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going to 540

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    Default going to 540

    ok i have 454/ls6 stock, 850 holley, going to very mild 540, was going to use same carb. will this work? if so how much bigger jet size to start? thanks
    Last edited by ibelio; 12-16-2011 at 03:49 PM.

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    Senior Member Reservoir Dog's Avatar
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    It should work, I would start off with about 4-6 jets higher. The engine will tell you how much fuel it needs. Make a pass wide open throttle, shut the engine off as soon as you make your pass and check acouple of spark plugs ( 1 and 8). They should be dark tan (the electrode), if you're using a msd it will be white so look to see how many threads are showing dis coloration (should see three to four threads od discoloration). Don't idle for more than acouple of seconds as this will give you faults reading.

    With that 850 carb on your 540 you might want to think about getting a Wilson super sucker spacer or HVH. This will increase the air/fuel velocitythrough the carb, making think it has a bigger carb.

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    Senior Member H20MOFO's Avatar
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    Quote Originally Posted by ibelio View Post
    ok i have 454/ls6 stock, 850 holley, going to very mild 540, was going to use same carb. will this work? if so how much bigger jet size to start? thanks
    I dont think I was aware a 454 could be taken to 540...thought 496 was pretty much it. What bore,stroke,rod combo makes 540?
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    it is a totally different engine

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    Senior Member H20MOFO's Avatar
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    Quote Originally Posted by H20MOFO View Post
    I dont think I was aware a 454 could be taken to 540...thought 496 was pretty much it. What bore,stroke,rod combo makes 540?
    Edit....my bad.(454/540) As far as the carb question....I always thought the carb didnt know/care what what size motor it was on(jet wise)....it was designed to use/mix x amout of fuel with x amout of air. I probably should have quit while I was behind. lol
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    Quote Originally Posted by H20MOFO View Post
    I dont think I was aware a 454 could be taken to 540...thought 496 was pretty much it. What bore,stroke,rod combo makes 540?
    I was wondering the same thing...

    Matt

    Quote Originally Posted by ibelio View Post
    it is a totally different engine

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    Quote Originally Posted by H20MOFO View Post
    Edit....my bad.(454/540) As far as the carb question....I always thought the carb didnt know/care what what size motor it was on(jet wise)....it was designed to use/mix x amout of fuel with x amout of air. I probably should have quit while I was behind. lol

    It dosent, but it will criple the hp potential of your motor, basically chocking the amount of fuel it would normally want. Say your 540 made 700 hp with 1050 dominator @ 6800rpm, then change to the 850. Now you're going to make around 500-550 @ 5500 to 5800. This is not actual but just an example of how running a smaller carb change your hp. It won't lean the motor out, because you are jetting the fuel to the amour of air that passes through the carb.

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    Senior Member EVILFORCE's Avatar
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    You guys better get this figured out before Bob see's it. Yes you might be a jet or 2 off but it will be close if it was before. Now RUNNNNNN.



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    Quote Originally Posted by EVILFORCE View Post
    You guys better get this figured out before Bob see's it. Yes you might be a jet or 2 off but it will be close if it was before. Now RUNNNNNN.



    I'm just a outsider looking in. Still trying to figure out the comparision involving a 1050 dom and a 850 on the same motor, when the op asked about the same carb on a different motor.


    A more important question for the OP isn't the size if the engine. I could basically care less. But are the manifolds the same type. Single plane VS dual plane. Cam duration is a another concern.
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    need more info but you said mild so should be fine if the jetting was right on the 454 , may have to go down a couple sizes as the 540 will pull harder on the boosters . but like the Dog said wouldn't do well past 5500 .
    Quote Originally Posted by gn7 If your ran a cammer your odds of finishing WERE ZERO.

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    gn7
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    Quote Originally Posted by canuc View Post
    need more info but you said mild so should be fine if the jetting was right on the 454 , may have to go down a couple sizes as the 540 will pull harder on the boosters . But like the dog said wouldn't do well past 5500 .
    BAM!!!!!!!!

    People that think that you have jet a carb up when its installed on a larger engine have their think of how a carb works upside down.

    Like canuc stated, if it was good on the 454 it wil be pretty close on the 540, and may infzact need a light jet reducction because it be a tad rich. specially on the top end.

    It a little touchier jetting a 540 with a 850 than a 454. It could be fine in the lower and mid range and go fat on top. I would much rather wrestle with a 1050 dom on a mild 454 than a 850 on a 540.
    Ibelio, it will be pretty damn close as is, and it sure as hell isn't going to go lean on you. But unless this thing is really mild, you leaving some power on the table with that carb.
    Last edited by gn7; 12-17-2011 at 09:42 PM.
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    thanks gn7 i was scared it would be lean and burn a piston. fat is ok with me ps wont be going past 5400 rpm. thanks
    Last edited by ibelio; 12-18-2011 at 10:48 AM.

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