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Refitting A GT4 Distributor

Discussion in 'Technical Q&A' started by 208 GT4, Jul 1, 2005.

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  1. 208 GT4

    208 GT4 Formula 3

    Dec 27, 2003
    1,769
    Brighton (UK)
    Full Name:
    Dan
    #1 208 GT4, Jul 1, 2005
    OK, so following on from my thread about ignition problems with my twin distributor 208 GT4 I took the suspect distributor off to check for point gap, loose bits and general operation.

    It looks OK and testing with a voltmeter it seems to be doing what it ought to - i.e. producing pulses as the cam is turned.

    Now I've got to refit it. I had marked the exterior so I can make sure the distributor itself is in exactly the right place. However I thought that the drive shaft had only 2 positions, but it is in fact a splined shaft with about 20 possible positions. I had a rough idea of where the rotor arm was when I took it off. There is a mark on the body of the distributor under where the cap sits for alignment, presumably this much match up with a known engine position?

    The other distributor hasn't been disturbed, so can I match it to a position of the other rotor arm maybe?

    Any help appreciated!

    Dan
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,931
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #2 Steve Magnusson, Jul 1, 2005
    Which bank is removed?

    You need to put the engine with piston #1 (or #5) at its idle firing point (near the end of the compression stroke, not the end of the exhaust stroke) and then mount the 1/4 (or 5/8) distributor with the rotor end facing the red mark on the dist housing rim:

    http://ferrarichat.com/forum/showthread.php?t=57362&highlight

    Do a search on "308 distributor mark" -- many other relevant threads.

    If you need some pointers on how to make sure that you're at the #1 (or #5) idle firing point, give a shout.
     
  3. Ken

    Ken F1 World Champ

    Oct 19, 2001
    16,078
    Arlington Heights IL
    Full Name:
    Kenneth
    #3 Ken, Jul 1, 2005
    The engine hasn't turned, so what you need is to have the rotor pointing the same way when you replace it as it was when you took it out. The cap should only go on one way. So if the distributor can be replaced more than one way (my car has two) try one and see where the rotor is pointing when it's pushed home. If it's wrong, try again!

    I will add that you should really learn to static time your car, and then fine tune it running. Even with the twin distributor setup you have it can't be that hard, and it's a useful skill to learn. I've taken my distributor out several times and I don't even attempt to mark the position; I retime it. In fact, I put a new rotor in last weekend and it needed a couple degrees adjustment after that so I wouldn't trust that my timing was spot on. Maybe Ferraris are more precise?

    Ken
     
  4. 208 GT4

    208 GT4 Formula 3

    Dec 27, 2003
    1,769
    Brighton (UK)
    Full Name:
    Dan
    #4 208 GT4, Jul 1, 2005
    Thanks Steve and Ken,

    I've got it running again sort of. I judged where the rotor should be based on the position of the other rotor and the firing order. I couldn't see any of the timing marks on the flywheel, but I can only turn the engine on the starter, and with the small viewing window and compression, I guess it wasn't stopping nicely near Top Dead Centre for me? Any recommendations for turning the engine by hand? I thought of putting it in a high gear and rolling the car, but there wasn't room for that in my garage.

    Anyway with the distributor bolts loosened enough to be able to turn it, I started the engine. I rotated the distributor, and it was better in one direction than the other. I then stopped the engine and moved the rotor driveshaft one spline in the opposite direction. Then ran the engine again, this time it ran best when the marks I'd made earlier on the engine and distributor lined up, so I guess I've found the right spline.

    It's still misfiring a bit on the front bank, but there's a healthy spark from the carbon contact in the middle of the distributor cap, but a weak one at the plugs. So the plug leads are next on the hit list.

    Thanks again for the advice.

    Dan
     
  5. Ken

    Ken F1 World Champ

    Oct 19, 2001
    16,078
    Arlington Heights IL
    Full Name:
    Kenneth
    #5 Ken, Jul 2, 2005
    Get yourself a floor jack and jack the rear. Have the car in 5th and rotate the rear tire (either one) as if the car was moving forward until the flywheel mark is at whatever your static advance should be. The tricky part is you need to be on the power stroke and it's 50-50. On my car, I just pop the oil fill cap and I know when the cams on #4 are pointed at each other I'm good. I'm sure someone here can help you for your car. I find the "thumb over the spark plug hole" method to be difficult.

    You were lucky to get it working by eyeballing the static! Yes, you CAN adjust the advance by twisting the distributor while running to get the best idle but you may find you have too much advance that way. If you try to start the car and it makes a funny "whoosh" before turning over, it's NOT the starter. It's too much static advance.

    Ken







     
  6. 208 GT4

    208 GT4 Formula 3

    Dec 27, 2003
    1,769
    Brighton (UK)
    Full Name:
    Dan
    #6 208 GT4, Jul 2, 2005
    Thanks for that Ken, it had occured to me to try jacking it and turning the wheel, but I thought the differential would just make the other side turn and I didn't have an assistant to help with the other wheel.

    Anyway, you will be pleased to know that I've got it all sorted now.

    It turned out to be a faulty Condenser (which was new on last week!) I had tried putting a different Condenser on - one of the first things I tried - but it turned out I had accidentally undone the connection through the wall of the distributor. I'd retightened it by feel, but found when I had the distributor off that the wire to the contact breaker wasn't seated properly. Hence it not firing when I had tried the other Condenser.

    Eyeballing the static wasn't too difficult really, because I knew for a fact the timing was good if I could just find the right spline and line up the marks on the engine & distributor. From the firing order I could logically narrow it down to a 90deg arc, and that left me with 5 possible spline positions to try. The eyeballing effect reduced that to 3 probable positions.
     
  7. Steve King

    Steve King F1 Rookie

    Feb 15, 2001
    4,367
    NY
    #7 Steve King, Jul 2, 2005
    1st never turn the engine backwards. So get yourself a larget socket (36MM) and use the crankshaft bolt . You can turn the engine over by hand and either have someone watch the timing marks as the come up or you can do it yourself but it takes a little longer. Once you have it on PM1-4 and on TDC you are set to install the dizzy. Look at the cap and see where #1 is and mark it on the dizzy. Now install the dizzy and you should be ready to start it and set the timing. Do the same for the 2nd dizzy only set that at PM5-8 on the flywheel.
    Ken just as a point of reference the F car dizzy have a spline shaft , either 8 or 10 splines and can be installed many different ways. Unlike a chev or ford dizzy which can only be installed 2 ways this gets a little tricky. Also the easiest to set the points on this is on the bench. Althought it can be done it is almost impossible to install points with the dizzy in the car. There is a spider which holds the upper shaft bearing that is in the way. Oh and the reason you don't turn the engine backwards is because the timing belt can jump a tooth and that will gernade the motor. Good luck
     

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