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small engine starting problem

Discussion in 'The Garage' started by gmcman, Feb 21, 2007.

  1. gmcman

    gmcman Registered Member

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    I have a '67 gmc 1/2 ton with a 305 4-barrell. I am learning to start this in the cold weather.I give the throttle 1-2 pumps and then crank the engine. The problem is that it doesn't start until you let off the key.If you were to keep cranking it won't fire up.The instant you let off the key it fires. This caused a problem awhile ago before I realised it would start by letting off the key. Ended up with a flooded,extremely cold engine that I had to leave for another day. lol. Any help on this would be greatly appreciated.

    '81 gmc 1/2 ton 4x4 350 4-speed 208 trasfercase
    '67 gmc 1/2 2-wheel 305 turbo-350
     
  2. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    Well, because the 305 didn't exhist in 67 I can assume that it was swapped in at some point. And in that swap it the feed to the distributor most likely was only hooked in as an ignition on, so when you turn the key to start it cuts off power to it, like it would to your radio.
     
  3. gmcman

    gmcman Registered Member

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    You might be right! I never thought of that.It has HEI and the only thing I thought of was maybe there was a resistor not removed for the old points system and when cranking the voltage was too low at the distributor. Thanks! I'll check that out tomorrow.
     
  4. diesel4me

    diesel4me 1 ton status Premium Member

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    He nailed it!..

    Chevy 305 is right--when someone swapped the 305 and HEI in your '67,they likely used the original ignition coil wire to power the HEI--a NO NO!..it's a resistance wire, that delivers about 9 volts at reduced amperage ,for points!..

    An HEI needs a full 12 volts to work right..I'd find a place in the fuse box that is hot only when the key is "ON" and in the "START" position,and run a new 10 or 12 gauge wire from there,to the "BATT+" terminal on the HEI..that will likely cure your starting and plug fouling dilema..:crazy:
     
  5. resurrected_jimmy

    resurrected_jimmy 1/2 ton status

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    I was thought he had a GMC 305 6 cylinder when I first read this and was wondering where he found an HEI for that motor :D..... Would have been cool though :o
     
  6. diesel4me

    diesel4me 1 ton status Premium Member

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    Might be one!??

    We had 3 of those 305 V6's(or 351 V6??--they look identical) at the junkyard,one was in a 1971 GMC C2500 factory,with a SM465!..the others were in a School bus and a GMC "big" truck like a C60...Those 305 and 351 V6's were very rugged and strong,all of them had over 200K on them, and ran perfectly..were used in Busses a lot of years..

    They all had points,(and the crappy Stromberg 2 bbl carbs),but I have seen later year busses and trucks with 305 and 351 V6 motors,it could be that they may have had some with HEI in them??..not sure what year GM stopped using or making those V6's..

    It's not always hard to adapt an HEI into something that never had it..I've see 409's with HEI,all it took was a custom made "collar" that acts as a bushing to make it fit the block,and get the gear to mesh correctly with the cam gear that drives it..I bet adapting one to a 305 or 351 V6 might not be so hard also,if GM never had one factory available..or you could just buy an aftermarket "points eliminator" kit...:crazy:
     
  7. BadBob

    BadBob 1/2 ton status

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    Apparently the 401, 432, and 478 are too
     
  8. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    woah, woah, woah... you mean to tell me there are such things as a 305 cubic inch V6?

    That is CrAzY!!
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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  10. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    Thanks :waytogo:

    I had heard about the GMC V12 before, but not about the big block V6s.
     
  11. diesel4me

    diesel4me 1 ton status Premium Member

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    Bus motors!..

    The vocational school I went too had a fleet of 70's GMC school busses,most of them had either the 401 V-6, or the 637 V8's!...

    I worked on a few of them in shop class,doing oil changes and other routine maintenence..the 637 V8 gas motor is an impressive looking beast!..looks like a 454,only the valve covers are even wider and longer!..I drooled every time I looked at them,and couldn't help wondering if I could stuff one into a K5 or a pickup!.:wink1: ....not sure if one would fit in though..they were coupled to Alison automatics,that shifted like a slegde hammer!..:crazy:
     
  12. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    They were workhorses from what I understand. 3500 rpm was about max...similar to a diesel.

    Rene
     

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