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73' K5 underhood sticker says to use premium fuel?

Discussion in 'The Garage' started by JpEater, Feb 5, 2007.

  1. JpEater

    JpEater 1/2 ton status

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    I just picked up a 73 K5. I noticed on the underhood sticker on the core support that it said to use premium fuel only. It is a 350. I just have never seen an underhood sticker say that on a 350 powered full size rig. Any thoughts? I am going to sell the motor. It does have the big balancer so I think that it is 4 bolt main.
     
  2. dhcomp

    dhcomp 3/4 ton status Premium Member

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    Some mechanic told me all 350's are hi performance engines and require premium. I laughed in his face, and reminded him its a 13 yr old truck. chances of me springing for premium are slim.....
     
  3. 1977k5

    1977k5 3/4 ton status Vendor

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    It could be meant to run on leaded premium (100 octane) :dunno:
     
  4. JpEater

    JpEater 1/2 ton status

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    Was leaded gas still available in 73? The only thing I can figure is it was a universal sticker that GM used and just printed the vin# on it. I don't know.
     
  5. WantedaDodge

    WantedaDodge 1/2 ton status

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    Dude, they sold leaded gas up till like '94...
     
  6. WantedaDodge

    WantedaDodge 1/2 ton status

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    and no, I wouldn't run 92 octane premium, unless you really want to. anything from '73 and up should run fine on 87 unless it's got problems.
     
  7. dremu

    dremu Officious Thread Derailer Premium Member

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    Check the owner's manual; I betcha they mean premium ca. 1973, which would have a RESEARCH octane of 100 or something ... nowadays the octane ratings are (R+M)/2, i.e. the average of the research octane and the, umm, M-word octane.

    Somebody who's a history buff will pipe in with what the M-word is =))

    Anyway, a 350, especially that old, will run on today's hi-test, if you tune for it (fiddle with timing), will run on today's cheap stuff (retard it a bit, IIRC), and in a pinch, bat's piss if you fiddle with the carb settings. I've done the first two on mine with no ill effects. (Not having enough bats to generate multiple gallons of bat's piss has kept me from #3.)

    -- A
     
    Last edited: Feb 5, 2007
  8. JpEater

    JpEater 1/2 ton status

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    Leaded gas left the pumps WAY before 94', Dude.
     
  9. JpEater

    JpEater 1/2 ton status

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    I got the blazer in trade for fixing another blazer. I robbed the needed part off of the one that I got so I don't have any money in it. I am parting it out. On another note the guy I got it from said that it hadn't been run since 99' or 2000. I had to rig a gravity feed tank to the carb and got it fired up. I was surprised to see no smoke or hear no knocking. Ran surprisingly well too aside from an extremely leaky carb.
     
  10. 76zimmer

    76zimmer Flyin Rat Premium Member GMOTM Winner

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    I believe the M was for Motor octane.
     
  11. 76zimmer

    76zimmer Flyin Rat Premium Member GMOTM Winner

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    Tell him to look at the 350 8.5 comp engines and say that with a straight face.
     
  12. blazinzuk

    blazinzuk Buzzbox voodoo Premium Member GMOTM Winner

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    straight from my orginal 1973 blazers owners manuel, 91 octane UNLEADED fuel. That is what GM put as the recomended fuel for my truck
     
  13. BKinzey

    BKinzey 1/2 ton status

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    So does it ping? If not don't worry about it. If it does either give it more octane or retard the timming:D
     
  14. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    Federal laws never said you couldn't sell leaded gas, they only said the new cars must use unleaded gas.
    Well, not until 1995 anyway.
    From Federal excerpts:
    There were definitely a few pumps with lead when I was going to college in Michigan's UP, circa 1990 or so.
    Downstate in Detroit, I know there was one station with a leaded pump until at least 1988.
    I think the leaded pumps hung around more in the rural areas as people usally have older cars in rural areas.
     
  15. SkysTheLimit

    SkysTheLimit 1/2 ton status

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    I know around the little backwoods town near Orlando that I grew up in had leaded gas at least up until mid 80's. I remember my dad filling up his old F100 with leaded. I think he got rid of it in 87.
     
  16. tomford

    tomford 1/2 ton status Premium Member

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    They still sell leaded gas... for aviation, most single engine planes use 100 octaine Low Lead gas


    tom ford
     
  17. dremu

    dremu Officious Thread Derailer Premium Member

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    Yeah, but again note that octane ratings then are not the same as now. :doah:

    Though we're going with the whole leaded-unleaded thing. I thought the only difference was hardened valve seats?

    -- A
     
  18. goldwing2000

    goldwing2000 Guest

    I had a '70 Cadillac that I filled with regular leaded until '95. Luckily there was a station just around the corner from my house that carried it.

    When I started running unleaded, it burned a valve almost immediately. :mad:

    Sold the car not long after. Wish I hadn't. :(
     
  19. diesel4me

    diesel4me 1 ton status Premium Member

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    confusing huh??..

    The '73 Chevelle I yanked a 307 from had a sticker on the radiator support ,saying to use "at least 91 octane fuel"..!...and the lowly 307 has an 8-1 compression ratio (if that) in 73!...I never used premium fuel,it never knocked or dieseled,and ran great with timing set at stock specs,or even a bit more advanced..

    I think todays "gas" is much different that we had in '73...no lead now,more alcohol,and many different additives than we had then..plus its "oxogenated",meaning it has oxogen added to help it burn hotter and cleaner..

    I feel its a wives tale that unleaded gas "burns valves"...unless you are towing or running wide open all the time,the valves will survive just fine without lead..I think they just wanted to scare everyone into buying "lead substitute" to increase sales, more than anything..I've owned many "pre 72" leaded motors and ran them hard for years on todays fuel, with zero vale troubles...

    Its more likely the "oxogenated" gas is responsible for possibly shortening valve life,not the lack of lead..they found that lead got in the crankcase and fouled the oil, and oil passages quite often,it wasn't the "miracle" they thought it would be for preventing wear..any vehicle that burns a valve on unleaded probably was about to anyway,regardless of what fuel was used,in my opionion..:crazy:
     
  20. 1979jimmy350

    1979jimmy350 1/2 ton status

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    uh i still see leaded pumps somplaces, where i used to go to school in Illinois the one gas station has it in a pump, and Now where im at in the UP you can still get it becasue we run our lawn tractor toy on 110 leaded
     

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