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Thread: 4/7 sbc cam swap

  1. #1

    4/7 sbc cam swap

    I was wanting to know the advantages of this cam? "no certain cam" Is it a good cam for the street/ strip? Thinking of 400+ sbc thanks

  2. #2
    Senior Member RACING JUNKIE
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    Don't waste your money on a 4/7 swap cam unless it's an all out race motor, it was originally designed fot high RPM, and susposed to smooth out hormonics which gains HP, do i have one YES, but on an 800HP motor not 400 hP.

    JMO

    Zip.

  3. #3
    Senior Member MASTER BUILDER
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    We see absolutely no difference on the dyno in power with the swap. we do use it with heavy N20,blown or turbo applications,anything else is a waste of money.Bill
    Hendrens Racing Engines
    1310 U.S. Hwy 221 North
    Rutherfordton N.C. 28139
    828-286-0780 Bill, Steve, Mike
    www.hendrensracingengines.com

  4. #4
    Senior Member DYNO OPERATOR
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    4/7 swap cams do not improve fuel distribution. Even when said by some of tbhe highest most professional. voices in motorsports that is not what it does. The people pushing them don't even know why it is suppoosed to help.

    As far as the problem of two adjacent cylinders fireing and one robbing the other from fuel I can agree with that. The 4/7 swap can not cure that. IT simply moves that 5-7 problem to now be a 2-4 problem. Nothing gained in fuel distribution corrections, like everyone and his brother say it does. The 4/7-2/3 swap also still ends with two adjacent cylinders firing, so the problem of fuel distribution is moved to the 1-3 cylinders. No matter which cylinders get swapped that same fuel distribution problem will still exist.

    So don't believe all the false hype about why the 4/7 swap is better from cam companies or anyone who has not understood why it is done in the first place.

    The 4/7 swap was pioneered by Warren Johnson as early as 1984 in a DRCE 1 Olds engine. NHRA refused to allow it in. Now everyone does it, but has no clue what it helps. It can help though.

    When the two adjacent firing cylinders are in the end of the coolant flow chain it causes the rear cylinders of that bank to run hotter with higher EGT's. That can reduce power unless tuning compensated. Still it can reduce power becuase of the crutch needed in tuning to get the cylinder EGT down in the hot cylinders.

    When you move the two adjacent firing cylinders to be in either the front of the coolant chain, those cylinders are getting fresh coolant from the water supply so them having uneven heating does not exist. That is the whole misunderstood reason for the 4/7 swap.

    With the 4/7 - 2/3 swap which is used on all current pro stock engines, that cylinder uneven heat issue has been moved to the last cylinders in the coolant flow path so that the heated coolant is now exited immediately with nothing restricting it as it would be restricted in flow if stuck way in the back of the cooolant flow path as is in stock engines.

    The HUGE benefit is that the firing cylinders will exert a more even shock load on the rotating crank with less harmonic deflections and will give a much smoother running engine with less stress on the crank meaning less twisting actions, less harmonic distortions and it all riuns and works together smoother.

    All of the GM LS late model, engines use this 4/7 - 2/3 swap which was pioneered in conjuction by Steve Lowe of LSM System Engineering, not for horsepower but for better bottom end reliability with a smoother running engine. Listen to them run. Feel them as they are idling or running. That is from the C Swap or 4/7 - 2/3 swap firing order.

    The problem is that only two current sources can supply that 4/7 - 2/3 swap core and every cam core company out there can supply the 4/7 swap cores. One core company is ofeering a few popular sizes in a 4/7 - 2/3 but not many.

    So 4/7 can help becuase of the more even cooling on the cylinders, not becuase it corrects fuel distribution issues as everyone selling them claims.

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

  5. #5
    Hey guys, thanks alot just a beginner here!!! You never learn if ya dont ask people that deal with this kind of stuff every day!!!! What would be a good cam for a street/ strip? Was thinking of a 406 or bigger like a 421 with dart 215 alu. heads and pump gas 6 inch rods. im building a little vega! Thanks again!!!

  6. #6
    Senior Member RACING JUNKIE
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    Quote Originally Posted by bigdawg71
    Hey guys, thanks alot just a beginner here!!! You never learn if ya dont ask people that deal with this kind of stuff every day!!!! What would be a good cam for a street/ strip? Was thinking of a 406 or bigger like a 421 with dart 215 alu. heads and pump gas 6 inch rods. im building a little vega! Thanks again!!!
    Around .660 to .680 with 108 degrees split, seems to work good with light car.

    JMO

    Zip.

  7. #7
    Senior Member RACING JUNKIE
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    Quote Originally Posted by edvancedengines
    4/7 swap cams do not improve fuel distribution. Even when said by some of tbhe highest most professional. voices in motorsports that is not what it does. The people pushing them don't even know why it is suppoosed to help.

    As far as the problem of two adjacent cylinders fireing and one robbing the other from fuel I can agree with that. The 4/7 swap can not cure that. IT simply moves that 5-7 problem to now be a 2-4 problem. Nothing gained in fuel distribution corrections, like everyone and his brother say it does. The 4/7-2/3 swap also still ends with two adjacent cylinders firing, so the problem of fuel distribution is moved to the 1-3 cylinders. No matter which cylinders get swapped that same fuel distribution problem will still exist.

    So don't believe all the false hype about why the 4/7 swap is better from cam companies or anyone who has not understood why it is done in the first place.

    The 4/7 swap was pioneered by Warren Johnson as early as 1984 in a DRCE 1 Olds engine. NHRA refused to allow it in. Now everyone does it, but has no clue what it helps. It can help though.

    When the two adjacent firing cylinders are in the end of the coolant flow chain it causes the rear cylinders of that bank to run hotter with higher EGT's. That can reduce power unless tuning compensated. Still it can reduce power becuase of the crutch needed in tuning to get the cylinder EGT down in the hot cylinders.

    When you move the two adjacent firing cylinders to be in either the front of the coolant chain, those cylinders are getting fresh coolant from the water supply so them having uneven heating does not exist. That is the whole misunderstood reason for the 4/7 swap.

    With the 4/7 - 2/3 swap which is used on all current pro stock engines, that cylinder uneven heat issue has been moved to the last cylinders in the coolant flow path so that the heated coolant is now exited immediately with nothing restricting it as it would be restricted in flow if stuck way in the back of the cooolant flow path as is in stock engines.

    The HUGE benefit is that the firing cylinders will exert a more even shock load on the rotating crank with less harmonic deflections and will give a much smoother running engine with less stress on the crank meaning less twisting actions, less harmonic distortions and it all riuns and works together smoother.

    All of the GM LS late model, engines use this 4/7 - 2/3 swap which was pioneered in conjuction by Steve Lowe of LSM System Engineering, not for horsepower but for better bottom end reliability with a smoother running engine. Listen to them run. Feel them as they are idling or running. That is from the C Swap or 4/7 - 2/3 swap firing order.

    The problem is that only two current sources can supply that 4/7 - 2/3 swap core and every cam core company out there can supply the 4/7 swap cores. One core company is ofeering a few popular sizes in a 4/7 - 2/3 but not many.

    So 4/7 can help becuase of the more even cooling on the cylinders, not becuase it corrects fuel distribution issues as everyone selling them claims.

    Ed
    Once again, awesome info. This site is great.

  8. #8
    I thought I was a motorhead.Ed is a God.What an amazing piece of information,thanks.It all makes so much sense,specially the LS stuff. I have couple LS powered vehicles,so true.Thanks again Ed.
    There is no replacement for displacement.

  9. #9
    Senior Member MASTER BUILDER
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    I thought the 4/7 swap was adopted from the sbf which did it quite a few years ago

  10. #10
    Senior Member DYNO OPERATOR
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    Been said many times that the Ford is the same firing order.

    Anyone look to see how a Ford's Cylinders are numbered?

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


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