Technical > Matt Shaff's Engine Shop
4 7 and 4 7 2 3 swap cams
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:
--- Quote from: wideopen231 on June 09, 2017, 07:18:54 PM --- 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.
--- End quote ---
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/
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