All small blocks share same crank ?

Small Block Mopar Engine

  1. pearljam724

    pearljam724 Well-Known Member

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    I have a 72 - 360. I’m wanting to know if all small blocks share the same crankshaft ? To my understanding the only difference the 360 has in reference to parts is a different oil pan and heads.
     
  2. pishta

    pishta I know I'm right....

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    no. 273-340 cranks are interchangeable dimensionally (67 on had a larger convertor snout), 360 cranks had larger mains and a larger rear main seal.
     
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    • Jadaharabi

      Jadaharabi FABO Gold Member FABO Gold Member

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      The 360 had larger main bearings and as stated a larger rear oil seal area.
      ALL 360 factory cranks are cast.

      ALL 273, 318 and 340s use the same size main and rod bearing.

      All mopar small blocks use the same size rod bearings, 273, 318, 340 and the 360.

      The factory used both cast and forged cranks in the 272, 318 and 340s. Each had its own balance requirements.
      Yes you can use a 273 crank in a 318 or 340 but you may need to rebalance it.
      Some of the 273 &318s have a differant size on the back of the crank where the converter engages it.
       
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      • Jadaharabi

        Jadaharabi FABO Gold Member FABO Gold Member

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        Yes differant oil pan. The rear of the pan is a differant size than the others. However later on Chrysler changed the 5.2(318) magnum to use the 5.9(360) pan.
        The heads on the early 360s were some of the same used on the low compression 340s. Some of them were 1.88 J heads.
        The windage tray used on the 360 has wider spaceing for the mounting bolt holes.
        This was Accomplished two ways. The first way was they made a separate windage tray for the 360. The second way was they slotted or oblonged the mounting bolt holes of the 340 tray so that it fits both motors.
        Because of the larger main bearings they had to move the main cap bolts farther apart.

        My list of differances

        Larger mains equals larger main bearing and a larger rear seal.
        Differant oil pan
        Differant mounting holes for windage tray
        I have also found the 360 main cap bolts to be about 1/4 onch shorter but not alway
         
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        • pearljam724

          pearljam724 Well-Known Member

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          Thanks guys. I’ve been chasing a driveline vibration at 70mph. Addressed many things to no avail. Only thing I haven’t addressed yet. Is driveshaft balance and tranny mount. Which I ll do both soon. If that’s not it. The crank may be bent or out of balance. That’s the only other option left I see. But, nothing vibrates when car is in motion under 70. Does anyone sell a 360 crank new for a 72 engine ?
           
        • Ottmundr

          Ottmundr 68 Fastback

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          Scat Cast Crankshafts 9-360-3580-6123
          Note, this is an INTERNAL balance crank.

          Crankshafts Product Search | SCAT Crankshafts

          just put in the stuff I highlighted in green

          scat_cranshafts_75tall-e1436623469954.png

          CRANKSHAFTS SEARCH

          HomeCrankshaftsCrankshafts Product Search
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          Part #:
          Short Part #:
          Series:
          Make:
          Engine: 360
          Type:
          Material:
          Rear Main Seal:
          Balance:
          Stroke: 3.58
          Rod Length:
          Rod Journal:
          PrintExcelCSVCopy

          Part # Short Part # Series Make Engine Type Material Rear Main Seal Balance Stroke Rod Length Rod Journal
          4-360-3580-6123 436010 Standard Weight Chrysler 360 Small Block Forged 4340 Steel 2-Piece Int Bal, May Req Heavy Metal 3.580 6.123 2.125
          4-360-3580-6123-2 436010-2 Pro Series Lightweight Chrysler 360 Small Block Forged 4340 Steel 2-Piece Int Bal, May Req Heavy Metal 3.580 6.123 2.125
          4-360-3580-6123-3 436010-3 Superlight Crankshaft Chrysler 360 Small Block Forged 4340 Steel 2-Piece Int Bal, May Req Heavy Metal 3.580 6.123 2.125
          9-360-3580-6123 936010 Pro Stock Chrysler 360 Small Block Cast Steel 2-Piece Internal Balance, May Require Mallory 3.580 6.123 2.125
           
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          • stixx

            stixx Well-Known Member

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            Before you tear into the motor and change the cam have the driveshaft balanced.
            A bent crank would cause vibration at any rpm, as a crank out of balance would do it in first and second gear?
             
          • JDMopar

            JDMopar Well-Known Member

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            I would think if the crank was out of balance, it would vibrate at the same RPM while the car is sitting still as it does at 70mph?
             
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            • 67Dart273

              67Dart273 FABO Gold Member FABO Gold Member

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              I doubt the crank is "bent." You need to detail THE REST of your combo. What are you running for transmission? If this is a stick IT MUST use a weighted flywheel to "balance" the 360 crank, needs external weighting. Likewise you must have a 360 weighted balancer

              If you have a conventional torqueflite (and not the newer OD trans) the converter MUST have weighting welded to the front face same purpose as a stick flywheel.

              Have you been able to determine if it vibrates in park or neutral at the same RPM range as you feel at speed? That will quickly tell you if it's an engine/ balance/ transmission problem, or something else in the drive train.

              And don't discount wheels/ tires out of true/ out of balance, BOTH FRONT AND REAR
               
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              • stixx

                stixx Well-Known Member

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                Very good point. Was chasing a vibration myself long time ago that turned out to be a rear tire out of balance...
                 
              • Jadaharabi

                Jadaharabi FABO Gold Member FABO Gold Member

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                Check the driveshaft for balance and straightness and the tire balance or for bent rim if running steel wheels.
                 
              • JBurch

                JBurch Well-Known Member

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                Also check your u-joint phasing, that could also be a possible cause of vibration, one more thing to check
                 
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                • pishta

                  pishta I know I'm right....

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                  Hmmm.. How you gonna fix that? I'd check tires for a 70 wiggle.
                   
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                  • pearljam724

                    pearljam724 Well-Known Member

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                    I changed U joints. Vibrated before and after. Wheels and tires are brand new and balanced. Not the slightest slop in drive shaft front or rear. So that leaves out u joints, bushing and yoke. Tail shaft bushings usually leak when worn. No slop or leaks. Driveline doesn’t make a peep until I hit 70. Then it hums a little. I noticed no drive shaft weights when I changed u joints. So im thinking it needs balanced. Or driveshaft, possibly yoke is bent. I bought the car a year ago. It rides, drives, corners like a new car. Improved a lot of things since then. Just haven’t corrected the 70 hum. Pretty sure it’s driveshaft. I’m going to take driveshaft to a shop now that it’s winter. If that not shim rear end another 2 degrees. If no results. I don’t know.
                     
                    Last edited: Nov 10, 2019
                  • Sterling

                    Sterling Well-Known Member

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                    Just because the tires are new and balanced doesn't mean they are not the problem. I just worked on my friends Lexus, he said it has a thump from the rear at 80 mph. I removed the rear wheels, 1 wheel was bent, and 1 tire was bad. He just had 4 new tires installed. Both rear tires were at least 4 oz. out of balance each.
                     
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                    • JBurch

                      JBurch Well-Known Member

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                      Build a new driveshaft, or cut it apart and insure u-joints are in alignment
                       
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                      • toolmanmike

                        toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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                        Only if you have a 2 piece driveshaft with a slip yoke in the middle. Trucks yes, cars no unless someone cut a yoke off and welded it back on in the wrong place.
                         
                      • pishta

                        pishta I know I'm right....

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                        We had 4 new tires mounted and balanced at home and drive to Utah, we experienced a vibe at 80 but it went away down at 75 (?) so when we got to St. George, we took it to the same chain and had them look at it. Both rears were out of balance and one had a broken belt (big dimple on side of new tire side wall.."uh, is this supposed to look like this?" ...Nope. Did we toss a weight too? Doubtful, as the weights were stick on's inside the rim and there was no where for them to go. So we got a new tire and a balance job under warranty. They were very nice about it too. Butter smooth on way home until we hit the crappy CA freeways, then it was just loud. We pay the most in fuel taxes but have the shittiest freeways? Oh yeah, I forgot who's running the show here for the last 30 years.....
                         
                      • JBurch

                        JBurch Well-Known Member

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                        Do we know for sure that some one has not done just that???? It's worth a check to make sure it is not the problem.
                         
                      • Jadaharabi

                        Jadaharabi FABO Gold Member FABO Gold Member

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                        I use to make pump driveshafts for tanker trucks. Would measure them, cut, put the end on, weld them, install and test.
                        We called it timing the driveshaft when you put the end on. We lined it up straight with the other end.
                         
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                        • toolmanmike

                          toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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                          Exactly. and you better line the yokes up or you will get a vibration you can't balance out.
                           
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                          • Jadaharabi

                            Jadaharabi FABO Gold Member FABO Gold Member

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                            If the yokes are not lined up in effect you have a twisted driveshaft and there is no way to balance it out.
                             
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                            • 66fyssh

                              66fyssh Don't Stop Believin' FABO Gold Member

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                              Years ago I had a very slight vibration. First thing I did was take the driveshaft to the shop. While it was there for balancing I had him replace the U-joints. He even painted it for me!!

                              No more vibration!!
                               
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                              • toolmanmike

                                toolmanmike FABO MODERATOR Staff Member FABO Gold Member

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                                We're getting a little off subject here but this is a good video about driveshaft phasing.
                                 
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                                • Wyrmrider

                                  Wyrmrider FABO Gold Member FABO Gold Member

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