4 to 7 swap cam

Old 11-19-2007, 02:50 PM
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Default 4 to 7 swap cam

hi i here there is another swap now beside the
4to 7 anyone knows of this and if so
does comp cam have a # or any info would be great from

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Old 11-19-2007, 02:58 PM
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Yes there is another the 4&7 + 2&3 swap out there I believe,maybe more info,I am sure others will post up here

But its hard to beat the regular firing order swap cams
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Old 11-19-2007, 07:04 PM
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I don't think there is much to gain, except moving the paired ports to get better cooling.
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Old 11-19-2007, 11:34 PM
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I hope Ed doesnt mind me qouting him here, I found this reply to a 4/7 question awhile back that I found very informative and interesting its worth another read.

Posted: Sat Sep 22, 2007 1:02 pm Post subject:


"4/7 swap cams do not improve fuel distribution. Even when said by some of the 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 firing 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".

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Old 11-20-2007, 05:42 AM
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Its a waste of money, unless you have a high end, high rpm,custom sheet metal comp or pro-stock engine. Have had the oppurtunity to test numerous engines over the years, with both normal cams, and after a freshen up, the customer wanted the swap cam, because he saw on Hot Rod tv that it was worth 40hp, no other change. :roll: . 0hp, 0 et gain. This is from more than 1 test, with the same cam profile from Comp, except 4/7 swapped. Think about if for a minute with some common sense. All you did, was made 2 cylinders fire at a different time. YOu did NOTHING to increase flow, add compression, change to a bigger carb, etc etc, how can that gain 40hp?? How many of you guys have spent $1200+ on a new, custom super flowed carb, to pick up 8hp, or put in a new cam that had 10 more degrees of duration and .100 more lift to find 14hp, or have your heads ported to pick up 40 or 50hp and be thrilled with that gain? Now come on, switch 2 wires around, and 40hp, NOT

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