Is It Backwards? Why Does it Work?

Small Block Mopar Engine

  1. eekvonzipper

    eekvonzipper My Member is Legendary! FABO Gold Member

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    I set my new gears in my chain dot-to-dot (Crank Dot Up/ Cam Dot Down)
    When I set it on the little 273 the Cam Gear was 180 out...
    So I flipped it over in the chain so Both Dot's Were Up.
    I put it all back together and It Fired Right Up!
    It has the old style timing cover with the mark on the Passer side.
    Is it supposed to be this way?
    Did I just get lucky or was the old chain somehow set-up wrong and I copied it?

    old chain.jpg

    new chain.jpg
     
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    • 67Dart273

      67Dart273 FABO Gold Member FABO Gold Member

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      This comes up once a month. The cam goes 1/2 crank speed. It's called "ratio." The cam sprocket is twice as big and twice as many teeth as the crank sprocket. So the cam goes 1/2 the speed of the crank. Every other turn OF THE CRANK the dots meet, and every off turn from that, the two dots are on the "other side" of the cam sprocket. 1 turn of the crank, cam dot up, 1 turn of the crank, cam dot down

      Use a straightedge, make darn sure they are in time. The dist does NOT fire no1 when the dots are 'dot to dot' it fires no6. Keep that in mind when you get around to that
       
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      • eekvonzipper

        eekvonzipper My Member is Legendary! FABO Gold Member

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        So, I'm Good? It Does Absolutely fire on One! It Runs Great.

        no1.jpg
         
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        • RustyRatRod

          RustyRatRod Lemmie see your b00bs. FABO Gold Member

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          Lined up dot to dot is timed up on #6. The correct position for #1 firing position is both dots at 12 o'clock.....yet there are few and far between service manuals that show that. The reason is because it's become the industry standard to line the dots up, time the engine correctly, install the distributor at what would be 180 out. That's because it's much easier to determine that the dots are aligned if they are at their closest.
           
          Last edited: Nov 18, 2020
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          • pishta

            pishta I know I'm right....

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            ^^ you beat me to it^^^
            It runs great, dont dwell on it. dot to dot is easier to line up but you still time the spark to the TDC of #1 compression stroke.
             
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            • crackedback

              crackedback FABO Gold Member FABO Gold Member

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              You sure about both being at 6 o'clock...

              That puts the piston at bottom of bore for #1, IIRC

              I think you meant both marks at 12 o'clock.
               
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              • RustyRatRod

                RustyRatRod Lemmie see your b00bs. FABO Gold Member

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                Yeah Thanks. I meant both 12. My bad. I had a brain fart.
                 
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                • RustyRatRod

                  RustyRatRod Lemmie see your b00bs. FABO Gold Member

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                  I changed that stupid chit. Thanks Rob. lol
                   
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                  • eekvonzipper

                    eekvonzipper My Member is Legendary! FABO Gold Member

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                    Lol. Thank You Everyone! Especially You Triple R.
                     
                  • j par

                    j par Well-hung Member

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                    You're on it first correctly and triple-r screws it up then gets all the credit LOL..
                     
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                    • crackedback

                      crackedback FABO Gold Member FABO Gold Member

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                      Use the "I'm in australia excuse" Everything upside down.
                       
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                      • RustyRatRod

                        RustyRatRod Lemmie see your b00bs. FABO Gold Member

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                        That's right. Even toilets go the wrong way. lol
                         
                      • James Clews

                        James Clews Well-Known Member

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                        Rusty! no you guys are upside down , not us! We have not had a corona case in two weeks, how many have you guys had?
                         
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                        • RustyRatRod

                          RustyRatRod Lemmie see your b00bs. FABO Gold Member

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                          Too dang many, James.
                           
                        • dodge71demon

                          dodge71demon Well-Known Member

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                          Thought this would turn into something else but didn't -- good job
                           
                        • krazykuda

                          krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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                          Why do you have THREE throttle return springs on the carb??? That could cause some side loading on the throttle plate shaft and cause it to wear in an oval shape over time... I would recommend going with two at the most, three is a little much...

                          Your gas pedal must be so stiff with all of those springs, your leg will look like Quagmire's arm after internet porn....

                          Quagmire internet.jpg
                           
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                          • jazak5

                            jazak5 Well-Known Member

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                            You live on one of the toughest places on earth !!! Once a penal colony and everything is dangerous or poisonous....COVID-19 is the sniffles !!!
                            :lol:
                             
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                            • Tooljunkie

                              Tooljunkie King of cobble/master of the broken bolt FABO Gold Member

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                              I remember a neighbour and his diesel mechanic buddy doing the same thing on a chevy small block. Picture in manual showed dots together. Says thats how they did it. There were actually words that said turn crank to bring both marks to top before installing distributor. They didnt read that part. I pulled dist, turned rotor 180 and it fired right up.
                               
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                              • 69FBCuda

                                69FBCuda Life in the Fast Lane FABO Gold Member

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                                Gotta Love that feeling when it's "right" and fires up for the Big purrrrr, might even beat Sex...............:lol:
                                 
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                                • Cuda416

                                  Cuda416 FABO Gold Member FABO Gold Member

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                                  Well let's see... 25 million, to 330 million people.... You're not even the same size as Texas... soo....
                                   
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                                  • Treblig

                                    Treblig Well-Known Member

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                                    Here's a couple of cases on me:

                                    im-46433?width=1280&size=1.jpg
                                     
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                                    • SGBARRACUDA

                                      SGBARRACUDA ROY FABO Gold Member

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                                      'There, I couldn’t have explained it any better.
                                       
                                    • krazykuda

                                      krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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                                      You said penal...


                                      Speaking of penal colony and poisonous:

                                      The Lone Ranger has to take a whiz so he stops along the trail to go in the bushes... While in middle of relieving himself a poisonous rattle snake bites him on his 'penal colony'....

                                      He sends Tonto into town to get a doctor... Tonto finds the doctor and he tells him what happened to the Lone Ranger... The doctor tells Tonto that you have to suck all the poison out of the bite...

                                      Tonto rides back to the Lone Ranger and when he arrives, the Ranger asks him, "What did the doctor say???"

                                      Tonto replies, "You're gonna die..."
                                       
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                                      • Cuda416

                                        Cuda416 FABO Gold Member FABO Gold Member

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                                        So did they change this on magnums? We did it dot to dot, rotor pointing to #1 TDC and it fired up on the first crank. Am I missing something really basic and got really lucky?
                                         
                                      • pishta

                                        pishta I know I'm right....

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                                        Here is the physical layout of the cam lobes: the key to the cam points right up the #1 exhaust lobe. The key to the crank points right up the #1 cylinder so dot up in the crank is TDC of the #1 piston (either compression or end of exhaust) . With DOTS UP, your intake is fully closed on the #1.---with DOT TO DOT, your #1 intake valve is open. the intake lobe is about 60 degrees behind the exhaust lobe going clockwise from the front so if the cam key is at about 4:00, your intake valve is open. count back to the #6 intake and I bet its closed (TDC compression) when your DOT to DOT. That's just how it is. Someone can prove me wrong if you show us the cam lobe orientation on a bare cam.
                                         
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