i have heard great things about these cams/ firing order switch.

i know comp cams have one advertised, and lunatti offers one for an extra 100 bucks, it basically switches the cam lobe on cylinder's 4 and 7 and you have to switch the spark plug wires.

it is said to give about an extra 20 hp over similar grind performance cams, and offers about 7 percent less stress on the crank as well.

anyone else heard of this, i guess doing this has been 1 of pro racer's secret for years now but is just now getting some light shined on it, i saw this over at camaroz28.com, and was wondering what people think over here about it?

im upgrading my setup and this is a major possibility.

heres the thread i was checking out http://camaross.com/forums/showthread.php?=225034

 

i've heard the gains are a little more than that. 35 or so depending on the grind and engine. looking into one myself. Sick

 

Let us know how it works out, Sick. I am a little wary, because I don't see any advantage, as there are still 2 cylinders firing one after the other on the same bank, but less crankshaft stress is a possibility. It reminds me a of something that was being touted many years ago, the 1/4 speed double lobed cam. It was supposed to increase power, allow higher RPM, and cut down on valve train stress. It actually did none of these things and was abandoned.

 

i was watching Horsepower on the tube and they did a build on an engine dynoed it before and after the 4 7 swap. and got gains of 35 to 40 extra horses. if so ... it would definately be worth my while to try one in my 305. i have seemed to hit a brickwall of sorts in gains.
i recently installed a set of new heads milled and ported with 1.94 valves. started using racing fuel as well since my CR when up another half and was turning the same speed and time as with the stock heads. really cooked my goose. i did take your advise tho and readjusted the valves with it running and hot and found that my valves appeared to be a little too tight. as much as a whole turn on some of them. it seems to be running alot better. gonna take to the drags this weekend and find out. Sick

 

It's the real deal. I've been using 4 & 7 lobe swap cams for Years in big and small block racing engines. It's an old racer secret that the public is just now onto. Depending on the engine I've seen 25 on an oval track 350 to 90+ on a 600" big block drag race engine. You know, You just can't keep everything secret forever. There are alot more tricks that common sense will dictate and others will find about them also eventually.

 

Dosnt the LS1 use that firing order? Bill is right its been around for awile ether lingenfelter or smoky yanik sp.. used it years ago. To my understanding it is more advantagous with bigger cube higher rpm engines. I believe some are even switching 2 and 3. I think ford used that firing order also. Bill that 350 you spoke of was it a 2 bbl dual plane what was the specifics?? I talked to crane when I bought my cam they said it would not be advantagous in a lower rpm motor.. This is a very interesting topic.

 

It was a Nascar Late Model ( 355 cubic inch, GM Bowtie Heads w no porting, Edelbrock dual plane intake, Flat top pistons with 5.7 rods, Moroso oval track oil pan, Holley 350 2bbl, Solid flat tappet cam, Special honing with low drag rings, etc. ) and the most power I was able to get using a conventional firing order was in the neighborhood of 340 - 345. With the lobe swap, and no other changes, We saw 371 on the Superflow Dyno. We always calibrated it at least once a week and these were back to back tests with the same engine only 3 hours apart. The power peak on these engines is always around 5600 - 5800 RPM. We use a wide centerline because of the long straightaway ( 110 degrees ) and only advance the cam 2 degrees. The drivers like to run the motors up to 7000 and thay all seem to do well in doing that. At 7000, the power drops off to about 330 - 335 but it pulls like a bear up to 6800. I've tried 112 centerlines but it left too much on the table out of the corner. I hope this fills You in.

 

Thank you very much. My next question is where does the power come from is it because the air flow through the manifold is more favorable or is it a harmonic issue or both. The LS1 seems to swap 4/7 and 2/3 also I wonder why?

 

You have to remember that the LS1 is a whole different duck. I feel the power gain was because the firing was more natural for the engine design ( Cylinder / Crank Layout ) because it helps in the combustion process. Seems to keep it from fighting itself less. The LS1 deal is based on the same principal but is slightly different.

 

people have complained about the LT1/LT4 intakes having trouble filling the rear cylinders, as it was cleared up for me, My guess is that switching the firing order solves that problem which is where the extra horsepower comes from, as well as improved valvetrain harmonics from the reduced stress in the crank,

i did wonder about the o2 sensors, but was told if they all are in working order, it would be fine

i recently talked to a guy who built motors for IMCA wondering more about it, he said "it makes such a significant HP increase is because it balances the efficiency of the motor by seperating the #5 and #7 cylinders on the firing order. These 2 cylinders constantly scavenge each other on the conventional firing order camshaft and always show lean"