Spring pressure

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by Dragsterbus, Sep 16, 2009.

  1. Dragsterbus

    Dragsterbus Member

    Joined:
    Oct 9, 2008
    Messages:
    141
    Likes Received:
    0
    Hi , i'm about to order a set of springs for my Hemi , it's a 526 with a 14-71, 12-1 comp, 2" installed height , '96 Dart heads, Ti and Stainless Manley valves ,Manton Pushrods, and i'm going to rev it to about 8K ish but want it to live if it goes over, I'm probably going with Pac springs, My Question is what pressure springs should i get ?
    Thankyou for any help/advice
    Wayne
     
    #1
  2. Ken Sitko

    Ken Sitko Super Comp

    Joined:
    Oct 21, 2003
    Messages:
    759
    Likes Received:
    0
    If you go with the PAC springs (that's what we use) make sure you get the latest mods from Manton, drilled rockers & adjusters, so you get lots of oil to the push rods. Also a good idea to have the thick walled push rods if you run lots of spring pressure. We run about 600 lbs on the seat, but we have a screw blower. 450 or 500 lbs should be good with a roots.
     
    #2
  3. secondwindracing

    secondwindracing top alcohol

    Joined:
    Feb 10, 2004
    Messages:
    2,857
    Likes Received:
    4
    but ken you are running fat heads and he is running a fuel head..I think he can use 375 to 400 on the intake,,what do you think?..dave
     
    #3
  4. mudmankipp

    mudmankipp New Member

    Joined:
    Oct 13, 2008
    Messages:
    71
    Likes Received:
    0
    i have been running 320 on my fuel heads with a roots. you guys got me wondering if i need more spring.
     
    #4
  5. Ken Sitko

    Ken Sitko Super Comp

    Joined:
    Oct 21, 2003
    Messages:
    759
    Likes Received:
    0
    I don't think it matters what kind of head you run. I think the main things to consider are the weight of the valve, the diameter of the valve head (area) and the boost. If you are not sure what it takes to open the intake valve, set up with your normal spring pressure and make up a jig to put regulated air inside the port. If the valve tries to pop open at 50 psi, and your blower puts out close to 50 psi, then you need more spring.
     
    #5
  6. jim phillips

    jim phillips ta/fc

    Joined:
    Apr 29, 2007
    Messages:
    1,242
    Likes Received:
    0
    i never ran under 340lb with the fuel heads 385lbs to 400lbs @2.100 with a roots but you need to keep an eye on the valves get good locks and just watch for wear over time
     
    #6
  7. BLOWN INCOME

    Joined:
    Feb 14, 2005
    Messages:
    612
    Likes Received:
    0
    We never run more then 350# pressure, get rid of them at 310#..big springs are hard on valve train...50 + years racing ,you don't need big pressure for roots and 8,000 rpm.. More spring pressure when you get big,big boost numbers (48/50lbs +)...at 8000 rpm i would'nt think you will have 40 lbs...we run 350/360 lbs on our aj 96 hemi fuel heads with a littlefield 14:71 hh, 46 lbs of boost..
    Santo
    330 332-1752
     
    #7
  8. eli

    eli Banned

    Joined:
    Dec 24, 2005
    Messages:
    1,657
    Likes Received:
    1
    how many valves are on the seat at any particular time

    how many valves are on the seat at any particular time

    --------------------------------------------------------------------------------

    Can one of you rocket scientist tell me how many valves are on the seat at any particular time and how many valves are open or on the over lap in a V8 ?
    When you figure this out, think about how much boost is trying to open a intake valve.
     
    #8
  9. Les Mellows

    Les Mellows New Member

    Joined:
    Jul 18, 2003
    Messages:
    319
    Likes Received:
    0
    I agree with Mr. Sitko and I also believe 475-600 #s is where you need to be and PAC is the right choice in my opinion . The harmonics and heat produced with a "weak" (under 400 #) spring will increase and compound other valve train issues . You will also have seat, valve facing and guide maintenance that often is overlooked when the valve is chattering in many differing size orbits around the guide center. You will notice the difference in maintenance , power and valve train life !

    NOTE: I also believe you may have too much compression in your set up .... but that doesn't mean it can't work for what you are doing. You must do it for a reason ?
     
    #9
  10. d.kirkalkyburner

    Joined:
    Sep 4, 2004
    Messages:
    187
    Likes Received:
    0
    Now i maybe wrong but how many valves are open at once doesnt have an impact on the total boost number you see on the racepak. If the racepak says 50 lbs. than 50lbs. is waht is tryin to open any closed intake valve no matter how many intakes are open!!!
     
    #10
  11. eli

    eli Banned

    Joined:
    Dec 24, 2005
    Messages:
    1,657
    Likes Received:
    1
    So, what your saying is that the blower is putting out a lot more than 50 lb's of boost yes?
     
    #11
  12. Dragsterbus

    Dragsterbus Member

    Joined:
    Oct 9, 2008
    Messages:
    141
    Likes Received:
    0
    Wow thanks for the replies ! there's a few different opinions here, I was thinking somewhere around the 450 mark myself but wanted to see what you guys think,
    my engine has too much compression? what would you recommend ?
    the boost will be around 35-40 llbs from it's previous figures.
    My Valves are, 2.375 " Titanium inlet and 2" stainless on the exhaust .
    Just had to tig up the 'o' ring grooves in the inlet as the 'o' ring was hanging into the inlet port (Not good) going to match port it next week then re cut the grooves further out,
    if it was easy everyone would do it !:)
     
    #12
    Last edited: Oct 15, 2009
  13. eli

    eli Banned

    Joined:
    Dec 24, 2005
    Messages:
    1,657
    Likes Received:
    1
    When I was building and tuneing the motors for my brothers TA/FC 511 ci in brad 5 back in 2003, we ran 5.66 255 i had the springs at 375 lb's now he has them at 425 not running any better and is snaping the tips off the ex valves or pushing the valve tip tru the retainer, so what changed since 2003 beside his bank book balance? again californised :rolleyes:
     
    #13
  14. Dragsterbus

    Dragsterbus Member

    Joined:
    Oct 9, 2008
    Messages:
    141
    Likes Received:
    0
    Ha ha, i like my bank balance the way it is which is why i'm asking you guys !
    (actually the bank could do with a top up !)
     
    #14
  15. troysitko

    troysitko New Member

    Joined:
    Jan 20, 2008
    Messages:
    29
    Likes Received:
    0
    Your 450 mark sounds really good. Depending on how hard you run it, you might start getting valve float on the exhaust. A 2" stainless valve is heavy and will pull down on a weak spring. You might consider a lighter valve if the price doesn't bother you too much.
     
    #15
  16. Dragsterbus

    Dragsterbus Member

    Joined:
    Oct 9, 2008
    Messages:
    141
    Likes Received:
    0
    Thanks for all the replys everyone, I'm not planning on running it really hard (yes it's going in the bus on my Avatar) I want it to last rather than run it really hard and damage it all the time
    Thanks again
    Wayne
     
    #16
  17. secondwindracing

    secondwindracing top alcohol

    Joined:
    Feb 10, 2004
    Messages:
    2,857
    Likes Received:
    4
    hey Wayne..this has been a great thread..lots of info..Dave
     
    #17
  18. SoDak

    SoDak Active Member

    Joined:
    Dec 29, 2006
    Messages:
    1,509
    Likes Received:
    2
    600 lbs! :eek: For real?

    What kind of spring compressor do you use? Does Mr. T run your compressor:D
     
    #18
  19. Dragsterbus

    Dragsterbus Member

    Joined:
    Oct 9, 2008
    Messages:
    141
    Likes Received:
    0
    I was thinking the comp was a little high :D, how much effect would .020" added to the gasket thickness have on the compression ? is there a formula for thou to comp points is what i'm trying to get at ?
    6.80's @ 200 Nice !:D
     
    #19
  20. eli

    eli Banned

    Joined:
    Dec 24, 2005
    Messages:
    1,657
    Likes Received:
    1
    Here you go, http://www.csgnetwork.com/compcalc.html
     
    #20

Share This Page