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Thread: BBC Rods

  1. #1
    Junior Member APPRENTICE
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    BBC Rods

    I have a 468 with a GM forged steel crank,TRW .500 domed pistons and 3/8 rods that have had the beams polished,floated and ARP rod bolts installed.The engine will have a rons toilet running alcohol.What RPM limit will I be at? I know these pistons are VERY heavy.I also know that the alcohol will add more stress.Should I just change to a 7/16 rod or bite the bullit and buy aftermarket rods. The car this engine will be in is a 83 camaro backhalf that weighs 3200#,glide,12 bolt 5.13gears and a 31/14.15 tire.Any help will be GREATLY appreciated! THANKS Nick

  2. #2
    Administrator RACING JUNKIE bjuice's Avatar
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    why not spend $400 on your bottom end with a set of aftermarket rods (with good rod bolts L-19) and rest assure your bottom end stays together...

    "PAY ME A LITTLE NOW OR A-LOT LATER".....

    My opinion Only....

    i think ONEBADGMC had a nice set of Carillo rods for sale at a decent price...... :wink:

    Brian

  3. #3
    Senior Member RACING JUNKIE
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    Thanks Brian... But they are Oliver, and would probably (honestly) be over kill for his engine, but they'd be the last set of rods he'd probably ever need, lol.

    I ran 7/16 Dimple rods for years with a mild blown application (9.5:1 @ 12 PSI) without any issues. That was shifting at 6800-7000.
    -WJ Birmingham

    OneBadGMC.com

  4. #4
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    BBC Rods

    Thanks Brian.The engine is assembled as a shortblockand I was trying to get out of tearing it back apart,I know just being lazy! I ran a set of these rods in a 461 with a .250 domed trw piston a few years ago on gas and didnot have a problem with them. But I was told with alcohol they would not survive.Just looking for some different opinions. I have a set 7/16 dot rods in the shop,but I might just have to buy the better rod.Thanks Nick

  5. #5
    Senior Member DYNO OPERATOR
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    Bigger rods are always better and stronger. Bigger rods mean re-balancing.

    Sounds like you have a good set of 3/8 rods. Have no idea your intended power or rpm. I will suggest from personal experience in a very high hp per cube engine from years back to keep rpm below 8,000 rpm and to cut to neutral at finish line for rod life.

    I will not even say what power level I used them with and got away with but it was substantial. The fact of the 3/8 rods is what kept me from revving higher.

    I am not advising to do what I did just simply telling you I made them live. I protected my rods by not letting the engine see any decelleration forces at all.

    Ed
    " Let all things that hath breath, praise the Lord. Praise Ye the Lord" Psalms 150 vs 6.

  6. #6
    Senior Member RACING JUNKIE
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    Quote Originally Posted by edvancedengines
    Bigger rods are always better and stronger. Bigger rods mean re-balancing.

    Sounds like you have a good set of 3/8 rods. Have no idea your intended power or rpm. I will suggest from personal experience in a very high hp per cube engine from years back to keep rpm below 8,000 rpm and to cut to neutral at finish line for rod life.

    I will not even say what power level I used them with and got away with but it was substantial. The fact of the 3/8 rods is what kept me from revving higher.

    I am not advising to do what I did just simply telling you I made them live. I protected my rods by not letting the engine see any decelleration forces at all.

    Ed
    Ed;

    Ok, I've heard (not yet confirmed with an actual transmission shop), that throwing a T-400 into neutral at speed will cause the transmission to switch to the first gear set, and can possibly explode due to the excessive rpm.

    Can you confirm/deny this?

    Since the T-400 free wheels when you let off the go pedal, I've always left it in high gear until greatly diminished speeds.

    On the T-350/PG, I can understand what you're saying since those transmissions have braking action.

    Thoughts?
    -WJ Birmingham

    OneBadGMC.com

  7. #7
    Senior Member MASTER BUILDER
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    Quote Originally Posted by bjuice
    why not spend $400 on your bottom end with a set of aftermarket rods (with good rod bolts L-19) and rest assure your bottom end stays together...

    "PAY ME A LITTLE NOW OR A-LOT LATER".....

    My opinion Only....

    i think ONEBADGMC had a nice set of Carillo rods for sale at a decent price...... :wink:

    Brian
    What Brian said! I know too many people who didn't spend enough money on the rods and expected them to hold up. Good luck!

  8. #8
    Senior Member MASTER BUILDER
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    Re: BBC Rods

    Quote Originally Posted by nghollis
    I have a 468 with a GM forged steel crank,TRW .500 domed pistons and 3/8 rods that have had the beams polished,floated and ARP rod bolts installed.The engine will have a rons toilet running alcohol.What RPM limit will I be at? I know these pistons are VERY heavy.I also know that the alcohol will add more stress.Should I just change to a 7/16 rod or bite the bullit and buy aftermarket rods. The car this engine will be in is a 83 camaro backhalf that weighs 3200#,glide,12 bolt 5.13gears and a 31/14.15 tire.Any help will be GREATLY appreciated! THANKS Nick
    If you are talking about a set of 7/16 dimple rods, I will try and find you one of my rods that came apart on a 468 12.5 motor running 7300 rpm and after 10 passes destroyed the crank, block, and cam. I was young and let someone tell me that these rods were the next best thing to sliced bread. :shock:

    My current engine is 540 with Eagle rods and L-19 rod bolts that runs 8000-8200 RPM for 12-15 seconds. I have around 30 passes on those and no failures...yet. I have not pulled the engine apart to freshen it up this year, but hopefully I will get to it this month.

  9. #9
    I would rather spend my money on a good set of rods and bolts then on the crank....

  10. #10
    Senior Member DYNO OPERATOR
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    I am sorry but I know very little about any automatics. I have been told by more than one reputable source that it is dangerous to neutral a 400 tranny. I guess I missed or didn't see anything about him using the 400 here.

    I always ran a clutch shifted 4 speed in my old car when it ran what it ran so going to neutral was easy for me.

    If someone busted a 7/16 bolt factory LS-7 rod at only 7,300 rpm there had to be something else wrong or the rod defective.

    Not only me but I know many who have turned that rod over 9,000 rpm with mucho horsepower. Years ago in the early and all through the 1970's that rod was heavily used in both NHRA and IHRA Pro Stock in the early years when Richie Zul, Dick Aarons, Wally Booth, Bill Mitchell (Motion Chevy) Warren Johnson, Sonny Bryant and many others were running with the stock block, stock rod, TRW Piston combinations and they were all buzzing the little things to 8,800 to 9,000 rpm back then.

    I do definetly agree that a better rod would be best, but will also say if his engine was clearanced right and has good lubrication and he takes care of them the 3/8 rods can work fine with moderate powered engines at less than 8,000 rpm. MY little 461 with the 3/8 Dorman HPX Bolts did not even have floated pins. They were pressed. Didn't keep a 2985 lb car from running 8's in 1984. Had some really great heads though. LIghter weight pistons can also be a benefit.

    Ed
    " Let all things that hath breath, praise the Lord. Praise Ye the Lord" Psalms 150 vs 6.


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