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  • ProFlo Mopar Distributor Rotor Phasing

    After all the concerns and uncertainties that have been discussed here regarding possible rotor phasing issues with the ProFlo Mopar Distributors, we have done some investigating and determined that the Rotor phasing is Correct.

    As show in photos below, at 12-degrees base timing (Yellow Mark) and 36-degrees of advance (Red Mark), the rotor tip is well within the range of the distributor cap terminal.


    1. Short Tooth Mid Sensor @12-degrees.jpg

    Short Tooth Aligned to Middle of the Hall-Effect Sensor with the Crankshaft/Balancer at 12-degrees BTDC


    2. Rotor Tip at 12-degrees.jpg

    Rotor Tip Position (Yellow) in Relation to #1 Cylinder (Distributor Cap) Terminal Location at 12-degrees BTDC on the Crankshaft/Balancer

    At 12-degrees, the rotor tip is close to center of the cap terminal.


    3. Rotor Tip at 36-degrees.jpg

    Rotor Tip Position (Red) in Relation to #1 Cylinder (Distributor Cap) Terminal Location at 36-degrees BTDC on the Crankshaft/Balancer

    At 36-degrees, the leading edge of the rotor is at the terminal and well within range to the correct cap terminal.


    4. Rotor Tip to Terminal.jpg

    Rotor tip position in relation to #1 Cylinder (Distributor Cap) Terminal Location at 12-degrees & 36-degrees BTDC with Distributor Cap installed.

  • #2
    Post from Mopar Pete:


    Hi all. Just an update with the cold start issue. Seems to be fixed. I went back to the start and reset the base timing. Marked the distributor body to where number 1 post is. I had a spare cap, so drilled a 1/2 inch hole in the top between number 1 post and the coil post. Rotated engine to where 12 degrees btdc is and started engine. adjusted the timing to verify 12 degrees with a new timing light, unlocked the timing and locked the dizzy down.
    then with the timing light, I shone the light through the top of the hole in the dizzy and bought engine up to 3000rpm. The rotor was igniting between number 1 and number 2 post. There was a little hesitation in the engine around 3000rpm, so took it for a drive to confirm. Sure enough, engine stuttered, backfired and stumbled as soon as it went over 3k rpm under light throttle.
    Just installed the MSD adjustable rotor. Rotated engine to 25degrees ( in the middle of my timing range) and lined the rotor tip up with the mark I had placed on the dizzy body where number 1 post is.
    Started engine , an verified with timing light. Bought engine revs back up to 3k rpm, and the rotor tip is smack bang on number 1 post.
    Took it for another drive. Huge improvement all around. Throttle response is better, AFRs and Fuel trims are better, no hesitation what so ever. WOT is awesome, no breaking up at all.
    So to diagnose the initial problem with the cold start issue. I was certain I had 12degrees BTDC before, but turns out the timing gun I had was faulty. I had my suspicions a while back but needed another gun to confirm.
    Ended up purchasing another timing light, and sure enough the faulty light was about 7-10 degrees off actual timing. I've never struck that before.
    Thanks everyone for your input, it was much appreciated.
    Don't get too caught up in the numbers.
    Just give the Engine what it wants &
    Let the numbers be what they are.

    Jim McFarland....

    Comment


    • #3
      This just proved again there is an issue with rotor phasing contrary to what EFI tech says otherwise the adjustable rotor wouldn’t be needed.

      Comment


      • #4
        Rotation on a LA MOPAR small block is the opposite way. It is clock wise. So not shure what these photos are of.
        ​​​​​​. I have ran my Pro-Flow4 for over two years , on my LA 340. Well over 10,000 miles ago. I did put an adjustable rotor on it, but it is only 2° from a stock setting or "0°. But that was because I had it frome my old setup. I wanted to see un burnt area on the outer edges of the rotor face. Good luck.
        Last edited by Rays1969cud; 08-07-2022, 04:20 AM.

        Comment


        • #5
          Originally posted by 2700 Cast View Post
          Post from Mopar Pete:


          Hi all. Just an update with the cold start issue. Seems to be fixed. I went back to the start and reset the base timing. Marked the distributor body to where number 1 post is. I had a spare cap, so drilled a 1/2 inch hole in the top between number 1 post and the coil post. Rotated engine to where 12 degrees btdc is and started engine. adjusted the timing to verify 12 degrees with a new timing light, unlocked the timing and locked the dizzy down.
          then with the timing light, I shone the light through the top of the hole in the dizzy and bought engine up to 3000rpm. The rotor was igniting between number 1 and number 2 post. There was a little hesitation in the engine around 3000rpm, so took it for a drive to confirm. Sure enough, engine stuttered, backfired and stumbled as soon as it went over 3k rpm under light throttle.
          Just installed the MSD adjustable rotor. Rotated engine to 25degrees ( in the middle of my timing range) and lined the rotor tip up with the mark I had placed on the dizzy body where number 1 post is.
          Started engine , an verified with timing light. Bought engine revs back up to 3k rpm, and the rotor tip is smack bang on number 1 post.
          Took it for another drive. Huge improvement all around. Throttle response is better, AFRs and Fuel trims are better, no hesitation what so ever. WOT is awesome, no breaking up at all.
          So to diagnose the initial problem with the cold start issue. I was certain I had 12degrees BTDC before, but turns out the timing gun I had was faulty. I had my suspicions a while back but needed another gun to confirm.
          Ended up purchasing another timing light, and sure enough the faulty light was about 7-10 degrees off actual timing. I've never struck that before.
          Thanks everyone for your input, it was much appreciated.
          So did you move the adjustable rotor off the 0° point?
          I had trouble with my timing and it turned out my 1970 block was machined low were the oil pump gear rests, causing my timing to be sporadic at idle speed. Glad you got it. Have over 15,000 miles on the system.

          Comment


          • #6
            Originally posted by Rays1969cud View Post
            Rotation on a LA MOPAR small block is the opposite way. It is clock wise. So not shure what these photos are of.
            ​​​​​​. I have ran my Pro-Flow4 for over two years , on my LA 340. Well over 10,000 miles ago. I did put an adjustable rotor on it, but it is only 2° from a stock setting or "0°. But that was because I had it frome my old setup. I wanted to see un burnt area on the outer edges of the rotor face. Good luck.
            The picture is of a BB Mopar. If you read it you’ll see he lines up the adjustable rotor with the mark for number 1 at 25*. Same thing I did to eliminate the timing issue I had. If you don’t have timing issues on the SB Mopar then your either lucky or you aren’t asking for timing over 32*. Either way another issue Edelbrock refuses to admit to although someone here posted their new kit had the wide rotor like the Ford distributor uses.

            Comment


            • #7
              Edelbrock changes the parts that come with the kits all the time. So it's really hard to judge a part as a "reference item".

              I haven't had a chance to catch-up with the design for the no-profile distributor ( for coil near plugs ) for the small block yet....need to find a company to laser me out a trigger disc. All the ones I've found in my area are Chinese, and I know first hand what happens when you hand over a design to one of these companies.

              Anyway.
              I'm working on 4 turbo motors, 2 natural aspirated motors, and 2 of my own motors. So I haven't had time to catch-up with my list of Edelbrock projects yet... maybe next month looks good prototyping.
              "Do you know how whipped an engine has to be to blow that loud?"....Bug from the movie Uncle Buck
              https://forums.edelbrock.com/filedat...?photoid=42773

              Comment


              • #8
                JM73340 I run 30° @ 2600 with 6° Vacuum advance. Doing a steady 70 mpg I have from 15.5 to 17 inches. I see 32° to 34°. Mostly 32°. My long term is between -4 and -8 short 0 to - 4. When I ran a carb. A 750 I used no vacuum advance with all in at 2600 - 36°. Driving 60 I see 31- 32°. With short and long term about the same. This system doesn't seem to need as much advance. But my motor is mine. Edelbrock RPM heads that have been ported a lot. A Hughes Roller cam. Many little things over thirty years. So what works for me probably will not work for you. Good luck and have fun.
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