Building a big cam 3 400

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Adisiwaya, Sep 12, 2021.

  1. Adisiwaya

    Adisiwaya Light Load Member

    Mar 25, 2017
    Appreciate the help. Going to stay doing the tear down soon as I get it back. I'm told to make sure it's not a lpf? Block? Don't think I'm understanding what that person was talking about.

    Now this is going into a truck that had a 3406b (well won't mention I rebuilt it... Lasted 25k miles before it randomly decided to have a piston explode.. thanks IPD)

    Now how do I figure out which liners I need? Do I risk rebuilding it myself or have a builder do it? Closest guy who knows his #### is 4 hours away down in Mankato MN. I want to do it right as well as all new bolts, rods, cam. As well as balanced. Is there any worth while to balance a crank?

    It's going in my truck which will be getting a ict/double eagle/etc sleeper soon after the engine is put in if anyone has any leads on one in Midwest shoot me a pm
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  3. Dino soar

    Dino soar Road Train Member

    Dec 8, 2017
    I don't know what your level of engine building is so I can't advise you whether to rebuild or not yourself.

    The lpf liners means they are lower press-fit. In the earlier big cam engines, I think before big cam 4, the engines from the factory had upper press-fit liners. They worked, but they moved around quite a bit. So then the engineers realized they can install lower press-fit liners and they're much stronger.

    If your engine has upper press-fit liners then someone has to come out with the tool and they cut the block to fit the lower press-fit liners. If you are doing a rebuild and especially with more horsepower you want to have lower press-fit liners.

    As far as the crankshaft goes as long as the clearances are good it's just rebuilt. If the crank has to come out then the machine shop will magnaflux and cut it.

    Now on the front of the engine there is a balancer and if the engine has some time on it you should just replace it.

    The camshaft is the same as the crankshaft. If there's nothing wrong you just keep using it. I would only replace that if you are certain there is significant wear that it needs to be replaced.

    But what I would replace are all of the accessory and maintenance items and make certain that you have the timing tool and the timing of that engine is set correctly.
    Adisiwaya and BoxCarKidd Thank this.
  4. Nss

    Nss Light Load Member

    Jul 5, 2021
    Lpf is .370 deep at the counter bore. 20/40 is an over size liner. Check block for cracks around counterbore and to water jacket holes. If is cracked you need water hole inserts also
    Adisiwaya Thanks this.
  5. BoxCarKidd

    BoxCarKidd Road Train Member

    Aug 26, 2014
    Cummins liners had the part number stamped in them. You can tell what they are and replace as is that way.
    Many aftermarket liners had numbers painted on them. You may never find a number and have to measure everything.
    As said: Only go back with lower press fit liners.
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