4 - 7 firing order swap cam - Vibration reducer? - Team Camaro Tech
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post #1 of 11 (permalink) Old Dec 1st, 05, 07:33 PM Thread Starter
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Question 4 - 7 firing order swap cam - Vibration reducer?

Comp Cams claims their 4-7 firing order swap cams reduce crankshaft deflection. Does this mean the engine will run smoother, as in, smoother that you can feel in the car????????????????

I mean, I'd love my engine to run as smooth as a Lexus engine. If I thought this cam would make the engine even smoother, I think I'd go for it, especially since I got the engine laying in pieces ready to be put back together from a fresh overhaul. Comp says they can make them in pretty much any grind. It's a very interesting concept.

In case you haven't heard of this, it takes your standard Chevy firing order, 1-8-4-3-6-5-7-2, and makes it 1-8-7-3-6-5-4-2. All you gotta do is swap the cam and change the two wires on the distributor cap.

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post #2 of 11 (permalink) Old Dec 1st, 05, 07:40 PM
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Re: 4 - 7 firing order swap cam - Vibration reducer?

I can't see that it does much. You still have two cylinders in each bank firing consecutively.
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post #3 of 11 (permalink) Old Dec 1st, 05, 07:43 PM
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Re: 4 - 7 firing order swap cam - Vibration reducer?

I have talked to some Comp engineers about this. And though I have not used one of these cams yet, moving the firing of 7 & 5 away from each other has to do a lot for improving harmonics, I would think...

I mean that's essentially what they did with the 3rd Gen LS1 and its derivatives, making the firing order 1-8-7-2-6-5-4-3

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post #4 of 11 (permalink) Old Dec 1st, 05, 07:44 PM
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Re: 4 - 7 firing order swap cam - Vibration reducer?

Nevermind...

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post #5 of 11 (permalink) Old Dec 1st, 05, 08:19 PM
 
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Re: 4 - 7 firing order swap cam - Vibration reducer?

WE HAVE INSTALLED A 7-4 SWAP IN OUR 69 CAMARO ALL STEEL 3450LBS N/A 598 IN BIG CHIEF, www.hardcoreparts.ca might have picked up about 10 horse on dyno however the cylinders run cooler in the 5/7 area...hard to tell if runs smoother with 800 plus lift roller but engine does sound little different on idle...........we have run 8.70 at 156............on 10.5 tire
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post #6 of 11 (permalink) Old Dec 1st, 05, 09:28 PM
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Re: 4 - 7 firing order swap cam - Vibration reducer?

the car we race has a 7-4 swap cam in it, changed from a standard firing order. honestly, its tough to say how much it did at all, we changed the cam profile at the same time so its hard to say, but it really seemed to tame the idle ever so slightly. this too however is an .800+ lift cam in a 632 inch nitrous motor. apparently the swap helps fuel distribution, or so we were told, and that was the main reason we went that route. besides we were getting a new cam and it cant hurt.
pro1, nice times you car sounds similar to the race car, its a 70 nova, all steel, 3500# race weight (with added weight, car is 3280 normally), drce headed aluminum big block, 632" its gone 7.90 at 174 on 10.5 tires at 3500#, and 7.70 at 176 w/o weight, with a bit smaller tune up, on big tires. those 10.5's kick butt, it loved them!

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post #7 of 11 (permalink) Old Dec 1st, 05, 09:31 PM
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Re: 4 - 7 firing order swap cam - Vibration reducer?

Quote:
Originally Posted by 68rs406
apparently the swap helps fuel distribution, or so we were told,
That's what I've heard, too. with 5 & 7 firing 90 degrees apart it hurts the mixture distribution, especially with a single plane manifold.





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post #8 of 11 (permalink) Old Dec 1st, 05, 09:40 PM
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Re: 4 - 7 firing order swap cam - Vibration reducer?

yeah jim, thats really the main reason the 7-4 swap was chosen, the motor was prone to run hot at 5/7, and the fogger jets had to be a jet size or so fatter on those two to keep the motor happy, esp. on a larger tune up. doesn't seem to be as much of an issue now.

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post #9 of 11 (permalink) Old Dec 2nd, 05, 01:25 AM
 
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Re: 4 - 7 firing order swap cam - Vibration reducer?

68rs406...........THANKS SEAN......SOUNDS LIKE YOU HAVE A VERY IMPRESSIVE NOVA YOURSELF..YA GOTTA LIKE THE BIG INCH ENGINES...LATER
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post #10 of 11 (permalink) Old Dec 2nd, 05, 07:44 AM
 
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Re: 4 - 7 firing order swap cam - Vibration reducer?

ChevySS this is strait from ISKY
Quote:
The 4/7 Swap reduces crankshaft torsional vibration for smoother dampening & more power.
Here is what Comp Cams says
Quote:
Smart engine builders understand the benefits of a 4&7 firing order swap camshaft, which exchanges the 4 and 7 camshaft lobe timing in small and big block Chevrolet engines. While some builders have realized significant horsepower gains, all of them experience the exceptionally smooth torque curve possible with this new firing order technology.
SO to answer your question
Quote:
Does this mean the engine will run
smoother, as in, smoother that you can feel in the car????????????????
I really havent ever noticed a difference just sitting in the seat. I do know Pro Stock cars have run these for a long time in 500in motors. But they will spend a ton of money for a ounce of power. NASCAR did in the past also (rules change) is what ended that. So there are benifits. Its pretty much a personal choice deciding if the slight gains are worth what you are going to pay.
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post #11 of 11 (permalink) Old Dec 2nd, 05, 08:44 AM Thread Starter
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Re: 4 - 7 firing order swap cam - Vibration reducer?

Hey guys, thanks for replies. I believe it was originally designed to balance air/fuel flow in certain applications, like carb and single-plane intake.

My car now has Accel fuel injection, so I can't imagine I'd get any more power. But it's always nice to reduce NVH (noise, vibration & harshness) and that's what I'd be primarily focused on if I was gonna do this mod. It seems like the manufacturers use the word "smoother" quite often when talking about the 4-7 swap. I am guessing "smoother" means less work for the harmonic damper, but not a noticeably smoother seat-of-the-pants feel in the car.

TexasPP, thanks for the quotes..........

Dave F. in Rhode Island
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