Timing help for 308 GT4 with R1 points only | FerrariChat

Timing help for 308 GT4 with R1 points only

Discussion in 'Technical Q&A' started by sammyb, Aug 7, 2009.

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  1. sammyb

    sammyb Formula 3

    Jun 23, 2006
    1,857
    Where wife tells me
    Full Name:
    Sam
    Working with my friends to finally get the 308 GT4 back running. We've removed the R2 (retarded) points and are only running on the R1s. We're setting timing and carbs...and we're finding one of the distributors seems to want a major amount of advance (like 30-degrees.)

    Someone had suggested 7 deg BTDC as a starting point, but we can't get anywhere close to that. We're thinking maybe the combination of points dwell being off, as well as the placement of the points (too far back--therefore retarded, maybe?)

    When we go to lower the idle and richen the mixture, we're getting huge pops and backfires.

    Any ideas, tips, tricks...especially given we're not running the retard points?
     
  2. Harry

    Harry Karting

    Nov 1, 2003
    93
    Germany
    Check again the orientiation of distributors and rotors. It can be wrong with the described results.

    Regards
    Harry
     
  3. jm3

    jm3 F1 Rookie

    Oct 3, 2002
    4,364
    United States
    Full Name:
    JM3
    308 GT4 is very low compression, and my best results are about 36 total anyway, so dont worry. The factory specs are for smog, not for performance. Eventually I think you will want to convert to electronic ignition in one distrubotor, using the second as a slave, which makes the car run 100% better.


    Jay
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,039
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    +1 -- and the relation of the R1 points to the rotor in each distributor.

    Remember, it is not like the cams (where you set the engine in a single position and line-up all the cams at the same time) -- for the ignition:

    1. set the engine to the PM1-4 (or, to be uber-picky, the 1-4 AF 7 deg) position when cyl #1 is at the end of its compression stroke -- install the 1-4 dist so that the 1-4 rotor points at the notch in the 1-4 distributor rim (and the 1-4 R1 points should just be opening in that same position too), then

    2. rotate the crankshaft 90 deg, in the direction of normal engine running, to the PM5-8 (or the 5-8 AF 7 deg) position -- install the 5-8 dist so that the 5-8 rotor points at the notch in the 5-8 distributor rim (and the 5-8 R1 points should just be opening in that position too).
     
  5. sammyb

    sammyb Formula 3

    Jun 23, 2006
    1,857
    Where wife tells me
    Full Name:
    Sam
    Thanks guys. After I posted this, I was doing a mental checklist and I figured out that I might have inadvertantly really retarded the system by placing the points too far back on the circumference of the dizzy plates. I think I'm going to go back in and if they are far back, move them both to a more central position.
     
  6. Ferraripilot

    Ferraripilot F1 World Champ
    Owner Project Master

    May 10, 2006
    17,171
    Atlanta
    Full Name:
    John!
    Total timing on these engines at 6k+ rpm is 39-41 degrees. The 34 degree mark is only a reference marker prior to the final advance spring in the distributor kicking in which -if the distributor springs are set up correctly- does not kick in until 5k with max reached at 6k. So many of these engines are "set up" with distributors that are incredibly out of whack and are advancing a huge amount at idle essentially screwing up the whole process. Make sure the distributor is not 180 out and that you are timing it off of the correct marks on the flywheel. Use different colored marking on the flywheel marks for each bank you are working on.

    Regarding upgrading the ignition system. I cannot say with enough emphasis how much of a nice upgrade it is. There is a night and day difference in drivability. Any flat spots in the acceleration curve that might have been there before are totally gone. I am a big fan of the crane xr700 modules firing twin high energy inductive boxes or cd boxes (msd etc). The xr700 by itself is not really enough, but it does get rid of points and fits nicely inside one distributor. Use xr700 with an MSD or Mallory 3rli and wow, life is good. One thing about the Crane though, it is a pain to set up perfectly. Great upgrade and the car still looks original when the boxes are hidden properly. The pertronix arrangement is good as well, but I personally do not prefer it because the sensors can get 'fried' if you leave the ignition key on too long without the car running.
     
  7. SMS

    SMS F1 Veteran

    Jan 7, 2004
    6,772
    Indy
    Full Name:
    Bill S.
    ???
    I have not seen what you are talking about. My advance curve is all in at 5000 (34 degrees) and revving beyond that upward of 7k stays rock steady at 34. Same on three different 308s.
     
  8. Ferraripilot

    Ferraripilot F1 World Champ
    Owner Project Master

    May 10, 2006
    17,171
    Atlanta
    Full Name:
    John!
    The 308 2v carb engines have have two difference kinds of distributors. The 127g is the Euro style which advances a total of 13 distributor degrees + or - 2 degrees which equals 26 degrees at the flywheel + or - 4. Euro distributor engines are set at idle of approx 12-13 degrees initial idle timing. Max advance is the initial timing plus the distributor timing for a total of 38-40 degrees at 6k rpm, which is the rpm where the distributor stop advancing. The 159 style distributors have 16 degrees distributor advance or 32 at the flywheel. US cars are set at 7 degrees initial timing. Initial plus 32 distributor advance at 6k rpm is 38-40 degrees advance. These distributors do not stop advancing at 5k rpm, and the 34 degree flywheel mark for 2v carb engines is a marker for checking distributor advance only. Total timing is well above when the dist stops advancing at 6k.

    It's the QV engines which cannot take as much total timing. Totally different ball game with 2v carb engines though.
     
  9. robertgarven

    robertgarven F1 Veteran
    Owner

    Feb 24, 2002
    5,269
    Ventura, California
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    Robert Garven
    Friends,

    Im resurrecting this post as I am trying to tune a Euro GT4....

    Rob
     
  10. 348KYD

    348KYD Karting

    Jul 29, 2007
    65
    Bedfordshire, UK
    Full Name:
    Nick
    I fitted Pertronix and the difference was night and day ....
     
  11. robertgarven

    robertgarven F1 Veteran
    Owner

    Feb 24, 2002
    5,269
    Ventura, California
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    Robert Garven
    I am trying to keep everything stock as much as possible this is t a 74 euro car with 2 S159 A distributors running 1 set of points.
     
  12. 2dinos

    2dinos F1 Rookie

    Jan 13, 2007
    2,772
    My fav dizzy trick(s):

    To be certain you're at TDC 'power stroke', and not 'exhaust stroke', open the oil cap, and look for the cam marks when installing dizzy for static setup. Great also 'cause rear bank is cyls # 1-4. I would hook up a small light and battery across R-2 (Or could be R-1) and set timing position by rotating until light goes out to know when distrib will fire on cyl #1. then proceed as mentioned for 5-8 bank and use my little light setup on cyl #5. This gets me to the finish line a lot quicker, meaning she usually fires right up, and is very close. Then use timing light for final setting.
     
  13. 2dinos

    2dinos F1 Rookie

    Jan 13, 2007
    2,772
    BTW - Setting up distib's advance on machine is a must! You must check for smooth action with no stalling / sticking of advance, AND predictable intuitive function return per specifications . ie if distrib goes fine UP to 3500 (7k - crank), but advance stays stuck as rev's go down to 1000 (2k-crank), not good. This will be seen on machine and should be corrected. Go back in and check for wear or corrosion on advance mechanism. Is it well lubed etc?
     
  14. robertgarven

    robertgarven F1 Veteran
    Owner

    Feb 24, 2002
    5,269
    Ventura, California
    Full Name:
    Robert Garven
    Thanks to all for advice and suggestions. This car was a frame off restoration and every nut and bolt was rebuilt or replaced. I have a restored Sun machine also. I wish I could post a video of the engine. Almost everything I have doubted or double checked on this car was correct, so I am just trying to rule out everything in order. The car screams above off idle, its just the small area between idle and off idle where I have the problem. I am thinking its a fuel problem just want to check the timing first.
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