340 issue after camshaft change

Small Block Mopar Engine

  1. Sabremech

    Sabremech Member

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    Good morning. Here’s the particulars:
    68 340 4 speed. 3.55 gear. 10.5 to 1 pistons. Edelbrock air gap intake, 800 CFM carb, stock HP exhaust manifolds. 2.5 inch exhaust.

    Thanks.
     
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    • RustyRatRod

      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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      • Kendog 170

        Kendog 170 Let the boy go !

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        Don't want hijack thread but RRR would that cam work good with 323 gear ? That's the only difference with my Dart .
         
      • Kendog 170

        Kendog 170 Let the boy go !

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        Sabermech Are you from Burlington Ma. ?
         
      • RustyRatRod

        RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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        It sure will.
         
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        • 66fs

          66fs FABO Gold Member FABO Gold Member

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          Since you have the adjustable rockers, I'd recommend going with a solid cam, Isky or Racer Brown. They always sound great and have the performance to back it up. Maybe Racer Brown ST-14, or call and get a custom grind.
           
        • Sabremech

          Sabremech Member

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        • RustyRatRod

          RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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          It's an excellent all around grind.
           
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          • Sabremech

            Sabremech Member

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            Burlington, Wi.
             
          • Sabremech

            Sabremech Member

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            This particular one is junk.
             
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            • RustyRatRod

              RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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              That's a good idea. Of course he'll need different pushrods, but the difference in power will be remarkable.
               
            • RustyRatRod

              RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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              It's not very probable......but it is certainly possible.
               
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              • Sabremech

                Sabremech Member

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                At this point, it’s very probable the grind is not right.
                 
              • 66fs

                66fs FABO Gold Member FABO Gold Member

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                Maybe compare lobes and angles with the old cam?
                 
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                • RustyRatRod

                  RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                  That's not a bad idea. It would look close to the eye if it was ground right.
                   
                • RustyRatRod

                  RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                  I had a friend with a similar problem once with a Chevy. We finally took the cam back out and it was broken. We figured it had to have a crack in it new and went ahead and broke when we tried to bust it off.
                   
                • RustyRatRod

                  RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                  It's kinda sounding like it......or it's broken like I was talkin about.
                   
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                  • Dale Davies

                    Dale Davies Well-Known Member

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                    There could be an issue with your term snug. People have different interpretations of what snug means. What I do is turn the adjuster down so the pushrod still can be lifted up and down slightly (say 1/32"). At this point your index finger gently on the side of the pushrod and moved back and forth will easily turn the pushrod. Turn the adjuster down until that easy rotation stops. At this point there is zero lash but the hydraulic mechanizm is not being pushed down. Now the prescribed 1/4 to 3/4 turn on the adjuster can be made to position the lifter piston in the center of its travel.
                    If the snug interpretation is the pushrod can not be rotated using a finger and thumb, the lifter is probably collapsed to the bottom. Then the preload 1/4 to 3/4 turn is opening the valve.
                    Personally I prefer the 1/4 turn as it moves the piston down slightly allowing the lifter to function as designed, but not much for pumpup on high revs. If you do get to the pumpup state, power will go flat.
                     
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                    • Dale Davies

                      Dale Davies Well-Known Member

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                      Always works for me. One finger to get zero lash and the little spring in the lifter will provide enough drag to stop the pushrod from turning.
                       
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                      • Dale Davies

                        Dale Davies Well-Known Member

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                        Cam pt# or grind# should be etched or stamped on the cam somewhere. Does that matchwhat you paid for. A call to the manufacturer would be inorder. They do not want a bad reputation getting spread, so should offer some suggestions or replace the cam.
                        Small block and 351 Fords can have the confusing firing order issue, but that is not the case here.
                         
                      • Swinger 340

                        Swinger 340 Well-Known Member

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                        Hope I'm not over stepping here. I am not a engine rebuilder, but have installed cams before. I do not want to repeat what was already stated. I do hope cam lube was applied to the lobs while install, do to all the dry runs, before proper cam break-in. Never had this issue, but I would think a Dial gauge reading at the rocker arms would let you know if the cam was in defect, before taking down the install again. Just saying!!!
                         
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                        • 6pak

                          6pak Active Member

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                          Hey
                          Im a long time reader but usually not a participant on these threads.
                          Because they they seem to be hijacked to some different topic. AND
                          What I hate, is, a lot of times the topic starter never chimes up with what the solution is!!!

                          I started at the opening question and jumped to page 4.
                          Hydralic lifter- you have the intake installed and can’t see the lifter. And you cannot see how much you are compressing when you adjust. It could bleed down while adjusting. Cant go by feel.
                          Hell, adjust loose and let em rattle till you get her started and running.

                          Myself, I like to run the oil pump primer rod on a drill, to make sure the lifters are pumped to the top before playing with hyd. Lash adjustments.

                          my 2 cents may not be worth the zinc they are made out of.
                          I welcome any thoughts and comments.
                           
                          Last edited: Jul 21, 2021
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                          • Dale Davies

                            Dale Davies Well-Known Member

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                            IMHO, you need to get to the bottom of the problem. To do that requires degreeing the cam. You do not need to remove the head to find true TDC. A small screw driver or bit of coat hanger or welding rod will let you feel the piston come to the top and start to drop. Back up a few degrees and install the degree wheel. A piston stop can be made by grinding or cutting the crimp that holds the porceline in and push it out. Weld a nut on to use the largest diameter redi rod that fits through the plug body. Grind one end of the redi rod round and then cut it off about 3" to 4" long. Loctite a nut on the cut end to turn.
                            Now you can install the body in the #1 plug hole and thread the piston stop rod in until it just touchs the piston crown. Back it out one turn and roate the engine about 30° to 40° ATDC. Turn the piston stop down about 3 turns. Now you can back up the rotation until slight resistance is felt. Note the degree indicated. Now rotate in the normal direction until you feel the slight resistance again and note the degree reading. Now pull the stop out and rotate to half way between the two noted degrees and move the zero mark to line up. Just to be certain at this point I would go to 40° ATDC again and install the piston stop. Now check your ATDC and BTDC degrees. They should be identical. Now you can check timing per the cam card supplied with the cam.
                            There could be an error with the cam grind with regard to the relation to the keyway or a key slot in a timing gear could be off. With #1piston at true TDC the crank timing gear dot should be straight up and the cam gear dotright opposite. You know this. #1 or #6 should have both lifters raised a slight bit with the other on the base circle compression. If not, one part is likely machined wrong.
                            At this point you likely will remove the timing set to get at the cam. Try it on another engine. Maybe someone close has an engine apart or a spare. This will verify the timing set which is way less expensive than a cam. If it is the problem and you purchase another cam and heave the one you just took out 10' into the scape heap, you could still have the problem.
                            Realising that most companies unfortunately have stuff manufactured in the land of recycled Yak turds means either the company or the customer needs to have a QA/QC program to ensure quality.
                             
                            Last edited: Jul 21, 2021
                          • RustyRatRod

                            RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                            My definition of snug is, not torqued with a torque wrench, but tight enough that it will NOT back off. That's for "whatever" size fastener.
                             
                          • 12many

                            12many Well-Known Member

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                            You learn what snug means by experience. That means that ultimately you learned “feel” by: stripping shit until you learned to ease up on being ham fisted. Feel the bolt/nut. Slow and easy up to snug and no more. Grandpa taught me that one.
                             
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