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Thread: will my stock rods take high compression??

  1. #1
    Registered User pr1mo360's Avatar
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    will my stock rods take high compression??

    will my stock rods hold to 12:5:1 compression?? i got theese pistons for cheap but i dont think i can afford those hbeam rods....should i just wait and save up for the rods or will i be okay for a while??
    also if the pistons use 6.0 rods would using a 6.0 be the same as using pistons that use 5.7 rods with 5.7 rods, right?
    Last edited by pr1mo360; 11-17-2002 at 02:28 AM.

  2. #2
    Administrator Blazin Low's Avatar
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    thats alot of compression on stock rods, and I would also be worried about the crank...

    not sure about the rod length tho
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    Member #356 alowerlevel's Avatar
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    Im not quite sure what your asking about the lenght of the rods but I will give it a shot. You cant use 6.0 pistons with 5.7 rods and vice-versa. And the advantage to using a 6.0" rod is it dwells longer at TDC and produces slightly more power by allowing the air/fuel mixture to be burned more efficently. (I think)
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    Registered User ZZ4Blazer's Avatar
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    Why are you going so high?
    Jim 94 Stepside
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    Quote Originally Posted by Harley
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    If you do go that high you will be running racing fuel all the time.I runo $5 a gallon?You would have to rebuild you whole bottom end.Also what size cc combustion chambers do you have?Do they match the dome on the piston?I would take all that into consideration before taking another step.

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    Registered User pr1mo360's Avatar
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    65CC is my combustion chamber size...it should be less than 12:5:1 with my combustion chamber,im rebuilding my whole engine and using theese pistons. i found some 6" eage esp rods on ebay for cheap hopefully ill win. the pistons i got were slightly used and very cheap so if they dont work i wont be so pissed..you dont think the crank will hold up? could i use some thick headgaskets to lower the compression?

  7. #7
    Burnout!!! badassblazer01's Avatar
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    headgaskets aren't going to lower your compression that much. maybe 2-3 tenths. but i wouldn't risk you're engine with stock rods running that much compression. good way to tear up an engine real quick.

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    no way man.I would go with a forged crank and rods.You are going to need them..

  9. #9
    Registered User pr1mo360's Avatar
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    you sure ill need a forged crank?

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    Registered User pr1mo360's Avatar
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    can i have a machine shope grind the domes down to like 11:1, would that work?

  11. #11
    Registered User ZZ4Blazer's Avatar
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    Gaskets can make a big difference. I've seen as big as .06, and as thin as .15. With everything but the thickness the same, that can equal to almost a whole point differce.
    Jim 94 Stepside
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    NX kit in the works
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    Quote Originally Posted by Harley
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  12. #12
    Fully Erect Member LowKat's Avatar
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    Most forged high compression pistons have enough thickness in the domes to shave them some. I don't know about 1.5 points though.

    You could look for some 76cc heads. That would lower you about 1 compression point. Some 76cc had 1.94 & 1.50 valves. The #441 from a 1970's 350" are some of the best and had pretty large 150 cfm intake runners.

    A forged crank is a good thing if you're planing on a high RPM's
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    LiTtLe WiLd MaN Blaz'd8717's Avatar
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    12.5 comp is a little high. OK real high. In order to lower your compression you would have to do what i did. Well first of all are they steel heads or aluminum. With flat tops and 58cc heads i'm running 10.0-1's and i have to retart my timing cause 10-1's is the max for 93 octane. Is it going to be for the track or everyday driving. I work in a machine shop and a lot of pistons get cut down. Tell ya what just save up spend about 2,000 g's sell all your motor parts and just get JB's Auto Machine to build u a bad ass small block for your type of driving youll never go wrong there i know . (I WORK THERE)
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  14. #14
    Registered User ZZ4Blazer's Avatar
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    I've got flat tops, and 58CC heads. 10.1 compression. I have my timing advanced to 34degrees, and I only run 91 octane.
    Jim 94 Stepside
    ZZ430 clone V8
    NX kit in the works
    Tremec T56 6 speed
    8.5" rear
    Quote Originally Posted by Harley
    Go before show any day of the week.

  15. #15
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    Contrary to popular belive rods rarely fail during compression, mostly during extension. High rpm's and no load on the motor is very bad. This is why reving the crap out of motor during a burn out can break alot of stuff. Get your self some decent rod bolts, have them installed and the rods resized and it will be fine.

    I am not old enough to remeber, but back when there was lead in gas, 11:1 CR was the norm for a street car. And they all used stock rods.

    Later
    Steve

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