A/F readings with a lambda

[66chargertoy]

So,,,,need a little help deciphering my readings on the charger. First off, thanks Ron for your lambda unit that I borrowed from you the other day . Here is the scoop on my set up first.
-mild 440, automatic
-running at 190 degrees
-13 degrees initial timing with a total of 36, but still getting some pre-ignition
-3.55 sure grip
-readings at cruise is 60 mph
-readings at idle 850 rpm
-750 proform race vacuum secondaries
-15 Hg of vacuum

So here are my readings that I got this morning

Idle 14.5  1.00 %
Cruise at 60 mph 13.8  94%
WOT 11.9  81%

So what should be nominal for this build.
Thanks.
Denis

[firefighter3931]

Denis,

Under what conditions is it detonating ? Full throttle (only) or when you roll into it going from cruise to WOT ?

Try disconnecting the vacuum advance and see if it detonates. 

The idle & cruise afr's look good but the WOT is a bit fat....you're shooting for high 12's/low 13's so you need to pull some jet out of the secondaries.

How do the plugs look ?


Ron

[66chargertoy]

Hey Ron , detonating is coming in when going from cruise to full throttle, basically when I put a load on it. It's much less than before, but still there. Will knock the secondaries down two sizes and will posts the numbers again. Also will run it with no vacuum advance.
Denis

Also, at 60 mph engine is revving at 2500 rpm

[firefighter3931]

Hey Ron , detonating is coming in when going from cruise to full throttle, basically when I put a load on it. It's much less than before, but still there. Will knock the secondaries down two sizes and will posts the numbers again. Also will run it with no vacuum advance.
Denis

Sure, it'll run fine with no vac advance.    The vac advance mechanism just pulls extra timing into the motor at cruise and it's possible that yours is pulling too much extra timing. 

Just disconnect it and plug the port off in the carb and re-test. 


Ron

[flyinlow]

 A little richer than best power at WOT maybe. 14.7 is perfect at cruise, you are close , maybe a step leaner jets like Ron says.

I have a similar mild build 440.  TQ,SD, OD trans    AEM analog A/F gauge

idle low 13's   ....a little rich ,but idles best there

cruise 2000 rpm  About 15

WOT  mid 12's

I run vacuum advance but restricted it to about 6 deg. or it knocks

sparkplug and oil life are good

[66chargertoy]

Still playing with it yesterday and dropped the secondaries to 79, vacuum disconnected, initial timing set at 12 degrees with total of 36 degrees. Took it for a test run.
Pre-ignition is gone The strong gas smell at WOT is almost gone now and pulls nice and hard. I'll tell you when you have the lambda unit in one hand checking the readings and testing the WOT at the same time, it's could get pretty harry

This is what I have now

Idle- 14.5  1.00 %
cruise- 13.1
WOT- 12.6

So far looks like I'm good with the secondaries. Should I drop down one size for the primaries?

[flyinlow]

. I'll tell you when you have the lambda unit in one hand checking the readings and testing the WOT at the same time, it's could get pretty harry

Try it with an assistant.(wife) Honey can you tell me what the Air/Fuel ratio gauge says while I drive down this entrance ramp. After merging with traffic. "well what did it read?"

"It stayed right on 14 the whole time"....WTF?  uh ," Honey, next time read the pretty red and silver gauge in the center, not the voltmeter".

[66chargertoy]

That's funny sh-t right there Wife's not to receptive to the WOT she usually slaps me on the arm whenever I mash the pedal . My 18 year old daughter on the other hand just loves it and get a big kick out of it So, think I should drop the primaries one notch?

[flyinlow]

Try it .  13.1 at cruise is a little rich. If you are richer than 14.7:1  when you do not need to be (WOT), you are  making your sparkplugs ,oil and the air we breath dirty for no reason. Some combinations with bigger cams and large cold intakes might run smoother at idle and cruise with a little richer mixture.