4-7 Swap
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 897
Likes: 12
From: Land of Whiskey Rebels, PA
4-7 Swap
I saw this on, I think, Horsepower TV. They said you can buy a camshaft where the numbers 4 and 7 firing order are reversed. You just switch the wires on the distributor cap. It is supposed to increase HP and torque.
Has anyone ever heard of, or tried, this setup? How can you change the cam's firing order, but not the crank's? How is that possible?
Has anyone ever heard of, or tried, this setup? How can you change the cam's firing order, but not the crank's? How is that possible?
Le Mans Master
Joined: Apr 2005
Posts: 8,077
Likes: 4
From: Scarborough ONTARIO
check on Compcams: http://www.compperformancegroupstore.../merchant.mvc?
These are either solid roller or mechanical tappet cams and recommended for 396-454 motors and mini 11.5:1 compression needed, basically it makes more power but iam sure it will not pass emmision and driveability will be sucks, mainly desinged for drag racing purpose. Seems like they make good power. One of my friend (camaro guy) suggested me this along with Brodix 18 Deg heads will make killer power. But i need to pass Emmission and gotta have good driveabilty too.
These are either solid roller or mechanical tappet cams and recommended for 396-454 motors and mini 11.5:1 compression needed, basically it makes more power but iam sure it will not pass emmision and driveability will be sucks, mainly desinged for drag racing purpose. Seems like they make good power. One of my friend (camaro guy) suggested me this along with Brodix 18 Deg heads will make killer power. But i need to pass Emmission and gotta have good driveabilty too.
Elite Torch Red Member
Joined: Sep 1999
Posts: 57,805
Likes: 23
From: Exit 89 GSP,Lakewood,NJ The Land Of Mojo
Cental/South NJ Events Coordinator
CI 1-2-3-4-5-6-7-8-9-10-11-12 Vet
CI-II Burnout & Drag Champ
St. Jude Donor '03-'04-'05-'06-'07
I saw this on, I think, Horsepower TV. They said you can buy a camshaft where the numbers 4 and 7 firing order are reversed. You just switch the wires on the distributor cap. It is supposed to increase HP and torque.
Has anyone ever heard of, or tried, this setup? How can you change the cam's firing order, but not the crank's? How is that possible?
Has anyone ever heard of, or tried, this setup? How can you change the cam's firing order, but not the crank's? How is that possible?
Elite Torch Red Member
Joined: Sep 1999
Posts: 57,805
Likes: 23
From: Exit 89 GSP,Lakewood,NJ The Land Of Mojo
Cental/South NJ Events Coordinator
CI 1-2-3-4-5-6-7-8-9-10-11-12 Vet
CI-II Burnout & Drag Champ
St. Jude Donor '03-'04-'05-'06-'07
Racer
Joined: Sep 2005
Posts: 271
Likes: 0
From: New Freedom PA
Tried in in my race car
I saw this on, I think, Horsepower TV. They said you can buy a camshaft where the numbers 4 and 7 firing order are reversed. You just switch the wires on the distributor cap. It is supposed to increase HP and torque.
Has anyone ever heard of, or tried, this setup? How can you change the cam's firing order, but not the crank's? How is that possible?
Has anyone ever heard of, or tried, this setup? How can you change the cam's firing order, but not the crank's? How is that possible?
It made about 5 Hp increase on the Dyno at 8000 RPM , My engine Machinist said the Hp improvements only come at Rpm's above 6000 , Don't think IMO it woth it for a C4 LT!.
motor is 331 , 5 speed Liberty
Cam specs were identical 636 lift for both on intake and exh.
Desert
Last edited by Desert1957; Feb 24, 2007 at 07:24 AM. Reason: additional info
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Cylinders are "paired" in any engine w/ 4 or more of them. In the Chevy V8 the pairs are 1-6, 8-5, 4-7, 3-2. That means that the pistons in these cylinders travel up and down together but at opposite points of the combustion cycle. That means that you have to work within these pairings for any changes in the firing order.
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 897
Likes: 12
From: Land of Whiskey Rebels, PA
Oh, OK. I got it. So, really, you could do a "swap" with any pair (1-6, 5-8, etc.), right? Looks like it to me. This modification is, obviously, not for my car (L-98). But, I wouldn't have known if I hadn't asked.
Thanks for the education, guys. (God, I love learning this stuff.)
Mike
'90 'vert
Thanks for the education, guys. (God, I love learning this stuff.)
Mike
'90 'vert
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Large Impressive Member
Joined: Jul 2003
Posts: 65,811
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Oh, OK. I got it. So, really, you could do a "swap" with any pair (1-6, 5-8, etc.), right? Looks like it to me. This modification is, obviously, not for my car (L-98). But, I wouldn't have known if I hadn't asked.
Thanks for the education, guys. (God, I love learning this stuff.)
Mike
'90 'vert
Thanks for the education, guys. (God, I love learning this stuff.)
Mike
'90 'vert
Precisely. 
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
I have done some reading on cam/crank timing and engine performance... it's really hairy stuff, and I don't pretend to totally understand it, but some timing patterns are more effecient than others.
IIRC, Ferrari used a flat-crank design on the F360, apparently, because it allowed for better air flow and power production. It all makes sense in a way. It also helped internally balance the motor...
It's all a very abstract and advanced concept...
IIRC, Ferrari used a flat-crank design on the F360, apparently, because it allowed for better air flow and power production. It all makes sense in a way. It also helped internally balance the motor...
It's all a very abstract and advanced concept...
Advanced
Joined: Apr 2005
Posts: 66
Likes: 0
From: San Diego CA
It's not that abstract. Ferrari uses flat cranks primarily to take advantage of exhaust scavenging to enhance intake charge cylinder fill. Tuned length headers are required.
Couple that with tuned intakes and cyl heads with great flow characteristics and the right cams - that's how they get such high specific horsepower outputs from their motors...
That's also why their V8s sound they way they do...
Couple that with tuned intakes and cyl heads with great flow characteristics and the right cams - that's how they get such high specific horsepower outputs from their motors...
That's also why their V8s sound they way they do...
Melting Slicks
Joined: Jul 2006
Posts: 3,356
Likes: 1
From: Chesapeake Va
4-7 swaps were a Pro Stock "secret" going back 15 years. I dont remember who pioneered it, wanna say it was Steve Schmit.
They obviously must work as they still use em today. I belive the SB ford has the same firing order, if you reassign the cyl #s like a chevrolet.
LS1s vin G are 18436572
LS2s vin U are 18736542
As for the flat, or 180 degree cranks, I remember reading an article years ago, about Warren Johnson trying to develope one (engine)
He said it never did what he was hoping it would do, so he scrapped it. It was an article about what some of those guys spend in R&D stuff that never sees the light of day.
If I remember correctly he said it was still sitting in a back corner of his shop.
They obviously must work as they still use em today. I belive the SB ford has the same firing order, if you reassign the cyl #s like a chevrolet.
LS1s vin G are 18436572
LS2s vin U are 18736542
As for the flat, or 180 degree cranks, I remember reading an article years ago, about Warren Johnson trying to develope one (engine)
He said it never did what he was hoping it would do, so he scrapped it. It was an article about what some of those guys spend in R&D stuff that never sees the light of day.
If I remember correctly he said it was still sitting in a back corner of his shop.
