FA ratio

[need help]

572RB with 365 CFM heads, 14:1 comp,multiport EFI, .700 solid roller. Suggested FA ratio for start up?

[camcojb]

Air/fuel ratio? If you're talking about idle a/f, most of my large roller cam EFI setups liked low to mid 13's a/f at idle, very unhappy trying to lean them out to 14.7:1 like a milder combo would use. I just give them what they want, in my case the richer a/f at idle made more vacuum and the engine was a lot happier sounding. Don't get hung up on making them lean out to a certain number.

[andrewb70]

I always run close to 14.7:1 at idle, regardless of cam specs. Sometimes even targeting even leaner if the cam has a lot of overlap.

Andrew

[camcojb]

Originally Posted by andrewb70

I always run close to 14.7:1 at idle, regardless of cam specs. Sometimes even targeting even leaner if the cam has a lot of overlap.

Andrew

I don't know how big his cam is, but my 540 with 700 lift, 260/270ish duration @.050 was not happy at 14.7:1. It would run, but it picked up vacuum and rpm by richening it into the mid to high 13's. I've always been the "give it what it wants" kind of tuner, right or wrong it works for me.

[Che70velle]

Let the spark plugs do the talking. It’s the only way to correctly tune, and the engine will get exactly what it wants. Large overlap camshafts will have you chasing your tail, if you shoot for strictly a number.