Trying to remove low end torque w/camshaft

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by ProMod83, Aug 23, 2015.

  1. ProMod83

    ProMod83 Member

    Joined:
    Apr 12, 2009
    Messages:
    152
    Likes Received:
    3
    I am trying to get our timing curve in a little sooner. We have our cam in at 30BTDC now if we move it to 35 we should theoretically more the power band up?

    I am pulling over 20 degrees now to keep it from knocking the tires off but it is killing my 330 times.

    I was thinking I could go from the 116 lSA to 117 but not sure what all that would give me or if it's worth it.

    Has anyone played with cam timing and have on track experience?
     
    #1
  2. Sandracer695

    Sandracer695 Member

    Joined:
    Jan 8, 2005
    Messages:
    228
    Likes Received:
    4
    Moving your cam from 30 to 35 you will be advancing the cam and adding more low end power.
     
    #2
  3. ProMod83

    ProMod83 Member

    Joined:
    Apr 12, 2009
    Messages:
    152
    Likes Received:
    3
    Wouldn't having the valve open earlier kill cylinder pressure thus reducing torque?

    I thought 30BTDC is later than 35BTDC which comes up first and gets valve off seat sooner
     
    #3
  4. ozrace

    ozrace New Member

    Joined:
    Dec 8, 2012
    Messages:
    22
    Likes Received:
    1
    It's much more about the closing point ProMod83.. closing the intake valve earlier will capture more cylinder pressure and increase low-end torque.
     
    #4
  5. ProMod83

    ProMod83 Member

    Joined:
    Apr 12, 2009
    Messages:
    152
    Likes Received:
    3
    Ok so open valve later and it will close later killing so low end?

    I will try 25BTDC

    Thanks for the info guys
     
    #5
  6. bruce mullins

    bruce mullins Top Dragster

    Joined:
    Aug 2, 2003
    Messages:
    981
    Likes Received:
    3
    if you have the cam at 30 @ 50 already and still pulling 20 degrees out, you need to calm it down elsewhere.. I assume it's a converter car.. what motor ..brad? what blower? roots or screw? and what gears? sounds like the wrong gears if your driveshaft speed is out of control .. most auto combos have the cam around 32 to 35. 25 you may start running into clearance issues
     
    #6
  7. secondwindracing

    secondwindracing top alcohol

    Joined:
    Feb 10, 2004
    Messages:
    2,864
    Likes Received:
    5
    25 is very scary...Dave
     
    #7
  8. aj481x

    aj481x Member

    Joined:
    Jan 27, 2004
    Messages:
    919
    Likes Received:
    8
    5 degree changes are really big
     
    #8
  9. jay70cuda

    jay70cuda Member

    Joined:
    Sep 30, 2009
    Messages:
    960
    Likes Received:
    16
    Why can't you knock some gear out of it and leave the motor peppy. Making the motor lazy is gonna affect the big end when you want the nuts to pull it and run the mph
     
    #9
  10. ProMod83

    ProMod83 Member

    Joined:
    Apr 12, 2009
    Messages:
    152
    Likes Received:
    3
    Thanks for the info guys. I will try to through more fuel at where it is too aggressive instead.
     
    #10
  11. Randy G.

    Randy G. Top Alcohol

    Joined:
    Jun 9, 2003
    Messages:
    1,889
    Likes Received:
    31
    Best answer. You pay all that money to make big power, then you try to fix your combination by throwing power away.

    I remember doing a match race in Phoenix about 24 years ago. The track wasn't that great and a lot of us were trying to kill power hoping to run a 6.30 or something. That was when I had my new Steve Plueger car. As we go up for first round of eliminations that evening, John Force, with the same chassis I have, runs a 5 flat (quarter mile). I immediately thought "I wonder how many spark plug wires would he have to pull to slow his car down to run the 6.30's we figured was all the track could hold?" Being new to TA/FC I changed my thinking to "make all the power you can, because you spent a lot of money for it (blowers, heads, etc) and tune the car with clutch and gear instead of detuning the engine." Otherwise, why chase the newest greatest parts?

    I think that's why the same guys always seem to run better than everyone else. Mindset.
     
    #11
    Last edited: Aug 25, 2015
  12. jay70cuda

    jay70cuda Member

    Joined:
    Sep 30, 2009
    Messages:
    960
    Likes Received:
    16
    That is the quote of the year! Great answer randy.
     
    #12
  13. bruce mullins

    bruce mullins Top Dragster

    Joined:
    Aug 2, 2003
    Messages:
    981
    Likes Received:
    3
    once again.. if your pulling 20 degrees out, your gears are off.. you will never put enough fuel in it to calm it down if you have 20 out and still blowing tires off..
     
    #13
  14. ProMod83

    ProMod83 Member

    Joined:
    Apr 12, 2009
    Messages:
    152
    Likes Received:
    3
    Car has 1.24 low gear 5.00 rear gear now.

    I will try taking some pump out of the converter.
     
    #14
  15. Dale H.

    Dale H. Member

    Joined:
    Dec 7, 2005
    Messages:
    299
    Likes Received:
    5
    I knew a funny car racer that was running a converter and was having trouble spinning off the line. I asked him about it and he said he needed a taller gear but did not have one. I said to him to start off in 2nd gear and he did. The thing went quicker than ever before. It was an easy experiment to see what gear the car could take.

    -Dale
     
    #15
  16. ProMod83

    ProMod83 Member

    Joined:
    Apr 12, 2009
    Messages:
    152
    Likes Received:
    3
    I appreciate all the ideas and info the car 60's good and runs great till about 1.5 into the run that's where it wants to shake. I can make it down the track no problem with 20 deg out I want to add timing back but it shakes if you add even 2deg
     
    #16
  17. racinjason

    racinjason New Member

    Joined:
    Jan 24, 2014
    Messages:
    4
    Likes Received:
    0
    How old are the tyres?

    Jason.
     
    #17
  18. ProMod83

    ProMod83 Member

    Joined:
    Apr 12, 2009
    Messages:
    152
    Likes Received:
    3
    5 runs just tried a set of liners also to see if they would help over the beadlock.
     
    #18
  19. bruce mullins

    bruce mullins Top Dragster

    Joined:
    Aug 2, 2003
    Messages:
    981
    Likes Received:
    3
    are you running a grid? 1.5 out could be too slow causing the shake. what is your driveshaft speed at 1.0 .. too slow and the car will shake if the track is tight.
     
    #19
  20. jay70cuda

    jay70cuda Member

    Joined:
    Sep 30, 2009
    Messages:
    960
    Likes Received:
    16
    Jamb some power back in. Weak shake can fool you that far into the run. Your thinking power shake because it's moving when really it jut fell off the tire. I bet if you look at the g meter you'll see it's falling down and look at the shaft speed it's prolly going down too. Aka weak shake.
     
    #20

Share This Page