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  1. #1

    Carrillo & molnar connecting rod balancing

    Just had a question about rods and balancing from the brands offered in the store .


    I have several questions how important is rod balance weight ?

    When we purchase any of these brands are they balanced on overall all weight and on the short end or must we confirm .


    It would suck to pay too dollar for them and have to send them out and spend more to get both the short end and overall weight balanced.


  2. #2

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    My understanding is you can change pistons but if you do rods you need to balance. By the way my balanced engine just sings at 9k RPM. It's so happy

  3. #3
    Exactly my point I got a few ideas over the winter , rods pistons , flywheel so when I get my new pistons and rods do I need to rebalance and have to send it out to get balanced as a whole .

  4. #4
    If the crank was balanced at the factory and we are told all the pistons and rods are balance to x grams then is it a must ?? I see people left and right swapping pistons and rods and nothing about balancing .

  5. #5

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    I see your point. Regardless I don't think it's a big deal since you have everything out. Also I would look into getting the piston ceramic coated. Swain has some very cool coatings. Prices are about 50 per piston.

  6. #6
    Any of the shops owner in this forum offer this service ?

  7. #7
    Bob 1tommygunner1927's Avatar
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    The Carrillo rods and pistons come with a data sheet which displays big/small end weight and overall weight of each rod, and piston weight. If you have the proper tools, you can verify weights.

    Falicon cranks can modify the crankshaft with just weight info of the rods and pistons.
    http://www.faliconcranks.com/

  8. #8
    Eastside Powersports Slow 91's Avatar
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    Yes you should balance the crank. The factory rods are a lot heavier then the Carrillo rods.

  9. #9
    If at the end of the day an item is balanced why is there so much diff in the price ranging from 150- 350

  10. #10
    Sanfish's Avatar
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    There are two factors that need to be discussed. Static balance and dynamic balance (aka reciprocating). Having individual parts evenly balanced is only half the step. So even if the rods are perfectly balanced (big and small end) out of the box, you still need to know the precise weight break-down in order to set the proper bob-weight (and not just from what is published). Even rings, pins, clips, bearings, oil are added to the bob weight to properly balance a crank (ie. motor assy). You can't balance a crank without all the other data. A crank balanced job with bob-weight of 600grams will require different balance compared to 850grams bob-weight. Again, the balance job is based on the "specific" reciprocating weight. Just like with only the car tire/wheel assy balancing...you must re-balance if you move tite to different corner. Actually, even if you don't put wheel/tire back in exact same lug nut position.

    It's never recommended to swap parts once motor is balanced and the heavier the part you change, the more important it is to re-balance (except for rings, clips, bearings). When you are talking about 0.5grams....at 9000rpm that adds up.

    Ironically, the counter-balancer (and flywheel) on the 4TEC is considered a "static" part and not part of the balancing as discussed.
    Quote Originally Posted by DR2006RXP View Post
    If at the end of the day an item is balanced why is there so much diff in the price ranging from 150- 350
    Sometimes you need to drill more into the crank and it just takes time to do it over and over till its right. Maybe the machine shop isn't familiar with the 4tec because sometimes in the auto engines, you need to ADD weight to the crank (to off-set heavy rods/pistons).


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