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Hot Rods GMC 305 v6

Discussion in 'The Hokey Ass Message Board' started by badgascoupe, Dec 13, 2020.

  1. jaracer
    Joined: Oct 4, 2008
    Posts: 1,234


    Back in 63 I worked at a Texaco station. A guy in the neighborhood drove a GMC truck with a V6 for a tire service. He would drop it off when his day was done so we could park it inside at night. We probably topped off the tank also. Most of the time is was loaded with new tires. It had gobs of torque, but I never drove it on the road, just around the lot.
  2. Thanks
    I was working from memory and I knew it was an odd setup.

    There was a pulling tractor that ran around here that used a blown V-12. I don't do tractor pulls unless I just happen to be there so I cannot tell you how competitive it was or what happened with it. I talked to the mechanic in the pits and he said that he liked it real well. He seemed to be pretty knowledgeable about the game.
  3. Gabby
    Joined: Apr 14, 2007
    Posts: 274


    My dad had a GMC ton and a half V6 with a two speed rear. The rear was a 6 something and a 8 something gear..We hauled seafood with it. The loading dock was at the bottom of a hill. I seem him put the rear in lower and the transmission in high gear and take off up that hill with no problem to win a bet that he could do it. Only seem one V12 and that was in a large milk truck.
  4. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,695

    Member Emeritus

    OK, so who's going to be the first to drop one in a rod? Anyone? I am Butch/56sedandelivery.
    GlassThamesDoug and Blues4U like this.
  5. XXL__
    Joined: Dec 28, 2009
    Posts: 2,036


    The 6 or the 12?


  6. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,695

    Member Emeritus

    ^^^Well I'll be ding, danged, and hanged!!!^^^ Are those 4 barrel carburetors on the red rod? I'd like to see photos of the entire truck. We're bordering on Blastolene territory now. I am Butch/56sedandelivery
    belair likes this.
  7. FrozenMerc
    Joined: Sep 4, 2009
    Posts: 2,762


    I snapped this picture 10 years ago at Back to the 50's. The truck is wildly misproportioned with the stretched hood and short box / step side. An 8 ft box would have helped the looks out quite a bit.

  8. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,695

    Member Emeritus

    I agree on the length issue and needing a longer bed. Shortening up those front wheel wells would help a lot also. But, if the guy's happy, it's his truck after all. I am Butch/56sedandelivery.
  9. Automotive Stud
    Joined: Sep 26, 2004
    Posts: 4,175

    Automotive Stud

    I remember when the Rodder's Journal had their revival in Baltimore, I think it was the first year someone there had a '30's truck with the V12 mounted in the back instead of the bed. I didn't take a picture because I thought it was stupid.
  10. arkiehotrods
    Joined: Mar 9, 2006
    Posts: 6,554


  11. RJP
    Joined: Oct 5, 2005
    Posts: 2,015

    from PNW

    Wonder if the frame is boxed? That's roughly 1500lbs of engine sitting out there. And with 300 horses galloping under those valve covers the performance numbers must be staggering...
  12. ididntdoit1960
    Joined: Dec 13, 2011
    Posts: 1,015

    from Western MA

    Bluebear said it would be fine un-boxed
    belair, XXL__ and anthony myrick like this.
  13. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,777


    This one. It is mid-engine, bolted to a TH425 FWD transmission, all facing backwards, turning a reversed quick change. hw9vaggsq8851.jpeg
  14. sdluck
    Joined: Sep 19, 2006
    Posts: 2,799


    The pictures look like 2 barrels
    GlassThamesDoug and Blues4U like this.
  15. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,777


    That's what they came with. As far as I know the featured engine is stock.
  16. lippy
    Joined: Sep 27, 2006
    Posts: 5,688

    from Ks

    Gimpy, that COE cab deal is nuts!! I like it. lol
  17. gimpyshotrods
    Joined: May 20, 2009
    Posts: 18,777


    My 1929 Model A Closed Cab pickup will have a similar arrangement, but with a 6-71 blown Chrysler 354 Hemi.
  18. junkhorder
    Joined: Aug 7, 2020
    Posts: 11


    Hello. Have never found any performsnce parts for these. I have 4 trucks with 305c motors and have adapted 2 with holley 5512 two barrels. I only change out when strombergs start sucking vaccum at shaft. If your looking to wind up a little faster install the bigger exhaust manifolds and duals. Sound interesting with straight 2 1/2 to just over rear axle. I used to pull in 6 cyl class and go out through the gates every run. Remember to blow out spark plug recesses before changing plugs or have expensive lesson. Good luck
    V6RedTraveler and WalkerMD like this.
  19. Blues4U
    Joined: Oct 1, 2015
    Posts: 5,958

    from So Cal

    Looks like Holley 2300
  20. dan c
    Joined: Jan 30, 2012
    Posts: 2,260

    dan c

    "hemmings classic car" recently ran an article about these engines. 60* (so, even fire) and peak torque at about 1,200. the 305 was the smallest one; there were 3 or 4 larger sixes and the v12. installed for several years.
    GlassThamesDoug likes this.
  21. finn
    Joined: Jan 25, 2006
    Posts: 887


    Someone may have mentioned it earlier, but don’t forget the ill fated Toroflow Diesel and gas v8 variants.
    Truckdoctor Andy likes this.
  22. nosford
    Joined: Feb 7, 2011
    Posts: 561


    Talk about easy maintenance. Many years ago I had a job delivering soda pop for RC Cola in L.A. They had GMC 1.5 ton cab over trucks with a custom box on the back that had bays that held 36 cases of pop in the old wooden cases and the bottles were glass 12 oz variety. Coming back to the yard one night on the 60 freeway the 305 V6 blew a head gasket and put me at the side of the road. I walked up the off ramp and called in, they said they would send help. An hour later a service truck shows up with a Mexican mechanic named Juan who proceeds to change out a head on the side of the freeway. Hour and a half later I was pulling back into the yard like nothing had happened. Juan said he did that all the time like it was nothing. Cars whizzing past his ass on the side of the freeway wasn't nothing!
  23. 59pache
    Joined: Jun 25, 2010
    Posts: 118



    Sent from my iPhone using H.A.M.B.
    I have a 63 with the 305 and love it. It has never been out of the truck. I have considered swapping to a something else for more power but the truck just runs to good to mess with.
  24. I want to swap this V6 for a 1970 CST 402 bbc I have. Would like to use manual trans.

    Attached Files:

  25. Mine had all that done...7mpg... short trip truck...
  26. My 67 is an OK gravel dirt road farm truck. Useless on freeway with low reving V6. 60mph is pushing it.... just need a can of yoo hoo and stay on state routes. Leave at sun up to make it back by sun down...kinda Amish like.
    V6RedTraveler likes this.
  27. V6RedTraveler
    Joined: Apr 3, 2021
    Posts: 1


    I have a God Mother & County with a 305A block using 305E heads, completely Balanced, custom ground Reed RV Cam, Holley 4 with manual choke, duel exhaust, it gets about 12mpg, RPM range is 200 to 5200 (yes 5200 rpms). It is in a 1960 1000 with SM420 and Dana 44 w/ 31 spline axles and 3:55 gears. I can do 55 mph in third before shifting to four. Love my motor and its brut toque blown 3 ring and pinion and one driveline.
  28. Mine with 4 sumthing gears...7mpg. Sponsored by Shell Oil Co. Getting a 402bbc CST transplant.
    V6RedTraveler likes this.
  29. my 305 will be for sale ...running take out... in next few months.
  30. 55blacktie
    Joined: Aug 21, 2020
    Posts: 464


    In the 80s, I drove a school bus/w GMC V6 and Allison transmission. Returning from a field trip to Golden Gate Park, I missed a turn and ended up climbing a very steep hill. The bus slowed to a crawl, and I prayed it wouldn't stall. It didn't, and we made it over the top. A parent, who was following us in his stick-shift Mitsubishi, had to turn around because his clutch was slipping so badly. I later had some explaining to do for having taken a "detour."

    I also was a volunteer church-bus driver for many years. The buses were throwaway rust-belt buses. Same GMC V6, but with granny-4 transmissions, no air brakes or power steering. They were cheap, but not nearly as good, as diesel pushers, but you have to remember the rust. They ended up as scrap or sold to poor churches, like ours.
    GlassThamesDoug likes this.

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