Bartman Posted January 27, 2006 Share Posted January 27, 2006 I was reading an article in my Hot Rod magazine about a 4/7 swap. They did some dyno testing that seems to support that a 4/7 swap does indeed create additional horsepower. For those that haven't heard about this before, you get a special cam and change a couple of wires on your distributor to swap the firing order on your number 7 and number 4 cylinders. It's supposed to make the engine smoother and be easier on the crank. IIIRC from the article GM made this firing order change on the LS engines (as well as another firing order change)? Anyone have any experience with this change? Quote Link to comment Share on other sites More sharing options...
Guest SC457A Posted January 28, 2006 Share Posted January 28, 2006 i know a lot of racers that have the swap, but for a street car it is not really worth it in my opinion. it helps the intake distribute the air more evenly at higher rpms, and is a tad easier on bottom end, if you crank on it. just make sure to remember to swap the wires to the plugs. runs funny otherwise (seen a few racers forget) Quote Link to comment Share on other sites More sharing options...
Bartman Posted January 28, 2006 Author Share Posted January 28, 2006 The article thinks it might not be worth it for stock daily driver's, but for those big horsepower guys you may be able to get some extra ponies pretty cheap. The cam's are around $30 extra and on the 492 big block Hot Rod tested they "got a little extra midrange by as much as 12 numbers and added a repeatable 2-3 hp to the top end". For those of you who want to read more it's in the March 2006 edition. Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted January 29, 2006 Share Posted January 29, 2006 Yes, I've seen 20HP gains on SBC's on the dyno. Quote Link to comment Share on other sites More sharing options...
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