Engine build on the brain

Small Block Mopar Engine

  1. abodyjim

    abodyjim Well-Known Member

    Messages:
    197
    Likes Received:
    120
    Joined:
    May 2, 2016
    Location:
    Topeka Kansas
    Local Time:
    12:17 PM
    So I've been reading build treads and looking at parts I have and how they would work together. I got on Wallace calculator to see if the experts were right that helped pick the parts for a build I'm planning. Also so I understandi what I'm looking at, hearing and reading.
    So where I got confused is inlet valve closing ABDC on the calculator. I found some math that I believe gives me that °. Using my cam if correct it goes (291÷2+110-4-180=71.5°) . Now that 71.5 seems to be right or am I wrong and the number is 56.5° because this is the ABDC number . This number does not look correct when used. Some clarification would be great

    20180321_161005.jpg
     
  2. Wyrmrider

    Wyrmrider FABO Gold Member FABO Gold Member

    Messages:
    3,180
    Likes Received:
    1518
    Joined:
    Sep 5, 2016
    Location:
    los angeles
    Local Time:
    10:17 AM
    can't tell
    .020 is meaningless for input so is .050
    what's your lash?
    any idea what .006 at the valve is (taking the lash out of the investigation)
    or even .004 or .006 past the lash point
    any way to plot your cam
    what rocker ratio
     
    • Like Like x 1
    • abodyjim

      abodyjim Well-Known Member

      Messages:
      197
      Likes Received:
      120
      Joined:
      May 2, 2016
      Location:
      Topeka Kansas
      Local Time:
      12:17 PM
      The numbers are for 1.5 rockers and lash is .020. Also solid roller if that matters. The card is what I have from bullet. They spec'd it for the rest of the parts.
       
    • RustyRatRod

      RustyRatRod Weenie idiot loser. FABO Gold Member

      Messages:
      59,634
      Likes Received:
      30670
      Joined:
      Jun 7, 2010
      Location:
      Georgia
      Local Time:
      1:17 PM
      Your IVCE is right there on the cam card. Am I missing something?
       
    • RustyRatRod

      RustyRatRod Weenie idiot loser. FABO Gold Member

      Messages:
      59,634
      Likes Received:
      30670
      Joined:
      Jun 7, 2010
      Location:
      Georgia
      Local Time:
      1:17 PM
      Your 56.5 number is at .050". Depending on "which" calculators you use will dictate which number you put in. The United Engine calculator for example, has you add 15* to the .050" number, which would be the 71.5 you mention.
       
    • abodyjim

      abodyjim Well-Known Member

      Messages:
      197
      Likes Received:
      120
      Joined:
      May 2, 2016
      Location:
      Topeka Kansas
      Local Time:
      12:17 PM
      I was using Wallace calculator
       
    • RustyRatRod

      RustyRatRod Weenie idiot loser. FABO Gold Member

      Messages:
      59,634
      Likes Received:
      30670
      Joined:
      Jun 7, 2010
      Location:
      Georgia
      Local Time:
      1:17 PM
      Same difference.
       
    • abodyjim

      abodyjim Well-Known Member

      Messages:
      197
      Likes Received:
      120
      Joined:
      May 2, 2016
      Location:
      Topeka Kansas
      Local Time:
      12:17 PM
      That helps, so this is what I came up with. Iron open chamber W2's

      Screenshot_20200130-173335_Chrome.jpg
       
      • Like Like x 1
      • RustyRatRod

        RustyRatRod Weenie idiot loser. FABO Gold Member

        Messages:
        59,634
        Likes Received:
        30670
        Joined:
        Jun 7, 2010
        Location:
        Georgia
        Local Time:
        1:17 PM
        That's pushing the limits of pump gas, IMO with iron heads.
         
        • Agree Agree x 2
        • abodyjim

          abodyjim Well-Known Member

          Messages:
          197
          Likes Received:
          120
          Joined:
          May 2, 2016
          Location:
          Topeka Kansas
          Local Time:
          12:17 PM
          That's what i was thinking. Think I read 8.1 for iron. Those numbers are at zero deck height.
           
        • RustyRatRod

          RustyRatRod Weenie idiot loser. FABO Gold Member

          Messages:
          59,634
          Likes Received:
          30670
          Joined:
          Jun 7, 2010
          Location:
          Georgia
          Local Time:
          1:17 PM
          Well that's in a perfect world. If you really want to "not chance it" stay at 7.5 and under. Remember, bumper to bumper traffic, heat and humidity in the summer....all that will increase chances for detonation. Better safe than sorry. Besides, from 7.5 to 8.1 dynamic compression, how much do you think you're gaining?
           
          • Like Like x 1
          • Agree Agree x 1
          • 273

            273 Well-Known Member

            Messages:
            3,016
            Likes Received:
            781
            Joined:
            May 14, 2012
            Location:
            Ontario
            Local Time:
            1:17 PM

            Don’t let AJ hear you say that lol
             
            • Like Like x 2
            • Thanks! Thanks! x 1
            • Agree Agree x 1
            • AJ/FormS

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

              Messages:
              17,944
              Likes Received:
              6292
              Joined:
              Jan 19, 2014
              Location:
              South-Central Manitoba,Canada, 900ftelevation
              Local Time:
              12:17 PM
              hah
              You're on the right track;
              Heres how it goes;
              First you have to determine the installed position, and back-calculate where the intake opens.
              Next you add those degrees to one revolution or 360 degrees.
              Next you subtract the intake duration from the previously calculated 360+intake opening.
              This will result in a number that is left over(*1) to be the compression degrees. This number you then subtract from a half turn or 180 degrees to get the ICA,Intake closing Angle.

              Ok so, lets take an example of a popular cam, the
              268/276/114+4 Mopar cam
              Mopar wants it in at 4* advanced so 110.
              then; 268/2 less 110 is 24degrees to the overlap cycle. Adding that to 360 equals the total available degrees of 384, for intake plus compression.
              From that, we subtract the intake duration of 268 to get 116* dedicated to compressing the mixture.
              Backing up from TDC, this is 180-116=64* Ica. which is 64 ABDC, same as 116 BTDC.cuz from bottom to top is 180*.
              here it is in longhand;
              180-{[(360 +(268/2-110)]-268}=64

              This helps you nothing, except that you can use that Ica in other calculations to see what your cranking cylinder pressure might be. And knowing that, you can get an idea of how strong or weak the bottom end might be. And knowing that, helps you select a stall-rpm and rear gears.

              But one thing you always have to bear in mind; this number is a calculated number, based on an advertised number , that is not exactly when the intake closes. Most of the advertised numbers that you will find, are at some other than zero-lift number; such as at .008 tappet rise, or .006 tappet rise , or in some cases .001 or .002.
              What this means is that the number that the calculator spits out, is not altogether very accurate, because the valve might take some unknown number of degrees to actually close and seal. This number could be just a few degrees or it could be a lotta more degrees, and so to find it, you'll have to install it and measure it.
              However, knowing this now, allows you to cheat.
              If the calculator says that a certain combo will make 165psi, which is generally the ceiling for best pumpgas,
              but the number you inputted to the calculator was a result of a .008 spec, You know you have several degrees to play with as compared to a .006 spec'd cam. But even better is that if you know the cam has really long slow ramps, you might ultimately be able to run this combo on LESS than best pump gas. Now, if you're paying attention, this also gives you a chance to cheat some more and build to an even higher cylinder pressure, knowing that your pressure is gonna be real-world be less than what the Calculator spits out. Hmmmmmmmmmmmmmmmmmmmm
              Of course if you get greedy and it doesn't work out, it's best to have a back-up plan.
              Mine was the .028 gasket. All calcs were done with the .028. So then I would have the option of adding gasket, to reduce pressure. But this too comes with a caveat; I wanted a tight quench, so zero-decked the pistons. So, what I read was to stay out of the .050 to .080 range,which they said was prone to detonation. PLus the scuttlebut was that quench over .050 was no Q at all. so from .028 to .050 was a pretty limited range.
              To get away from the nervous cheating, I opted for aluminum heads which are not nearly as sensitive to this kindof trickiness.

              (*1) left over;
              the bigger the cam, the greater the intake duration will be, and you gotta take those degrees from somewhere,cuz you only have so many to spread around. So some will go into the overlap, and some will be stolen from compression.... because the total amount of degrees is fixed by 720 plus overlap. This cannot be changed.
              For instance; on a 292/292/108 cam the overlap is 76* so the total number of degrees available is 720+76= 796... but on a 262/268/112 cam, the overlap is 41, so the total available for distribution is 720+41= 761.
              It is for this exact reason why your static compression ratio has to be increased to maintain cylinder pressure, because a drop in cylinder pressure always, always, always, affects the low-rpm torque..... in a negative way.
              So if you follow that thinking, then an increase in cylinder pressure, always affects the low-rpm torque in a positive way........until you have so much that you either run into the dreaded detonation wall, or the engine just can't help but spin the tires every time you lay a lil throttle to her.... lol.
              For Street,I like the 360 cubic inch engine, cuz you can move the numbers around fairly economically anywhere in between . Smaller engine have to be biased one way or the other pretty hard, and bigger engines end up with a preponderance of low-rpm torque that is difficult to impossible to get rid of.
              My yardstick is 10 cubes per pound of chassis, so 360x10+3600 pound vehicle; car and driver. A 318 would be 318x10=3180........ and so on. My car is 3650 me in it, and the engine was bored to make 367 cid.
              Depending on your chosen parts, the 360 can be built between 8/1 and 11/1 with very little machining. which gives you a lotta lotta adjustability to fit just about any suitable for street, cam.
               
              Last edited: Jan 31, 2020
              • Like Like x 1
              • nm9stheham

                nm9stheham Well-Known Member

                Messages:
                11,899
                Likes Received:
                3777
                Joined:
                Dec 20, 2013
                Location:
                Waynesboro, VA
                Local Time:
                1:17 PM
                You are on the right tack with this, OP. So that is good. Just needs some adjustment....My hat's off to you for trying to figure this all out.

                Wyrm is asking the right questions.
                1. These calculators spit out their best results when the lifter lift is around .005-.006", or valve lift around .009-.010" for these engine's rocker ratios. (wyrm, check me on that matter...) Hydraulics are easy as that is where most cam mfr's measure the advertised duration. Soilds have to account for the lash to determine the angles.
                2. So if your valve lash is .020", the lifter has moved up approximately .013" to close that lash up and start moving the valve. So now you need to know how many more degrees it takes to move the lifter up another .005-.006", which depends on the rate of the lobe at that point.
                3. As you are probably not past the sloow lash ramps (where the lift is changing something like .0005" per crank degree) to the fast part of the ramps (where movement exceeds .002" per degree), then I'd make a guess at .001" lifter lift per degree of crank rotation in this area of the cam ramp.
                4. So, to figure the extra crank degrees to get the lifter to move up another .005-.006", then just reduce the .020" duration by 5 or 6 degrees on both the opening and closing ends, or 10-12 degrees total duration reduction.
                5. That would make the ICA for use in these calculators something like 71-5=66 degrees.
                6. If you change lash, then you re-figure it.
                7. This is all much easier and more accurate if you have the cam and can actually measure the angle for .005.-006 lift on the lifter. And since you have the cam card, I'd guess you have the cam..???
                8. Is your brain hurting yet? LOL
                This effects your DCR and so it looks rather critical for your setup on pump gas. So I'd personally make the cam measurements to be sure. I've asked for this data from Howards and Jones and got stiff -armed both times, so we're on our own for this.

                And I see you are entering the altitude for your locale, which is a very real effect. Guys at Denver need to run a lot more SCR to get a decent effective DCR, which is what really effects your cylinder pressures and moves you towards or away from detonation issues.

                FWIW.... Just my experience....as it applies to engine operation below 3000 RPM (below the main torque band) or so and seat-of-pants feel.....
                • You will feel .25 point change in DCR
                • The engine will feel very differently with a 0.5 point change in DCR
                • The engine will be a completely different engine with a 1 point change in DCR.
                Having said that, the high RPM performance will be much less effected. And the point about some margin for operational changes is well made. 91 octane does not seem as forgiving as 93 octane. Dry, cool air in the fall is your biggest enemy.
                 
                • Agree Agree x 2
                • Like Like x 1
                • AJ/FormS

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

                  Messages:
                  17,944
                  Likes Received:
                  6292
                  Joined:
                  Jan 19, 2014
                  Location:
                  South-Central Manitoba,Canada, 900ftelevation
                  Local Time:
                  12:17 PM
                  I agree with nm9,100%, and would like to add;
                  You can spend the money on pistons to pump up the Scr and you might feel the financial pinch, but once on the road you will never be sorry. Or,
                  You can leave the Scr where it is, and then experience the loss of performance below 3000/3500 with the stock convertor. And so then, for same money, you can buy/install the higher stall TC. Now you can blast off like you would have been able to with the higher cylinder pressure. In this instance,I call the TC a band-aid.
                  But the lower cylinder pressure will never make the midrange performance that the Scr change would have.
                  So IMO, the better way to go, while spending similar money, is to pump up the pressure in the first place. You will never be sorry......... unless you get too greedy.
                  Now, if you are gonna install alloy heads, it behooves you to pump it up, else the alloys will not work to their full potential. They will love 180 or more psi. Some fellas on FABO say that they are running 200 or a tic over still on pumpgas. As for me, I have run 180/185 on 87E10 with full timing,at 930ft elevation....... since 1999.
                  And I can tell you that this combo never fails to make me smile; whether idling in the driveway , romping around town, or tearing up the dragstrip. And, and, I run 3.55s with a 4speed, that I never have to rev up to blast off.
                  With lack of pressure,depending on the stall you choose, you will be looking at more rear gear, perhaps up to 3.91s ............... perhaps more.
                   
                  Last edited: Jan 31, 2020
                  • Like Like x 1
                  • abodyjim

                    abodyjim Well-Known Member

                    Messages:
                    197
                    Likes Received:
                    120
                    Joined:
                    May 2, 2016
                    Location:
                    Topeka Kansas
                    Local Time:
                    12:17 PM
                    Okay the smoke is rolling out my ears trying to get a handle on this. I also want to thank you all for helping here.
                    So this project is on hold right now but got me thinking about it again because of a friend that's looking at doing some trick flows on his small block.
                    I have already purchased the stroker kit and was building around the W2's and parts needed to use them because i already had them. Goal was to maximize their potential and a 360 block. I'm not overly concerned with being conservative. I was thinking very aggressive street when i started. Not understanding the whole dynamic thing I got flat top pistons. Thoughts were i could run race gas in it to play and detune it enough to survive on pump gas for cruises.
                    Now I'm wondering if I'm too far over that line. No machine work is done currently.
                    Test if I'm understanding, my intake duration @.02 is 291 and I subtract 6° from that gives me 285 which equals 68.5 which moves me even further into detonation? These are just numbers not measured and could change. Is there a problem with leaving the piston in the hole .020 opposed to a dish piston ? Also what is more critical a dynamic above 8 or cylinder pressure above 165?
                    The car is 3200 with me in it(guessing), 4spd(may go to o/d) ,any gear needed, 30" rear tire
                     
                  • abodyjim

                    abodyjim Well-Known Member

                    Messages:
                    197
                    Likes Received:
                    120
                    Joined:
                    May 2, 2016
                    Location:
                    Topeka Kansas
                    Local Time:
                    12:17 PM
                    So if I'm bench racing this correct using my parts I could set the pistons down .020 in the hole with .054 head gasket a revised Isa of 68.5 and put me on the edge of pump gas
                    Am I on the right track?

                    Screenshot_20200131-161711_Chrome.jpg
                     
                    Last edited: Jan 31, 2020
                  • AJ/FormS

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

                    Messages:
                    17,944
                    Likes Received:
                    6292
                    Joined:
                    Jan 19, 2014
                    Location:
                    South-Central Manitoba,Canada, 900ftelevation
                    Local Time:
                    12:17 PM
                    The problem I see is that with a solid lifter cam, we have to guess at the true zero lash point.
                    the general idea used to be, to add one cam size to the one you got, and work the calculator as if it was a FTH.
                    Or if you don't already have a cam, then work out ,on the calculator, what you want; then order the next bigger cam.
                    But with modern tight lash cams, this does not guarantee success.
                     
                  • AJ/FormS

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

                    Messages:
                    17,944
                    Likes Received:
                    6292
                    Joined:
                    Jan 19, 2014
                    Location:
                    South-Central Manitoba,Canada, 900ftelevation
                    Local Time:
                    12:17 PM
                    Help me out;
                    why would you "set" the pistons down .020 and then top it with a fat .054 gasket. With flat tops and closed chamber heads, this gets you a Quench of .074 which is useless for it's intended purpose. Generally, no quench requires a drop in SCR of 1/2 point to stay out of detonation.
                     
                    • Like Like x 1
                    • abodyjim

                      abodyjim Well-Known Member

                      Messages:
                      197
                      Likes Received:
                      120
                      Joined:
                      May 2, 2016
                      Location:
                      Topeka Kansas
                      Local Time:
                      12:17 PM
                      The heads are open chamber iron econo W2's. Already spent the money on porting ,rockers, headers and intake so they are staying. Thought I mentioned it, sorry for the confusion
                       
                    • AJ/FormS

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

                      Messages:
                      17,944
                      Likes Received:
                      6292
                      Joined:
                      Jan 19, 2014
                      Location:
                      South-Central Manitoba,Canada, 900ftelevation
                      Local Time:
                      12:17 PM
                      You're gonna have to choose; either automatic OR 4speed, cuz the builds between them are different.
                      With a 4-speed and on the street, the engine, in first gear,is married to the road ; That is to say, there is no fluid coupling and no TM (Torque Multiplication) to take advantage of.
                      My experience with the 292/108 cam and 11/1 Scr, showed me that at low rpm and therefore low speed, and the generally accepted but in my opinion, excessive timing, the engine firing pulses are so powerful that the car starts acting like a bucking bronco. And perhaps your minimum driving speed, before having to toe the clutch will be excessively high. With an auto, you don't have this problem.
                      Lemmee explain;
                      with 30" tires, and any gear, as stated above, and with something like 18* idle timing, and say you somehow get the transfer slots set right, and manage to get the idle speed down to 800rpm.
                      Ok then 800 rpm with say 4.30s, a 2.66 low gear,and 30s is......6.24 mph. But it is not likely that the rpm in gear idling down the road, will still be 800. Lets say it drops to 700. Then the speed will be 5.46mph.
                      So firstly, no person can march in a parade at 5.46mph, and you don't want to be toeing the clutch for an hour. Am I right?
                      Secondly, if you idle it any slower, the bucking bronco comes out. But to get down to 4 mph with a 700 rpm in-gear idle requires 5.87 gears. To keep the 4.30s and hit 4mph, requires an in-gear idle of 512rpm. That will never happen, so
                      Thirdly, forget parading.
                      Fourthly, with 18* of idle-timing, I really doubt you can get your transfer slots set right, and still have a normal idle down around 800rpm. And you need to be up close to that, for your oilpump to keep everything lubed up.
                      So then, IMO, there is no good reason to run 18*; it just wreaks havoc with the low speed operation.

                      So how did I cure my 292 cam? I didn't, I took it out and got rid of it as fast as I could.
                      But this same problem persisted with the 276/286/110 that I now run..... and here's my cure.
                      I had to reduce my road speed, and reduce my Idle timing.
                      Since I like 3.55s, I wasn't gonna sacrifice those, but my tires are just 27s. This compares to your 30s with 3.91s. I got me a Commando box with a 3.09low in it. So in first gear this now translates to 3.09x3.55x(24/27)= a 9.75 starter gear, corrected to a 24" tire with a 1ft radius. This compares to your 2.66x4.30x24/30=9.15 corrected also to a 24" tire. In other words your 4.30/30 combo will feel like 27s would with 3.33 gears.
                      The next thing I did was set my idle timing down to 14*. This allowed the transfers to sync up at 700rpm.
                      And then I got me a dash-mounted, dial-back, timing device with a range of 15 degrees.
                      So now I can get that 276 cam to idle down to 550 rpm in gear,cranked down to 5* idle-timing, and it pulls itself smoothly at 4 mph. I'm depending on the HV oilpump to keep the rods alive, and I don't hammer the gas pedal at that rpm. When I get off parade-duty, I just dial the timing back to 14*..
                      These are the tricks you need to know about to marry a big-cam,high-compression,manual-trans combo, to very low speed operation with street-type gears.
                      Sure YOU could toe the clutch.
                      But you know what that's gonna do......
                       
                      Last edited: Jan 31, 2020
                    • AJ/FormS

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

                      Messages:
                      17,944
                      Likes Received:
                      6292
                      Joined:
                      Jan 19, 2014
                      Location:
                      South-Central Manitoba,Canada, 900ftelevation
                      Local Time:
                      12:17 PM
                      Finally,if considering an overdrive, absolutely forget about the Mopar box. The rpm drops between gears, at speed are waaaay too wide for a combo like yours. I tried it with two cams; the smaller was a 270/276/110 cam, and the slightly larger 276/286/110; and nearly every gear from 2.76 to 4.88, and it was just terrible; there was no way to keep the engine on the power band of a performance 110 cam. I left it in the smaller combo for about a year , but that was that.
                      The ratios are 3.09-1.67-1.00-.73od and the splits are 54%-60% and 73%. meaning;
                      that at whatever rpm you shift out of, the rpm will fall to those %s. So shifting at say 6000rpm, the Rs will fall to 3240 on the 1-2 and to 3600 on the 2-3. With 4.30s and 30s, the 1-2 would be at 47mph. At the drop to 3240 your engine better have a chitload of torque, to get back up on the cam. The 2-3 shift would come at 6000/75 mph, and your street run is already done...... so at this point nobody cares about the 2-3 drop. But at the track, your Rs would fall to 3600 on the 2-3 shift... so again, yur a solid 800rpm off the powerband. IMO, this really sucked. So I was done with it. Not to mention I blew three of them up, trying to make it work.
                      I hate to sound cliched but trust me, you don't want that A833 od box.
                      And 4.30s are probably not nearly enough rear gear with the 30s.
                       
                      Last edited: Jan 31, 2020
                    • AJ/FormS

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

                      Messages:
                      17,944
                      Likes Received:
                      6292
                      Joined:
                      Jan 19, 2014
                      Location:
                      South-Central Manitoba,Canada, 900ftelevation
                      Local Time:
                      12:17 PM
                      No confusion, I was just too lazy to go hunt it up.
                      OKso then I get where yur coming from.
                       
                    • yellow rose

                      yellow rose Doctor of Thinkology.

                      Messages:
                      21,010
                      Likes Received:
                      17089
                      Joined:
                      Jun 19, 2015
                      Location:
                      Living on the razors edge
                      Local Time:
                      10:17 AM

                      This is why it's hard to do these engines correctly.

                      Piston guys don't want to make the correct Pistons for it.

                      This may sound contrary to what I always say, but it's not.

                      You are better off with a piston that has the deck positive to gain the CR you want than a dome, unless you can use both, like I am. I reduced the dome by ~.175ish and the deck is out .045 IIRC and that gets me 11.01:1 with an .059 gasket.

                      If I want to get to 11.25:1 I can go to an .039 gasket and get there.

                      If your CR is where you want it with a flat top, I would NOT care what the quench is. If everything else is correct, quench won't matter except it may be a bit more dirty emissions wise.

                      Get your cooling system in tip top shape, use a manifold without a heat crossover, get your ignition and carb tuned up and pay careful attention to spark plug heat range.

                      I'm running 11:1 on pump gas. With a relatively small cam if you actually plot the lobes. So it can be done if done correctly.
                       
                    • abodyjim

                      abodyjim Well-Known Member

                      Messages:
                      197
                      Likes Received:
                      120
                      Joined:
                      May 2, 2016
                      Location:
                      Topeka Kansas
                      Local Time:
                      12:17 PM
                      No chance of an automatic in this car. It's a non o/d 4 spd car but could go 5 speed so it can be road tripped. Tire size is the only thing that's a lock the rest can be changed or tweaked
                       
                      Last edited: Jan 31, 2020
                    1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
                      By continuing to use this site, you are consenting to our use of cookies.