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TR Camshaft Timing => need more details

Discussion in 'Technical Q&A' started by vincenzo, Nov 24, 2003.

  1. vincenzo

    vincenzo Formula 3
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    #1 vincenzo, Nov 24, 2003
    Last edited by a moderator: Sep 7, 2017
    The TR manual says:
    ***************************************
    If valve timing needs adjusting, proceed as follows:

    - Rotate the crankshaft until the camshaft has reached the required position (A.A. or C.S.), and lock it (the camshaft) in this position.

    - Remove the driving dowel from the pulley.

    - By turning the crankshaft in the engine direction of rotation, bring it to the exact angular value required for the timing.

    - Then align one hole on the pulley with another hole on the camshaft, and insert the driving dowel.
    ***************************************
    Obviously, this procedure only works if one needs to retard the cam.

    One must likely need to disassemble the pulley from the cam and re-align if advance is needed. How does one rearrange the assembly?

    Where can I find a better explanation of how the cam/ pulley 'vernier' holes are used for exact positioning?

    The enclosed scan shows the cam/pulley/teeth relationship.

    TIA,
    Vince
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  2. Ferrari_tech

    Ferrari_tech Formula 3

    Jul 28, 2003
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    If you search in the archives this subject has been thoroughly covered during the past months. You will find all the info regarding setting the valve timing from "scratch"

    MW
     
  3. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Vince -- You're reading that instruction in a too limited way. As you said, to retard the camshaft (relative to the crankshaft) you would rotate the crankshaft (a little bit) in the direction of rotation. To advance the camshaft, you do the same thing, but you rotate the crankshaft much more, say 359 deg, to get 1 deg advance -- it's perfectly clear now yes?;)

    "Then align one hole on the pulley with another hole on the camshaft, and insert the driving dowel." is also not the best translation IMO. What will happen is when you've got the camshaft and the crankshaft where you want them only one hole in each pattern will line up (or nearly line up) -- that's where you put the dowel. Worst case is two adjacent pairs of holes would each be misaligned by 1 deg (24 deg 30 min minus 22 deg 30 min divided by 2) so in that case you just have to pick one and misalign the camshaft pulley by 1 deg to put the dowel in.
     
  4. carguy

    carguy F1 Rookie

    Oct 30, 2002
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    Vincenzo...have you in fact determined if the cams need retiming? When doing my TR service I too asked many questions and got so many answers I couldn't tell fact from fiction. It took me several tries to finally determine that my cams were okay and didn't need adjusted. It is not an easy thing to do as there are several places for error that although small, result in the final readings being suspect. Also you should be aware that there are different cam timing specs for Euro cars versus U.S. cars for the intake cams....I think the U.S. cars intakes are retarded 3 degrees from the Euro ones. If your running functional cats then you must adhere to the U.S. spec.s, but if no cats you can run to the Euro spec.s but note that for future reference if cats are re-installed. Do the timing marks line up on the cams and retaining caps? Please keep us posted.
     
  5. vincenzo

    vincenzo Formula 3
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    Ferrari_uk_tech:
    Yes, the achieves were searched .... found lots of info - but nothing specific on using the vernier arrangement on the cam/pulley system.

    91tr:
    As the crank is rotated forward the 359 degrees or so to advance the cam.... the grunching sound we just heard was 6 pistons wiping out +/-12 valves (assuming only one of the two cams were fixed). The process you describe is correct - but again, I only see it working if one retards the cam.

    carguy:
    No, haven't pulled the motor yet. Assembling the parts and pieces at this time. Merely preparing contingency plans in advance. I 'hope' everything lines up 'spot on'. You are correct on the timing issue....
    Typical euro TR shop manuals say:
    Intake - 16 & 48 - - - before TDC & after BDC
    Exhaust - 54 & 10 - - - Before BDC and after TDC
    US Spec owner's manual says:
    Intake - 13 & 51 - - - before TDC & after BDC
    Exhaust - 54 & 10 - - - Before BDC and after TDC

    Hmmmm.... If I loose the cats and advance the Intake - how much more power awaits? Wonder if my wife would let me spring for a dyno? ;-) This could be fun.

    Will no doubt post more info....

    Thanks to all,
    Vince
     
  6. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
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    You need a dial indicator to set cam timmng!

    With pulleys and new belt installed, slowly rotate engine until the DI indicates the correct valve timing on one cam (usually a particular displacement of the affected valve -- 0.050).

    Pull pin coupling cam pulley to cam. Lock cam or leave DI indicating cam has not moved.

    Use degree wheel (or other means) to set crank to TDC for that bank.

    Find the correct hole that will allow the pin to engage the pulley and the cam.

    Torque to spec.

    What the picture is showing is that the angles for the pulley are different than the angles for the cam. The difference between these angles indicates you can set the timing to less than 1 degree of accuracy.
     
  7. vincenzo

    vincenzo Formula 3
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    The manual says: fix the cam/ rotate the crank.

    What if one were to 'fix' the crank, at say 12 deg before TDC, and then rotate the cam to initiate lift?

    Would a pair if vise grips on the cam provide sufficient leverage???
    Sounds horrible.

    Rgds,
    Vince
     
  8. vincenzo

    vincenzo Formula 3
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    Mitch:

    When you say:
    "Use degree wheel (or other means) to set crank to TDC for that bank."

    That is correct, but one can only move the engine in the direction of rotation "to set crank" .... no fair backing up... which means that one can only retard the cam in relationship to the crank.

    I must be missing something....

    Rgds,
    Vince
     
  9. carguy

    carguy F1 Rookie

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    I guess we need a definition as to what the shop manual means when it says "in direction of rotation". Does this mean the rotation that the engine sees when running, or does it mean the direction of rotation needed to get the proper timing? I believe you can rotate the motor backwards every-so-slightly to get a few degrees of cam advancement as needed. But be sure to remove the spark plugs first to minimize the force needed to turn the motor over. And watch very closely to see if the belt is trying to climb over pulley teeth or jump position.Then verify timing by going through several complete revolutions of the crank, and adjust again if needed. As for top dead center, the flywheel is marked for this event. I used a degree wheel on my engine and double checked the flywheel marks and they were exact on my motor. You will need a dial indicator to measure valve shim bucket travel, and this will require some sort of pointer or probe to be made up. It is very difficult to get a good contact point on the shim buckets, so the pointer will need to be bent or offset at the tip. Also orient the dial indicator so it's travel is in the same axis as the shim bucket travel. And then there's the famous "valve opening event at 0.5mm lift" issue. There are many opinions on the best way to do it. I would simply stick a shim in there that eliminates the clearance, making it "zero". Then zero out the dial indicator as appropriate, and rotate everything and watch for the magic 0.5mm travel to occur...this point should be the open/closing event to compare to the manual spec.s.

    I think advancing the cams to Euro spec.s will result in maybe 10 horsepower as that's the horsepower rating difference from U.S. to Euro. But this is just my uneducated opinion.

    To lock the cams in place, some have used vice grips on the intake and exhaust cams with the grips oriented so they criss-cross, and then duct taped them together. I made some nylon blocks to hold my cams in place. I'll try and find a pic to post.
     
  10. vincenzo

    vincenzo Formula 3
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    #10 vincenzo, Nov 25, 2003
    Last edited by a moderator: Sep 7, 2017
    Carguy:
    You said: "I believe you can rotate the motor backwards every-so-slightly to get a few degrees of cam advancement as needed. "

    I think you are right. As long a bit 'more' than enough cam advance is dialed in... and then the factory method is used to retard the cam back to the exact location.

    I intend to follow the factory prescribed timing method i.e.)
    ********************************************
    - Bring the valve clearance of cylinders 1 and 7 to 0.50 mm.

    - Using a dial gauge with tracer point on the tappet shim accurately note the moment of the opening and closing of the valves. An allowance of ± 1° on the angles is permitted.
    ********************************************

    I still need to get the vernier 'thing' figured out :)

    Your nylon cam blocks look like a good idea. If they fit 'ok', I'll be using those shown below.

    Rgds & Thanks,
    Vince
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  11. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Vince -- Although I agree with your caution and would quadruple-check before rotating the crank, are you sure that there's an interference when (all) the cams are fixed in their relative "cyl #1 at TDC fire" position? (i.e., I believe that no valve in either bank is fully open with the cams in that position)
    Can none of the professionals confirm/deny?
     
  12. carguy

    carguy F1 Rookie

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    So the motor is still in the car, are you turning it over by hand? If their has been contact with pistons & valves....yikes!! So either a cam belt has broken or at least jump timing by a significant amount. If so this is tragic...can you tell us what happened? How many miles and/or years on the belts?
     
  13. vincenzo

    vincenzo Formula 3
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    #13 vincenzo, Nov 25, 2003
    Last edited by a moderator: Sep 7, 2017
    Steve,
    Good point - -

    No, I don't know for a fact that there is interference when (all) the cams are fixed in their relative "cyl #1 at TDC fire" position.

    I think the crank is 120 degrees (unconfirmed) on the throws. Cam should 'more or less' be the same. Iterference **may** not be an issue.

    Sketched it out - - likely you are correct. Good point & thanks for the comment.

    Rgds,
    Vince
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  14. vincenzo

    vincenzo Formula 3
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    Carguy,
    No problems with the car. Just 5 years since the last service!
    Rgds,
    Vince
     
  15. Motob

    Motob Formula 3
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    Nov 11, 2003
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    Brian Brown
    Vise grips and nylon blocks are not needed to lock the cams in place. All you need is some paper. I use notepad paper which is a little thicker than regular typing paper. You cut the paper into 2"x1" strips. Fold each strip in half to double the thickness, so you now have 2"x.5" strips of paper double thickness. Loosen up the 2nd and 3rd cam bearing caps from the front of the motor and insert a strip of paper under each cap. Tighten the caps. The cams are now locked. This method works well enough that you can torque the cam sprocket bolts and not have the cams move.

    If you need to rotate a cam, do not vise grips. Instead, get a piece of round brass rod (1"Dia.) and remove the sharp edges from one end. Using a hammer and this drift, you can tap on the cam lobes and rotate the cam without marking it.

    Brian Brown
    Patrick Ottis Co.
    Berkeley, Ca
     

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