Yes they are but is pretty good stuff. Good topics and material for everyone.

^^^ wow on those cylinder heads

I think taking some notes from merc racing rather than castigating them would be wise. 2 things they do. 1075s have Pistons down in the hole far enough for them to have a perfectly flat surface. And they run pretty rich as many have noted.

I thought I read somewhere here that the 1075 engines ran on the leaner side?

Video from whipple running a 1075 merc with there blowers. AFR's displayed on the screen look to be in the 12.3 to 12.7 range during the pull

Great info guys! I think we can all take this data and easily see the correlation to the sbc vs. ls combustion chamber design. A comparable ls will usually run about 10 degrees less total advance than its sbc based brother. Of course this would be factory type NA engines. Makes sense, less total = less force against the rotating assembly going in the opposite direction of power production.

then I wonder why some engines are fat. They know the 1075 gets rebuilt frequently enough to not die of spark knock?

it be cool to see what there target afr is on the 600/700sci engines .

My understanding of the thread is AFR is used to set the engine up, but after this is done, its best to use EGT to monitor.

Just bought the FAST duel AFR which plan to use next season to verify tune. Once all done, it sounds like I need to pull the AFR and install EGT probes, or did I miss something?