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Thread: So what is going on???

  
  1. #1
    OVER-BOOST!! roberto2000's Avatar
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    SVO's: 1985 4E + 1c 84 1e

    So what is going on???

    I finally have the car running and tuned. The car pulls very hard and has lots of power...Problem is it only makes power up to 4200 rpm then starts going wonky and loosing power at around 4500 rpm
    The fuel during the run stays nice at 11.5-11.8 all the way up when getting on it. The tuner and the others were asking about spark plug gap, valve float/ springs, and one guy asked about lifter leak down???
    what do you guys think could be the issue???
    I can take the car out tomorrow and data log a run up and post it if that would help
    I know some have asked about flow rates of the head..it is a home ported big valve head.
    Attached Thumbnails Attached Thumbnails dyno2.jpg  
    Rob

    85 4e

  2. #2
    Director, and Idiot Savant Gator's Avatar
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    Alright...now imma have to have a few beers to allow for proper head scratchin time...but for now...

    What psi was this? did you try and push it further with more ? Was it popping/wheezing out of power ? or did the graph just move to the left ?

    As Mike inquired, where is the cam set at ?

    Silly question next, but i have seen it done before more than once....Did you use the correct marks on the gear ( or use the E-bar ( or whatever its called )) method to set it at straight-up ?

    My fear is that there may be something a miss...and your tuner is that good where he is tuning around it.

  3. #3
    OVER-BOOST!! svobud's Avatar
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    SVO's: 1985.5 1B
    Looks like: Cam and where you indexed it is wrong as Gator is suggesting. And as Mike suggested - start moving your timing at the distributor and see if your results change in the peak hp.

  4. #4
    OVER-BOOST!! GAboySVO's Avatar
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    Rob,

    FYI, when my 2.1 cam is set at both valves closed (TDC) The alignment mark on the racer walsh adjustable cam pulley is pointing a 12*. I don't think the 2.1 cam lines up like the stock stuff. I think you will need to re-index the cam as all have suggested to really know where TDC is on the 2.1 cam, then adjust from there to your liking. Put a vacuum gauge on and adjust the cam to bring the vacuum as close to normal.

    As I didn't do the indexing or ebar when I put it together the first time, I had to move the cam pulley several teeth to get it in the ball park and then use the adjustment to fine tune the torgue curve.
    Mike S

    '86 SVO 9L Leather
    '86 SVO 9L Road Warrior
    '96 300ZXTT

  5. #5
    OVER-BOOST!! JTurbo's Avatar
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    Sounds like we need a tech session in KY.....

    86 SVO 1C

  6. #6
    Director SvoTy's Avatar
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    Rob do you have the right keepers for the new valves? Might check and see what the seat pressure is, I had the same issue with my first set of valves, they were just a little longer and I had to use a SBC keeper if I remember right.

  7. #7
    OVER-BOOST!! roberto2000's Avatar
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    SVO's: 1985 4E + 1c 84 1e
    I have the Cam installed Via the string method and at 0*
    Mike I also have the Racer Walsh pulley
    The boost is set to 20psi
    Mike S...I remember you posting on how you liked the cam at 10* adv. I tried that and the car was low on power when we retarded the cam to 0* the #'s shot up 80 hp
    I guess the only grey area there is would be the ignition timing?
    I set the cam with the string and lined up the distributor but I cannot set the timing with the spout out or in for that matter (don't have that anymore)
    I start the car and look at the spark map zeroing in on the map where the car is running and see what the spark timing is. From there I set this on the timing light and check against the crank and this value is usually at 0* ( spark map is around 32* idle)
    Does this sound proper?
    If I retard the cam as Mr Flemming suggests will this throw off the whole tune??

    Thanks so far for the input
    Last edited by roberto2000; 10-02-2009 at 01:53 AM.
    Rob

    85 4e

  8. #8
    OVER-BOOST!! roberto2000's Avatar
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    SVO's: 1985 4E + 1c 84 1e
    I am using SD system....Holley Commander
    Rob

    85 4e

  9. #9
    OVER-BOOST!! GAboySVO's Avatar
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    Rob, What I'm trying to say is that the TDC timing mark on the RW cam pulley no longer lines up with the stock pointer, so I could use that as my starting or reference point. So my earlier post about advancing the cam was a little erroneous because I was assuming the new cam pointed to the the stock pointer at TDC which it doesn't. I'm going to put the head back on tomorrow, so I will take a picture of where the cam TDC mark is when the crank is at TDC.
    Mike S

    '86 SVO 9L Leather
    '86 SVO 9L Road Warrior
    '96 300ZXTT

  10. #10
    OVER-BOOST!! roberto2000's Avatar
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    SVO's: 1985 4E + 1c 84 1e
    Mike S thanks for the picture offer that would be great since we both have the RW pulley maybe it can shed some light.
    Rob

    85 4e

  11. #11
    OVER-BOOST!! GAboySVO's Avatar
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    Rob,

    Here is how I had to set my cam to get enough vacuum and move the power band down a bit. This is at TDC. With it set like this, it did start to run out of power at about 5700 rpm. I will most like be adjusting it depending on how long the straight aways are on the various road course I will be running.

    At Road Atlanta, I reached max power in 4th way before the braking zone and didn't want to shift to 5th.

    Now back to work.....
    Attached Thumbnails Attached Thumbnails DSC02366.jpg  
    Mike S

    '86 SVO 9L Leather
    '86 SVO 9L Road Warrior
    '96 300ZXTT

  12. #12
    OVER-BOOST!! roberto2000's Avatar
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    SVO's: 1985 4E + 1c 84 1e
    Mike judging from that picture it looks to be one tooth on the belt off of the zero mark on the cam pulley
    Rob

    85 4e

  13. #13
    Director, and Idiot Savant Gator's Avatar
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    Have you guys had your head milled or block decked ?

    Cause if ya had you can toss the stock marks on a cam gear right out the window.

  14. #14
    OVER-BOOST!! DRAGPAK's Avatar
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    I would e bar the cam in and recheck tdc on the crank .

  15. #15
    OVER-BOOST!! GAboySVO's Avatar
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    Quote Originally Posted by roberto2000 View Post
    Mike judging from that picture it looks to be one tooth on the belt off of the zero mark on the cam pulley

    Yeah, I had to move it around to get good vacuum and enough power in the 3000 to 5500 rpm range.
    Mike S

    '86 SVO 9L Leather
    '86 SVO 9L Road Warrior
    '96 300ZXTT

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