Okay Camshaft Gurus..Let's talk about the 4/7 swap

[BUSBY]

wow ... stumbled across this thread ... old school right here boys!
4/7 swap IMO not worth it. Tried it w/ my uncle (NHRA 1970's & 80's) from time to time.
George Striegel (Clay Smith Cams) was one of the originators of the idea. From what I was told by him it was born from the Ford Windsor deals ... using the firing order for the Windsor from the 289/302 engines I believe. (I'm sure there are some Ford guru's here that can chime in on that, but I think those who are running small Ford hard swap the cams around).
Info is primarialy right on here ... but it never really worked in any great HP gains ... acutally we ended up spending too much money chasing it 2 or 3 different times.
IMO ... spend your money on your heads on getting them done right ... that is where the tricks are kept!

[flat broke]

I can't say what the GM revised firing order is good for on my motor compared to a traditional firing order engine of the same build, but I will offer this up for deliberation. There has been a string of pump gas sub-500ci 4.25 stroke BBCs to come out of DNE in the past few years, and for the most part, each motor has seen better hp than it's comparable predecessor. One of the changes that was made between my incarnation and earlier builds is the addition of the revised firing order on the cam grind.
As Chris mentioned, perhaps it is only good for 3-4 HP, but when a custom ground cam costs $XXX, you might as well choose the grind that will give you the most hp for your $. People always talk smack about the "little things" that the big name builders do, and how they are are great for competition, but you wont see the gains in every day performance applications. As I look at the attention to detail spent on my motor, I can tell you that when you add enough of those "stupid little things" together, you get a measurable increase in peformance.
Will the revised firing order make your boat faster than your buddy's? By itself no, but if the same attention to efficiency is applied throughout the entire build, you will end up with a sizeable difference.
Just my $.02
Chris

[steelcomp]

perhaps Info or Steel can put a little lite on this swap...back in the 60's when every1 was looking for a little more HP...there was a T/F team that tried a 180* cam that fired like 2 seperate 4 cyl engs...they ran pretty gd...made alot of HP...of course...they were blown on nitro...i dont know if they stuck with it or not...also...there was a co. called WH Ducoil who made a dual coil distributor for Fords (thats what i had..427ci FE) that u wired like a 4 cyl useing the stock cam pattern (no lobe swap)...it worked great for me...i think there is alot to this 4/7 swap...cause of the intake chg & certain cyl's running lean...especially on the BBC...look at Info's schematic & u will see that the new GM fireing order has the swap!...i think this swap (i could be wrong) comes in the 502's....Info..Steel...shed some lite on this
Ron (fastrat)
I remember the TF motor you're talking about, but don't remember who. If I'm not mistaken, they ran what's called a flat crank. All the rod journals were directly opposed. I also remember the Ducoli...my dad had a 55 "Bird that had a stroked 406FE (462ci) and it had a Ducoil in it. Also had one on the motor in our boat...a J2 Olds.
I really can't shed much light on the 4/7 swap thing. Just haven't had that much experience with it.

[steelcomp]

I can't say what the GM revised firing order is good for on my motor compared to a traditional firing order engine of the same build, but I will offer this up for deliberation. There has been a string of pump gas sub-500ci 4.25 stroke BBCs to come out of DNE in the past few years, and for the most part, each motor has seen better hp than it's comparable predecessor. One of the changes that was made between my incarnation and earlier builds is the addition of the revised firing order on the cam grind.
As Chris mentioned, perhaps it is only good for 3-4 HP, but when a custom ground cam costs $XXX, you might as well choose the grind that will give you the most hp for your $. People always talk smack about the "little things" that the big name builders do, and how they are are great for competition, but you wont see the gains in every day performance applications. As I look at the attention to detail spent on my motor, I can tell you that when you add enough of those "stupid little things" together, you get a measurable increase in peformance.
Will the revised firing order make your boat faster than your buddy's? By itself no, but if the same attention to efficiency is applied throughout the entire build, you will end up with a sizeable difference.
Just my $.02
Chris
Good post Chris. This is exactly what my point was before. For the guy buying parts from Smmit and trying to bolt them together, the 4/7 is a waste of money. For a guy like Dave, or when you are capable of addressing every detail as best as possible, or as a customer's budget will allow, then it seems to makes sense to take advantage of what the swap has to offer. Even then, though, the gains are minimal. But at that point, a gain is a gain, and they all count. I doubt it's worth it in a jet boat, though, unless you're running a reduction, or some ungodly small impeller, and can really zing the motor. I doubt there's much to be gained at the 6500 rpm level, but I could be wrong.

[FASTRAT]

I remember the TF motor you're talking about, but don't remember who. If I'm not mistaken, they ran what's called a flat crank. All the rod journals were directly opposed. I also remember the Ducoli...my dad had a 55 "Bird that had a stroked 406FE (462ci) and it had a Ducoil in it. Also had one on the motor in our boat...a J2 Olds.
I really can't shed much light on the 4/7 swap thing. Just haven't had that much experience with it.
hey steel...
im loseing it here lol...ur rite...it was a 180* crank...not the cam...i was doughin' lol...anyways...do u think it would work in a BBC?
glad to hear that someone else besides me had tried the Ducoil...i wish i still had mine
Ron (fastrat)

[steelcomp]

hey steel...
im loseing it here lol...ur rite...it was a 180* crank...not the cam...i was doughin' lol...anyways...do u think it would work in a BBC?
glad to hear that someone else besides me had tried the Ducoil...i wish i still had mine
Ron (fastrat)
Crank's a crank, block's a block, rods and pistons don't know what they're hooked to.
It's all about the harmonic phases when it comes to balancing. V8's balance better than most any configuration. Next are 60 deg v12's and 6's. Flat fours and 6's like Porsches and VW's and Lycoming's and others are on the bottom of the list, just above a 90 deg v6 or v12. If the flat crank would work in the v8 better than what we have now, it'd be in every one. Falconer took two SB Chevys and made a 90 deg v12, somewhere in the neighborhood of 600ci. It's a bitchen motor, but they have a bad rep for breaking cranks. V12's (and 6's) need to balance at 60 deg, not 90.
I'm hoping someone else will chime in here, because I really am not sure the 180 deg. v8 had a flat crank in it...but I think it did. I think they discovered that flat opposed cranks need opposing or in line cylinders to work correctly. I haven't talked about this stuff for so long I've forgotten all the terminology. There's basically two frequencies of balancing when a motor is running. and the different configurations effects these two frequencies differently.
Ouch...my brain hurts. Might be a good topic for a new thread.

[ttmott]

Historically, if I remember correctly, the greatest gains, firing order wise, was to balance the exhaust pulses in the headers (non zoomie). In all GM firing orders there exist two pulses on each side next to each other in the order causing ineffeciencies in cylinder scavenging and intake charge. There existed what they called 180 degree headers that crosses over the conflicting two exhaust tubes to the other side collector balancing the pulse timing. Some short track cars still use the 180 deg systems. The piping for the exhaust is a bundle of snakes. It would be interesting to see what DNE has to say about this.
Tom

[72 Hondo]

I could be WRONG but, I heard the 4/7 swap had something to do with triing to run the Chevy small block? in a reverse rotation.

[steve d]

I remember the TF motor you're talking about, but don't remember who. If I'm not mistaken, they ran what's called a flat crank. All the rod journals were directly opposed. I also remember the Ducoli...my dad had a 55 "Bird that had a stroked 406FE (462ci) and it had a Ducoil in it. Also had one on the motor in our boat...a J2 Olds.
I really can't shed much light on the 4/7 swap thing. Just haven't had that much experience with it.
Back in the 70's there was a Sprint Car #111, in CRA at Ascot that ran a Keith Black motor---They had a name for the motor--damn can't remember-anyway this motor fired two cylinders at a time. Shot like hell comin out. Ran for a few years--nothing much came of it. Is this what you would call a flat crank? Seems like it would vibrate like an old Triumph V.T.---Steve

[UBFJ #454]

It's my opinion, in terms of gaining Hp, that unless someone is going to build, as Chris says "A (Truly) Competition Motor" (a naturally aspirated motor) and go the route of using and integrating such things as a Tuned Intake Manifold (Built & Tuned To The Specific Heads Your Using); High Flow Heads w/Appropriate Chamber Size, Valves, and Push Rod Geometry; Special Ground Larger Diameter Roller Cam(s); Tuned Step Headers; Etc. ... Your not going to gain much by doing the 4/7 Swap ... The dampening of Harmonics, especially with a smaller dia. stock cam and its valve train, is something one should consider though.
$800 for a 4/7 Swap cam seems a bit Pricey to me ... Our Special Grind 55 mm 4/7 Swap LSM Roller Cam wasn't even close to that.