Thread: 4-7 firing order swap cams

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Just wondering if anyone has tried them yet in roller cams for the sbc's. I've studied it a bit and read some mixed results....But then none of the "results" carried specific information about the entire engine...like maybe the guy was using junk valve springs and blamed poor performance on the swapped firing order cam.

Any feedback?

yep have about 10 builds with 4/7 swaps

How do they work, Pat??? Any big, noticeable difference in smoothness or performance? or is it just a gimmick?

I haven't heard of this before.

I'm curious as to the reason behind this as well.

Here's a quick run down.

Testing Lunati Cams - Hot Rod Magazine

have a set of blown 502 in a 46 foot boat.4 in street car the rest all in drag cars or mud racing .most of the time if custom roller i will do the 4/7 swap its about the same price .i seen were some say theres a gain with them all of the stuff i build seams to run good no phone calls .not one of my customers had dyno sheets with two cams with one with the 4/7 swap and other stock .for a all out effort it may be EZ on parts. small gain on hp and tq .Erson stocks alot of shelf 4/7 grinds so there not allways customs if you find something that works for the job

Pat--Thanks! our discussion around here was on the "easier on parts aspect of the 4-7 swap, but the small gains in hp are always welcome, seem $30.00 is cheap to improve both!

Mike--Thanks for the article link! Supports much the same as what Pat learned. When the engine builders and the experts come to the same conclusions it's going to be good enough for me! I've had days I'd kill for 8 or 9 improvement on hp and torque at the rpm ranges the article and dyno results show the gains. Graphing out the gain @ rpm, especially with a 5 speed, one could alter his shift points a bit and spend more time per gear with the engine producing peak power! Some days it can make up the extra few hundredths a guy might need cuz some young clown treed me!!! Maybe a younger drive and the 4-7 swap would be even more better????

Originally Posted by Dave Severson

Maybe a younger driver and the 4-7 swap would be even more better????

Younger driver!!! Bite your tounge, Dave!!

I appreciate the sentiment, but sometimes I have to wonder, Rog!!! Got really slow the end of last year, shifts were fine but never saw an .00_ light the last 4 or 5 times out. Weather permitting, Saturday is test and tune from our rainout so I can see how things are this year before the points stuff begans if I decide to chase points this year! Spent a lot of time with the practice tree this winter, have to see how things work out--made some good improvements with the practice tree... Or maybe if I actually ran every weekend instead of 4 or 5 times a summer, but that never used to matter, either......

Originally Posted by Dave Severson

Pat--Thanks! our discussion around here was on the "easier on parts aspect of the 4-7 swap, but the small gains in hp are always welcome, seem $30.00 is cheap to improve both!

yep all my custom grinds are 4/7 as they get used in max effort engines .a very small amount of more money . if it helps with bottom end parts crank then its worth it to us.one of my customers been using a 4/7 for many years with 400hp of Nos .crank is not the top of the line but allways checks out great .the 8000 + rpms and the Nos as well. i would of bet it would of been busted in two parts many years ago i can not say its only the 4/7 swap but for the price its a no brainer

Wow!!! That's really great to hear Pat!!! With the price of parts the way it is, anything that makes them live longer is good in my book! 8000 on NOS and staying together, how big a shot is he putting to it? Man, even a 150 shot has been know to put the quick kill on cranks at that rpm!!!!!

Thats some thing i can never get a strait answer on. they just smile say around 300 to 400HP i do not think they would wast any time on a 150 shot. they are hard hitters

Even better new, thanks Pat!

Originally Posted by Dave Severson

Even better new, thanks Pat!

yep there making 800+hp off and 1100 hp EZ on the Nos