Performance timing

Electrical and Ignition

  1. dazedand confused

    dazedand confused Well-Known Member

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    I already checked out an article on here: Total timing. But too much arguing back and forth about timing set up? Here's what i am dealing with/ engine set up: 85 318 engine block with flat top pistons not high compression but only 9.1 compression . Short block was built by a really good machine shop and cam was degried correctly . Rest of short block is stock . Here are the cam specs: Erson cam part number
    E 420121 GRIND: TQ20H
    Lobe separation angle 112+4
    Overlap : either 68 or 88 ? Paper faded
    Intake open 38 exhaust closed 30
    Intake closed 74 exhaust opens 82
    Valve lift int/exh 0.449
    Duration int/exh 292
    Over lap -10
    I bought a mopar performance distributor with performance curve vaccum can plugged off.
    My questions is what is the correct time suppost to be? Do i set it at idle or does it need to be at 1000 rpm 2000,2500 or 3000 to set timing? I called mopar performance and the guy asked me what the number of the distributor is???? I told him i bought it from mancini racing and its for a small block mopar . He still wanted to know the number of distributor?? I follow Nicks Garage on youtube and asked him what the timing should be and told him what distributor i have and he wanted to know what the distributor total degree is ??? I have no clue on any of that ? I just want a basic step by step instructions on what to do ! Like start the vehicle up and let it warm up, grab a timing light etc . I have a timing light with a degree dial on it . Do i leave it at 0 ect.
     
  2. 67Dart273

    67Dart273 FABO Gold Member FABO Gold Member

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    You need to do some more reading. If you have not done so, read the article in this thread, posted by AbodyJoe

    Initial timing settings

    Here's what you have, and it all adds up, except that usually, vacuum advance is NOT included in speaking of "total" timing. Total timing is with your foot on the gas, at high RPM, with all the advance "in" except for vacuum, which drops out under a heavy foot---as there is no vacuum

    Optimum timing VARIES as there are hundreds of variables on builds........types of pistons, and combustion chambers, cam specs and cam timing, compression ratio, and even the load on the vehicle, which is quite different between say, an A body and a 3/4T 4x4. And of course varies with fuel

    Also understand that "normal" specifications, such as the service manuals and other books, spec in "distributor degrees" which is 1//2 the amount of "as measured at the crank

    For a beginning figure, start with 15--25 BTDC at the slowest idle you can get, trying to make sure none of the mechanical advance is "in"---which varies by RPM

    You want say, 18--20 in the distributor, less with a "hotter" engine. A starting figure for "total timing"---------which is measured at fairly high RPM---to get the advance 'all in' with the vacuum disconnected, is maybe 34--36 degrees.

    So "let's say" that you have a dist. with an even 20 "crank degrees" (10 dist) in the mechanical advance. If you set the initial (idle) timing at 15, those two add up to your 35 degrees example.

    The vacuum is ON TOP of this figure, and that total of all three---initial + distributor+ vacuum when your foot is light and running "level" at cruise---can be 50--55 degrees, sometimes more.
     
    Last edited: Jan 1, 2020
  3. 318willrun

    318willrun Utube channel 318willrun

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    You'll have to let the engine decide. Nobody can say what that will be. IF you want a general starting point, then I'll say 15* initial/35* total. But you'll have to see what your motor likes. You may end up at 20* initial/34 total. My 318 is at 20* initial/40* total. Again, nobody can say exactly what your engine will like best.
     
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    • 67Dart273

      67Dart273 FABO Gold Member FABO Gold Member

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      ^^And that is true^^ Crackedback on here talks of "as much timing as it can stand" inititial without bucking on the starter. I like to tune idle for highest vacuum reading. Either of these two is a guide for initial

      Total under power you need to look for ping (knock) and learn to read plugs and look for detonation. Once you have established those two points-----workable initial and total under power, you can "go back" and have the dist recurved to effect those two timing points. And work with the springs to get it to advance WHEN (at what RPM) seems best
       
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      • 512Stroker

        512Stroker We are all here because we are not all there.

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        Bring it over and I will time it for you.
        It's easier to show you than to explain it to you here. LOL
         
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        • 66fyssh

          66fyssh Don't Stop Believin' FABO Gold Member

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          I know you mentioned looking back through the threads. Here's a good thread if you haven't already seen it.

          Establishing Initial Timing


          Initial timing is set at idle. Total timing, as most people use it, is initial plus mechanical advance (vacuum advance disconnected).
           
        • 66fyssh

          66fyssh Don't Stop Believin' FABO Gold Member

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          That's an awesome offer. Take him up on it!!
           
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          • dazedand confused

            dazedand confused Well-Known Member

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            What initial timing ? At idle in park?
            35 total is that at 2500 or 3000 rpm??? I dont work on timing and cam degreeing on a daily bases so i have no clue what all this automotive manual talk is? I run a vaccum gauge that color coded with - - red,yellow,blue --> red area being bad and blue on opposite side being the best .
             
          • dazedand confused

            dazedand confused Well-Known Member

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            512 Stroker i have no idea where freedom missouri is i live 10 miles south of branson mo.
             
          • 512Stroker

            512Stroker We are all here because we are not all there.

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            Lake of the Ozarks
            Do you have the new distributor in? Does the engine run and idle?
             
          • dazedand confused

            dazedand confused Well-Known Member

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            Yep the distributor is in the 318 in my D150 truck. It has a smooth idle in park and in drive . It idles in park at 1000 rpm And in drive at 650 rpm . I have a 600 cfm edelbrock carb on the motor. It used to fry the tires with the worn out 360 it had when power breaking it but it had walmart wranglers A/t now it has highperformance street tires from big O now it just axles winds or wheel hopes? Im planning on getting rid of the thin 4 leaf springs and swapping to 3/4 ton thick 6 leaf springs
             
          • 512Stroker

            512Stroker We are all here because we are not all there.

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            Easy enough
            Set the dial on your timing light to "0"
            With the vacuum advance plugged set the timing at idle, around 700 rpm, to 15 degrees.
            Drive it, if it does not ping, advance the timing at idle another 2 degrees = 17 degrees
            Keep doing this unit you hear the engine ping under load, this is known as detonation = bad.
            Back the timing down 2 degrees - no ping - lock the distributor down and forget it.
            Try to run the same fuel
            This is the most simple way to time your engine. There are different more advance methods but this will get you down the road, just dont let it ping under load.
            Make sure you reconnect your vacuum advance,
             
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            • vntned

              vntned Well-Known Member

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              I've used a couple of the new Mopar distributors. They should have 20degrees of built in advance out of the box. Set your base at 12-15deg, then try it out. After that it's just doing what the engine likes.
               
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              • halifaxhops

                halifaxhops It's going to get stupid around here! FABO Gold Member

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                a lot of the MP distribs are in pretty fast. Think @Mattax has the charts on here somewhere.
                 
              • abodyjoe

                abodyjoe Well-Known Member

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                initial timing is it at idle. toatal will be where ever you make it via the advance slots int he dist and springs in the dist. could all be in by 1300 or 4000 depending on whats in the dist.
                 
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                • abodyjoe

                  abodyjoe Well-Known Member

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                  not sure it can be explained any more simple then these two articles..

                  timing 1.jpg

                  timing 2.jpg

                  timing 3.jpg

                  timing 4.jpg
                   
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                  • halifaxhops

                    halifaxhops It's going to get stupid around here! FABO Gold Member

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                    Those MP springs are seriously light.
                    Mr-Gasket-925B-Distributor-Advance-Mechanical-1-Set.jpg
                     
                  • halifaxhops

                    halifaxhops It's going to get stupid around here! FABO Gold Member

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                    That article does cover it all.
                     
                  • halifaxhops

                    halifaxhops It's going to get stupid around here! FABO Gold Member

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                    Found one similar
                    upload_2019-5-20_18-30-11-png.png
                     
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                    • FlDart360

                      FlDart360 Well-Known Member

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                      Could you explain the term Bucking on the starter. Is that when you release the key after trying to start the car and it sounds as if the engine is going backwards?
                       
                    • 67Dart273

                      67Dart273 FABO Gold Member FABO Gold Member

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                      No it's when you have so much advance, and when you are cranking it and the engine fires, that it tries to fire "backwards" This used to be (when I was young) TYPICAL of poor timing curves in Chevs. You'd hear some guy crank the thing, and then it would abrubtly slow down when cranking ---difficult to describe unless you hear it
                       
                    • FlDart360

                      FlDart360 Well-Known Member

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                      Learn something new...thanks
                       
                    • AJ/FormS

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

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                      You installed a 292/112 cam into a 9.1Scr ,318 ?... I'll be interested to see how this works out. Have you done a compression test?

                      Your idle timing is ballparked at 292x.05 plus 2=17. But with an automatic and a high-stall, it doesn't much matter. What does matter is that you get the the transfer slot exposure underneath the butterflies set right. That cam in my 367 liked the exposure set to a lil taller than wide but not as high as 50%taller, I'll guess at 30-40%. Then I set the idle-speed with timing. Mine was a stick car so 800. With an auto, you might be looking at 650/700 in gear/ and 100 to 150 more in Park/Neutral. If your combo won't come in there, you probably have too much timing.
                      To run the 108LSA version of that cam in my 367 at 11.3Scr,and to get the transfers set up right (750DP), I had to drill one hole in each primary butterfly, up near the idle discharge ports, and about 1/4 " from the edge. The hole size ended up at 7/32 . It's easy to get carried away and drill too big; be forewarned.
                      The secondaries, I closed up tight but not sticking. It ran a jobber PCV. That cam , after the power-timing was set, liked lots and lots of Vacuum advance and in as fast and hard as I could bring it. I modded the Vcan to get 22*. Cruise timing was 50* at 2800rpm.... but it liked a lot more; 50* was all I could give it with the factory parts. I ran it at 207*F and fresh cold air sealed to the carb.
                      your requirements may vary.

                      by the math, I get
                      292/292/112+4/68 overlap(60 effective)/106 compression/98 exhaust, Ica of 74*
                       
                    • Slantsix64

                      Slantsix64 Well-Known Member

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                      Lol. True
                       
                    • dazedand confused

                      dazedand confused Well-Known Member

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                      AjJ/FormS
                      I'm still running a pcv on one of the valve covers and a chrome push on breather on the other . Do need to get rid of the pcv valve and use another push on breather? Also i have a stock torque converter. Do you have a photo of the holes you drilled in the primary butter flys?
                       
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