Anyone here ever have their pistons machined?

Big Block A body Tech

  1. -Sledgehammer-

    -Sledgehammer- Mopar Performance

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    I ran same heads you have now before with no issues on 100 % local 93 at 10.89 to I also run now 100% local 93 with 11.89 to 1 static compression RACED on Local 93.

    I'm sorry but it keeps seeming like you bandaid after bandaid. Your .017 in the hole and want to add .075 gasket for .092? That's like stock 440 specs when they had leaded gas at the pumps. Hope you get it fîgured out.

    Not my fastest or quickest pass but I'm promise you this 9.72 past is on 100% local 93.

    [ame]http://youtube.com/watch?v=sGaM3_XAh28[/ame]
     
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    • -Sledgehammer-

      -Sledgehammer- Mopar Performance

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      BTW- my timing is locked out also.
       
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      • txstang84

        txstang84 Well-Known Member

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        FD, as far as milling the heads an equivalent amount as the pistons are in the hole, and using that to equate CR, well, it's not that simple. If you're talking about milling a wedge shaped chamber versus a cylindrical object, geometry says the volumes won't be the same for a given distance.

        I'm apparently going to have to re-read your original thread a little...
         
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        • txstang84

          txstang84 Well-Known Member

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          That's a sick ass Dart sledge
           
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          • Kern Dog

            Kern Dog Well-Known Member

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            After I wrote that, it occurred to me that the quench pad affects the volume. The head milling affects about 3/4 of the chamber compared to what it would with an open chamber design.
            The real test will be when the heads are cc'd. At that point I'll be able to know the true number. Looking back, I figured that the milling and carbon buidup had me closer to 11.0 to 1. I applaud those that are able to make that work. I know that I wasn't able to do it. I first tried switching from stock steel rocker arms to 1.6 roller rocker arms. This was with the 509 cam. There was no difference. I switched to a cam with more lift, duration and what I was told was a LATER intake closing. The info on the intake closing of the 509 cam is still undetermined, but it appears that the new cam closes earlier because of the increase in cylinder pressure and detonation. I tried different carb jets and power valves. Different carburetor. Different distributors, different spark curves. I installed a wideband UEGO guage to monitor the A/F ratio. I have tuned the carb to run at the highest possible idle vacuum and had the A/F ratio dang close to 14.7 at idle, 14.7 at cruise and 13.0 at WOT. I tried a 50/50 mix of 91 and 100 octane. ALL of those efforts and the car still knocked. I ran a 50/50 mix of the 100 and 110 race fuel and the car ran faster than ever. It idled the same and cruised the same but at WOT, it flat out screamed! NO detonation at all. This was with 16 degrees of initial timing and 30 degrees total. I did not bump the timing to 34 or 35 to see how much faster it would be nor if the detonation would come back.
            It came down to 2 options: Raise the octane or lower the compression ratio.
            Seeing and reading about others that like to drive their Muscle cars inspired me to do the same. In 2003 I made my first road trip in the car to Reno Nevada, about 225 miles round trip. This was with the first 440 I built, a standard bore, rering job with 9.2 compression and a 280/474 cam. The car ran great with zero knock and decent mileage. In 2011 I decided to drive to Los Angeles for the CPW Spring Fling. That was a 1000 mile round trip. It was also a real shakedown run. The car ran then as it has since I first built the 493: Great until I was past 3/4 throttle. Since then I have looked at many options to achieve the great street manners that I had with that 1st 440. This engine has more of everything...Cam, Compression, Carburetion, Exhaust. Maybe I have somehow overlooked a small detail that would have made a difference. I can say that if this sucker knocks after these changes, I will surely be baffled!

            The combustion chambers had some carbon on them but not too much. Same with the tops of the pistons. Obviously as more continues to accumulate, the CR will rise. I figure that if I have a reasonable safety margain in terms of compression, I'll be able to run the engine longer without any detonation.
             
          • txstang84

            txstang84 Well-Known Member

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            FD, maybe I missed the passages about your A/F ratio tuning, but while 13.0 WOT is typical, but not necessarily ideal for every engine.

            Did you ever dip it down to the 12.5 or so range during all your tuning?
            Did you try fattening up the mixture when you slowed the timing?
            Did you ever try running a colder plug?

            I know I should probably re-read the original thread, but hey, you're here now
             
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            • Kern Dog

              Kern Dog Well-Known Member

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              With bigger jets, I had it as rich as 11.0 at WOT and it still knocked. I tried doing the changes one at a time in order to isolate the results. The only time that I was able to get it to run knock free at WOT on 91 fuel was when I backed the timing off so far it wouldn't idle without stalling. It was at 6 * initial and 20 total. This was only for testing purposes! I didn't drive it long like that.
              Colder plug? I'm running a Champion RC9YC. I used to run the RC12YCs that Edelbrock calls for, but switched to the 9s to stop the run on-dieseling problem it once had.
               
            • IQ52

              IQ52 Well-Known Member

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              Joe Blow from Idaho here.

              You have NEVER been ready to hear the answers I have on how I solved the problem, even running those compression ratios ON THE STREET. I have watched and listened and continually shook my head at this shotgun approach and decided to never become involved again, in THIS FIASCO, after our first contact. You will eventually solve the problem, but it could have been so much easier without so many uninformed advisers.

              Notice that all the guys that can do it, haven't said HOW THEY DO IT, with specific recommendations? How's all that free advice workin' out?
               
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              • -Sledgehammer-

                -Sledgehammer- Mopar Performance

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                Thank you
                 
              • Kern Dog

                Kern Dog Well-Known Member

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                Yes, I have noticed that very few people seem to give specifics. Its as if they don't know them or are guarding some family secret.
                It appears from all these threads that my case is unusual and that nobody has ever dealt with it before. I refuse to believe that. It is great that others are able to make their combinations work, but an actual line by line recipe would have really cleared things up. Nobody is paid to dispense advice here. We all donate our time in the sake of entertainment. Personally, I do get satisfaction when I am able to answer a members question with a solution that helps. I've been a gearhead for years but I know that even a newbie is capable of providing help sometimes.
                I know that without question, a piston change would have solved the problem. Dished pistons with a quench pad would have dropped me into 9.5 even after zero deck. Months ago when I first got serious about this, the majority of guys that responded blamed the MP 509 cam for being an antique and wrote that a "bigger" cam would stop the knock.
                I agree with IQ, this has been a "shotgun" approach. Maybe other guys would have quietly dropped off the radar after a series of failed attempts. We have all seen this....A member starts a post and never returns. Maybe they fixed their problem, maybe they didn't. In a way, I am sacrificing my ego for the sake of providing a learning experience. AFTER this is figured out, I will certainly have a recipe to show others what to do, what NOT to do and how I arrived at the conclusion.
                 
              • desmo900

                desmo900 FABO Gold Member FABO Gold Member

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                I am still trying to figure out how disassembling your engine and machining the pistons to lower your compression ratio in an attempt to quell your detonation issue is easier than methodically trying to adjust your timing (as many have suggested)? Maybe this issue can't be solved by timing adjustments alone but isn't it a hell of lot easier to try than to remove your engine and rebuild it?

                You have started SIX different threads related to this issue. This could have been an interesting educational experience for many but it is a convoluted mess.

                Btw, what part of the country do you live in? This isn't listed in your profile information and we are discussing different qualities of gas in different parts of the country but we have no idea where you are located.
                 
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                • Kern Dog

                  Kern Dog Well-Known Member

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                  I have repeatedly mentioned that 91 octane is the tops for easily available pump gas. Is 91 different in Idaho than it is out here in California?
                  I can get 100 at some stations, but it isn't enough.
                  Timing? I can see that you may have missed that I actually did cover that topic.....I HAVE tried different springs, different distributors, different curves and it didn't help at all. I tried different ECUs, different gaps for the reluctor, new plug wires, cap and rotor and the problem remained.
                  Again, with the 509 cam it knocked. With the 1.6 ratio rocker arms it wasn't any different though the cranking compression numbers became closer together. The change to the Lunati cam made things worse. Whatever "tuning" may have helped with the 509 cam would have had to been even better once the Lunati cam was in.
                  The point of this thread was to explore some options. For now I'm going another route.
                   
                • txstang84

                  txstang84 Well-Known Member

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                  I can't say for certain as atmospheric concerns may've been the big problem, but a friend of mine a few years back had his Mustang tuned in San Antonio for 91 octane fuel...it ran 12.50s all day in the Texas heat with no detonation whatsoever. He PCSd to SoCal and 91 octane there pinged like crazy. He said the only way to keep it from pinging above 50% throttle was to pour in additives at every fill up or pedal it out like a butler everywhere he drove
                   
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                  • 72BBSwinger

                    72BBSwinger Well-Known Member

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                    Elevation effects detonation. Lower altitude makes it worse. I would go colder on the plugs. No matter what you read, if you don't try it, it doesn't matter.
                     
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                    • -Sledgehammer-

                      -Sledgehammer- Mopar Performance

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                      lunati 316/326 cam - note where I have the red circle on your cam card below the HIGHER you get that number up (the intake valve closing ABDC) is your friend! The cam I ran your same heads on my 500" challenger closed at 69 and the cam I have now is 73 .... also FYI on rpm range cam cards like that one are for stock stroke specs so with your stroker engine you are more like 3500-7200

                      [​IMG]


                      just so you know Im not lying about my cylinder pressures...had a jump box on the battery also.
                      [ame="http://www.youtube.com/watch?v=Th0RDZXuUHA"]Cylinder Pressure - YouTube[/ame]


                      :burnout:
                       
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                      • -Sledgehammer-

                        -Sledgehammer- Mopar Performance

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                        I might have tried this comparable cam first.... but thats just me! good luck getting it all figured out.

                        [​IMG]
                         
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                        • txstang84

                          txstang84 Well-Known Member

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                          ...And after looking it up, where he was is actually higher in a large portion of places. Rancho Cucamonga elevation according to wiki, ranges from 1400-3000'...San Antonio 772' average, and Abilene is 1780'. I know also, DA can play effectively play with that number, but I'm much more inclined to conclude the folks in Cali buy different blended fuels due to the Air Resources Board out there.

                          ...more specifically, California blends removed MTBE, which last time I recall any reading about it, reduces potential for preignition.
                           
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                          • Kern Dog

                            Kern Dog Well-Known Member

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                            Sledge: It was very considerate of you to put up those pages. I appreciate that.
                            It looks like that cam card is for a Chevy BB Lunati. The specs for mine are slightly different. The Mopar version has an intake closing of 56.5 @ .050. The Mopar Performance specs on that other page are at a gross number. I've had a hell of a time finding actual specs @ .050 of the 509. The most reliable data I discovered was found AFTER I had swapped in the Lunati. The website I found listed the 509 as having a 58 degree intake closing @ .050. This would explain why the engine knocks more now...It closes 1.5 degrees earlier with the new cam! I would gladly accept the MP specs if they matched the standard of measure that other cam manufacturers use. Some people trash talk the MP cams, but I've ran 5 of them and only one of them went bad.
                            Since the heads are being ported as we mull all of this over, I'm still going with thicker head gaskets. I like the performance of this Lunati cam. That MP .590 solid has just a wee too much lift for my 1.6 rocker arms. I'm supposedly limited to .600 lift with the springs in the Edelbrock heads and the 1.6 ratio takes the lift to .629. Even deducting for lash, I'm still over the limit. Whats the fix for that? Do the spring seats get machined or is it the top ends of the valve guides?
                             
                          • -Sledgehammer-

                            -Sledgehammer- Mopar Performance

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                            I know that had Chevy engine but I was trying to make a point about the intake closing ABDC. The .557 cam is up there also. Good luck with everything.
                             
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                            • famous bob

                              famous bob mopar misfit FABO Gold Member

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                              haven`t read this whole post, but I turned a set of hemi pro-stock pistons down in a lathe to super/s specs back in the day. they just kissed the head at high RPM`s. which tom hoover said was just right if u didn`t break anything. jim hale in van buren, ark had a jig made up for just that purpose------------just sayin---bob
                               
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                              • vitamindart

                                vitamindart Well-Known Member

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                                well I run 11.0 to 1 on 93 octane 10% ethanol pump gas in my dart without issues.
                                timing is locked out at 32 degrees.
                                but, I knew what I wanted mine to run on when I built it. I also listened to the advise of
                                the people on this board who know what they are doing.
                                here is how I did it.

                                440 block .030 over
                                eagle stoker crank
                                KB reverse dome pistons .008 out of the hole ( yes out of the hole )
                                .051 felpro gasket ( .043 quench )
                                indy sr heads w/closed chambers
                                custom roller cam 690/705 282/292 dur.
                                850 demon on the street 1150 dominator for the track.
                                fender well headers 3.5" exhaust.

                                runs great on pump gas w/o issue No pinging.
                                I believe the large cam & quench make all the difference.

                                I have run almost 12 to 1 in a 440 with similar results.
                                and this thing pulls like a freight train!
                                 
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                                • Kern Dog

                                  Kern Dog Well-Known Member

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                                  The 2 points of additional octane surely helps.
                                  We're not that different. My compression is close to 11.0 to one. I had timing limited to 30/31 degrees. You have quench and a huge cam. Those two factors along with 2 more points of octane seem to work for you. Thanks for posting your specs. That stuff helps shine a light where I was lacking.
                                  Don at FBO ignition told me that the way I had my timing set, it was limiting the power. He felt that the slight loss of power from reducing the compression will be MORE than offset by the HP gains of running more timing.
                                  ***************************************************************
                                  Sledge:
                                  I appreciate the info on the intake closing. I have heard much about how moving it around has a huge impact on cylinder pressure and detonation.
                                   
                                • 72BBSwinger

                                  72BBSwinger Well-Known Member

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                                  Frank, have you considered just having a set of 75cc Eddy heads done with the valvetrain in your existing heads?
                                   
                                • RustyRatRod

                                  RustyRatRod 30 Degrees Outta Whack FABO Gold Member

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                                  FYI, you're comparing two completely different specs. The Lunati spec is given @.050" the MP spec is not.

                                   
                                • Kern Dog

                                  Kern Dog Well-Known Member

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                                  Man! That would bump my compression to 11.65 !
                                   
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