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308 2v timing question

Discussion in 'Technical Q&A' started by blainewest, May 4, 2006.

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  1. blainewest

    blainewest Formula Junior

    Aug 26, 2005
    729
    Kelowna, BC
    Full Name:
    Blaine W
    #1 blainewest, May 4, 2006
    I'm in the middle of replacing my timing belts/tensionsers and it is turning into a larger job than planned. Decided to also replace cam seals, adjust valve clearance, install electromotive ignition etc. etc. Anyway I'm checking the timing on the rear bank dizzy and I've got the flywheel to the PM 1-4 mark and my understanding is that the rotor should be pointing at the no. 1 cylinder terminal on the dizzy. It is not...seems to be pointing past it about 1/2" maybe.

    Then I checked the marks on the cam and cap that are visible through the oil filler hole...and these marks are not close to lined up....the mark on the cam is again past the cap mark by about (guessing) almost an eighth turn of the cam.

    My understanding is that when the PM 1-4 mark is lined up with the bell housing mark that the cam mark and cam cap mark should be more or less lined up. Is this correct? Isn't this in fact the method for dialing in the correct cam positioning upon replacement?

    If so...how could my marks (cam and cap) be that far out and still run? BTW the car ran superbly, smooth, no hesitation etc. Any help is greatly appreciated. Blaine.
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,932
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #2 Steve Magnusson, May 4, 2006
    Are you sure that you are on the PM1-4 mark? If it's actually the PM5-8 mark, the 1-4 cams would be rotated by exactly 1/8 turn.
     
  3. tomoshea

    tomoshea Formula Junior

    Dec 29, 2003
    541
    Ireland
    Full Name:
    Tom O'Shea
    #3 tomoshea, May 4, 2006
    Without going through the hassle of doing a full degreeing of cams here is what I recommend you do.

    1) Replace the belts, looking at the cams from harmonic balancer end put the cam alignment mark close to the left side of the cap alignment mark(this is the wider mark)

    2) release the tensioner - i.e put tension on the belt

    3) complete 1 full rotation of the engine by hand back to TDC

    Now check the alignment of the cam marks with the cap marks at TDC

    If the cam marks are within the cap marks no need to do anything with the cam drives, just lock everything in place and now look at the dizzy, i.e goto 4, if the cam marks are still outside the cap marks goto 6)

    4) Mark cylinder 1 contact point on the outside of the dizzy to cam metal plate.

    5) Move the flywheel to AF6 mark - now the rortor should be nearly aligned with the mark on the cap, if not you need to remove the dizzy from the head and reposition it so that one of the splines gives you better alignment with cylinder 1 contact point.

    6) (Make sure the flywheel is at TDC before progressing) - Only do the following with one cam at a time - If a cam mark is outside the boundaries you need to start playing around with repositioning the cam drives so that you do get them aligned inside the cap guide. This is not rocket science just slow and time consuming and involves firstly removing the nut at the end of each Cam (careful you will need someone to help you if you do not remove the cam from the seats, or the cam may turn dinging your valves, best doen with an air gun and a strong friend)that holds the cam drive in place and removing the dowels underneeth this nut that holds the cam drives in position on each of the cam shafts. Now set the cam with the marks centrally aligned in the cap mark, find a dowel position that allows the cam and the belt teeth to align in this position and lock in position, lock the cam nut( with your strong friend). Put the belt on, re-tenison the belt, complete 1 turn and check at TDC the mark is still within the cap mark. Complete again as necessary on all the cams until within spec.

    7) If after completing 6) your dizzy is still well away from the mark, complete steps 4) and 5)

    Hope that helps - easy when you have done it!, difficult to explain in email!
     
    Reid likes this.
  4. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    7,022
    Groton, MA
    Full Name:
    Verell Boaen
    #4 Verell, May 4, 2006
    You probably know this, but the 1-4 bank is the rear bank, the 5-8 bank is closest to the front of the car. With the engine on PM1-4, the 5-8 distributor will be 45 degrees off.
     
  5. blainewest

    blainewest Formula Junior

    Aug 26, 2005
    729
    Kelowna, BC
    Full Name:
    Blaine W
    #5 blainewest, May 4, 2006
    Thanks for the all the advice guys. Thanks Verrel for pointing that out. That is the bank I was working on (rear). Just to make sure I've got the basics correct..the number one cylinder is the right rear cylinder yes? It's marked that way on the cam cover. It also seems to be top dead center when the flywheel PM 1-4 mark is matched to the bell housing mark.

    The markings on my flywheel are as follows "AF 7' I PM 1-4 I I-3' ". The "I" represents the marks and the ' on the flywheel is the small circle degree sign. The PM 5-8 is marked the same way except of course the PM 5-8 characters.

    I am planning on removing all the cams during this service so do I not simply, when replacing the cams, line up the marks (cam and cap) on all four cams, following the procedure outlined above, put the belts on then follow the factory procedure for re-installing the dizzies?

    One more stupid question...is it possible that the flywheel was installed (by whoever last had it out) incorrectly or will it only go on one way?
     
  6. blainewest

    blainewest Formula Junior

    Aug 26, 2005
    729
    Kelowna, BC
    Full Name:
    Blaine W
    #6 blainewest, May 4, 2006
    Well boys ..... relief! After a couple hours at it tonight I removed the rear cam cover and (drum roll )....the marks on both cams and thier caps line up perfectly. I was mislead because looking through the filler hole I mistook a mark for the cap mark. This mistaken mark was a nick that someone had put on the cap. Now on to the front bank.
     
  7. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    7,022
    Groton, MA
    Full Name:
    Verell Boaen
    #7 Verell, May 5, 2006
    The flywheel can only go on one way. One of the flywheel bolts is out of position relative to the other bolts in the circular pattern. If you pull the flywheel, mark it & the crank to speed reinstallation.
     

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