#4 and #7 firing order swap

[oldred95]

HPTV just put a four seven cam into a small block race motor using the exact same specs as a regular firing order cam and made an extra 32 HP simply by switching the #4 and #7 cylinders firing order. They said the cam costs an extra 90 bucks but for that kind of gain out of just changing firing order I'd say its well worth it. Has anyone done this swap before and have any first hand experience with it?

[mcnulty1]

I wonder if I could do that with an '01 Sierra, 5.3

[89stroker]

no you can't do that on the 5.3 because it doesn't have a distributer.

[domestictuner]

no you can't do that on the 5.3 because it doesn't have a distributer.

you could re-wire the coil boxes

[1500chevy5.7l]

so you can just swap the firing order of 4-7 how does that help?

[oldred95]

so you can just swap the firing order of 4-7 how does that help?

They said the cam manufacturer couldn't exactly explain the phenomina but they think it has something to do with creating a more equal balance of incoming air and fuel into the #4 and #7 cylinders or something along those lines.

You would think it would cause a miss fire or something but apparently not. Now that I know about this I'm going to check into it some more, if I can email that cam manufacturer and see what they can tell me and if this mod works for only NA applications or boost or anything in general.

[red4x4chevy]

You can not do that to a 5.3 because they have a new firing order. On anything on the street it will not really help with power a huge amount, but maybe up to 15 or 20 horse max. It will however create a smother powerband and help the crank last longer it helps to keep the loads on the crank down by changing thoose two cylinders firing order.

[fastredgmc]

how much power did this engine make?
Thats a big increase i could see if it were a 1000hp engine but anything else i cant see a increse like that. I know a guy that put one in a 500hp 406 and didnt notice a thing. Also herd of many dyno runs with nothing more than maybe 5 hp difference. They tell you anything on TV or magazines just make the advitiser happy

I think the ls1 engines aleady have that firing order.

[oldred95]

how much power did this engine make?
Thats a big increase i could see if it were a 1000hp engine but anything else i cant see a increse like that. I know a guy that put one in a 500hp 406 and didnt notice a thing. Also herd of many dyno runs with nothing more than maybe 5 hp difference. They tell you anything on TV or magazines just make the advitiser happy

I think the ls1 engines aleady have that firing order.

It was a 406 small block running AFR heads and 9:1 compression on 87 octane and it made 495 HP and 500 ft lbs at the crank on the engine dyno. After the cam swap HP was was 527 IIRC and I don't remember the torque.

[thegreat1]

do you guys think an engine without the cam will still run with the 4-7 wire swap. ill be the guinea pig and try it on my truck to see if anything changes!

[horsepwraddict]

it just balances things out so certain cylinder aren't 'fighting' each other, makeing more smooth power. It doesn't cause a misfire because you just swap the plug wires on the dizzy...even alot of the racers dont use it, thats saying something when the guys who will do anything to get every last ounce of power out of a motor dont beleive in it.

[horsepwraddict]

do you guys think an engine without the cam will still run with the 4-7 wire swap. ill be the guinea pig and try it on my truck to see if anything changes!

prob not. vavles wont be times correctly

[oldred95]

I might go swap wires for the hell of it. But if all you have to do is swap wires then where does the different cam profile come in. This chit gets confusing as soon as you start to actually think how it works.

[horsepwraddict]

I might go swap wires for the hell of it. But if all you have to do is swap wires then where does the different cam profile come in. This chit gets confusing as soon as you start to actually think how it works.

because the plugs will be firing on the wrong strokes.

[blu92]

no, it won't run right. Stop and think about it for a minute. You need to change both the cam and the dist. firing order. Hot Rod mag. did a story about it a while back. As I recall it did make some horsepower, but only on certain combos and it def. didn't make any difference for the street. My $.02

[oldred95]

I can't even find the cam manufacturer on the good old powerblock website. They said it was Laser something but thats all I remember. I'll try to remember and watch it again tomorrow to get the name of the place.

[WildmanZ28]

Any cam manufactuer can grind you a 4-7 swap cam. I've heard of it done on SBC's & BBC's. I'd like to see how it works in a more mild, "street" application. I have a feeling it wouldn't be worth it, and am curious about the idle quality.

Does anyone else remeber the odd fire & even fire Buick V6's? I do, the odd fire ones ran rough compared to the even fire motors.

[TITANIUM]

So this was just a wire swap. Same ole cam?

[cooker2003]

Those cylinders will not even fire if you only swap the plug wires. There is no reason to try it. You have to swap the cam along with the firing order.

[WildmanZ28]

So this was just a wire swap. Same ole cam?

No, it's both. Think like an 80's 5.0L, the non-HP had a std. firing order, and the HO motors have a 351W firing order. The cams match the firing order on the distributor. Otherwise you'd have cylinders firing and nothign in them to burn, and cylinders not firing with fuel being dumped into them.