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Thread: beheaded 540

  1. #1
    mrgoslow
    had a question posed to me today and didnt have a good answer. what are the downfalls of running large oval port heads with big valves and all the good work using a bench on a n/a 540, 9.5-1 that will never see more than 6k in a jet? are there tremendous gains at that rpm with 310 ish alum heads? any input would be nice.
    thanx.

  2. #2
    UBFJ #454
    310 ish Heads aren't Big Heads ... Actually, they're kinda small these days. Big Heads flow something like 500+ nowadays.

  3. #3
    mrgoslow
    correct, but i guess i wasnt clear. at that rpm (less than 6K) will there be a significant gain between fully massaged large oval (781) w/ big valves and an aftermarket aluminum head in the 310cc range on a 540 ci n/a engine. anyone have any dyno experience which would be relevant?

  4. #4
    UBFJ #454
    To me 310 heads seem a bit small for a NA 540 cid motor, especially at the rpms you say you want to limit it to ... gonna take quite a cam for enough to get into & fill 540 cubes. If you were going to be running even a small blower with mild boost, the 310's might make you happy, but, NA'd ... ??????
    If you were building a high compression, NA'd 454 cid with 2, say 750's worked out to maybe 800+, you should be able to get somewhere in the vicinity of 650 Hp with not too radical a cam at the rpms your talking about using the 310's.

  5. #5
    TIMINATOR
    I would use the 310s, the ovals are fine for a 454 at that rpm, but the 540 would like the 310s. I run a 572 at 5800 rpm(rollered,loooong rods,single dominator), and have tried the Canfield 360s,ported Canfield 310s,AFR 335s, and Dart(YUCCCHHH!!!). AFR 335s are IT (for the 572 anyway). JMO, but I HAVE tried it. TIMINATOR

  6. #6
    DeputyDawg
    I'll second the AFR 335s. I have them on my 540! I don't think the 781s would work very well on a 540 even with the 6k rpm limit.

  7. #7
    steelcomp
    For any na motor the key is port velocity, and a good general rule of thumb is the smaller the port giving the best flow no's is going to have the highest velocity. You'll always want to choose the head with the smallest port that will give you the flow numbers you need. You can do a little of your own homework here and check the "selecting the camshaft" thread that Chris Straub has posted, and find what kind of flow you need for your motor at your desired rpm. The Can 310 isa a strong flowing head, and flows better across the board than most 320's and many in the 345 range. Once you choose a head, tyake the time to choose the right cam for your application. It'll give you the most bang for your buck if you're stepping up to aluminum heads. :coffeycup

  8. #8
    Senior Member
    Join Date
    Feb 2009
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    L.B.
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    850
    For any na motor the key is port velocity, and a good general rule of thumb is the smaller the port giving the best flow no's is going to have the highest velocity. You'll always want to choose the head with the smallest port that will give you the flow numbers you need. You can do a little of your own homework here and check the "selecting the camshaft" thread that Chris Straub has posted, and find what kind of flow you need for your motor at your desired rpm. The Can 310 isa a strong flowing head, and flows better across the board than most 320's and many in the 345 range. Once you choose a head, tyake the time to choose the right cam for your application. It'll give you the most bang for your buck if you're stepping up to aluminum heads. :coffeycup
    With these larger cubes and na with more velocity, will you gain in lower end torque and less top end?-----Steve

  9. #9
    Liberator TJ1984
    310 ish Heads aren't Big Heads ... Actually, they're kinda small these days. Big Heads flow something like 500+ nowadays.
    Scott , what are ya diggin' at ???
    my 320's out of the box flowed 403 int and something like 311 on ex.
    I'll be in this weekend and got flowbench sheets at home if ya need to look at them.....
    thinkin' of goin to different heads???
    Gopher
    What #'s did Randy pull on your heads since we are talking the same flowbench

  10. #10
    BrendellaJet
    Im using Canfield cnc 335 on my 540. Should run about 6200 rpm on a B impeller. Hoping for 800 hp. Big mechanical roller cam with jesel shaft rockers and 11.?? compression.

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