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307 to ?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Roostr84, Jun 3, 2001.

  1. Roostr84

    Roostr84 1/2 ton status

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    I want to rebuild the 307 in my Blazer, the thing is I have been thinking about dropping a 350 crank in there with some custom pistons or maybe even a 400 crank if it wouldnt't be too much machine work on the block. Anybody done this? I know most people would say get a 350 but I have the motor already and it is original so I figure I will use what I got, plus it would be an interesting project anyway. Thanks for any recommendations you guys can give.

    Chris =)
    http:// www.roostr84.coloradok5.com
     
  2. my friend colin(k5blazerus) has a 307 with a 350 crank. it comes out to a 327. he didn't have to do any special machine work either. here is his web site:
    http://bluebeast.coloradok5.com/
     
  3. Hathaway

    Hathaway 1/2 ton status

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    You guys mean a 305? Or is the 307 an older engine than the 305 or what? I'm still confused on cubic inches very easily :) I've got the 5.0L v8 and its a 305....

    Dan, '86 K5, 5.0L v8, NP208, TH700R4, open 10bolts front and rear, 3.43gearing, K&N filter, 31x10.50R15 Trailhandlers
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    The 307 was an older sbc...not the most popular incarnation either.

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  5. Roostr84

    Roostr84 1/2 ton status

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    Basically its a 283 with a 327 crank. They are (stock) low compression and low on power, although I think with the right parts they could be a decent little motor.With its larger bore (than the 305) and given the same stroke as a 305/350 I think it would be cool. I am gonna give it a shot but I think i may try to go the 400 crank aproach with a comp extreme energy 4x4 cam and a good set of small bore heads such as the vortec 305 version or world product sr torquers or something along those lines. Ulltimatley AFR's small bore heads would be real sweet but they are $$$. Any other ideas would be greatly appreciated.

    Chris =)
    http:// www.roostr84.coloradok5.com
     
  6. Jeff427

    Jeff427 1/2 ton status

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    307 blocks are notoriously soft. Ditch the block, and put the crank in a 350 block, and you will have a 327 (with the correct bore and stroke for production 327s).

    Jeff427
    <font color=red>Mud Dog Off Road Club</font color=red>
    http://lyonsdesign.bigstep.com
     
  7. Roostr84

    Roostr84 1/2 ton status

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    Yeah i appreciate that thought but like i said I want to use what I have, plus I have a buddy who has a modified 307 in his chevelle that runs 13 flat in the 1/4, which isnt too bad. I guess it just depends on the block some you get lucky some you dont, would they have the nickel content etc stamped on the sides of the block or not?

    Chris =)
    http:// www.roostr84.coloradok5.com
     
  8. Jeff427

    Jeff427 1/2 ton status

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    I don't know about the nickel content, but you should be able to buy a rebuildable 350 core at a junk yard for not much more than scrap price. I can get them a the local yard for $25. You would have to by a crank somewhere won't you?

    Jeff427
    <font color=red>Mud Dog Off Road Club</font color=red>
    http://lyonsdesign.bigstep.com
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I'm with you Jeff...I can't understand the affection with a 307 when 350 4 bolt blocks are so plentiful and cheap. I guess anything can be built but that doesn't mean it makes sense.

    Just my 2 cents...[​IMG]

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  10. wayne

    wayne 3/4 ton status

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    If you are interested, I have a rebuilt 350 with a rebuilt th350 in my 73 pick up for sale for $650.00. This includes everything from aircleaner to pan and all accerories. It has Summit headers, polyurethane mounts on engine and trans, Edelbrock Performer intake and 750 cfm carb, crome valve covers and aircleaner, big 7 blade flex fan, the trans has a B&M deep pan and crome dipstick, I will even through in a Hurst Quarter Stick shifter. The trans is in a 2 wheel drive so you can sell it or use it on another project. I can run it before it is pulled if you are interested. The block is a 3970010 block with 2 bolt mains. I am in Gettysburg Pa so I am not that far from you if you are in NJ. I need to get rid of this stuff because I do not have the time or the money to do 2 projects.

    <A target="_blank" HREF=http://jamonline.homestead.com/fromthegroundupK54x4/89Jimmy.html>http://jamonline.homestead.com/fromthegroundupK54x4/89Jimmy.html</A>
    <font color=blue>Happy Trails<font color=blue>
    <font color=blue>Wayne<font color=blue>
     
  11. Jeff427

    Jeff427 1/2 ton status

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    If you really want to keep it original, just rebuild the 307. Are you trying to keep it all numbers matching or something? If that's the case then just use the 350 crank in it (they are internally balanced so it would be a little easier to get a flywheel and balancer for it. I have heard of people only getting 60-70K before oil consumption started in 307s though.

    Jeff427
    <font color=red>Mud Dog Off Road Club</font color=red>
    http://lyonsdesign.bigstep.com
     
  12. Roostr84

    Roostr84 1/2 ton status

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    Nah I am not trying to keep it numbers matching I just thought it might make an interesting and fun little project. It seems that so many people either love or hate this motor. I pulled it out originally with 170,000 miles on it and it only had a little smoke coming out. I am dropping an all forged 355 in my truck currently but wanted a back up just in case. I understand the sentiment towards 350's in fact I have 3 usable goodwrench blocks in my shed, I just wanted to try something a little different. Thanks for the input guys.

    Chris =)
    http:// www.roostr84.coloradok5.com
     

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