fact or false

[Lt1_8U]

today i was watching the speed channel and they were building a 383 chevy and towards the end of the show they were dynoing the motor and they stated that sometimes by switching spark plug wires 4 and 7 you can make more power. has anyone tried doing this or ever heard of this?

thanks

jim

[Tru2Chevy]

Yes, you can - however it's not that simple. You need a 4-7 swap cam as well, and it won't always make more power. Depends a lot on your setup.

- Justin

[Lt1_8U]

ahh okay, i figured it was more involved than just switching wires lol they didnt explain it, they just stated that sometimes it makes more power. they also said they have additives to make your exhaust smell like, cherries, and a whole bunch of stuff haha pretty weird

[BonzoHansen]

fact, but everything I've read/been told it the advantage is really for high revving, high hp engines engines. Happy reading

[sweetbmxrider]

It also loads the mains evenly, supposed to help something somehow?

[Lt1_8U]

Originally Posted by BonzoHansen

fact, but everything I've read/been told it the advantage is really for high revving, high hp engines engines. Happy reading

a lot of different information out there lol. supposedly the horsepower tv build picked up 33 hp by doing this

[dugeman]

I have a 4-7 swap on my motor ,it's done thru the cam , then firing order. Doesn't really make any more hp, but smoothes the motor and help cooling . It's a little more involved ,and some motor s will make a few more ponies.

[Lt1_8U]

Originally Posted by dugeman

I have a 4-7 swap on my motor ,it's done thru the cam , then firing order. Doesn't really make any more hp, but smoothes the motor and help cooling . It's a little more involved ,and some motor s will make a few more ponies.

thanks for the input, thats a nice motor you have there

[jam01]

Originally Posted by Lt1_8U

ahh okay, i figured it was more involved than just switching wires lol they didnt explain it, they just stated that sometimes it makes more power. they also said they have additives to make your exhaust smell like, cherries, and a whole bunch of stuff haha pretty weird

that was for the barrel of alcohol, it has no smell to it thats what the additive does along with adding lubricant to the fuel.

[Pampered-Z]

The SBC 4-7 swap is an old school trick used allot when racing classes had intake/carb restictions. One of the issues with a small plenum volume was that the normal firing order resulted in the air flow in the intake to "reverse direction? between the #1/#8 and #2/#7 cylinders (I think they were the one), but baciscally starving the rear cyclinders. Changing the firing order elinimated the reversal from front to back,and made more power, the swap ( ala ford firing order, now LSx firing order ) does also place less stress on the crank, it is also why they sound different/smoother then a older style SBC.

I don't think those scents are ment for unleaded fuel? In the past they wern't. if you ant a nice smell, put CAM2 in the car!

[Blacdout96]

So if it smoothed the engine, allowed it to prevent it from starving the engine, etc. how come GM didn't do it on production SBC?

[91chevywt]

Originally Posted by Blacdout96

So if it smoothed the engine, allowed it to prevent it from starving the engine, etc. how come GM didn't do it on production SBC?

They did it on the LS1

[Lt1_8U]

Originally Posted by Pampered-Z

The SBC 4-7 swap is an old school trick used allot when racing classes had intake/carb restictions. One of the issues with a small plenum volume was that the normal firing order resulted in the air flow in the intake to "reverse direction? between the #1/#8 and #2/#7 cylinders (I think they were the one), but baciscally starving the rear cyclinders. Changing the firing order elinimated the reversal from front to back,and made more power, the swap ( ala ford firing order, now LSx firing order ) does also place less stress on the crank, it is also why they sound different/smoother then a older style SBC.

I don't think those scents are ment for unleaded fuel? In the past they wern't. if you ant a nice smell, put CAM2 in the car!

haha that true, i love that smell! thanks for the info!

[Pampered-Z]

Originally Posted by Blacdout96

So if it smoothed the engine, allowed it to prevent it from starving the engine, etc. how come GM didn't do it on production SBC?

My opinion on that is because they lose the traditional sound and SBC characterizes Sound, torque curve (along with changing all their tooling such). You do give up some low/midrange torque. If you are running a single plane intake or high rise that increases the plenum volume this does cure allot of the starvation issues.

the 4-7 swap isn't going to give you big gains, all else being equal, let use a fairly stock 250-275HP engine you may pick up 10-15HP at best, it not going to make you run like an LS1, an LS1 has allot of other things that allow it to rev the way it does, light reciprocal weight, short stroke, eliminated crank pressure etc.