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check out my SBC belly button engine - just a teaser.

Discussion in 'The Hokey Ass Message Board' started by 31Vicky with a hemi, Jun 30, 2012.

  1. VoodooTwin
    Joined: Jul 13, 2011
    Posts: 3,455

    from Noo Yawk

    Yup, them's the ones. You're in good shape!
  2. Rex_A_Lott
    Joined: Feb 5, 2007
    Posts: 1,019


    Just wondered if you kept the small valves or if you went bigger and if you did any bowl blending and/or port work?
    I'm really curious how this performs. It sounds like it would be a good combo in a light car or small truck.
    Looks good!
  3. Heads have the 1.84/1.50 stock valves. Very minor and minimal blendind and casting bugger removal. Radiused and broke the Sharp edges in the combustion chamber. Probably spent 20-30 mins on each head.

    10.4x static compression ratio. Should run pretty good.
  4. Thanks Jim,
    I spent a few more hours reading about this.
    True stall..
    Flash stall...
    Brake stall...
    Trans brakes and converters
    Dynometer measure of torque ratio or multiplication.

    Apparently even the manufactures need a crystal ball to figure it out. Funny thing is, most have a different explanation they never say or explain why they are correct, they just swear the other guy is wrong.

    No wonder I can't understand it. It's ok I don't have to understand it - all I need to know is that somethings just are.
    Last edited: Jul 1, 2012
  5. Shane Spencer
    Joined: Oct 3, 2009
    Posts: 2,159

    Shane Spencer

    good lookin mill dude
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 47,946


    yup, there are lots of things in life that are better off being mysteries
  7. hotrod brice
    Joined: Dec 16, 2008
    Posts: 61

    hotrod brice
    from molino,Fl.

    Some people's belly buttons are ugly!kinda like the sista's i used to go to high school with.that's a nicely detailed engine.I love the extreme energy line of cams.later on.Brice
  8. falcongeorge
    Joined: Aug 26, 2010
    Posts: 18,341

    from BC

    Used a TON of P10s back in the day...
  9. young'n'poor
    Joined: Jan 26, 2006
    Posts: 1,280

    from Anoka. MN

    The few threads about 307s on here have inspired me to grab one. I got one from a guy at work still attached to the 70 k10 it was in. It runs with no smoke or noise and has pretty good oil pressure and compression so im gonna throw some 305 heads on it and play. Not sure what to put it in yet though...
  10. blue57ford
    Joined: Jul 24, 2005
    Posts: 490


    In a time where I spend $200-$300,sometimes more, for parts to overhaul a transmission (thats not counting the t. converter) I get a kick outta things like this. My dad would tell me about getting overhaul kits for $8 and t. converters for $20-$25. Hell, when I started working for my dad some 10 years ago, an input sprag for a 700 would cost about $16. They now go for about $35. Sorry to hijack abit. Just wanted to share.
  11. The Vega converters are not a very efficient design for V8 applications plus not very strong, as expected..
    If you want slippage though ,you'll get plenty of it

    You'd be much better served to spend the extra money and have a 9.5 (245 mm , GM core based) converter built.
    Frankly, I don't understand why you have the converter ready to go ,and you don't even have the application yet.

    The easiest way for me to explain the stall situation is; You're dealing with a fluid coupling. Without getting too technical , you are using engine torque to "shear" the fluid applied to the turbine, which is connected to the trans input shaft.
    The more torque applied , the easier it is shear the fluid ,as opposed to "stalling" the engine...thus more RPM becomes available..

    Hope that helps...
  12. Dyce
    Joined: Sep 12, 2006
    Posts: 1,908


    You'll like the engine!! 10.4 might be a little bit of a high estimate on the compression ratio. Might ping if it's that high anyway with the shit gas now.
  13. Frankly, I don't understand why you have the converter ready to go ,and you don't even have the application yet.

    from elsewhere in this thread

    It's ok I don't have to understand it
    - all I need to know is that somethings just are.

    Yes it helps but its still all Very confusing -

    Thru my research yesterday and prior to that, every manufacturer used an arbitrary & hypothetical (read made up ) assumption of an engine base to specify a stall figure. They are all different so a 2500 stall from one is not necessarily equal to 2500 stall from another.

    That right there makes it an apples and oranges comparison to each other and especially to stock which is of no value. Some manufactures of custom built converters will offer one stall change free of charge to get you dialed in. Wonder why they need to do that ?

    If using "brake stall" method to measure or test is the most inaccurate way to determine what particular converter that you may have installed in a particular car actually is. There is no way to tell if you need to go up or down if you want to change it based on the arbitrary method above. However brake stall method will tell you how the entire driveline will react as a unit.

    Using a flash stall method is more accurate to determine what stall converter you have, and how to guess at changing it. The problem arises when you don't have one to try first. Choosing one is like throwing darts blindfolded - they do try to point you in the direction of board when the throwing begins but you are still guessing. It's even a bigger crap shoot changing to different manufacturer.

    Here's another train of thought that I found contradictory, these thoughts make things confusing.
    an engine that produces more torque will flash the converter at higher Rpms. Making improvements to your engine that increase its output will require a higher stall converter.

    Fuck it, it would be easier to figure out women, ahhh but just as hard to pick the right one the first time. Two words to solve this - manual transmission.
  14. The compression calculators and published results from others who have actually measured come up in the same general area for static compression.

    3.875 bore
    3.25 stroke
    Gasket is 4.1 x 0.017
    0.025 down the hole
    58cc combustion chamber.
    Flat tops with small valve reliefs.

    The 0.042 quench

    This combo is supposed to be quite impressive from the missfit, shunned, inbred 307 & 305. (read cheap to free)
    I have about sunk 200 into the 307, and that will be lost if it don't pan out. I wanted fresh rings to hold the upped compression, but looking back I think I should have left it alone to see what happened and done them if they couldn't hold it.
    Last edited: Jul 2, 2012
  15. n847
    Joined: Apr 22, 2010
    Posts: 2,706


    Awesome...Thnaks for the info on the TC...I was told my old one was from a Vega, but no cover, so I guess not! Oh and sorry for opening that can of worms!
  16. greaseguns
    Joined: Dec 24, 2006
    Posts: 135


    I like it alot........ I have a 283 in mine..........are we conservative or libral then?
  17. Got a few other things done. Figured out I have a few more to do.
    Made the mid mount alt Bracket.
    Reworked the power steering bracket.
    Going to clean up and detail both of those.
    Need to get a Chrome ps pump pulley and alt pulley&fan.

  18. squirrel
    Joined: Sep 23, 2004
    Posts: 47,946


    Fortunately, converter selection is not as critical as you seem to assume. As a rule of thumb, you can assume that most stall speed ratings for mild performance converters (not race converters) will be based on a mild performance engine. And you can fudge the numbers up or down depending on what your engine is like. So...if you're building a mild 307 you'd probably want to buy a converter that is rated a couple hundred RPM higher stall than you would need based on the number. If you were doing a big block, you might select one that is rated a tad lower than you think you need.

    And you also need to consider your own driving preferences, if you're into maximum acceleration, you might go a few hundred higher than needed, and if you're into cruising you might go a few hundred lower.

    Same with the type of car...if it's a light car, go higher stall, if it's a big boat of a car go lower...unless you want it to really have some oomph off the line, then you'd go with a higher stall.
  19. So...if you'rebuilding a mild 307 you'd probably want to buy a converter that is rated a couple hundred RPM higher stall than you would need based on the number.

    Exactly why I chose the tried and true vega converter. It's not a monster engine & everything is supposed to wake up around 1500 rpm based on a 350 Cubic inches, figured it be a bit more aggressive and slightly higher rpm in a 307.
  20. Cool mill man. Nice job.
  21. The one free stall change usually applies to race converters.
    A lot of race customers don't have a dyno sheet available, indicating where peak torque is at. Therefore, it takes an educated guess to put the converter right on the money first time out.
    Since most race dynos don't start a pull at the low rpm (and stall) requirements for a street and strip , or hole shot converter anyway,
    you are left with the advice and experience of the builder.
    That same builder would go broke adjusting converters in that low price range anyway.

    Again , the builder would have to know the exact torque level he was dealing with.. Then experience has to take over, because there are several factors that affect stall speed and stall ratio in a converter.

    And again a Vega converter is an inefficient POS designed for a time bomb 4 cylinder...
    Good luck with your "283 stroker motor" project.
  22. Thanks mark !
    It's been fun so far.
    I could not see getting anything custom built until I find out if I'm happy or not with what I've got.
    I kinda like my "283 stroker motor"
    Last edited: Jul 2, 2012
  23. Marky, I see from your profile that you are a builder of converters.
    That makes for an interesting tech, Maybe you could do one and separate the wheat from the chaff and explain them from A-Z.

  24. I have a diagram somewhere that I lifted from an old Car Craft article, I think.
    It is an opened up converter drawing that really helps explain the inner working.
    I'll see if I can find it and scan it in..Good idea for the thread.
  25. Thanks for all the compliments guys. ! !
  26. I posted this in a new thread..So far no comment ,and dropping fast.

  27. Damn Yankee
    Joined: Aug 6, 2006
    Posts: 28

    Damn Yankee

    how come its not painted chevrolet orange? sorry just a cheby freak here.
  28. I wanted my belly button to be different,
  29. Well I'll light her off tomorrow.
    Kind of excited for sure.
    I checked the cranking compression quickly on #1 and its 185 on a cold fresh motor.
    That's a 45 point jump , before I tore it down was 140.

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