[PAUL K]

Originally Posted by Squidward

For full throttle, what are your metrics for too much/too little, for either AFR or timing? Do you shoot for best et/mph, but just shy of detonation? Plug color?

Best MPH or HP cross checked with A/F & plug reading

Originally Posted by Squidward

I put in a digital gauge cluster/speedo that can measure 0-60's or other parameters, so I can get some feedback on performance. There are other phone apps I've used that can log performance with GPS. Track time is impossible, but some 0-60 or 1/8th pulls on the street are a possibility.

It might be easier to test 30-60 mph times or another range that you're comfortable with. It will eliminate traction and transmission shift inconsistency. Forty to seventy in second gear works well on my daily.

Originally Posted by Squidward

Concerning tuning the timing curve:
For idle I've always used an initial setting that gives best vacuum, but is usually 2 degrees shy of where the engine has trouble cranking. I run manifold advance.

My starter chugs at 18 init, so I ran it at 16 for years. Recently, I moved it back to 14 for a little more margin on the total timing. So my idle timing is 29 (14 init + 15 vac) at 820 rpm. Engine makes best of 15" with this timing, so I think this is a pretty good setting so far.

[I]Sound reasonable?

Yes, but usually less initial timing works better on milder combinations.

Originally Posted by Squidward

Would it be worth messing with the idle AFR setting to further get best vacuum? I run FiTech, so that would be pretty easy.

Probably, I like a lean idle setting with as little initial as the engine is happy with.

Originally Posted by Squidward

Now, for the WOT timing: Should one shoot for best performance that is shy of detonation? This part gets me a little, because I have thrown a lot of timing at this engine (up to 40 total) before and have never HEARD any detonation. I have 22 mechanical, and IIRC a light-medium spring combo. So total is probably 36 (14+22) by 2500 or so.

Some engines will be hard to time with the "hear detonation and back it off two degrees" deal. That strategy was popular when engines requiring high octane were run on lower octane fuel.

Unleaded fuel generally likes less timing. Most of our race gas 455's work best at 36 but the pump gas combos prefer 32-34. That's for factory iron head builds. A 3.75 stroke engine usually wants a little more timing.

Originally Posted by Squidward

WOT AFR: I know this should be richer, because lean causes engine damage.
Would proper settings be evaluated by measured performance and spark plug color?
Should one start out rich, make some pulls, and adjust leaner until proper plug color is reached with best performance results? I see some people like to stay a little on the richer side for safety margin.

Start rich and go lean. Best performance/power sets the WOT tune but remember A/F will effect timing. After the A/F is set, dial in the timing and go back and fine tune the A/F

Originally Posted by Squidward

I won't overload the discussion asking about cruise timing and AFR right Small bites...

Cruise timing can be set with a vacuum gauge.

Originally Posted by Squidward

Thanks for the help! I'm hoping others might benefit from this thread too. I plan on reporting back with some results to validate what I learn.

You're welcome, I hope others share their input. We're all trying to learn.