slade69

http://www.summitracing.com/int/part...ake/oldsmobile


They claim it increases power to change the firing order between cylinders 4 and 7. What is the theory behind?

jpc647

I haven't heard of this, but I'm interested on what some of the engine builders on here chime in with.

joe_padavano

I have no personal experience, but here's a back-to-back test on a BBC that picked up as much as 12 ft-lb and 13 HP with no other changes. Read the article carefully, however, as the amount of improvement (or lack thereof) apparently depends on how modified the engine is. There is even anecdotal information that with stock castings on an SBC, the 4/7 swap DECREASED HP slightly.