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spark plug wire change over heating now

Discussion in '308/328' started by Ago, Aug 4, 2012.

  1. Ago

    Ago Rookie

    May 4, 2006
    23
    Kamloops BC Canada
    Full Name:
    Agostino Pietramala
    Just changed the plugs and wires on my 81 308 ,now it over heats ,was going good before the change,what did I do wrong,would wrong firing order do this what is the proper firing order on a dual distributer car thanks
     
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  3. Sledge4.2

    Sledge4.2 F1 Rookie
    Silver Subscribed

    Oct 19, 2007
    4,706
    Marin
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    Geno
    how does it run?
     
  4. Matto

    Matto Formula 3

    Dec 26, 2011
    2,058
    Mooresville, NC USA
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    Matthew
    #3 Matto, Aug 4, 2012
    Last edited: Aug 4, 2012
    +1.....is it running rough?
     
  5. Bxtech

    Bxtech Formula Junior

    May 4, 2006
    543
    SF Bay Area
    Weird. As you already suspected, the only way that could make it overheat is if you got the firing order incorrect. You should definitely feel a difference in the way it runs if that's the case. Unless something else went wrong at the same time and it just decided to do so at the same time you changed the wires? Please let us know what you find out. Thx.
     
  6. mike996

    mike996 F1 Veteran

    Jun 14, 2008
    5,841
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    Mike 996
    Did you replace the wires one at a time to ensure no confusion or did you pull them all and then install the new ones. Unless you do this regularly and are familiar with the numbering of the cyls, the firing order, and the terminal numbers on the distributers, it is easy to mis-wire.

    Some engines will run quite well with certain wires "crossed," with little evidence of misfiring But overheating will result from retarded timing and firing the plug at the wrong time could do this, depending on the specific mis-wiring. Small block Chevy motors, for example, run quite well with cyls 5/7 plug wires inadvertently swapped - almost unnoticeable from a misfire point of view but will cause overheating.

    Did you do anything else at the time that could have retarded the ignition timing from the correct setting?
     
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  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
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    Going CW around the distributor caps (as viewed when standing on the LH side of the chassis and facing the clutch end), the spark plug wires should be connected in the order:

    On the 1-4 distributor = 1-3-4-2

    On the 5-8 distributor = 5-7-8-6

    The overall firing order is = 1-5-3-7-4-8-2-6
     
  9. shawxhurst

    shawxhurst Formula Junior

    Nov 6, 2006
    672
    San Diego
    Full Name:
    Steve Hawxhurst
    Vert odd. Since the ignition system has no relationship with the cooling system I wonder if you fixed one problem and unmasked another. A 308, in my experience, will run pretty decently only hitting on seven only - so much so that you may not have noticed a loss of power. Happened to me when I went to the shop and the tech immediately pointed out that I had a plug extender not seated to the top of the plug. Fixing that added more power and hence more heat. Hard to believe I didn't notice it but I was cruising at low rpm in 5th gear on my way to the shop. I would start by bleeding the cooling system and then chase other cooling related components like thermostat and water pump. It may be just a coincidence that something in the cooling system may have started to fade when you were doing the ignition work. Check to see that your fans are working properly.
     
  10. MNExotics

    MNExotics Formula 3

    Dec 13, 2010
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    Keep it simple and verify the wire order that Steve has above. The GTS/Bi has fixed distributor and the timing cannot be adjusted. If that is all correctmove to the cooling system and verify the coolant level is correct and the system has been bled of air and verify the fans come on. If that doesn't do it let us know and we will go deeper.
     
  11. Ago

    Ago Rookie

    May 4, 2006
    23
    Kamloops BC Canada
    Full Name:
    Agostino Pietramala
    I looked at the water pump today it is not pumping at all,engine is warm rad is cold.tok off top rad hose I have no flow ,that must mean water pump,I flushed out rad till water ran clear,Shaft is turning on the pump so something must be wrong with the impeller
     
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  13. Ago

    Ago Rookie

    May 4, 2006
    23
    Kamloops BC Canada
    Full Name:
    Agostino Pietramala
    It is just a fluke it all happened at once,it is the water pump.It just stopped pumping,no flow at the rad
     
  14. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    It could be that the key between the w.p. shaft and the impeller has sheared off, so the impeller is not turning, but another possibility is that your thermostat is stuck in the "cold" position (which only recirculates coolant inside the engine and prevents flow thru the radiator) and/or the piece meant to seal off the opening to prevent internal recirculation, when warm, has failed -- see Fig 9 on page C10 of the 308GT4 WSM. Good hunting!
     
  15. Ago

    Ago Rookie

    May 4, 2006
    23
    Kamloops BC Canada
    Full Name:
    Agostino Pietramala
    took out thermostat so it is running wide open still getting hot i will try checking that keyway
     
  16. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #13 Steve Magnusson, Aug 4, 2012
    Last edited: Aug 4, 2012
    MISTAKE! This causes the coolant to only recirculate inside the engine and OVERHEAT. Not only does the thermostat have a valve that opens to let coolant go to the radiator, it also has a valve that blocks the coolant from recirculating -- please study Fig 9 on page C10 and heed the warning printed there:

    "Warning : It is not possible to eliminate the thermostatic valve as the circulation would mainly take place through the by-pass thus excluding the radiator"
     
  17. Ago

    Ago Rookie

    May 4, 2006
    23
    Kamloops BC Canada
    Full Name:
    Agostino Pietramala
    Thanks I didnt know that I will try it again to day with the thermostat in and see if it is pumping
     
  18. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #15 Steve Magnusson, Aug 5, 2012
    Last edited by a moderator: Sep 7, 2017
    Good, but before doing that just put the thermostat itself in some boiling water on the stove to confirm that it opens in that condition, and inspect it to confirm the circular sealing disc (the amber colored disc shown in the photo) on the end of the shaft is in decent condition (this disc is what seals off the recirculation path inside the engine). Also confirm that the dimension A of ~44.5 mm as shown on this page C12 from the Mondial 281/83 WSM is achieved:
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  19. Ago

    Ago Rookie

    May 4, 2006
    23
    Kamloops BC Canada
    Full Name:
    Agostino Pietramala
    confermed it opens next dismantel water pump
     
  20. Ago

    Ago Rookie

    May 4, 2006
    23
    Kamloops BC Canada
    Full Name:
    Agostino Pietramala
    pulled water pump missing impeller nut so the impeler came off the shaft .pump is ok just wrecked impeller where can you get a good impeller without have to get a new pump
     
  21. Barnone 308

    Barnone 308 Formula Junior

    Mar 22, 2004
    430
    canada

    Hi Steve, When I took my wires off my 1978 Ferrari 308 GTS I never marked them. I figure I go with firing order based on valve cover numbers and distributor. Anyways after doing a valve adjust I putting everything back my car won't start. I have attached a picture of how I put my plugs back based on the number on the valve covers and the numbers on the distributor. Does this look correct to you.
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  22. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    Jan 11, 2001
    20,313
    Texas
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    Steve Magnusson
    Yes, your diagram seems correct. Saw your other post, and, with the stock US '78-'79 wiring, you would get no spark on any cylinder at idle (throttle microswitch closed) with the R2 point set always closed. Have you tried putting a timing light on the #1 spark plug wire during starter motor cranking and:

    1. confirmed/denied if spark is occurring, and

    2. that it's in the neighborhood of the PM1-4 mark (if it is occurring)?
     

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