Help me tune my dizzy?

Electrical and Ignition

  1. vntned

    vntned Well-Known Member

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    So I just fired up my fresh motor and broke in the cam yesterday. Next step is to set my timing and adjust the carb. My question is what would be a recommended initial timing setting, and how soon would I want the full advance to come in by?

    My setup is as follows:

    360 .060" over
    Measured 9.3:1scr
    Cleaned up 587 heads with 1.88/1.60s
    CompCams 268AH10
    222/226 @0.050"
    464/464 lift
    110LSA
    106 intake centerline

    LD340 intake manifold
    StreetDemon 750cfm
    340hp exhaust manifolds
    "Ready to Run" electronic dizzy

    This is in a '64 Dart 170, A833 4spd(2.66 first), 3.55fd gear in the back.
     
  2. TrailBeast

    TrailBeast AKA Mopars4us on Youtube

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    The problem isn't so much how much initial, but can you limit the total mechanical afterwards.
    If the "ready to run" distributor can't be limited in some way you will need to use one that can.

    Just a suggestion on your motor at your approximate elevation would be probably 20 or so initial and a mechanical total of 34 all in by 2,000-2,500.
    That would be a good start I think.
    I might be able to help with the total advance limit if you can post exactly what distributor you have. (part number or where it came from)
     
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    • AJ/FormS

      AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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      With a 4 speed and 3.55s, I might consider slowing it down some from all-in by 2000-2500. You don't have the luxury of the TC.

      I ran a similar combo with 28* at 2800, and all in by 3400. I ran 87E10 set up like that. I was running 10.9 Scr tho and 8.6Dcr corrected to 1000ft.
      At your compression ratio tho, you might be able to getaway with TrailBeasts start recommendation. But I like to sneak up on it.
       
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      • vntned

        vntned Well-Known Member

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        The dizzy is one of those white box, Chinese, "Ready to Run" units. I have know idea how much mech advance is built into it or at what rpm it comes in. I intend on figuring that out my next day off though.
         
      • seabee

        seabee FABO Gold Member FABO Gold Member

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        I recently pulled one of those apart and adjusted the mechanical advance in it. Unfortunately, no vac adjustment.
        " Ready To Run " Distributor Dissasembly (Pic Heavy)
         
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        • RustyRatRod

          RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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          Can you give the compression cranking pressure?
           
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          • Lustle

            Lustle Well-Known Member

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            Ideally you want to setup for initial timing first. The best way (to me) to do this. Is to get the distributor (not a dizzy) in and hookup a vacuum gauge (manifold vacuum). Make sure the vacuum advance on the carb is NOT connected for any of this. Set the idle where you want it, say 750 rpm. And MAKE SURE your carb is setup properly, t-port sync, no vac leaks and such. Or the carb can up the RPM on its own, causing confusion about whether the initial timing is increasing RPM or the carb is. Then start with something conservative. Say 10 degrees. Slowly bring the initial up. If the RPM and vac goes up. Keep going, making sure to reset the idle to your start idle with every adjustment. If you don't bring the idle back down. Then of course the vac gauge will read high. So resetting the idle is very important. You also want to make sure you aren't getting into the mechanical advance on the distributor. Some distributors can start their mechanical advance at 1000 RPM or less. If you are into the advance, it will screw up your initial timing. If you have to. Lock the mechanical advance out so you can get a proper reading. Once you hit max vac on the vac gauge. Back it down 1-2 degrees. Lock it down. Remember your initial timing.

            Next step? Hot start. By now the engine should be very hot. Shut the engine off. Leave it for five minutes. Start it again. If it fires right up. You should be ok. Let it run for a few minutes again. Then shut it off again. Leave it for ten minutes. Start it again. If it fires right up. You should be ok. What you are testing here is the "hot start". That is, how well the engine cranks with a lot of initial timing and a starter that's heat soaked from the exhaust running right past it. This test is very important if you have headers. They can cause MAJOR heat soak into the starter. And if you run too much initial timing. The starter won't work proper. OR it might even kick back. Never a good thing. If there is hot start problems. You will need to back the initial down. I suggest 1-2 degrees at a time. You don't wanna lose too much initial timing.

            Once you find your good initial. Then you know what to time for your total. MOST small blocks like 34-36. It's uncommon for them to fall out of this area. And it's usually the result of better combustion chamber heads (ie more efficient) or power adder. Or whatever else. So once you know your initial, say 20 degrees. Set your distributor advance for 14-16 degrees, usually all in by 3000 rpm. This is another most common thing. Although some guys run shorter or longer distributor timing. The best way to test total timing, is a track. Set it for 34 degrees. Record MPH/ET. Up it to 35 degrees. Record MPH/ET. Set it for 36 degrees. Record MPH/ET. Whichever one you get best MPH/ET on, is better. If it's best at 34, you could even try going down to 33/32 and see if it picks up. If it's best at 36, you could try 37 or 38 and see if it picks up.

            As always. LISTEN for pining/detonation. Not something you should run into on your build. But always something to listen for when setting timing. Usually after I do a tune up like this (carb adjustments, new timing, etc) I also like to get a fresh set of plugs. The constant dicking around with stuff can foul the old plugs. And for a whopping 2 bucks each. It's an easy thing to change to help keep the car running as best as possible.

            IDEALLY you want the MOST timing possible at the crank itself (initial) possible. The less mechanical advance you have. The better. The most initial possible will give you the best low end power. When I adjusted my setup and went up to 22 initial. The car was a whole different beast. It ran like a scalded dog. Way better idle. Way better throttle response on the low end. Just a much better tune.

            That's the procedure. As for whether your distributor can be adjusted or not? I have no idea. Some of the mopar style distributors need to have the weight slots welded up. My setup (firecore) has the adjustable weights, there's little screws you tighten down. Super simple. Just use the adjustment keys, or a proper size drill bit:

            14° = .130” or 3.3mm or #30 drill

            16° = .149” or #25 drill

            18° = .167” or #19 drill

            20° = .184” or #13 drill

            22° = .202” or #7 drill

            24° = .225” or 5.7mm or #1 drill

            26° = .240” or 6.1mm or B drill

            28° = .260” or 6.6 mm or G drill

            And set it from there. It will depend on your distributor, yours might not be able to do this. One thing you might as well check while setting up the distributor. Is the reluctor gap. Should be .008, butttt as long as you're "near" that, you're ok. lots of guys end up between .007 and .010. Make sure to use a brass feeler gauge to do this.

            That should pretty much get you there.

            EDIT: Some edits for shit I forgot cause it's late and I am doing six things at once. Also I might have left some small details out. Other's may chime in with them.
             
            Last edited: May 23, 2017
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            • TrailBeast

              TrailBeast AKA Mopars4us on Youtube

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              • j par

                j par Well-hung Member

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                THANK YOU for addressing that wrong term used for distributor! That makes me nuts well I'm already nuts of course but that's besides the point. Unless you're Snoop Dogg himself saying dizzy sounds....not right. And don't get me wrong I like rap anyone ever heard of CW McCall? ( try" Wolf Creek Pass" OR "crispy Critters")
                And by the way that is an excellent tune up procedure and I will have to use it myself thank you very much.

                 
              • 318willrun

                318willrun Utube channel 318willrun

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                My way is most unpopular..... but I'll share it anyways. As everyone lets the car decide where the initial should be, I also let the car decide where total should be. If it's 34*, then so be it, if it's 44*, so be it.
                 
              • roccodart440

                roccodart440 Well-Known Member

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                I'd try for 18-20 degrees of advance all in by 3000. Me personally, I run 18/36 all in by 3500.
                 
              • seabee

                seabee FABO Gold Member FABO Gold Member

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                Out of the box my "ready to run" distributor had 20' mechanical all in by 1750rpm. Bending the spring tabs got me to about 2500 now.

                The problem is that vac advance is another 20 so having an intial around 22' will get you above 60'. For my engine, that was getting lower engine noise, so I have the vac disconnected.
                 
              • roccodart440

                roccodart440 Well-Known Member

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                does it like 42 total? Seems high to me.
                 
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                • seabee

                  seabee FABO Gold Member FABO Gold Member

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                  Runs pretty good. It is almost daily driven on the street and highway. I am looking to do the hei conversion on my Mopar distributor so I can really get dialed in though.
                   
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                  • roccodart440

                    roccodart440 Well-Known Member

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                    I ran the MPP dizzy and went to a MSD pro billet. engine was much smoother after and the curve was easy to adjust. I'm sure that HEI will be similar. I'd back your total down a bit and see how it likes it. I'd do a pull at 34, 36 and 38 and compare the numbers if you are on a chassis dyno or ET's if at the strip.
                     
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                    • seabee

                      seabee FABO Gold Member FABO Gold Member

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                      I think so too. It is driven 99% of the time under 3000rpms with kids in the car. Cruising around town it runs like a top. I imagine of I were measuring ET's and such it would be a different ballgame.
                       
                    • Lustle

                      Lustle Well-Known Member

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                      When you say you let the car decide. Do you mean that you tune it for whatever the car likes best? Or just leave whatever mechanical advance the cam has and set your initial and not worry about total?

                      If you just leave whatever mechanical it has. I'd be concerned if you were running a lot of initial. Say you are running 26 degrees initial. The distributor also has 26 degrees mechanical and brings it all in by 2600 rpm. There are a lot of factory distributors like this. You'd be running 50+ timing by 2600 rpm. Under WOT load I would think you'd have problems.

                      I know when I first reset my initial. I just left the total where it was for a while. Wanted to see how it drove, how it hot started day to day kinda thing. And I did notice that around 3000 rpm under load at WOT I got some breakup. But as soon as you moved passed it. It was fine. I always figured that was just from the mechanical advance. Came in too much and too hard. Do you ever run into that problem setting them up the way you do?
                       
                    • 318willrun

                      318willrun Utube channel 318willrun

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                      Yes, tune to whatever the car likes best. I gave the example of how people let the "car" decide where the initial should be, I do the same with total. I've had many small blocks run the best, and turn the best E.T. at above 40* total.
                       
                    • Lustle

                      Lustle Well-Known Member

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                      Ahhh that makes sense. For a second I thought you meant just let total fall where it may lol. That would be interesting.

                      Yeah like I mentioned it's best to tune total. While most guys will end up in that 34-36 area. The best thing you can do is take it to a track and run it. Keep playing with timing, as much as it sucks to pull your distributor apart 10 times a day. That will tell you what the car likes most. I know there are some guys will really efficient heads only ending up around 30 total timing. Sounds odd. But if that's where it makes best MPH/ET that's where you should leave it.
                       
                    • RustyRatRod

                      RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                      I have had lots of engines run well above 40* total timing. They were low compression engines that were over cammed. Between advanced cam timing and advanced ignition timing though, they ran pretty dang good.

                      That's why I asked about compression pressure, but of course, as so common, that key question was ignored.
                       
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                      • 318willrun

                        318willrun Utube channel 318willrun

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                        I've always had to run alot more timing on low compression motors. I set intitial, then I loose the initial as I set total "out of town-seat of the pants", then fine tune total at the strip, and the do what I need to do to the distributor put the initial back to what it was. Make sense?
                         
                      • Lustle

                        Lustle Well-Known Member

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                        Yeah low compression engines can do with more total. And vacuum. Some guys run 60* at low load highway speeds with low compression 318's and such. Great mileage!

                        Your question hasn't been ignored. The OP simply hasn't responded since you posted it.
                         
                      • vntned

                        vntned Well-Known Member

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                        Not sure on cylinder pressure yet RRR. I literally fired it up, did the cam break in and shut it off to cool down Sunday night. I haven't had the chance to do anymore to it yet due to work.

                        Since it looks like I might be limited on the tune ability of my $50 dizzy, I think I'm gonna start by finding out how much mech advance is built into it by setting my full advance to 34deg, and see where the initial falls. I'm thinking this should give me a good idea of where I'm at and a good starting point for adjustment. Probably gonna have to end up getting a more tuner friendly, aka quality distributor, to really dial in the motor.

                        Right now I just wanna get a basic tune in it so I can start driving it again!
                         
                      • AJ/FormS

                        AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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                        This is the exact wrong thing to do.
                        Firstly the power timing is now 20 plus 22=42, all in by 2500. This is perfect for part throttle cruise, but will hammer your bearings to death under full power at 2200rpm and probably still be hammering well into the 4000s, and beyond. If you disconnected your secondaries the engine might stand a chance. Furthermore with the vacuum advance now disconnected, there will be large periods of time that the engine will not be receiving the advance it needs and so it will waste fuel being as it is retarded for the mode of operation.
                        A much better idea is to back up the idle-timing to 14 degrees, and let the power-timing be 14 plus 20=34@2500 .This will at least be correct at WOT. Then hook the vcan back up. The 20 degrees in it will not be applied until the manifold vacuum at the sparkport tells it to. So it might add 4 degrees by say 1400 rpm and 4 more by 1700, and 4 more by 2000, and so on until it is all in by 2600 under light cruise. Now the engine might be seeing ; 14 plus 20 plus 20vacuum= 54* @ 2600rpm at hiway cruising. This may be just right. And when you are cruising along at 2600, and you decide to floor it, then the 20* in the Vcan will drop out leaving you perhaps in second gear @ 4000 or so rpm where the all-in timing is just 34*. Now yer talking!
                        This covers all the bases.
                        It may not be 100% correct, but at least the engine won't hammer out the rod bearings or split off the skirts.
                         
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                        • seabee

                          seabee FABO Gold Member FABO Gold Member

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                          So my numbers were actually off. I strobed it today and found the initial at 22' and the total Mech at 39' (17')

                          I'll set the total to 34', attach the vac and see what happens.


                          And sorry Vntned for the derail.
                           
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