4 7 and 4 7 2 3 swap cams

[wideopen231]

anyone know how much gains one can expect from running 4 7 swap or 4 7 2 3 swap cam. Buying custom grind anyway.Its 48* cam for raised cam block,so already paying thru nose and might as well get all I can while spending  money. Not to sure I can g et 4 7 2 3 deal done but 4 7 is not problem.

[dreracecar]

I am of the belief that if there was any signifegant gain, you would not have to ask the question and the person grinding the cam would tell you.

 I know some blown nitro guys have tried it, no gains to speak of , but it helps even out the cyl's

[Paul New]

I had a 4/7 swap on my blown SBC once  but never had a non swapped cam with that combo. I can tell you it was the best sounding SBC I had ever had, until my latest SBC

[wideopen231]

 Do not figure its huge gain. But 8 or 10 hp is a gain. Would fuel car ever know that? Probably not with 10,000 on tap, unless you mean Nostalgia fuel. Now on my piddly  950 to 1000  its a gain. Not huge but they add up.

 No cam grinder yet,which is why I don't know the  4 7 2 3 swap is even a consideration. Comp cams has the 4 7 cores for 48* motor.

[wideopen231]

If the only benefit is smoother running engine that's easier on crank.At 3000 for cranks I have its worth trouble.

[dusterdave173]

Bullet is my cam grinder of choice on east coast   If you call them I think you will get some of the best advice available
Never go wrong with Isky either   Bullet always and I mean always delivers what I expect and more from a cam and you always talk to a pro not a trainee

[dreracecar]

Do not figure its huge gain. But 8 or 10 hp is a gain. Would fuel car ever know that? Probably not with 10,000 on tap, unless you mean Nostalgia fuel. Now on my piddly  950 to 1000  its a gain. Not huge but they add up.

 No cam grinder yet,which is why I don't know the  4 7 2 3 swap is even a consideration. Comp cams has the 4 7 cores for 48* motor.

 Are you going to DYNO the engine??? then buy both and do a swap and get real numbers. Every combination gets different results from changes, some help and some hurt. We did it years ago with my 410 chevy sprint because the way the filters were on the stacks 5 and 7 were conflicting.

  For me personally, at my level of racing, I tend to stay with standard config parts to be able to get them sooner when there is a prob ( say a broken lifter) then having to wait for a custom one off to be made. again - thats just me and I can make the difference up someplace else

[dusterdave173]

I agree with that 100%
We have dyno tested back to back and on many you get nothing--a few you get a few--really big CI drag gas engines eehh...maybe worth it   I think KISS rule all the time   and honestly FED's are usually exhibition style racing anyway--just get it going end to end and enjoy  The guys at Bullet are just the best--no tricks of the week--just an amazing understanding of what really works---all about how accurate the info you give is--we all know that new builds are the toughest because you can't really answer on the money--but a combo you have been banging on with lots of records--well ...you can almost always make a move that helps

[JrFuel Hayden]

I have been running a 4-7 swap in my SBC Heritage JrFueler for 9 years. Never compaired to a non-swap cam, the closest to that would be the SBC compare would be the non-raised runner 23° engine we ran before the RR 23°, and 55mm raised cam Dart block, which we made at least 120 more hp, but I only dyno'd the RR engine, at 850 hp. Yes it sounds good, and I've seen and heard another SBC JF engine with the 4-7 swap and the 2-3 swap, and yes it sounds different, and it was a fast combo, but maybe because it was a very light car at 1355 lbs with driver, 5 lbs more than the min.  He ran 7.0's when we were running 7.0's.
The way I understand it is the firing order swaps are a advantage for the NA gas burning engines with collector pipes, because of how it affects the pulses in the collector.  I have heard the only cam cores available for Chevy's are the 4-7 or 4-7, 2-3 swaps. What I hear is there is no added power for NA Zoomie engines.
The reason the big show blown Nitro teams run swaps is it's easier on the cranks, they live a little longer, but now I hear they are only getting 2 runs on them before the rod journals crack. There is a price to pay for 11k+ hp. They also have to check the rod length after every run to look for too much change or rod cap spread.
Thank the dragracing Gods we don't live in their world and check books.   
Jon

[Roger]

When I was trying to understand the 4/7 swap I came across this article that looked at several different explanations from various professionals of why the swap might increase performance. Some of the reasoning has already been discussed here. Don’t know if it helps answer the original question but might shed some more insight into it.

http://www.hotrod.com/articles/lunati-cams/

[wideopen231]

Yea there is about 100 articles on line. 4 or 5 say same thing. LOL My view is if I can get 4 7 swap for same money and have not seen any real down side, why not. Changing back is matter of swapping two wires on cap. If it smooth's out harmonics then I'm good with that too. May be a while. Even the cam being better fit is only 40#tq gain and that's for only about 1250 to 1500 rpm range then its almost nothing.  The 296-500 cam I have  is about 12 to 18* too much 296 @ .050. But hey its sitting here and cost zero plus have 2 of them.

[Roger]

That was the point, lots of opinions and no absolute answers:) The swap doesn’t appear to have a negative effect on performance so it may be worth a try. Or maybe have one of your existing cams reground with less duration?

[dreracecar]

You will not get any absolute answers here because every combo people run here is different. Like I said before,  if the swap made any significant gains and all the racer had to do was swap 2 wires, why would the cam grinder offer any other verson??? Isnt the purpose of a cam grinder is to make a better product.

 Customer came in a few months ago with a damaged cam, the needles came apart in a roller lifter and wanted to know what I thought because he had a race in 2 weeks. It was a Bullet Can (very nice) but numbers did not match any listing, It was a custom grind for the original engine builder and made to order. sent it back for repair (with shipping a 10 day turnaround) in the meantime installed a comperable non swap cam and new lifters.  He was racing Super Comp on a index and just dialed the car in and went rounds until his brain melted and had a horrible RT.

[masracingtd1167]

When we used to dyno the Comp motors we tried different cams with the 2 cyl and 4 cyl swap and never saw much of a gain ! The best thing you can do is talk to your cam builder and let him make a decision on  what cam to use and give him as much information as possible !

[ricardo1967]

Like I said before,  if the swap made any significant gains and all the racer had to do was swap 2 wires, why would the cam grinder offer any other verson??? Isnt the purpose of a cam grinder is to make a better product.

Well Bruce, I have a different perspective here. They can charge extra $ for the 4-7 swap. Basically the same reason why McDonald's offers hamburgers and cheeseburgers.