7/4 swap

[underdog]

I searched the forum but didn't find anything on this.

Can anyone tell me the advantage of a 7 / 4 swap cam on a small block chevy ?

Just remember there are no wrong answers just wrong questions and I ask a bunch of wrong questions !

Thanks

[Trmnatr]

I searched the forum but didn't find anything on this.

Can anyone tell me the advantage of a 7 / 4 swap cam on a small block chevy ?

Just remember there are no wrong answers just wrong questions and I ask a bunch of wrong questions !

Thanks


There is no wrong question,,,

The std firing order is 1-8-4-3-6-5-7-2
The 4/7 swap order is 1-8-7-3-6-5-4-2

It is a little smoother that std firing order,,, Crane cams doesnt charge extra for 4/7 swap and in my opinion you shouldnt pay extra for 4/7 swap

The one firing order i like that you do pay a little more for is 4/7 & 2/3 firing order swap, much smoother on the crank, bearings look better, and idles smoother
1-8-7-2-6-5-4-3

[gremmen]

Does the 4/7 swap give any better performance in HP or Torque. My brother is thinking of doing it to a 377 c.i alcohol motor.

[Trmnatr]

Does the 4/7 swap give any better performance in HP or Torque. My brother is thinking of doing it to a 377 c.i alcohol motor.

I have never seen it hurt,,,,

Dont pay extra for it,,, so if the 4/7 swap is the same cost go for it. If not, dont

I can get Crane for you with a 4/7 swap,, 4/7 & 2/3 firing order swaps cost more

We can do a small base circle and 4/7 swap for the same $$ 99.5% of the time unless its an odd ball application

[Awesome Bill]

We find no power with alky, and very little at best with the 4/7. What it does do is help even the cooling situation out with the driver side firing order sequence from front to back. This gets the water hotter and hotter. The front cylinder to the rear is always 20-30° hotter. What the 4/7 and 2/3 will do is correct some flow issues in the inherent single 4 barrel intake manifolds.

On the dyno, with 8 egts, we get temps from 1-8 sometimes 250° difference and there is really nothing to do about it. Put it on a blower, and all of them are within 25°. What we have found with the 4/7 and 2/3 cam, it does help the hot #1 cylinder go down in egts in some applications. We have yet to install a std firing order, 18436572, then 4/7 18736542 then 4/7-2/3 18726543 and see if it helps. If any one has actually done dyno test with the exact same cam and got information I would love to hear about it.

As far a smoothness, I have never heard or seen anything being smoother than a properly balanced engine. It is almost impossible for this to cause rough or smooth idling. But maybe. So if you can even the cylinders out, you can make more power by keeping a tigher egt package. That will always make more power. This is only on a single 4 as cast manifold. It does little to nothing with properly built sheet metal manifolds and same with as cast tunnel rams.