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Thread: Finally tore the motor apart

  1. #1
    Taspeed's Avatar
    Taspeed is offline Cadillac Owners Member
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    Finally tore the motor apart

    Well I aquired the car needing head gaskets about a year ago. Haven't had a chance till now to get it apart and running. I pulled the motor last week and when i went to pull the heads I noticed that the exhaust cams were retarded a bit and the intake cams were advanced a bit. What i am trying to determine is if this was done on purpose or it was an accident when someone changed the timing chains or something? I may need to have the heads decked a few thousandths to make sure they are flat and not warped so valve clearance and timing is a concern since i dont know a lot about the n* yet. Is it common to change the cam timing in these motors in that manner, and what are the ramifications tuning wise to doing this?


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  3. #2
    zonie77 is offline Cadillac Owners Connoisseur
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    Re: Finally tore the motor apart

    Changing cam timing is not common. I haven't seen any mention of it as a tuning aid. People that wound up 1 tooth off had driveability problems.

    http://www.cadillacforums.com/forums...ir-part-i.html

    Here's some info that may help. There are plenty of others.

  4. #3
    Submariner409's Avatar
    Submariner409 is offline If it won't run, chrome it
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    Re: Finally tore the motor apart

    There is absolutely no advantage in advancing or retarding the cam(s) in a Northstar. The old adage that advancing a (single) cam 4 degrees moves the power band down about 800 rpm and the opposite from retarding it the same amount does not hold true in a DOHC engine. The Northstar is an interference engine, meaning that, if you mis-time the cam(s), you run the very real risk of one or more sets of valves hitting the pistons.

    Time the cams according to the GM/Helm Factory Service Manual or subscribe to www.alldatadiy.com.

  5. #4
    Taspeed's Avatar
    Taspeed is offline Cadillac Owners Member
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    Re: Finally tore the motor apart

    that is what i thought. I just found it odd that the cams weren't timed 90* to the top of the head. They were both off a bit.

  6. #5
    97EldoCoupe's Avatar
    97EldoCoupe is offline Owner of Northstar Performance
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    Re: Finally tore the motor apart

    I know the intake cams can cause valve-to-piston interferance but I don't think the exhaust valves can, as they are recessed further into the head and on a different angle. I'll have to check next chance I get. The pistons have valve reliefs too, but they won`t help in the event that a chain should snap....


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