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Smoking 305

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by FunBlazer, Aug 11, 2002.

  1. FunBlazer

    FunBlazer Registered Member

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    Does anyone still have there stock 305 in there rigs?? Do they smoke? My 87 smokes like hell when you first start it(I know its the valve seals, or guides) but the stupid thing smokes even going down the road(not very bad though, but still bad enough to see it). So my Question is If I was gonna pull out the 305 and stuff a 350 in it would I have to change the "brain"(ECM)?? I was thinking about just rebuilding the engine thats in it, but I want more power(is there ever enough?? /forums/images/icons/smile.gif )
     
  2. bigblock454

    bigblock454 Clack Clack Clack Premium Member

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    Yea, mine smokes on startup. If you put in a 350 you only need to change the ROM chip inside of the computer. I "think" the throttle bodies are the same.
     
  3. FunBlazer

    FunBlazer Registered Member

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    Does it matter what year I get the "chip" out of?? cause if it is that easy I'll put a 350 in it.
     
  4. wrathORC

    wrathORC 1/2 ton status

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    I believe an 87-91 chip is the same between over the years. The only time you'll need a different chip is if the injectors are different. I don't remember if the injectors were different between the two or not. I'd just stick a 350 in it and hook up what you've got. As long as the injectors aren't too small then the brainbox will just increase the output. Worst case scenario is that you'll have to get different injectors and a different brainbox.

    I'm sure there is someone out there that knows more about this than me though.

    My 305 was great when I got it (just shy of 64,000 miles). Sounded strong. Lit up the tires without effort. Took it out on the highway and I pretty much lost cylinder #2. I figure I broke a ring. She smoked pretty good when she shifted after that. I think on the 500 miles to my Dad's place I burned three quarts and was two quarts low when I got there.

    You can build a 305 to make over 200 horses without much effort but why bother if you can get a 350 cheap enough.
     
  5. FunBlazer

    FunBlazer Registered Member

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    So you say I could just bolt the 350 in and go? I supso that it would run if the "brains were different, it just wouldn't run very good. I have thought about putting a carb on it, but I like the fuel injection(makes for easier starts in the winter). Any other input is appreciated. Thanks
     
  6. Rolled

    Rolled 1/2 ton status

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    I have an 87 with a 305 that also smokes at startup and at certain a rpm. Its the valve seals in my case.

    I asked guy I buy parts from (who I believe knows what he is talking about) about the 350 conversion and he told me the computer was the same and has done this a few times. He sounded like he was very sure of what he was telling me. I am leaning towards a 454 instead but might end up with a 355. If I do go with the 350 rebuild, I hope he is right ;-)


    Good luck

    Rolled
     
  7. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    My 305 has 106,000 miles on it ( 87,000 when purchased ). When you do upgrade your engine be sure to change the oil more often than you think you should. Another thing would be to change air filters after every 4x4 trip ( the cheapest good ones are 5 bucks , fram filters ). As for the engine swap, it would probably run for awhile with a stock cam and your own tbi but there are differences in the two. for one the 350 injectors are a little big bigger, as well as the throttle body cfm ( youre feeding 45 more cubes ), and the chip needs changing . Computer truck cams are being ground by crane and comp these are dual pattern and work realy well at giving you good bottom and decent top end power . the best way to descibe why you should change the computer stuff is this : try running while breathing trough a straw.
     
  8. wrathORC

    wrathORC 1/2 ton status

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    Yeap, I'd slap the 350 in it.

    You could call an auto parts store and see if the injectors for the two motors is different..
     
  9. alec78

    alec78 1/2 ton status

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    As far as calling a parts store, unless you know a good parts guy, I would strongly suggest calling a Chevy/GMC dealer. They will be far more familiar with the details as they only deal with GMs.
     

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