balance problems? other?

    Im not a machine guy so.....need advice.
    Last edited by Gizzard; 06-18-2021 at 07:08 AM.

  2. #42
    Super Moderator bmorgil's Avatar
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    You will hear a lot of different answers here. It solely depends on cylinder wall pressure. The short answer is no problem. As a GENERAL rule of thumb on a high performance street engine, you want to maintain at least .200 of total wall thickness on the thrust side and .120 on the other side of the cylinder wall. You should have no trouble maintaining that at .060 over. You don't want to machine the sleeve paper thin but it will have a.120 wall if it is a Melling sleeve. There should be enough left in the block to give you enough combined thickness. It isn't uncommon to bore the sleeves so all the pistons are the same size. I have run a few high pressure motors this way. Sometimes when you bore for a sleeve you go right through the old block. If this happens on yours obviously you shouldn't bore the sleeve. I don't think that will happen however on a .120 sleeve bore out. The sleeve has to be finished bored and or honed anyway.

    When it is in the boring machine it might be easier to just keep going and sleeve all 4. You already are half way there. See if the machinist will give you a deal on all 4. Then you are back to a stock combination.
    Last edited by bmorgil; 06-18-2021 at 07:15 AM.

  3. #43
    Super Moderator LarrBeard's Avatar
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    .060 Oversize

    Quote Originally Posted by Gizzard View Post
    Havent settled on a course of action.

    Question for someone smarter than me. Can a f134 sleeve be safely bored to 60 over? Is there enough meat? (existing sleeve is bored 30 over)

    Is two different bore sizes a no-no? For example : sleeves at 30 and remaining two cyls 60? Balance problems? other?

    Im not a machine guy so.....need advice.
    A. I would say that .060 is not getting into any thin wall problems. Standard rebuild kits for the F-134 go to .080 oversize on pistons.

    B. By the time you are done, cylinders 1,2 and 4 will be sleeved. I'd go ahead and put a sleeve in 3 and make every body the same size. You know, when you rev up to 2500 RPM you don't want to get into any harmonic balance issues on the engine. When you're done, you'll have an F-140 engine .....

  4. #44
    Member Gizzard's Avatar
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    Just talked to machine shop. We are boring both sleeves and remaining two cylinders out to 60 over.

  5. #45
    Super Moderator bmorgil's Avatar
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    Rock and roll Gizzard! Its gonna run sweet.

  6. #46
    Member Gizzard's Avatar
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    ...... yep, plus this will give me the excuse to buy new pistons, rods, hardware, etc.

    Not sure about the cam yet. Kinda leaning towards a new cam just because. ...... machinist is gonna see if it’s in spec.

    I told him I want all new valves and seat, guides, springs tappets.

  7. #47
    Member Gizzard's Avatar
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    Oh, btw, here’s a can of worms..... I read up on crank rear main seals last night till cobwebs filled my head. Rope vs best seals etc...... holy cow. Everyone has a different take on it. Hours worth of videos on you tube.

    At this point of the game, I’m not sure. Just don’t want any leaks.

  8. #48
    Super Moderator bmorgil's Avatar
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    The rope seal will eventually weep oil. Just the nature of the beast. I have seen them properly installed go past 50,000 but not much more. The rubber seal is going to be a less touchy installation and a better bet at a good seal the first try. It is important to check the dimension of the seal O.D. in the block. Not all blocks are the same. Not all seals have the same O.D..

    The best tip I can give about leaks is to do it the way the factory does it. This technique is used by the top engine builders in the world. Seal up the obvious "holes" in the crankcase and apply about 3 to 5 psi of air to the crankcase. I have several "Jerry rigged" adapters set up with an air regulator. By applying a few PSI to the crankcase you will quickly find any leaks. You will hear the air seeping by the ring gaps and that should be it. The crankcase should hold a little pressure for a just a second or two. The air pressure should only be escaping past the ring gap and out through the valves. Blocking the exhaust and the carb and any other vents, should produce a fairly leak free crankcase, If you hear air hissing out from anywhere besides the ring path, its a leak. A little dish soap and water on a brush and watch for bubbles.
    Last edited by bmorgil; 06-18-2021 at 12:01 PM.

  9. #49
    Member Gizzard's Avatar
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    Looking over the transfer case a little closer and I discover more of Bubba's fine handiwork


    Check out this action:

    IMG_2278.jpg

    IMG_2279.jpg



    ...........and what its supposed to look like for comparison:


    IMG_2280.jpg



    Oh boy....guess I'll be looking for one of them too

  10. #50
    Super Moderator bmorgil's Avatar
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    That's gotta have one more shift in it!

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