340 camshaft break-in. Well.....almost

Small Block Mopar Engine

  1. dartfreak75

    dartfreak75 Restore it, Dont part it! FABO Gold Member

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    If you would and can video the break in. I'm not far from that point and would like to see it done before I attempt to do it for the first time. Lol
     
  2. Rocket

    Rocket FABO Gold Member FABO Gold Member

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    I believe the reluctor gap should be 0.008

    May want to double check that spec.
     
  3. nm9stheham

    nm9stheham Well-Known Member

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    Checked with a non-magnetic feeler gauge to avoid any problems on it. (3 thickness of standard printer paper is .008-.009"...)
     
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    • daves66valiant

      daves66valiant 68 Dart 340/727:66 Signet Vert 340/5spd: 68 D100

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      Yes. Manual says brass. I have brass and steel. It’s gapped correctly. Missed a 0
       
    • 318willrun

      318willrun Utube channel 318willrun

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      Not a good, complete video, but this is me breaking in my 318 cam. 20 minutes of going between 2000 rpms and taking it up to 2800 rpms. Make sure not to overheat it, and have it on number one firing to start it - known good working carb full of gas. Nice to have a buddy/wife, kid or somebody else there as well.
       
      Last edited: Apr 13, 2019
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      • j par

        j par Well-hung Member

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        :popcorn:let's hear it!
         
      • dartfreak75

        dartfreak75 Restore it, Dont part it! FABO Gold Member

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        Thank you!! Bet the fingers get tired doing that for 20 mins Haha. How long after the start do you have to hit 2000-2800 rpm? Do have have time to check the timing and make adjustments? Or is it as soon as it hits put the the throttle down and hit 2000?
        Also something I dont understand and iv asked before and still didnt understand but didnt want to ask again is iv read you need to check the lifters for rotation which I understand why but how is that done while it's running at 2000 rpm? I can't see the lifters without the intake off?
         
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        • 4spdragtop

          4spdragtop CONGRATS NORTH AMERICA! FABO Gold Member

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          With retarded timing comes heat I believe. Too much gets detonation. That's why 2 or 3 pairs of experienced hands are good. One run throttle, one to run timing light and one to check for leaks and one to run camera lol. Get the rpms up as soon as safely possible in my opinion. Make a list!
          Not sure how to check for rotation? After cam break in remove vc's and check? Maybe hit the lifters with a sharpie before break in and check after?
           
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          • 318willrun

            318willrun Utube channel 318willrun

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            • I start with the idle adjustment turned up, so it would idle around 1800-2000 rpm's. Keep in mind, this doesn't have to go "flawless". I've had things force me to shut them down early, restart and continue. I've had cars not start right away due to no spark. None of which caused any issues. Valve spring pressure plays a part.
            • you wouldn't watch the "lifter rotate". Take a paint marker and put a line up top the push rod by the rocker. But don't bother unless you have suspicion of a flat lobe.
             
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            • dartfreak75

              dartfreak75 Restore it, Dont part it! FABO Gold Member

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              Thanks that's a good idea with the idle I was kinda thinking that but I didnt want to say something and sound stupid lol I wasnt sure if it would hurt something turning one up that much.
              I think I solved my carb situation. I have been really worried about rebuilding my own and running it on the breakin. So I have been talking to Dana on here and he/she is gonna build me a thermoquad. He rebuilds the cores for 155 (fabo discount) and charges 50 for the core. And he guarantees it to run he tests them out and sets it up on his engine. I may have to make adjustments and tune it to my engine but he said it will start and run for the break in. Plus it will give me the factory original look I'm seeking. And I wont have to run a stupid spacer on my spread bore 340 intake. It's a win win win for 205 bucks!! I will keep my carb and rebuild it just to learn on and practice with and after break in even see if it runs lol .
               
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              • crackedback

                crackedback FABO Gold Member FABO Gold Member

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                Detonation is not usually an issue when breaking in a cam. No load on the engine.

                Get it started as quickly as possible, no long crank times. That's usually a lack of fuel and not enough timing deal.
                Up to rpm 2000rpm
                Put timing light on it and get 36-40* of timing in it.
                Adjust RPM up and down a little 2000-2500 works pretty good.

                Have all the tools you need to do this set up BEFORE ever firing the engine

                Then watch for Murphy to arrive! LOL Murphy's Law
                 
                Last edited: Apr 13, 2019
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                • dartfreak75

                  dartfreak75 Restore it, Dont part it! FABO Gold Member

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                  Dont jenks me lol I'm a murphys law type guy anyways.
                   
                • dartfreak75

                  dartfreak75 Restore it, Dont part it! FABO Gold Member

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                  Any updates Dave?? Have you got it broken in yet?
                   
                • nm9stheham

                  nm9stheham Well-Known Member

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                  Check it on the engine stand prior to finally buttoning up; it'll be obvious with just a few rotations of the crank with some sharpie marks. (Another good reason to use moly based lifter lube, IMHO.) The rate of rotation will vary from lifter to lifter. Doing it afterwards and finding an issue is too late.
                   
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                  • Krooser

                    Krooser Reform School Graduate

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                    When we fired my kids Bmod dirt car motor the guy who assembled the engine had everything already set-up... timing set, fuel in the carb (!) and idle turned up. It was amazing to see the engine fire on the first crank after one shot of fuel. Ran a steady 2000 rpms. That's experience!

                    FYI... you needs the 2000 rpms to get the cam lobes splash lubed... that's why you should never idle the engine.
                     
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                    • MopaR&D

                      MopaR&D Nerd Member

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                      Bring it up to 2000 RPM minimum as soon as it fires, if something happens it's fine to shut 'er down before the 20 minutes is up just make sure on the restart it comes right back up to 2000+ RPM again. First time I did a cam break in I wasn't aware the block had to be pre-filled with coolant before installing the thermostat; thing overheated right quick and I probably messed up the bottom end but this was a stock worn-out 318 with a cam swap. Still put about 10k miles on it afterwards until the oil burning just got to be too much (rings and bores were toast).

                      Make sure it has plenty of ignition advance, it's under no load so it needs it or else it'll run hot and dump extra heat out the exhaust. Wouldn't hurt to hook up a vacuum gauge and tune the idle mixture screws a bit too, at that RPM with no load the carb will still be running mostly on the idle circuits and you really don't want it to be too lean. Just my 2 pennies...

                      EDIT: FYI that cam I broke in in that 318 I took out with all the lifters categorized to the correct lobes and reinstalled in a 360 and put another 25k miles on it. It was a Lunati Voodoo HFT.
                       
                      Last edited: May 8, 2019
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                      • FlDart360

                        FlDart360 Well-Known Member

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                        Just curious about this i checked mine scene my motor is out of the car right now. I found mine is no where close to .008 or 203mm. My feeler gauge is very old so i think 203mm is the same as .008? if the gap is to large what problem might you have? My car starts and runs.
                         
                      • nm9stheham

                        nm9stheham Well-Known Member

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                        I think you mean .203 mm = .008"....
                        Too large would result in misfiring. Timing cylincer-to-cylinder might be a bit more variable.
                        BTW, it is supposedly a no-no to use a ferrous feeler gauge for this.... I assume it can magnetize the metal bits in the reluctor gap.
                         
                      • FlDart360

                        FlDart360 Well-Known Member

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                        I will use your 3 sheets of printer paper suggestion.
                         
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