273 cam & crank timing marks, confussed

Small Block Mopar Engine

  1. challenger57

    challenger57 cuda57

    Messages:
    207
    Likes Received:
    15
    Joined:
    Sep 21, 2007
    Location:
    york, pa.
    Local Time:
    2:21 AM
    I'm confussed about the timing mark alignment dots when installing a new cam. Should they be crank dot at 12 and cam dot at 6 or both at 12. Iam currently at 12 and 12 with # 1at TDC. The car runs but has no botttm power. If it should be 12 and 6 shouldn't I just be able to rotate the crank 360 and reinstall dist. at #1? Thanks for any help Mark
     
  2. 66dartgt

    66dartgt Well-Known Member

    Messages:
    821
    Likes Received:
    5
    Joined:
    Jan 11, 2006
    Location:
    chgo suburbs
    Local Time:
    2:21 AM
    Sorry for the bad news - but the crank is supposed to be 12 and the cam at 6. Someone smarter than me, will have to answer your second question. My feeling is that changing the dist position won't fix the problem. You need to re-time the cam, unless I am wrong..
     
  3. 340mopar

    340mopar Sorgermotorsports

    Messages:
    3,676
    Likes Received:
    12
    Joined:
    Jan 25, 2006
    Location:
    Soap Lake, WA
    Local Time:
    12:21 AM
    With the cam at 6 and the crank at 12 the engine will be at #6 firing not #1. There is nothing to change. The way you have it now (12 & 12) is the same as (6 & 12) the only difference is there is one crank (360 degrees)revolution difference.

    If you rotate the crank 360 degrees and re-install the distributor the motor will not start because the distributor will be 180 degrees off. You can't force a firing order just by changing the distributor location. The firing order is a product of the camshaft arrangement.


    The 273 is not known for very much bottom end power, especially if it has a large cam. Advancing the cam 2 or 4 degrees may give you some more bottom end power. You should check the cam with a degree wheel to see were it is now.


    Chuck
     
  4. fubar

    fubar 64DART GT 340

    Messages:
    70
    Likes Received:
    1
    Joined:
    Jan 21, 2008
    Location:
    Jackson mich
    Local Time:
    2:21 AM
    Sorry to say if it were me I'd tear it all apart and put it together with the cam and crank in their respective positions with the cam at 6 and the crank at 12 and put the distributor in its stock state so you just might pick up some bottom end.
     
  5. 63dartman

    63dartman Well-Known Member

    Messages:
    2,241
    Likes Received:
    15
    Joined:
    Dec 11, 2005
    Location:
    rio rancho, nm
    Local Time:
    1:21 AM
    The timing marks should be at 12 and 12 to have #1 cylinder at tdc. You do not need to tear it down? You have it right. Now if you were building a chevy motor it's 12 and 6 for #1 at tdc. I think that's where all the confusion comes from.
     
  6. C130 Chief

    C130 Chief Mechanical Genius

    Messages:
    3,076
    Likes Received:
    233
    Joined:
    Nov 23, 2005
    Location:
    Boise, ID
    Local Time:
    1:21 AM
    Crank sprocket is EXACTLY half the size of the cam sprocket in ALL 4 cycle engines. Every other revolution of the crank the cam "dot" will be at 6 o'clock position with the crank "dot" at 12 o'clock. The pistons don't know if they are at TDC on the compression or exhaust stroke. The distributor position is relative to the cam shaft only.

    Ever wonder why you can set your timing off #6 cylinder the same as #1?
     
  7. 340demon

    340demon old man

    Messages:
    243
    Likes Received:
    35
    Joined:
    Apr 9, 2006
    Location:
    Ocean Shores, Wa
    Local Time:
    12:21 AM
    if it runs but with no power you may be one tooth off on the cam install thats why it is best to degree the cam when it is installed the guys are right 12 and 12 or 12 and 6 will put
    #1 and #6 both atTDC on both mopar and gm motors
     
  8. mullinax95

    mullinax95 Well-Known Member

    Messages:
    11,537
    Likes Received:
    399
    Joined:
    Oct 25, 2006
    Location:
    Anderson, SC
    Local Time:
    3:21 AM
    Go with the 12 and 12 method and make sure when you install the oil pump driveshaft and distributor gear is pointing toward the #1 cylinder. So when you install the distributor you will be good to go. The gear will spin some when it finally seats so you have to compensate for that.

    Good luck on the 273 but I have tried everything to get some low end out of it and I have did nothing but wasted time and money. Mine is bored .060 also. It takes nothing to over cam the motor also...been there done that. A .441 lift or .420 is about as far as you can go with the 273.....anything larger than that you can say good bye to low end torque.
     
  9. challenger57

    challenger57 cuda57

    Messages:
    207
    Likes Received:
    15
    Joined:
    Sep 21, 2007
    Location:
    york, pa.
    Local Time:
    2:21 AM
    Finally some straight non confussing answers with the 12 and 12 method which is what I thought was correct. Thanks guys. Now for the 273, I think it is history by way of a 360 I have if i could only identify the cam #940162. I remember it put out alot of fumes when it was in my former challenger, so I suspect it has a good bit of duration to it. Thanks for any info
     
  10. redfastback

    redfastback Don't ask me... my garage is empty

    Messages:
    3,679
    Likes Received:
    11
    Joined:
    Apr 17, 2006
    Location:
    california
    Local Time:
    12:21 AM
    huh? a chevy has the exact same firing order bigblock and smallblock that a smallblock mopar has. even the same distributor rotation.

    just put it at 12 o'clock on the cam and 6 o'clock at the crank and you will be set. use a straight edge to make sure you're not 1 tooth off.
     
  1. This site uses cookies to help personalize content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.