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GMC 305 V6 Hard to find parts??

Discussion in 'General Chevy & GMC Pickups Talk' started by cssreb, Sep 28, 2004.

  1. cssreb

    cssreb Member

    Hi Everyone..

    I am looking at buying a GMC truck for the 305 V6 engine. I have heard the engine is very tough and one of the best engines in GM but I also heard that parts are hard to find.

    I am looking for advise for -or- against using the GMC 305 V6 in my Truck.

    Any advise would be greatly appreciated.
    Thanks.. Russ
  2. Old77

    Old77 Member

    RE: GMC 305 V6 Hard to find par

    This may be a dumb counter question but is there a such thing as a 305 V6? If you really mean a 305 V8 replacement parts are not really that hard to find for that since it was used for so many years and for so many applications. They are pretty common but just not really in high demand. However, if you actually mean the 4.3L v6 then you can find replacement parts but nothing much in the way of performance upgrades. Know what I mean? Of course, I could be dumb and there might actually be a 305 V6 out there that was used a long time ago. If there is, disregard and let me know if I'm mistaken.
  3. tech1

    tech1 Member

    RE: GMC 305 V6 Hard to find par

    yes there was a 305 ci v-6 in the G.M.C. trucks. someone got me on that on a couple of years ago. I argued and argued till the old guy pulled out the book that looks like the first book ever written and sure enough there was a 305 v-6 and i felt really stupid. that man is my father-in-law and thats why you should listen to your elders.:D
  4. cssreb

    cssreb Member

    RE: GMC 305 V6 Hard to find par

    Hi Old77

    Thanks for your response. I thought the same as you did but yes Virginia, there is a Santa Claus.. ah.. I mean a 305 V6. Take a look at the following web page: http://www.6066gmctrucks.org/305V6.htm

    You are correct.. they were around a while ago.. the one I am looking at is from a 66 GMC. They considerer it to be a big block. They look a little weird as the spark plugs are on the inside of the cylinder heads by the intake instead of the outside by the exhaust.

    My 65 Chevy has a striaght 6 (230) in it. everyone tells me to stick a Chevy V8 in it but then I have to hope the motor mounts line up, the gas pedel linkage fits/works etc.. my thought is this V6 will drop right in with minimal alterations needed.

    Besides, everyone has seen a Chevy 350 but how many have seen a 305 V6

    Again.. thanks for your response..

  5. Old77

    Old77 Member

    RE: GMC 305 V6 Hard to find par

    Well, I learned something new today:) I can't give you any advice on the swap that you're talking about really. I personally would rather put a 350 in it but I'm sure you're right about needing to do some sort of modifications to get it to go in there having to do with motor mounts but I'm sure that it's able to be done. Maybe even Chevy Duty could help you out if you called up there to see what they say. Anyway, thanks for the info. Maybe I can win some money off this knowledge from my friends:) They'll think I'm crazy:) Having a 305 v6 would definitely be a unique application:)
  6. DrMike

    DrMike Member

    RE: GMC 305 V6 Hard to find par

    Hey Russ,

    Yes that was a very good engine and a powerhouse of one at that. They were used only in GMC trucks and buses from 1960-1974. I'm afraid you will be unhappy to hear that the engine will not just bolt up in your 65 Chevy without doing some creative manufacturing of engine mounts. As far as clearing your steering column, it should not be a problem.

    Parts are hard to come by for it. My church has a 66 GMC bus that we can't find parts for. Going to end up modifying it to accept a Big Block Chevy for the power. A 350 won't cut it.

    Hope this helps.

    Dr Mike
  7. 72cheyenne

    72cheyenne Guest

    RE: GMC 305 V6 Hard to find par

    Hello guys,

    I'm giong to type in lowercase now because my wife said I was yelling at you. I wasn't, but what the hey.

    The 305 v6, yep, GMC only like was stated earlier 60-74.
    It was designed to be an industrial engine, much like the tall deck big block chevy 366-454 cid engines. They produced lots of them during those years, however few made it into pick-up trucks. the poor gas milage and low rpms made it short lived. If you were going to use it for stump pulling or in a 2 ton with lots of gears, it would shine.
    you would not be happy with the performance on the street.
    Parts are available but expensive. The only way I've seen new parts is in the industrial field ie; farm equipment, tractor/big rig part suppliers...etc.
    I've even seen a v12 in the same design as the 305 v6, 2 carbs, 2 manifolds, 4 heads, 4valve covers, 4 exhaust manifolds and then the normal waterpump, bellhousing and stuff.

    The engine swap to the v8 from the 292 L6 is much simpler than you think.
    By the way the 292 was an industrial engine too.


  8. nsula_country

    nsula_country Member

    RE: GMC 305 V6 Hard to find par

    Back when the Mayflower was sailing, my grandfather had a 1963 3/4 ton with the 305 V-6. Also, I was thumbing through an old Chilton's from the '60s and in the larger trucks C50, C60 there were even some 400+ CID V-6's. I'd love to see one personaly.

    79 C20 Bonanza
    350/400 4bbl Q-Jet
    3.73 14-Bolt Corp.
  9. tech1

    tech1 Member

    RE: GMC 305 V6 Hard to find par

    i found some info on that 305e (and the 351e v-6)
    compression ratio was 7.75 to 1
    compression pressure was 125 p.s.i.
    spark plugs ac,c45ns
    plug gap is .035"
    plug torque is 25 ft. lbs.
    point gap is new-.019 old-.016
    dwell 31-34 degrees
    arm spring tension 19-23 oz.
    firing order 1-6-5-4-3-2
    timing without a.i.r. 7 1/2 degrees budc
    with a.i.r. (mech. trans.) 2 1/2 degrees audc
    with a.i.r. (auto. trans.) 7 1/2 degrees budc
    valve lash (hot) intake valves 0.012"
    exhaust valve 0.018"
    engine idle speed (rpm) without a.i.r. 500-550
    with a.i.r. mech, trans. 650
    with a.i.r. auto trans. 550
    bolt torque information (ft-lbs)
    cylinder haed bolts 60-65
    exhaust manifold bolts 15-20
    intake manifold bolts 20-25
    water outlet manifold bolts 20-25
    rocker arm shaft bracket bolts 20-25
    crankshaft hub bolts 180-200

    note to set timing disconnect vacum advance line and plug it at idle speed.

    compression pressure at cranking speed, wide open throttle-maximum variation between cylinders- 20 p.s.i.
  10. Pontiac1976

    Pontiac1976 Member

    Question : what year were they made in be for 68 ??? Are they a straight 6 or V6??
    because the only thing that come to mind is the 4.3 V6 witch looks like a 305 or 350 with the two back cylinders cut out.
    Last edited: Aug 25, 2006
  11. sls_06ion

    sls_06ion Member

    to give you an honest answer, I've got a 66 GMC 1/2 ton with a 351 v6, it would be great behing a 6spd tranny, but it's redline is 3700rpm and with a 4spd it's very impractical to drive around town, my advice swap in a 350, and yes parts are friggin expensive!!!

  12. 283 man

    283 man Member

    Yesterday after turkey day eating:) ,was driving home allways looking around for trucks like mine seen this 66 GMC 1/2 ton had the v6 badge on the side of the hood truck didnt look bad,just been sitting there for a while,I really hate seening trucks sat,yes 305v6 is hard to find.
  13. billydonn

    billydonn Member

    My dad had 60-61 GMC 1/2 ton with the V-6. Very tough engine. It was great as a grunt parts getter around town. He made it into a wrecker. But NOT a good engine for today's cruising. Cool to HAVE one maybe... but not good to DRIVE much. I learned to drive a stick in that truck- come to think of it.
  14. 64shortbed

    64shortbed Member

    the 64gmc long bed pickup im usein for parts has a 305 v6 in her sounds good only had her runnin 5 minits but oil presure good not knockin. im in western ks if anyone wants it? have not pulled it yet. and the tanny seems good too.when im get the shortbed put together ill have a good long wheel base frame too and other misc. parts oh buy the way if you didnt know already if you put the big v6 in youll have to put in the heavy springs too.
    Last edited: Aug 25, 2007
  15. billydonn

    billydonn Member

    64 shortbed: What condition is the 64 GMC hood? I might like to have one of those.
  16. 64shortbed

    64shortbed Member

    they are both usable no rust that i can see. one has some dents in the right hand front corner and down that side but is fixable. the other is staght except for the top is bowed in alittle that is the one i plain on useing just couse it requirs let work. im not goin to use the v6 emblems if any one is interested in those.
  17. PackRat

    PackRat Member

    Hey Y'all. New guy on the board, here.

    I think this page is the link you were looking for, on GMC engine data.


    FYI, I've got 3 305's in storage. 1 runs, one knocks lightly, and the other is time stuck. Someday I'm going to build a roadster around one.
  18. Happen

    Happen Member

    Hey guys, new to the board and found it while I am currently looking for parts for my 63 GMC. I am currently looking for a new thermostat housing for my 305 v6. It is beginning to become a problem due to the housing used for my truck was only used in 62 and 63. the engine designed change slightly after 64. I found one for a 66 and it didn't fit. if anyone knows where I might find one I would be grateful.

    FYI these guys are right the engine is not a street performer due to the RPM ranges, and I have a 4 speed with a 4.10 posi in the rear. I put 16 inch ford rims(8 lug) to help with the rpm speed range and tire wear. I have 15inch split rims that are original but buying rag tires is getting expensive. the engine was designed as a work horse not a hot rod. and the mounting of a 305 v6 is weird due to the trans has no mount on it only the block and bell housing has the mounts. the trans hangs off the back of the motor with only the bell housing bolts holding it on.

    and a safety note if you are pickin this engine out or stabbin it make sure you have a heavy duty engine pick case this engine is heavy. I broke mounts on my fathers picker when i rebuilt my v6 and he was not happy.
  19. 49terry

    49terry Member

    in need of power steering pump an bracket for 1966 GMC 305 V6,also a A/C bracket for same engine,hope someone can help me out,send e-mail to t-trucks@sbcglobal.net
  20. 49terry

    49terry Member

    gmc 305 v6 thermostat

    this is a vendage savage north of judsonia,arkansas,that may have the thermostat housing you are looken for,,heres the number give them a call ,weduesday threw saturday,9am to 4pm,,johnny morris savage yard,, 501-729-3090,he has lots of 60 thru 72 gmc...

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