273 rocker arm adjustment

Small Block Mopar Engine

  1. yellow rose

    yellow rose Doctor of Thinkology.

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    You will still need a geometry correction kit with roller rockers. Even more so with the rollers.
     
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    • RichB

      RichB CherryCuda65

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      Do you have the correct pushrods for hydraulic Lifters or are you using the original solid lifter pushrodS? They are different. The pushrods for hydraulic lifters must be 0.10 shorter than the solid lifter pushrods or the valves will not close.j
       
    • Marcohotrod

      Marcohotrod Well-Known Member

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      what brand of camshaft is it? must be old school cuz .472" is not high-lift today. the stock 340 had .442" lift. 40 pounds closed and 200 pounds open is less than a stock 340-which was about 90 closed at 1.65" and 240 at 1.20" . the 7821-16 comp cams pushrods at 7.23" would have been fine. 273 engines ran fine with those rockers without all the work u did. roller rockers will work fine with no machine work. I hope the springs have more load than u figure or she will have valve float and bounce at more than 3000 rpm
       
    • 70dart65coronet

      70dart65coronet mopar or nocar

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      getting ready to go to the Silverwood Coaster Classic Car show this labor day weekend in Athol, ID

      Its disheartening to think that i only get to take this car out once a year...anyway here is an update with bad news...

      i took the rocker shafts off to see how they were doing and they are galling again on the bottom of the shafts where the big oil hole is to lubricate where the rocker arms bear on the bottom of the shafts.

      Also noticed that some of the push rods ever so slightly contact the heads where the holes in the heads are for the push rods. it doesn't appear to be hurting anything just leaving very small marks in the push rods.

      I am going to try to contact B3 here at FABO to see what he thinks about this oiling problem, and also to correct the geometry with a kit.

      I just want to get this thing bullet proof.

      Steve

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    • yellow rose

      yellow rose Doctor of Thinkology.

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      Some things I see.

      Your geometry is probably not correct. That's why the pushrods are hitting the heads. As expected, the shafts need to go UP and AWAY from the valves. If that happens, the pushrods will no longer hit.

      Mike will tell you how to measure for geometry and he can help you.

      The shafts should have a groove across the oil feed hole. If you are running solid lifters. The lash allows some oil to get between the rocker and shaft when the valve is on the seat. If you are running a hydraulic lifter, there is never any clearance there, and without a groove, you can get some galling.

      Also, you see this galling when you get hot idle oil pressure lower than about 40 psi you just don't have enough flow and pressure to keep the rockers from grabbing the shafts. This is one reason why I always use a HV pump. You can get more oil clear up to the rockers sooner.
       
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      • 66fs

        66fs Well-Known Member

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        I feel this also works if you are running solid lifters. The lash allows some oil to get between the lifters and cam lobe.
         
      • nm9stheham

        nm9stheham Well-Known Member

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        Going back to the old discussion, I thought the plan WAS to add the banana grooves.....?? The contact of the pushrods on the guides may be slight but it ought to be none. As things move around at RPM, and the pushrods bow & flex a bit, who knows what will really happen.

        If you are getting this galling all across all holes, then is seems like a supply issue. Do you have head studs by any chance? There are several spots in the flow path to the shafts where there are restrictions.

        What oil is being used?
         
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        • 70dart65coronet

          70dart65coronet mopar or nocar

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          I do have ARP head studs...

          I believe i have a HV oil pump... when i crank the engine over with no spark plugs or fuel in it, and valve covers off. oil starts dripping off the top of the valve springs and i had to grab some rags before it makes a mess...

          The guy i bought the new shafts from, said that these ones come with bigger oil holes in it so banana grooves wouldn't be needed. I also got the push rods from him and one of the tips is already coming off...

          oil is a 20w50 kendal racing oil. i have a conservative rev limiter at 6000 rpm

          there is a couple of the rocker arms that i clearanced for the valve springs that are slighty rubbing still, very little

          a few pages back i measured the valve spring pressures and based on the comments, i think i did that wrong, i will have to learn how to do that and next time i have the springs off i can re check that

          The car runs great and its really responsive and quick.... i am on the path to make this thing bullet proof and have a piece of mind that im not going to break it
           
        • yellow rose

          yellow rose Doctor of Thinkology.

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          Unless you have .003 or more on the rods and mains that 20w50 is pretty heavy.

          Also, be careful spinning the engine over like that. Especially if the cam isn't broken in (assuming a flat lifter) because it can kill the cam right quick.

          Ok...just re read your post and it's running. Still be careful spinning the engine over like that. It doesn't take much to wipe the lube off the cam.

          Also, if you are running hydraulic lifters, you really need the grooves. With a small solid you can get away without them. But usually not with a hydraulic.
           
        • Wyrmrider

          Wyrmrider Well-Known Member

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          x2 on the banana groves and oil also cools do not restrict use a hv pump
          typical shaft wear
          steel can wear well with iron- up to a point of spring pressure and lube
          hard chrome and iron wear better but do not use flash chrome and I do not much like induction hardened (surface hardened not deep case hardened)
          hard chrome and bronze wear even better
          get to high spring pressure it's a whole new ball game
          chrome moly heat treated shafts and all that
           
        • nm9stheham

          nm9stheham Well-Known Member

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          x3 on the banana grooves. There is no good way to help spread the oil out under the rocker without it. The stamped rockers had a radial groove in the rocker itself to help spread the oil around.

          IIRC the shafts for the stamped rockers have a larger oil hole just like what you show for the rocker than the original shafts for the 273 rockers. So you may have ended up with rocker shafts for stamped rockers. (I have some new MP shafts here which also have the larger holes.) Not sure it makes any difference for surface hardness, but the 'it's OK because the hole are bigger' sounds like just made-up advice for oiling the 273 rockers with high spring pressures.... IMHO.

          And I am kinda leary about the 20W50 oil...it is going to be another restrictive matter in delivering oil to the shafts and rockers. That area is low pressure and low volume already and there already 2-3 restrictions in the path from the crank to inside the rocker. The ARP studs narrow down one more area through which the oil has to flow so that adds more flow resistance. If there is no other compelling reason to use 20W50, I'd consider dropping to 10W40.

          But at least the pushrod cups sound like they are doing well now; that's a big step forward from a couple of years ago!
           
        • pt70

          pt70 Active Member

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          The rocker shaft part numbers for a 1970 318 and for a 340-4 bbl are the same. The number for a 340-6 bbl is different. An old rocker shaft that came out of either a 318 or 273 shows wear/gouging at the rockers. It is made of a slightly tougher steel than mild steel, but is not hardened at all.

          20 w 50 is pretty close to straight 30 weight. I put together a 318 20 years ago. Crank was fine with over 120,000 miles. Replaced the bearings with federal mogul std. size. The bearings plastigaged at .0015. Ran it for 90,000 plus miles and it still has excellent oil pressure. It is in a 5000 plus pound van, so it worked hard on the hills. It always had 20 w 50 in it most of the year and 10 w 40 for the winter months [CT]. I never rev it when I start it if it is cold outside.
           
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          • nm9stheham

            nm9stheham Well-Known Member

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            Of course it has excellent oil pressure... you have 20W50 in there! Every pump will show higher oil pressure output into a given set of restrictions (i.e., an engine oiling system) with heavier oil as long as the pump can suck it up the tube, but this is because the flow rate is lower. The pressure sensor is at the start of the oiling path into the engine... it is a whole different story far down the oiling line once the oil gets through multiple restrictions. So pressure that you see on the gauge is not telling you the flow that you get up in the rockers.

            Don't confuse pressure with flow.... 2 entirely different things.
             
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            • 66fs

              66fs Well-Known Member

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              Ran 20-50 Valvoline Racing oil for 300,000 miles in the 67 Barracuda with a 273 and 200,000 miles in a 64 4 speed Barracuda HP 273. Daily drivers and had no oiling problems at all. Lived 5 years in South Dakota and years in Florida and more than a few places in between. 20-50 is not a problem.
               
            • yellow rose

              yellow rose Doctor of Thinkology.

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              How is a 20w50 close to a single grade 30? That doesn't take any sense. Viscosity is temperature relevant. So not matter what temperature you measure flow, the 20w50 will always be different.

              And at 212 degrees, you'd be lucky if that single grade 30 was still a 30, unless you are running an expensive oil.
               
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              • Wyrmrider

                Wyrmrider Well-Known Member

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                20-50 is not a problem
                ran it and 0-50 for years with old school clearances
                however today we run tighter clearances, thinner rings, rev higher
                no question that most wear is at start up (or carb choke wash)
                and a 0W oil flows better cold no matter what your cold is
                so I use 0W-40 most places
                except on new Subaru where 0W-20 is called for
                check out the new (er) VW 508 spec for 0W-20 makes all older specs obsolete
                GM has service bulletins out that recommend 0W-xx instead of the OEM manuals 5W-xx
                The new Corvette 0W-40 is about as good as you can get
                DEXOS 2 great base stocks requied and over 900 zn and phosphorous
                I'll say it again do not add ZDDP to SN oils makes EP worse
                and the new VW 508 has a Calcium based EP so no ZDDP there either
                It interesting that the MOBIL 1 ESP family meets
                The VW 508 spec
                THE VW 507 spec for the TDI turbo diesel (low particulates, low SAP)
                Meets the latest MB spec for both gas and diesel
                and Meets the new Corvette DEXOS 2 Spec
                Made from Natural Gas
                I'm going to have son switch VW TDI from the 5-30 to the 0W-40
                (The 40 is a low 40 high 30 spec) he is way out of warranty but the particulate filter is pricey if you screw it up
                THE ESP line is specially designed for the latest catalytic converters and sensors where additives engender expensive replacements
                Not pushing Mobil- others have similar
                BTW VW has been treating him royally with the emissions scandal recalls
                 
              • pt70

                pt70 Active Member

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                Back in the day I had an Olds V-8 with a mechanical oil pressure gauge. Both 30 wt and 20w50 had 40 psi at cold idle. Both had 30 psi at hot idle. When I changed to 10w30 for the winter months, the hot idle pressure dropped to 20 psi, even though the outside air temp was much lower.

                As far as I know, all oil loses viscosity as it heats up. And they lose viscosity at huge rate from 32 degrees to 212 degrees F. By a factor of almost 100 to 1 !!! And it is not in a straight line either. So when you drain the oil on a hot day after a long drive, the oil drains out like a cow pissing on a flat rock, regardless what weight oil you have in the engine. You can put different weight oils in your freezer overnight and do your own comparison tests in the morning.
                 
              • nm9stheham

                nm9stheham Well-Known Member

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                The whole point of suggesting that a lighter oil be tried is for flow rate, not for pressure. The pressures inside the SBM rockers are already very, very low... like under 10 psi and probably only a couple of psi at idle. There are roughly half a dozen or more flow restrictions in the path from the oil pressure sensor before the oil gets into the rocker shafts, not counting the 'timed' oil restriction in the cam's 'flow interruptor'; that only lets oil flow for roughly 5% of the time. Since these rockers have been modified for MORE outflow, and there is another added minor restriction (head studs), anything that will increase oil flow ought to be considered....IMHO.
                 
              • 66fs

                66fs Well-Known Member

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                Ran 20-50 in 96 Neon DOHC. 250,000 miles runs like new. Not buying the light oil stuff. Your engine your money. Just my experience.
                 
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