Thread: Fireing order change ?????

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Buddy told me he read an article about swapping #5 & #7 in the firing order and gaining 20 horsepower. Any body got any input on this ?????

Like Denny said, it makes some gains at high rpm, and may be good for a racing engine. If you're changing the cam anyhow, it might be worth the money. Isn't a 4-7 swap though, instead of a 5-7? 4-7 are matching cylinders.

From the Crane website:

The 4-7 swap firing order can help intake manifold distribution inequities, reduce the load on the rear main bearing, and perhaps gain torque and horsepower in certain RPM ranges. Although some drastic claims have been made for this modification, a power increase of 1 to 2 percent is realistic in some situations. No machining is necessary, just slide the cam in, swap some spark plug wires, and there you go!

As an aside, Chevy switched the firing order on the LS motors. They swapped 7&2 for 4&3.

1-8-7-2-6-5-4-3 LS motors
1-8-4-3-6-5-7-2 Std Chevy Firing Order

Thanks guys, A buddy was on my butt about not doing this on the kids limited 305 sprint car motor, I had never heard of it and kinda blew him off as he has come up with some hairbrained ideas in the past You might be right on that firing order Jack. I'm gonna research this some and it might be worth another call to Schnieder cams.....

the ls1 can be ground on a custom cam core for any engine and have talk to guys doing the big block chevy and thinking of one my self .the 4-7 swap is the one that every one has gone to. and have built some big blocks with is swap you may want to look at PBM Erson cams

They say its suppose to even the forces out a little more on the crank also...

run cooler cut down on crank deflection smoother torque curves helps you get a hot date with x porn star i am looking at the ls1 to see if it helps move the cam lobes a way from the rods on the crank that about it

We discovered that the change (swap) of cylinders years ago provided crankshaft "Wind-up". Similiar to an old style top that we used to wind up with the string and spin out on the floor. Like a gyro. It promotes better rotational movement making it easier to spin the mass which relates to workable horse power. Now for the nay sayers. Watch old top fuel and funny car videos. Look at the flame difference from left bank to the right. Standard firing order. Now look them at present day. More even burn and less push when one cylinder goes away. Hhhmmmmmm.....there's always movement in the feilds which we play. Keep digging in guys,this is fun stuff.

Originally Posted by nitrowarrior

We discovered that the change (swap) of cylinders years ago provided crankshaft "Wind-up". Similiar to an old style top that we used to wind up with the string and spin out on the floor. Like a gyro. It promotes better rotational movement making it easier to spin the mass which relates to workable horse power. Now for the nay sayers. Watch old top fuel and funny care videos. Look at the flame difference from left bank to the right. Standard firing order. Now look them at present day. More even burn and less push when one cylinder goes away. Hhhmmmmmm.....there's always movement in the feilds which we play. Keep digging in guys,this is fun stuff.

you think this is fun .come over and help me set my new 5.500 crank. i have used the 4-7 swap on bigger 4.250 cranks and up .i will run one with the 5.500 crank but the ls6 swap has to be custom made core $$$$$$$$$$$

Pat, you're getting me excited here. I love that you play with the big stuff and make it challenging.

if it wasn't inappropriate, I'd ask you to marry me. JUST KIDDING...this homey don't play that way.

Originally Posted by nitrowarrior

Pat, you're getting me excited here. I love that you play with the big stuff and make it challenging.

well the crank is not hear .i can not wait this helps me learn .17 years ago a 4.500 was a big deal when i set my first crank that big i was thinking i was the man? . now it is small and 4.750 are the deal. i need the crank so i can make the dry sump pan and hoping i can get the rods to clear the cam lobes??

Get the crank in your possesion. I 'll bet that a smaller base circle and maybe (just maybe) the counter weights can be trimmed on the crank grinder to clear. I like pushing the edge. Heavy metal balance etc. I'll bet it will work. Keep me posted.

Originally Posted by nitrowarrior

Get the crank in your possesion. I 'll bet that a smaller base circle and maybe (just maybe) the counter weights can be trimmed on the crank grinder to clear. I like pushing the edge. Heavy metal balance etc. I'll bet it will work. Keep me posted.

well if it hits it will be at the rod side by top of the bolt the crank is cut for 7.300 rods my rods will be7.400 long and i will plug the crank if i have to or run ex damper and auto fly wheel his will not be hi rpm engine and we have run the 454 ex bal engine to 7000 rpms the cam is move up 400 then stock and will run steel rods so this should help

Pat I didn't spend the time to think that project through. I have had that problem and by using the smaller base circle, it was alliviated to where I had to worry about block and cylinder dwell areas. Sorry for that. I sometimes let my brain go way ahead of the question at hand and "ASSUME" the clearance problems are well down line from where you were headed with your post. OOPS!