Timing

Discussion in 'PSI Superchargers Tech Questions' started by BB/AM1188, Aug 30, 2005.

  1. BB/AM1188

    BB/AM1188 New Member

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    What is a starting pointfor timing on a blown 321 SBC on alky? We were told 34 degrees by a big name builder but we burnt the electrodes on the spark plugs and burnt some exhaust valves and pistons. Another blown comp racer told us to start at about 26-27 degrees and work from there but it should never go above 30. Does that sound right?
     
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  2. DQUES

    DQUES Member

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    You might want to list a little more info on your combo such as , comp ratio , mag type and amps , blower size and speed , cyl head cc's . These might help you get a more accurate response .
     
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  3. BB/AM1188

    BB/AM1188 New Member

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    321 ci, 9:1 static comp ratio, only about 20-30 lbs of boost right now (were still working on the tuneup its a fresh motor)last time we ran it it was at 28% under now is at 16% but havent made a run that way yet.msd crank trigger ign. system. set at 34 degrees
     
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  4. Leon

    Leon New Member

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    Burnt ex valves and pistons? Id say more than anything it would be fuel,not timing. 9 to 1 isnt much static and 16 under i cant see how you can be getting 20# boost.What pump and what main and hi speed? What about secondary? What nozzles? Ports? Idle check and hi speed pressures? Secondary going off at what? Electronic ign? Car weight? Gear,tire? What pulleys?

    [ August 30, 2005, 10:17 PM: Message edited by: Leon ]
     
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  5. RBS

    RBS Authorized Merchant

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    which msd box are you using. also how big is your pump and nozzle sizes.
     
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  6. BB/AM1188

    BB/AM1188 New Member

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    at first we thought it was fuel to, but after talking to a few other blown racers they said it was most likley timing. The fuel system was just flowed by bill barret. he set it up eith a 85 main 85 hs. we have only tuned the main so far and have a 100 in there now. the port nozzles go are 42,40,28,36 from front to back that was also barrets setup.were pretty sure its very rich pump is enderle 110.im not sure if its actually 20 lbs.we burnt out our racepak so we are just goin off the gauge while we warm it up and its aprox. 20 lbs at 6000 rpms. pulleys were 35 on top and 25 on bottom but now are 35 and 30.

    [ August 31, 2005, 12:23 PM: Message edited by: BB/AM1188 ]
     
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  7. WADE RACING

    WADE RACING New Member

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    SOUNDS LIKE THE NUMBERS YOU LISTED FOR " PORT "
    NOZZLES WOULD BE CORRECT FOR HAT NOZZLES...EXCEPT****WHY ARE THE THIRD PAIR OF NOZZLES SO SMALL ****? ? ? ? ? ? ? ?THAT NUMBER SHOULD POSSIBLY BE 38 AND NOT 28.......!WITH UNDERDRIVE ON THE BLOWER AND IF THE FUEL SYSTEM HAS NO RESTRICTION AND IF YOU DO NOT HAVE A POPPET IN BACKWARD ( I have seen this and recently ! ) THERE IS NO WAY YOU COULD BURN THE PLUGS.................I WOULD SUGGEST YOU GO COMPLETELY THROUGH THE FUEL SYSTEM , HAVE THE MAG CHECKED BY SOMEONE TRUSTWORTHY AND THEN CALL GEORGE SANTOS AT ( 510 ) 3579041 AND PRAY THAT CELIA WILL LET YOU TALK TO HIM ! ! ! ! ! IF HE CAN'T HELP YOU , YOU ARE BEYOND HELP!
     
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  8. Leon

    Leon New Member

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    What about hat nozzles? Pump flow? No loop? Still need pressures and what was system pressure when flowed with nozzles? % going in? Can you post a pic of the plugs? Alc barrel or nitro style? If you have an MSD system,that means you have an onboard battery. What is voltage? Hope you have a 14 volt min on it.Msds need voltage to run correctly.Like trying to run a 220 motor on 110 volts.
     
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  9. Mike Canter

    Mike Canter Top Dragster
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    My suggestion is if the fuel system was flowed by Bill Barrett then you call Bill and tell him what is going on with the motor. He knows your fuel system and he is really good. Since you said Bill did the fuel system then I doubt that it is in the fuel system unless something was hooked up backwards when you put it on the car. I would suggest that the problem is in the ignition system and not the fuel system. Like I said call Bill Barrett back and talk it over with him because if you start taking everyone elses advice (all great advice, don't get me wrong) you will be totally lost and will have wasted the money on getting the fuel system flowed.
     
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  10. BB/AM1188

    BB/AM1188 New Member

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    WE did talk to Bill recently and he said that the fuel was setup very rich even with the 100 we put in the main. All of our flow sheets are in the trailer. I can post that info tonight if needed. The whole ign. system is right. WE just sent the box back to msd and they updated it. WE have had previous probs. with this motor (when it was 1st built and freshed a few times it was complete garbage so we switched to a new motor builder) we have gone through the ign. system many many times and the fuel many many times.we pulled some of the fuel nozzels and spun the motor and we are getting fuel. As i said at first we thought it was fuel also but we are getting the fuel. i will take a picture of the plugs tonight and post that also. were taking the motor apart tonight so we will go thorough everything mentioned.
     
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  11. Mike Canter

    Mike Canter Top Dragster
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    Did you ever say what type of MSD ignition you are running. Which one is it? The type ignition system sure makes a difference to what ignition timing you use.
     
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  12. kosky racing

    kosky racing Comp Eliminator

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    Been there and done that many of times last thing anyone wants to hear is did you check the fuel tank? Is this a new car? If the tank is not built properly it will go lean and do the things you described. Your prob. is not in timming or fuel or overdrive. You sure on the compression? I have had at least 2 fires because the tank and thew about 10 blowers on the ground and in the trash.All becauswe of the tanks.
     
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  13. BB/AM1188

    BB/AM1188 New Member

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    The car ran on gasoline first and the tank was not built right so we had it modified so it should be ok now. The MSD is a 72al. We are thinking now that mayb the crank trigger pickup moved on us so it was not actaully set at 34 degrees. WEll check that out tonitght also
     
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  14. Mike Canter

    Mike Canter Top Dragster
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    Since you have a 7AL2 and a crank trigger then are you using the shielded crank trigger cable???? You can tell because the end closest to the 7AL2 ignition box has a separate black ground wire that HAS TO BE ATTACHED to chassis ground. If you do not have this shielded cable then it is possible that all your problems are caused by random firing of the ignition due to Electromagnetic Interference (EMI) from spark plug firing or any electric motor(s) or other electrical devices. These EMI pulses act like the crank trigger pulse and will fire the ignition. This random firing of the plugs shows up like detonation and can destroy a motor. It took MSD some time to figure out the probablem and come out with the new shielde cable. I think it cost $22. I would not run again until you have installed it and grounded that wire.

    Also since you have a 7AL2 vice a ProMag 44 the timing will be very different. The timing recommendations that have been given in the high twenties sound like more for a ProMag 44. I believe after you get this problem fixed that you will be able to push the ignition timing into the 30's.

    See if this helps you http://www.draglist.com/artman/publish/guest_shoe/article_001172.shtml

    or at http://www.dragstuff.com/techarticles/reading-alcohol-spark-plugs.html
     
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  15. BB/AM1188

    BB/AM1188 New Member

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    Im not sure about the cable being there or not. would this cause complete random firing or just a slight diffrence? The box was purchased about 7 or 8 years ago so maybe its possible that we dont have it. The wire is actally connected to the box or the crank trigger?
     
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  16. Mike Canter

    Mike Canter Top Dragster
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    The EMI problem can show itself several different ways. One way is just a miss when going down the track and the other way to to fire so far out of sequence that it will destroy the motor and appear like detonation.
    This problem is why several years back nitrous Promods switched to Mallory ignitions then MSD figured it out. Racers would send the ignition boxes back to MSD and they would come back with nothing found wrong and they would be put back on the car and it would happen again.

    The shielded cable is the cable that connects to the crank trigger sensor and runs to the ignition box. I believe the part number for the newer stayle shielded cable is MSD 8862.

    Are you also running a spark plug gap of .019 or below?
     
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  17. BB/AM1188

    BB/AM1188 New Member

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    we just pulled the heads off the car and we did not burn any pistons or valves. we assumed we did because we had 50% leak but figured out why that happened. so the only thing that burnt was the spark plugs. only 4 of them burnt the electrode off the other 4 were just pitted but not missing. I dont think we have a shielded cable (the wires coming from the crank trigger are purple and green) no black. my question is now why would the electrodes burn off the plugs. we are running a gap of .020 now what should it be? any other suggestions?
     
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  18. Mike Canter

    Mike Canter Top Dragster
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    My recommendation is to stay with Bill's fuel setup and install the new MSD crank trigger cable attach the ground wire on the cable to chassis ground, put the timing at a safe 27* (for now) and give it a shot. Maybe just run half track and shut it down and take a look at the plugs.

    The random firing caused by the EMI will take all the plugs out on one side or randomly take out some plugs. It is unpredicatable but it is a sure thing it will drive you crazy.
     
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  19. BB/AM1188

    BB/AM1188 New Member

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    We will give that a try. Another thing we are thinking is mayb we are using the wrong plugs. What plugs should we be using in this motor. Now we are using NGK R5671-10. What should the gap be? we have been setting them at .020
     
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  20. Mike Canter

    Mike Canter Top Dragster
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    Those plugs are just great for your car. The gap is good, you can close gap up to .018 since you are so rich.
     
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