WHy is Driver exhaust Cam 100 Degrees advanced?

+ Reply to Thread
Results 1 to 8 of 8
  1. #1
    Senior Member Array
    Join Date
    Aug 2006
    Location
    Fort Lauderdale, FL
    Posts
    792

    Default WHy is Driver exhaust Cam 100 Degrees advanced?

    I am trying to degree my cams to finish an engine refresh. It's a teksid 4.6, Fox Lake Heads, Comp Custom cams (same as as their Stage 2 Cam with more lift) ...I can't seem to figure out why the driver side exhaust cam is 100 degrees advanced (15 degrees BTDC) when I check it on the degree wheel. It's lined up dot to dot, it should get in the ballpark! The passenger side falls in at 110 Exhaust Center Line when aligned dot to dot. Any ideas?

    - - - Updated - - -

    Not to be confused the engine is rotated in the picture to 26ish degrees ATDC, the Driver ECL is 15 BTDC which is like 100 degrees off
    Attached Images Attached Images  
    Last edited by lucheski; 05-20-2020 at 07:25 AM.

  2. Remove Advertisements
    ModularFords.com
    Advertisements
     

  3. #2

    Default

    What are the cam specs and where are the cams right now?

    BTW, your issue not withstanding, you would do yourself a big favor in the cam phasing process if you get rid of the OEM sprockets and got a set of the adjustable Comp primary sprockets along with a set of L&M's 9-way adjustable secondary sprockets. The OEM sprockets, primary or secondary, are extraordinarily hard to use for cam phasing and continuously move around. They will nor repeat assembly to assembly and always need to be re degreed, Because they are powdered metal they are extremely hard but brittle. When you file on them for cam phasing purposes it is like putting a scratch on a pane of glass. The scratch on the glass and the filing on the sprockets produces a stress riser which is fertile ground for a crack.


    Ed

  4. #3
    Senior Member Array
    Join Date
    Aug 2006
    Location
    Fort Lauderdale, FL
    Posts
    792

    Default

    Pass ECL 110*
    Driver ECL 15*
    I didn't bother doing the Intakes until the exhausts are done.

    Comp Cam Gears have been on National Back Order since 10/19. I've tried to get some for months (I've had an order into summit since then) to no avail hence the stock gears. IIRC there Colyes makes a set of adjustable gears, are they good?
    Currently installed are:
    L&M Adj Cam Secondary gears
    Accufab HD Secondary chains
    Accufab Cam Washer/Spacer kit
    Accufab Dowel Pin Upgrade
    Shelby Mike Billet Primary Chain Tensioner Arms


    The are the same cams i've been running for the last few years
    Attached Images Attached Images  
    Last edited by lucheski; 05-20-2020 at 12:26 PM.

  5. Remove Advertisements
    ModularFords.com
    Advertisements
     

  6. #4

    Default

    You may be OK, Hendri. When you check the cam phasing you need to re-establish TDC for each bank. If you do not one bank will be off by 90 degrees. In your case that would put the misbehaving driverside cam at a 105˚ CL rather than a 15˚ CL. In effect your LSA would be 107.5˙ with both cams advanced 2.5˚. This is what it looks like on Mark Olson's CamCharting S/W using the 0.050" cam card opening and closing specs.

    Name:  Hendri.jpg
Views: 122
Size:  38.8 KB

    This is what it looks like as you have them installed right now;

    Name:  Hendri1.png
Views: 121
Size:  69.2 KB

    Those are pretty zippy cams. That much overlap will make idle vacuum low and provide problems operating the boost bypass. If you can get them to a 116˚ centerline (or wider) with a couple of degrees advance the car will be more enjoyable to drive.

    Something that looks like this;

    Name:  Hendri3.png
Views: 122
Size:  68.7 KB

    The timing above is a 120.5˚ LSA advanced 4.5˚ which will provide excellent idle vacuum and bypass operation along with very robust low speed torque.



    Ed

  7. #5
    Senior Member Array
    Join Date
    Aug 2006
    Location
    Fort Lauderdale, FL
    Posts
    792

    Default

    I realize my mistake now, After setting TDC on Cylinder 1. I was checking cylinder number 5. Instead of cylinder number 6, or as you said I would have had reset TDC based on cyl 5

  8. #6

    Default

    Hendri,

    Don't forget that when you use cylinder #6 and cylinder #1 that their ignition events (and everything else) are 360˚ out of phase with cylinder #1. It is an easy mistake to use the same 0˚ position in the 720˚ engine operating cycle for the second cylinder bank and then that entire cylinder bank will not fire. It will be 360˚ out of phase with the ignition event In fact one of the site members here had a shop degree his cams and they did exactly that! His car still ran, albeit very roughly, and one half of the engine never heated up!


    Ed

  9. #7
    Senior Member Array
    Join Date
    Aug 2006
    Location
    Fort Lauderdale, FL
    Posts
    792

    Default

    Final Numbers
    Pass ECL 126
    Pass ICL 111.5
    Drvr ECL 126.5
    Drvr ICL 111.5

    I Reset TDC using cylinder 6 when doing the driver side. The ECL originally measured out to 110 on both sides, so i retarded the exhaust primary chain by one tooth on the chain to see where it would end up and I got 126* ECL on both sides
    Thanks Ed

  10. #8

    Default

    I've been in that maze before, Hendri. I know that lost feeling, so well.

    Congrats on finding your way out with your sanity.


    Ed

  11. Remove Advertisements
    ModularFords.com
    Advertisements
     

+ Reply to Thread