Pushrod selection

Small Block Mopar Engine

  1. 89on35s

    89on35s Inferno Red Duster FABO Gold Member

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    I am a 45 year old novice mechanic (Journeyman Electrician actually).I am learning automotive stuff now that lots of you guys learned in your teens so please go easy on me.
    I have been struggling trying to get rid of valve train noise on my 360 since I changed the mufflers out this spring and found out how bad it really is. It is nice and quiet for about the first 5 minutes then it starts to tick like crazy. Actually it's quite a quiet tick but it drives me fucking crazy! The tick goes up and down with RPM.
    I first looked for an exhaust leak. I crawled all under the car with a hose attached to my ear and my kids had big shop rags shoved into each tailpipe and I didnt hear a leak.
    When I popped the valve covers off I felt the rocker arms had too much play both side to side and up and down so I replaced them all with a stock set of 360 pushrods I had from a junk engine even though they all appeared straight and pretty much the same length. This maybe helped a very little bit but likely did nothing if I am being honest with myself.
    I replaced the lifters with new Melling hydraulic lifters (broken in properly) and the unknown spec cam looked good. The noise went away for a bit but on my first drive I cruised it for about a half hour nice and easy, then made a first gear pull to 6000 rpm like I always do at the track and the noise came back. I have been driving it around pretty gingerly for a week or so never leaving town or going over 2500 rpm and it is still the same. No worse, no better!
    I need to pop the valve covers and check the rockers again. My question is, when ordering pushrod for use with the stock stamped rocker arms will each one be a slightly different length? I just picked up a pushrod length measurement tool (adjustable length pushrod) and will measure each one. Any help would be greatly appreciated!

    Cley

    The patient- 74 Duster street car. 75 model year 360 with stock rotating assembly, unknown cam, stock 1.88 valve heads. A-500 automatic with 4.10 gears in the 8-3/4 rear end. Cheap Patriot headers with good Remflex header and collector gaskets. 2.5" Summit exhaust kit with Flowmaster 40s (all welded now).
     
  2. doug 371

    doug 371 Well-Known Member

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    check the valve heights with a straight edge next time you have it apart...maybe they're all over the place...any interest in switching to adjustable rockers?
     
  3. 89on35s

    89on35s Inferno Red Duster FABO Gold Member

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    I have a set of adjustable roller rockersbut i had planned them for another project. I never thought to check the valve height. Would that change over time?

    Cley
     
  4. 318willrun

    318willrun Utube channel 318willrun

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    Are the pushrods long enough to have reasonable preload on the lifters?
     
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    • toolmanmike

      toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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      My thought as well. Adjustable rockers would address the problem. Valve stem height too. Each valves gets the same preload past zero lash.
       
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      • PRH

        PRH Well-Known Member

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        Of course, these days the first question to ask in these situations is....... what’s the cam?
        Several of the newer profiles are just kinda noisy.
         
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        • toolmanmike

          toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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          With lobes shaped like the Eiffel Tower
           
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          • PRH

            PRH Well-Known Member

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            The lifters can be run with a pretty wide range of plunger preload.

            “Normal” style lifters would be fine with between .020-.080 preload.

            So, if the current lifters are within that range, changing the pushrods isn’t likely going to cure anything.

            Using a checking pushrod to compare the zero preload length vs the actual length of the PR, for all 16, will tell you where you’re at for preload.

            If you’re well with the proper range, and you’re not running cam that’s known to be noisy........ then you’re likely going to be looking at replacing the lifters to try and reduce the noise.
             
            Last edited: Jul 12, 2020
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            • beanhead

              beanhead Well-Known Member

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              Personally I wouldn't put the adjustable rockers on that combo. Yes you can 'adjust' them for more preload, but if the pushrods are already too short, you will have too much adjuster exposed beneath the rocker body and that can cause real problems. Then there's the possible (likely) geometry issues. Plus you'd be buying new pushrods anyway unless your new rockers already have cup adjusters? A lot of added hassle that may not even fix the issue. And checking pushrod length is FREE baby! Roll the engine until the lifter you're looking at is on the base circle/heel/back of the cam lobe. At that point the pushrod should be pressing the lifter cup away from it's retaining ring some=preload. If you have a minimum of .020" and IF you have regular hydraulic lifters, then the pushrod length is okay. You can safely preload them as much as .100" so uneven valve tip heights are inconsequential here unless they're WAY off. The plunger in the lifter will compensate within that range..so if the pushrods are preloading the lifters like they should, and there's no signs of a bad lifter/lifters, and all else is okay then the 'unknown' cam is likely the noisy kind PRH is talking about.
               
            • beanhead

              beanhead Well-Known Member

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              Shouldn't, unless the seats are sinking (or coming out:eek:)!
              Good luck sparky!
               
            • pishta

              pishta I know I'm right....

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              valve height can change based on seat condition. non hardened exhaust valves tend to eat the seats so the valve gets taller under the spring. Slants are the worst at this, but they came with adjustables until well into the 80's. I'd cut and run from the stamped rockers/new custom pushrods/static lifter preload crap shoot right now and get some 273 rockers and correct hydro cam/mech rocker 340TA length pushrods. Then you can give each valve the proper preload it seems to demand nowadays.
               
            • Wyrmrider

              Wyrmrider FABO Gold Member FABO Gold Member

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              comp xe cams are some of the noisey ones
              BTW guys
              when you take a cam designed for the base circle of a SBC and put it on the larger basecircle of a MOPAR or BBC the nose gets not so pointy
              which is a good thing with the heavier valves of the MOPARS and BBC compared with a SBC
              If you are buying new valves SBC valves are a cost effective altrnative and a performance benefit
               
            • 89on35s

              89on35s Inferno Red Duster FABO Gold Member

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              They definitely did feel loose. After researching it a bit more I think definitely too loose.
              It's an old cam. Been together since the 90s from what I can figure regarding the history of the car got it from.
              If the valves were sinking would that not increase preload on the lifters?

              I really appreciate all the comments and insights!

              Cley
               
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              • pishta

                pishta I know I'm right....

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                Yes it would but the base circle of a aftermarket cam may not be LA to start which would increase the distance from base to rocker, needing a longer pushrod to start...your "looseness" explained. Most comp cams for an LA require valvetrain change. check the catalog fine print.
                 
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                • 89on35s

                  89on35s Inferno Red Duster FABO Gold Member

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                  Let's see what this does! I pulled the valve covers off and before even turning the motor over at all I found a couple loose rocker arms. Like no preload at all. I decided to use the roller rockers from the 360 I have on the stand just to ensure this would cure my problem.
                  Cley
                  20200718_094953.jpg
                   
                • PRH

                  PRH Well-Known Member

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                  That should answer the question.

                  I think most people expect the tension from the lifter on the valvetrain to be tighter than what it really is.

                  After the motor is shut down and the internal pressure in the lifter normalizes....... any rocker you check that has the lifter sitting on the base circle will have only the tension from the tiny spring under the plunger...... that’s it.
                  The rockers will easily slide back and forth on the shaft.
                   
                  Last edited: Jul 18, 2020
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                  • 89on35s

                    89on35s Inferno Red Duster FABO Gold Member

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                    I understand it can slide side to side but I had a bit of play up and down too. Just got back from a test drive. Nice and quiet now!

                    Cley
                     
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                    • PRH

                      PRH Well-Known Member

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                      Perfect!!:thumbsup:
                       
                    • 89on35s

                      89on35s Inferno Red Duster FABO Gold Member

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                      Well, I thought I had it but………

                      My noise above 2000 rpm came back, probably worse than ever. I have not updated this thread for a while probably because I was embarrassed more than anything. I obviously did not realize how much I don’t know!

                      I first adjusted my preload at ¾ of a turn when I installed my adjustable rockers, so then I tried it at 1 full turn. The noise was worse. Then I tried 1/2 a turn and it was no better. A ¼ turn was no better. The entire time it is making more and more noise. It can’t be the pushrod length causing the issue. I even gave it a try with the old stock non adjustables again. That was the worst it’s been. Getting desparate I checked the convertor bolts as was suggested but all was good there.

                      So not knowing what to do, I pulled the heads, checked the valves, nothing sticking or anything, no valves touching pistons or anything crazy like that. It was a bitch of a job and a complete waste of time. When I put it all back together still not finding a smoking gun of any kind I consulted with @oldkimmer on the phone. We discussed the possibility of oil to the top end and orientation of the rocker shafts. I made sure the rocker shafts were in correctly, adjusted the preload to ½ turn after zero lash and started it up again. All sounded good for a couple minutes then a loud Tick-Tick-Tick was coming from the drivers side valve cover. Passenger side was quiet. I used a long screw driver to my ear to locate the sound. Well damn! That’s a new one!

                      So I pulled the drivers side valve cover off and one lifter seemed squishy as hell and the others seemed firm. Hah! A bad lifter! So I changed that lifter, put it all back together but it made no difference. I hated the sounds it was making during that lifter break in but I was pissed off and I let it eat! it was quiet at idle after the lifter I should mention that through all of this, oil pressure has been between 20 at idle when warm to 50 at 2000 rpm plus.

                      I guess next, I’ll pull the rocker shafts once again and see what I have for oil getting to the top end. The plan is to pull the distributor and drive shaft then run the pump with my priming shaft. I know I’ll have to turn the motor over some to get oil where I need it.

                      Is it possible that the stock replacement lifters I used cannot handle the pressure of the valve springs and cam I have? Unfortunately I don’t have the specs on them but I believe the springs must be decently stiff because I have never floated the valves on this engine. It hits 6000 rpm at the track, or it used to!

                      I see there are some really smart guys following this thread, so I am hoping for some advice!



                      Cley
                       
                    • oldkimmer

                      oldkimmer FABO Gold Member FABO Gold Member

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                      Dam, everytime is 2 steps back. I really feel for u buddy. Puts some rags around the engine bay and run the motor warmed up with the valve cover off. It may get pretty messy. With it idling see how much oil is up top. The take a hammer and put the handle on the rocker at the pushrod and push down. Report what happens. Kim
                       
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                      • 69_340_GTS

                        69_340_GTS Well-Known Member

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                        Dumb question: Are you adjusting each lifter when it is on the cam's base circle?
                         
                      • George Jets

                        George Jets 1967 Dart 2 Door FABO Gold Member

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                        Lots of people asking about valve stem height.

                        Here is a simple test to see how close you are to stock valve stem height.

                        A paint stick, 1 1/8" wide standing up on edge of the head valve cover gasket surface. Valve tips should be close to this height.

                        If valve tips are .050 to .075 ths below this, would say you need longer push rods to make up the difference.

                        20200828_112523.jpg

                        Here is another example of a 318 with stock valves, same same:

                        20200827_084517.jpg

                        Others are saying the base circle on your performance cam is smaller than stock . . needing longer pushrods as a result.
                         
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                        • dartfreak75

                          dartfreak75 Restore it, Dont part it! FABO Gold Member

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                          Start with the basics and dont rule out anything. What valve springs are you running?
                          Maybe start with a set of factory rockers just to see maybe its them.?
                          Sounds to me like the melling lifers are collapsing. Check your preload and make sure it's in spec with those lifters. You can get a adjustable pushrod for measuring for like 13 bucks on Ebay.
                           
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                          • 89on35s

                            89on35s Inferno Red Duster FABO Gold Member

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                            Yes, I am doing that.

                            Thanks, I'll check that. They are even height side to side. the thing that has me wondering is that this engine ran great for years with the other lifters. Would the lifter height be different?

                            Unfortunately I do not know what valve springs I am running. I did have them off with a hand compressor when I had the heads off and I'd say they are even in strength. I don't think I have any weak ones. I did grab an adjustable push rod, I have it at home now, I just thought since I had the adjustable rocker arms the length wasn't critical.

                            Is there such thing as a known good lifter I can use? I hate to replace brand new parts but maybe that's what I need to do.

                            Cley
                             
                          • George Jets

                            George Jets 1967 Dart 2 Door FABO Gold Member

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                            Cut your oil filter open and see what is in there. A plugging oil filter will start rattling the lifters after it has been run for a bit.

                            Prime example of particles of old gaskets or whatever in your oil pan (or crud) getting sucked up into the oil pickup screen after it has run for a bit.

                            If lifters start rattling after they have been started up running quiet, it means that the lifter feed is loosing it's oil pressure and can no longer pump up the lifters . . so they bleed back down and start to rattle.
                             
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