Quote:
Originally Posted by chiphead
The carb being rich is one thing helping to keep this engine out of detonation with 10:1 compression and 40* of timing! Those 670s are fuel hungry. Modern fast burn chambers may start to roll coal at 8:1 AFR. I imagine that if you leaned it out to about 11-12 AFR, it could start to pick up a few degrees of ping near peak torque. But yes, going to about 10.5 AFR in that region should be safe and may pick up a few ponies.
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Well, according to the chart it goes to the mid 12.x range by 3900-4000 RPM where the highest torque peak is, and that's about where I'd expect peak torque to be with a cam like this. True, it's making about the same torque down around 3000 with a much fatter AFR according to the chart, but if it's not pinging at 3900 at 12.4-12.7 I don't know why it would ping at 3000 at 11.5.
But, if what Paul says below is true and the AF ratio sensor is off then who knows what it actually was and it doesn't really matter anyway because it ran fine!
Quote:
Originally Posted by gtofreek
Yeah, I saw that but I'm not fully convinced his A/F meter was working right. The first run showed A/F ratios up around 126:1, then it would be 4:1 .2 seconds later. So we pulled plugs and looked at them, and the burn ring looked real good, so we didn't mess with it. Cliff built that carb for these engine specs, and it ran pretty flawlessly, and after reading the plugs, both the dyno operator[he has way more experience reading plugs than I do after more than 16,000 dyno pulls], and myself were convinced the carb needed no help.
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