Home | Register | Login | Contact Us

 
Auto Math
Classifieds
Forum
Gallery
Games
Garage
Tech Articles
Utilites
 
FAQFAQ    SearchSearch    RegisterRegister    Log inLog in    Log in to check your private messagesLog in to check your private messages    Forum Subscriptions1/4 Mile Table 

Swap Cams

 
Post new topic   Reply to topic    SMOKEmUP.com Forum Index -> Chevy - Big Block
View previous topic :: View next topic  
Author Message
Blown65
Member


Joined: 26 Feb 2003
Posts: 152
Location: Edmonton,Alberta Canada
3519.10 points


1965 Chevrolet Malibu

PostPosted: Fri Sep 18, 2009 4:29 pm    Post subject: Swap Cams Reply with quote

What does everybody think about the swap cams. I just had LSM grind me a new cam and he said I should run a 4/7-2/3 swap. Steve is about the most knowledgeable cam grinder I know so I went with it (didn't cost me anything extra) I have been hearing stories that they make more power and/or run smoother,and some people say they are not worth anything.

I've go one now, just looking to hear some opinions.

Cheers
Corey

_________________
Corey
CoMax Racing
Back to top
View user's profile Send private message
af2
Member


Joined: 01 Sep 2003
Posts: 5404
Location: grassvalley, ca
66667.72 points


1933 Willys Coupe

PostPosted: Fri Sep 18, 2009 4:47 pm    Post subject: Reply with quote

Make sure the wires are marked!!!! When thrashing in the Pitts. Laughing Laughing

I feel the LSx firing has to be good.

I see harmonics playing part.

As far as HP? I can't and won't believe Hot Rod or any one until I witness it.

Just my $.02 Very Happy
Back to top
View user's profile Send private message
Blown65
Member


Joined: 26 Feb 2003
Posts: 152
Location: Edmonton,Alberta Canada
3519.10 points


1965 Chevrolet Malibu

PostPosted: Fri Sep 18, 2009 5:55 pm    Post subject: Swap Cams Reply with quote

I am of the opinion that it will help harmonics but not the power as well.
As far as the plug wires, you must know me, if anybody is going to forget its going to be me. Embarassed


Corey

_________________
Corey
CoMax Racing
Back to top
View user's profile Send private message
af2
Member


Joined: 01 Sep 2003
Posts: 5404
Location: grassvalley, ca
66667.72 points


1933 Willys Coupe

PostPosted: Fri Sep 18, 2009 6:10 pm    Post subject: Re: Swap Cams Reply with quote

Blown65 wrote:
I am of the opinion that it will help harmonics but not the power as well.
As far as the plug wires, you must know me, if anybody is going to forget its going to be me. Embarassed


Corey


You forget I help my Uncle as little as possible because of the tension that makes it not fun.
He runs AA/S with the 6/71
Last time I helped was in Washington 3 years ago and won't go there again. I actually left the distributor cap unscrewed the 3rd run and it pissed me off because I don't do that.( yes I found it and apologized) then berated! finger The whole weekend was that way. Had to weld the tank from tire shake on the 1st run.
Way too much B/S going on. Evil or Very Mad
Back to top
View user's profile Send private message
Big Dave
Moderator


Joined: 04 Dec 2005
Posts: 2552
Location: Tampa Florida
116304.58 points



PostPosted: Fri Sep 18, 2009 7:03 pm    Post subject: Reply with quote

GM went to it with their new LS-x motors and all of the Pro Stock guys run it so there is something there, just not a lot.

Is it worth the expense yes, worth the hassel who knows.

Big Dave
Back to top
View user's profile Send private message
clay
Moderator


Joined: 24 Nov 2002
Posts: 3166
Location: South Carolina
316402.25 points


1972 Chevrolet Nova

PostPosted: Sat Sep 19, 2009 2:25 am    Post subject: Reply with quote

I too have heard it improves crank loading making it more even. As far as power is concerned, it seems to fall somewhat into the catagory of a exhaust crossover, it helps most of the time, but it never hurts so it's worth a try. I've never read or heard an explanation as to what is actually happening. My machinist suggested doing the 4-7 swap to me but after we talked back and forth for a while and my setup being a pressurized intake too he didn't think it would be very beneficial from a power perspective. I've never seen a swap cam vs. a convential on a positive pressure power adder setup, seems like the presurized intake should eliminate or reduce the gains it would give assuming it has something to do with rearranging the intake pulses for more effective cylinder filling on a N/A setup in the first place. Clay
_________________
I have done so much with so little for so long, I can now do anything with nothing.
Back to top
View user's profile Send private message
gilletteracing
Newbie


Joined: 10 Jan 2010
Posts: 2

216.72 points



PostPosted: Sun Jan 10, 2010 3:46 pm    Post subject: Reply with quote

I am new to the whole forum thing, but here is my thoughts on the firing order swap. On a bbc with a single plane intake and a balancer there is an advantage, i have seen about 20 hp. There are 3 things you are trying to help out by going to the 4723 swap. The first is harmonics, with the std firing order you are firing 657 together on the back of the crank, with the swap you are firing 31 together on the the front of the crank closer to the balancer. Two, With the std firing order 57 are always lien i think because 657 are trying to steel the same air and fuel from the plenum, by the time 7 fires their isn't enough left in the plenum to support it. Three, on a bbc you have good and bad intake runners, It seems that the bad runners are not as efficient and need more fuel than the good runners. The std firing order fires 6 (bad runner) 5 (good runner) 7 (bad runner) so your #7 is not only getting robbed of air and fuel but it needs more air and fuel to operate than say 5. You change the firing order and fire 3 (bad runner) 1 (good runner). 3 is going to rob air and fuel from 1 but that is what you are going for because 3 is a bad runner and needs more anyway.

A good dyno/carb guy can work out some of this stuff and keep the std firing order but it seems easier to tune with the 4723. With the newer cnc heads there doesn't seem to be as many gains, i think the wet flow on the bad runners has been improved making them more efficient. A duel plane intake throws another hitch into the ball game but 7 is still lien. There is a lot of variables every engine is different, i haven't seen anything bad from the 4723 swap.

These are just my thoughts, im not an aero engineer, they may be wrong, but i think this is what is going on with the swap
Back to top
View user's profile Send private message
FRITODAVE
Member


Joined: 05 Sep 2007
Posts: 166
Location: Victoria, KS
5170.64 points


1969 Plymouth Barracuda

PostPosted: Wed Jan 13, 2010 2:36 am    Post subject: Reply with quote

You guys are going to hate me with this. The placement of the header pipes at the collectors can negate the increase in power in certain situations. People just seem to forget about the exhaust system. Laughing Also, chevy engines are not the only ones in pro stock.
_________________
If you learn from your mistakes, then I must be a freaking genius!
Back to top
View user's profile Send private message
Blown65
Member


Joined: 26 Feb 2003
Posts: 152
Location: Edmonton,Alberta Canada
3519.10 points


1965 Chevrolet Malibu

PostPosted: Wed Jan 13, 2010 1:44 pm    Post subject: Swap Cams Reply with quote

I guess what I am getting from the input is that it really won't make much difference in the power level in a blown alcohol application. But in an NA situation maybe. I guess who ever first cam up with the swap idea found some power or they would have quit doing it. Very Happy

Corey

_________________
Corey
CoMax Racing
Back to top
View user's profile Send private message
Skunkworkx
Member


Joined: 02 Sep 2007
Posts: 352
Location: Harford Co. Maryland
10318.16 points


1968 Chevrolet Camaro

PostPosted: Wed Jan 13, 2010 11:14 pm    Post subject: Reply with quote

As for changing the harmonics...I'm sure its still there just in a different phase...Also heard stories both ways (good/bad)
_________________
68 Camaro LSx
AKA:RedЯum
Back to top
View user's profile Send private message
555nova
Member


Joined: 20 Feb 2008
Posts: 62

2155.50 points


1974 Chevrolet Nova

PostPosted: Thu Mar 11, 2010 11:21 pm    Post subject: Reply with quote

I just ordered a new cam from Bullet. When we talked about the 4/7 swap, they went into details about on a conventional headed BBC there is a 1-2hp loss over 6500rpm and a 1-2hp gain under that rpm.
On a big chief engine there is a 25 or so hp advantage. The main reason like many have said is the improved harmonics and decreases the load on the bearings, especially on a n20 motor.
Back to top
View user's profile Send private message
Big Dave
Moderator


Joined: 04 Dec 2005
Posts: 2552
Location: Tampa Florida
116304.58 points



PostPosted: Fri Mar 12, 2010 10:45 pm    Post subject: Re: Swap Cams Reply with quote

Blown65 wrote:
I guess what I am getting from the input is that it really won't make much difference in the power level in a blown alcohol application. But in an NA situation maybe. I guess who ever first cam up with the swap idea found some power or they would have quit doing it. Very Happy

Corey


A guy by the name of William Jenkins reportedly. Though I doubt if he was the very first to think of it. He also thought up the idea of strut front suspensions for tube frame cars instead of straight axels, and dry sump engines, and kick out oil pans, and a few other dodads. I believe he did some development work for GM's engineering department (engine research and development boys), but it was at a small company that went bankrupt last year called Chevrolet. Same company asked a professor to help them develope another engine for them (they must be pathetic engineers) It had Pontiac written all over this one so I guess we can let it slide (they called it a DRICE motor).

Big Dave

Big Dave
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    SMOKEmUP.com Forum Index -> Chevy - Big Block All times are GMT - 5 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
Home | Contact Us | Automath | Cam Files | Dyno Search | Forum | Garage | Picture Gallery | Reaction Timer

Copyright 1997-2014 SMOKEmUP.com All rights reserved.
Advertising Info     Disclaimer     Privacy Policy