Originally Posted by Silverback
Yep, one step at a time, something like this:
Yep, the other nice thing about using a briggs lawnmower engine is that I found that I can get the "good" headgaskets for $3.60 at the local Ace hardware... Cheaper than a $100 set of cometecs...
You can't take data from a flat head engine and transpose it onto an overhead valve engine. Flat heads have very serious issues with burn time and spark plug location. What the Singh grroves do is provide a burn path into the squish/quench zone of these type engines which somewhat defeats the purpose of this area by allowing the flame front to penetrate at a faster rate in the grooves. This reduces general squish/quench, but may be of some benefit from providing an aim of the squish specifically at the spark plug
rather than the more general squish more of less aimed at that side of the combustion chamber in hopes that something gets by the spark plug. I will admit that they seen to imporve idle quality in cammed engines, but that's usually not a feature we care much about and can solve that problem with multi-strike ignitions, albeit, that is the higher priced solution compared to grinding some grooves in the head.
Frankly, I went thru a period of playing with these things years ago and didn't see anything on the dyno nor felt anything in my sensitive butt that would cause me to view them as a useful exercise. I also don't see that they do any harm from the same data either, so I wouldn't discourage anyone from messing around with them. But all the data I hear about is touchy/feely, I haven't seen anybody back that up with numbers and as a PE, I'm looking for numbers.