blazin_blazer
1/2 ton status
a firing order swap for 4 and 7 cylinders...i no i've seen it mentioned alot but have never heard why?
CK5
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whats this do 4 u
- Thread starter blazin_blazer
- Start date
original balzer
1/2 ton status
I have seen claims of 47HP just doing the 4-7 swap. It is supposed to be a more natural fire order and make the engine run smoother and not fight its self, therefore releasing more power.
Its claimed you can do it to any engine even multi-port injection by simply swapping 4 and 7 wires on distributor and injectors and using the appropriate cam.
I would like to try it someday just for kicks.
Its claimed you can do it to any engine even multi-port injection by simply swapping 4 and 7 wires on distributor and injectors and using the appropriate cam.
I would like to try it someday just for kicks.
blazin_blazer
1/2 ton status
custom cam or are the cam makers making this readily available?
original balzer
1/2 ton status
I belive theres a couple manufactures making them now, but I couldnt tell you who or how much.
also I should have mentioned *any chevy v8* in my other post not just any engine.
EDIT: a quick web search brought up lunati and comp cams both trusted brand names and both have these cams available
also I should have mentioned *any chevy v8* in my other post not just any engine.
EDIT: a quick web search brought up lunati and comp cams both trusted brand names and both have these cams available
blazin_blazer
1/2 ton status
i knew what you meant.....almost 50hp ....they need to make it a standard part!
All of the newer chevy engines use the 7 / 4 switched firing order these days. It helps smooth the engine out (put a new 8.1L beside a 7.4L, and you'll be amazed just how much smoother the 8.1L is), makes better use of the air intake harmonics that already exist, and exhibit a more balanced force on the crankshaft.
Becuase of the better harmonics, forces being distributed etc, you can expect to see a bit of a power increase (somewhere to the degree of 10 hp or so), but the bigger benefits has to do with the increase in the life of your engine's rotating assembly due to the decrease in stress put on the crankshaft.
Becuase of the better harmonics, forces being distributed etc, you can expect to see a bit of a power increase (somewhere to the degree of 10 hp or so), but the bigger benefits has to do with the increase in the life of your engine's rotating assembly due to the decrease in stress put on the crankshaft.
original balzer
1/2 ton status
Edit: (the 47hp not what russell said) Thats just claims not backed up by proof. I found the article hot rod magazine put out online you can read all about it here.
http://www.hotrod.com/techfaq/113_0701_lunati_cams/index.html
http://www.hotrod.com/techfaq/113_0701_lunati_cams/index.html
blazin_blazer
1/2 ton status
thanks guys
I haven't looked alot but most of the 4 7 swap cams seem to be more geared to racing. I haven't seen very many low end cams, hopefully they will make a broader spectrum of these cams.
Randy92782
1 ton status
This should sum it up with out reading all that
Is it right for you?
Clearly, the 4/7 swap has benefits, but whether you'll see them or not in your engine depends on its purpose. Lunati's Humphreys explains, "It really has to do with good heads and intake. With stock castings, I wouldn't expect to see any difference." In fact, he went so far as to say he'd actually lost a little power once when testing the 4/7 swap on a stock 350 Chevy.
Some claim that the firing-order swap should not be used with a dual-plane intake, as the split-plenum arrangement is tuned for the conventional firing order. And while we have not tested that theory, consider this: Ford did not change the intake design when it changed the firing order. Also, Edelbrock's carbureted dual-plane for GM Gen III engines uses the same exact runner configuration as the old small-blocks.
Is it right for you?
Clearly, the 4/7 swap has benefits, but whether you'll see them or not in your engine depends on its purpose. Lunati's Humphreys explains, "It really has to do with good heads and intake. With stock castings, I wouldn't expect to see any difference." In fact, he went so far as to say he'd actually lost a little power once when testing the 4/7 swap on a stock 350 Chevy.
Some claim that the firing-order swap should not be used with a dual-plane intake, as the split-plenum arrangement is tuned for the conventional firing order. And while we have not tested that theory, consider this: Ford did not change the intake design when it changed the firing order. Also, Edelbrock's carbureted dual-plane for GM Gen III engines uses the same exact runner configuration as the old small-blocks.
