News

308 Distributor Question!!!

Discussion in 'Technical Q&A' started by robertgarven, Apr 3, 2005.

  1. robertgarven

    robertgarven F1 Rookie
    Rossa Subscribed Owner

    Feb 24, 2002
    4,970
    Ventura, California
    Full Name:
    Robert Garven
    #1 robertgarven, Apr 3, 2005
    Last edited by a moderator: Sep 7, 2017
    I am going on a FCA run so I was getting my 308 gt4 ready. I have done all the work on my car since I have had it and everytime I take something apart that had been "serviced" before I get a suprise. I checked my timing and the rear bank was off 10 degrees at idle. I thought my belt had jumped a tooth but I cranked the engine to PM 1-4 and the cam mark is aligned in the oil fill hole. I had replaced my points before but never had taken the advance springs out and was planning that after this trip. I took the distributor off and found the advance mechanism all frozen to I dissasemble the rear dist. to find not only half the advance weights gone but the ones left are not evenly distributed. Notice in the photo the yellow marked side has the weight nearest the pivot and the other side has the weight nearest the ouside!!!! The only 2 shops that worked on the car are considered experts here in S. CA but I have found missing suspension and clutch pieces so I am hoping that the last mechanic that worked on the car knows something that Magneti Marelli did not.

    Have any of you ever seen any thing like this before? I cleaned and re-greased the weights and reset the gap, changed the bearing and will pull the front one tomorrow to see what is in there. The car has ran great since I got it and it never misses a beat. I only hope that the front dist. has the same mod. if not I am not sure what to do. I have another pair of Dist. I bought off e-bay but they are a different model mine are S 159 B. They have all the weights but before I start switching stuff I thought i would run this by some of the techs here. I only have a few days before the event and I need to get the car running, since I have been running it for 12 years like this what harm could it do for another 400 miles????

    Boy what a mess!!!
    Image Unavailable, Please Login
     
  2. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    25,424
    Austin TX
    Full Name:
    Brian Crall
    Over the years many self described back yard tuners have made modifications to those to unlock all the horse power that those stupid people at Ferrari couldn't figure out how to get. It is often the same with the carbs. You may find in the end that even though you feel that over your tenure that the car has been great that you have not experienced how a proper running 308 can be.

    The distributors are a relic of the technology available to Ferrari at the time and if you are not a restoration type I would suggest going to a coil on plug type ignition system with electronic advance and you will never have to worry about maintaining distributors again.

    If you really want to keep them you will have to use both sets to make one good set and that will take among other things a couple of hours on a distributor machine to make them work right.
     
  3. thecarreaper

    thecarreaper F1 World Champ
    Silver Subscribed

    Sep 30, 2003
    15,373
    Savannah
    Full Name:
    name



    Brian is there any specifc set up you reccommend? i love my carb cars but i really really really hate points ignition. its the manin reason i want to sell my GTb and get somehting else i hate points that much.


    is there someone on the board that i can send my dizzys to to have them checked and set up. the local guy here charged my friend over $1300 to remove and "check" his distributers on the machine. hell i would rather pay someone to check the weights and put in a Pertronix or Crane set up.

    i really dislike points...... my car is running fine, and my flywheel is marked in color coded paint to check the timing. but i know the points are going to need attention sooner or later.
     
  4. Mike Florio

    Mike Florio Formula Junior

    Jun 19, 2003
    567
    NW Rural Nevada
    Full Name:
    Mike Florio
    #4 Mike Florio, Apr 3, 2005
    Last edited by a moderator: Sep 7, 2017
    Rob;

    After our conversation last night I went back to my notes from my Distributor rebuild and found the information we discussed. Basically, there are two weights and four spring/pin combinations. Each spring/pin combination comes into play at a different rpm. The spring/pin combination with the smallest clearance to the inner distributor case wall will contact the wall first, as the weight arms swing outward. Increasing rpm increases the force on that spring, and it compresses, then the second spring/pin combination contacts the wall and adds its resistance to the first, and so on until all four pins are in contact and maximum resistance keeps the weights from swinging out any more.

    The attached illustration shows my calculations for the clearances and associated rpm ranges.Mind that the rpm ranges are in distributor rpm, not crankshaft rpm. Multiply X2 to get crankshaft rpm.

    http://www.ferrarichat.com/forum/attachment.php?attachmentid=145392&stc=1

    From the looks of things, you have spring/pin combinations 1 and 2 installed if they were stock springs, that means that you would have a normal advance curve up to about 3400 engine rpm, (which should be +8 degrees), then you go right up to the max advance a lot earlier than 6000 rpm.

    If the previous err.... technician changed the springs and recalibrated the advance curve it presumably could be OK. An indication of too much advance at higher rpms would be "pinging" and maybe overheating.

    Hope this helps!
    Image Unavailable, Please Login
     
  5. robertgarven

    robertgarven F1 Rookie
    Rossa Subscribed Owner

    Feb 24, 2002
    4,970
    Ventura, California
    Full Name:
    Robert Garven
    Brian,

    I am commited to keeping the points. I have a couple of questions because I really trust your advice. I am good friends with Brian Keegan and said great things about you. BTW I have an old Allen distributor machine but I am in the process of getting it dialed in.

    1. If I take the other distributor off and it has the same set-up I clean and reset the gap, set static timing, would it hurt the engine to run it that way, as I said I have been running it like this for almost 12 years (20,000 mile since they were "rebuilt".) That way I could go on my trip and have unlimited time to play with them when I get back?

    2.Superformance has a 308 rebuild kit have you are anyone ever used it? I assume it comes with a whole new advance mechanism? Would you reccommend this? Or should I just take the parts out of the spare set and replace the weights, etc in mine?

    3. I am using Bosch grease as per Allen Bishops suggestion is that what you use?

    4. Do I need the o-ring in the spider, both the ebay and my distibutors had a groove but no ring. I only have 2 factory o-rings left. I have a whole box of metric o-rings could I use them if I have the right size are is this a proprietary part? I know this sound stupid but the trip is 500 miles through the back country......

    5. I had to tap the bearing on the shaft I used the center race, it was a tight fit on the spider although, how do you do this?

    6. Should I take the miata and be humiliated??&%$##

    7. What will I find when I do my carbs? corks for floats ;-0


    Thanks,

    Rob
     
  6. robertgarven

    robertgarven F1 Rookie
    Rossa Subscribed Owner

    Feb 24, 2002
    4,970
    Ventura, California
    Full Name:
    Robert Garven
    Thanks Mike.

    Do you have a suggestion? BTW Mike endured 3 frantic phone calls last night from me as my drama unfolded, we both have simillar Allen distributor machines just his is working!
     
  7. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    25,424
    Austin TX
    Full Name:
    Brian Crall
    #1 Sounds like a plan for now.
    #2 I almost never work on cars of that vintage anymore so I have not used it. If you go that route (sounds worthwhile) give us a report on what you think of the kit.
    #3 Same. Good stuff.
    #4 Not a special part. Find an O ring in the kit that fits and use it.
    #5 Thats OK. Just don't poke a hole in the seal.
    #6 No, bad idea.
    #7 Any time I get into a set of those carbs for the first time I measure all jet sizes. I don't just look at the markings, too many have been drilled. Due to our oxygenated rat urine gas I usually go up a size in the low speed jet (sometimes 2) and raise the float a mm or 2. One thing many people do not realize is that it is a different carb from the Euro or base version so to jet a US carb like a base version carb just doesn't work right.

    #8 Say hello to Bryan, he is the funniest man in Georgia.

    On your Allen dist machine as long as the strobe works you can just prop a regular tach dwell up on it and you're good to go.
     
  8. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    25,424
    Austin TX
    Full Name:
    Brian Crall
    I've seen a few advertised but since I do very little work on cars of that vintage anymore I have no personal experience of installing a system. One of the ones I have seen is from Carobu Engineering. They are very nice people call them and ask about it.
     
  9. bwassam

    bwassam Formula Junior

    Jan 3, 2005
    611
    North Bend, Oregon
    Full Name:
    Robert Wassam
    I heard that you can get a Crane electronic set up in LA for $1300 bucks. For my money, if your're going to spend that much, then you might as well go with the electronic ignition. If I did do that, then I'd hold onto the points distrubutors for when I sell the car. It's really not hard to switch back, but why would you? The rest of the world went to electronic ignition for a reason. Also, there's so many 308's out there that making it box stock is almost a moot point.

    Bob Wassam
     
    Jasonious likes this.
  10. thecarreaper

    thecarreaper F1 World Champ
    Silver Subscribed

    Sep 30, 2003
    15,373
    Savannah
    Full Name:
    name

    thank you, will do .
     
  11. matteo

    matteo F1 World Champ

    Aug 1, 2002
    13,748
    On a plane somewhere
    Full Name:
    Heir Butt
    On a side note about Rob. His GT4 is a award wining show car. Aftermarket parts are not a solution for him.

    Excellent advice BTW
     
  12. chrismorse

    chrismorse Formula 3

    Feb 16, 2004
    2,149
    way north california
    Full Name:
    chris morse
    As has been pointed out before by those vastly more experienced than i, points are antiquated technology - the points wear, the rubbing block wears, the timing degrades slowly and constantly untill the car will not run - happened to me a few thousand miles after i got the car.

    Anyway, it looks like the options are:

    1) stay with stock, maintain two distributors and 4 sets of points.

    2) Disable the low speed set of points and drive it with the two distributors.

    3) Move both high speed sets of points into one distributor and install two MSD boxes, like my PO, (unfortunately, you still have two sets of points and rubbing blocks. True, the points will last a long time with only a small triggering current passing through them, but the d%$N rubbing blocks still wear and require adjustment).

    4) Replace those two sets of points with either the Crane optical point replacement or Petronix magnetic inductive point replacements, either with the proprietary black boxes or use the triggers to fire two MSD boxes/coils.

    5) Go to the Euro single distributor, i believe that it has two sets of points, so you basically still have the same problems, only timing is simplified and maintenance costs are reduced.

    5) Replace the two distributors with a single distributor as in Malory Unilite, (for which I have no information) or,

    6) Have one of the stock distributors reworked by Norwood to make it an 8 cylinder distributor. This also requires that the tachometer be removed and be converted to an 8cyl unit. The principal benefits are that the conversion uses a $26 chevy distributor cap, (check the price of a 308 cap!!!!!!!!) an $8 rotor and a $28 Chrysler magnetic pickup - cost for the whole deal ~$975 including serviceing the distributor, reworking the advance curve,freight and some extra bulbs for the other instruments.

    7) Replace the distributors with a state of the art electronic Electromotive coil on plug conversion. Benefits, superior power and economy. detractions: non stock appearance, additional black box complexity - wild estimate of cost, (hlep me out here you guys that have done this) ?? $2500. ??

    In case you haven't guessed, I went the Norwood route, i haven't had a chance to install it because my work truck needs engine needs a rebuild. The parts are sitting in my living room, just don't quite have the time.

    Will post when completed.

    p.s. i think this could be made to look indistinguishable from a euro single distrib unit.

    hth,
    chris
    pps, sorry for the hijack.
     
  13. miked

    miked Formula Junior

    Feb 7, 2001
    619
    Cincinnati, Ohio
    Full Name:
    Mike Dawson
  14. yelcab

    yelcab F1 Veteran
    Consultant

    Nov 29, 2001
    9,222
    San Carlos, CA
    Full Name:
    Mitchell Le
     
  15. robertgarven

    robertgarven F1 Rookie
    Rossa Subscribed Owner

    Feb 24, 2002
    4,970
    Ventura, California
    Full Name:
    Robert Garven
    Well,

    Thanks to all (especially Mike) the I got the car running but will probably look into rebuilding the distributors when I get back. I learned more than I thought and hopefully will get them dialed in. I think I will call the superformance guys and ask about the rebuild kits. I ran a graph and both are within 1-2 degrees of each other but I fail to see why parts were omitted and will replace said parts like I did in my clutch and suspension. My car is only a silver award winner but I am very proud of it, what I have done, and all of you who have helped. For an ex rock drummer I am getting better at turning a wrench, well not much better! ;=& I look forward to correcting these distributors (with all your help!) then I will take the carbs apart to see whats missing there!

    Thanks again,

    Rob
     
  16. arnup

    arnup Rookie

    Mar 31, 2005
    24
    sydney
    Full Name:
    kevin
    Why not fit electronic programable advance. That will take care of the advance issue, a hall switch with HEI coil gives a fat spark with long duration. Another, to use Bosch advance system, reluctor and HEI coil. Cheapest ... module, hall and HEI coil. When points are new and disys set up correctly they work fine in short term. Electronic, you will never look back!
     
  17. robertgarven

    robertgarven F1 Rookie
    Rossa Subscribed Owner

    Feb 24, 2002
    4,970
    Ventura, California
    Full Name:
    Robert Garven
    #17 robertgarven, Apr 6, 2005
    Last edited by a moderator: Sep 7, 2017
    Well here is the data from the advance curves on my distributor compared to a stock one set up by Mike on his Allen machine. All measured on my modified (not by me) Allen machine.

    The yellow series 3 is the stock distibutor with advance in the spec range
    The purple series 1 is my rear distributor with the 2 missing pins
    The pink series 2 is my front distributor with the 2 missing pins

    Note: my two distibutors had a +or- 1 degree on each different run
    Mikes was pretty spot on not sure why this was??

    BTW I found 2 brand new (NOS) distributors and bought them except they have the early dog drive. (S159A) I am hoping that I can switch my spline drive shaft and use all the other parts. BTW anyone need a set of dog drive distributor shafts? :)
    I smell ebay...... :)

    PS this is not over.........till I gt it right
    Image Unavailable, Please Login
     
  18. robertgarven

    robertgarven F1 Rookie
    Rossa Subscribed Owner

    Feb 24, 2002
    4,970
    Ventura, California
    Full Name:
    Robert Garven
    Guys the starting point should all be at zero. hey I am a mac guy will try to fix it!

    Rob
     
  19. Mike Florio

    Mike Florio Formula Junior

    Jun 19, 2003
    567
    NW Rural Nevada
    Full Name:
    Mike Florio
    Rib:
    I'm pretty amazed with those curve plots. The only thing I can figure is that the PO used thtwo heavier springs in the lower speed holes, so the springs are slowing the advance and giving you that "belly" in the curve. They are also getting compressed more than they would in the proper holes.

    You have told me that your car performs pretty well, so maybe the PO is on to something. Could it have been an adjustment to allow it to run lower octane gas? It looks like at 3000 engine RPM it is 4 or 5 distributor degrees (8 or 10 crankshcft degrees) retarded from the standard curve. I'll bet it never pings on 85 octane gas, but you still have to do something about the loss of lead lubrication to the valves.

    How many distributors do you have in your collection now? 6?

    When an I going to get my CD of Rob Garven Heavy Metal hits?
     
  20. robertgarven

    robertgarven F1 Rookie
    Rossa Subscribed Owner

    Feb 24, 2002
    4,970
    Ventura, California
    Full Name:
    Robert Garven
    All I know is that I had an easier time with the distributors than the excel chart. I cannot get the starting point at zero on both axises! Mike I was protecting you from the music since you were a friend... but I will send some "if" I get back :) I am confused also but we will have to continue this then, obviously the advance is lessened in my 2 but the advance curve for the set up in the earlier part of the WS manual seems different also, plus some mechanics told me to set the static on 7 degrees? Well back to excel now :p And yes six non working distributors (well except the one you set up) so five then!
     
  21. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
    Full Name:
    Russ Turner
    #21 snj5, Apr 6, 2005
    Last edited by a moderator: Sep 7, 2017
    Robert,
    In case you do not have it, here is what I have on the Euro stock distributor curve. As has been said before, going to an optical trigger will increase your accuracy and lower maintenance costs with a stock appearance, or going to a dual hidden MSD will lower the voltage across the points (a la Dinoplex, except more reliable) giving a much longer point life as well as a better spark.
    Good luck!
    Image Unavailable, Please Login
     
  22. robertgarven

    robertgarven F1 Rookie
    Rossa Subscribed Owner

    Feb 24, 2002
    4,970
    Ventura, California
    Full Name:
    Robert Garven
    Well,

    My trip went OK except for the 4 river crossings and gravel roads and potholes for 200 miles. My car ran fine but I am still really confused by this distributor thing. I have been told by several mechanics that the 308 engine responds better when the advance is advanced from stock. Mine seems severly retarded. I know my machine is not calibrated but the distributor Mikes set up and sent me was at least in the ball park. I rebuilt the other spare 159B I had today and got some more retarded readings. I have a brand new set of S159A's and I am thinking of dropping the weights in my original distributor to see what I will do.

    My car seems to run very rich, accelerates quickly, never backfires or pings.

    What type of performance would you expect from a severely retarded distributor set up?

    Conversley what would you expect from a system that was advanced more than the factory specs?
     
  23. pma1010

    pma1010 F1 Rookie

    Jul 21, 2002
    2,558
    Chicago
    Full Name:
    Philip
    Robert
    Too little advance = loss of power, very high exhaust gas temps (EGTs).
    Too much advance = busted rods (or pistons).

    Put a timing light on it and check the advance on the motor. 34 BTDC at 5000 rpm is factory spec.

    You can run more advance at idle (I run about 18 degrees) which will help lift the torque curve but don't exceed 34 on a 2V.
    Philip
     
  24. robertgarven

    robertgarven F1 Rookie
    Rossa Subscribed Owner

    Feb 24, 2002
    4,970
    Ventura, California
    Full Name:
    Robert Garven
    I can't stop thinking about this and in the shower i had a thought. I set the static timing at 6 dgrees BTDC and with the distributor turning at 500 rpm - 1000 engine rpm, my distributors are reading 0 advance at 1000 rpm on my distributor machine. So really aren't all my figures on my chart 5-6 degress advanced since I am setting the initial advance 6 degrees ahead of the distributors mechanical advance set at 0?
     
  25. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    18,381
    Texas
    Full Name:
    Steve Magnusson
    Total operational advance = static advance + whatever the distributor is adding

    so at idle (500 RPM dist and 1000 RPM crankshaft RPM) you're total operational advance is the 6 deg BTDC.

    For the 308s with a single point set-up and the S159B:

    34 crankshaft deg BTDC (at 5000 RPM crankshaft) = 6 crankshaft deg BTDC idle set-up + 28 crankshaft deg BTDC from the dist at 2500 dist RPM (the charts show the distributor advance in distributor degrees so you have to double the value to get the crankshaft degrees -- i.e., 14 distributor degrees at 2500 distributor RPM from the chart = 28 crankshaft degrees at 5000 crankshaft RPM.)

    for the 308s with the R1/R2 set-up and the S159B:

    34~35 crankshaft deg BTDC (at 5000 RPM crankshaft) = 3 crankshaft deg ATDC idle set-up + 10 crankshaft deg BTDC when the microswitch opens + 28 crankshaft deg BTDC from the dist at 2500 dist RPM
     

Share This Page