Tuning a 4053 with AFR

[TODD]

OK don't want to take over Aron's post
So installed AFR gauges carb baseline is original 4053 restored by Eric at Vintage Musclecar
so jets 72/72 Front 76/76 rear
 PV 4.5 Front 4.5 rear

engine set at 12 degrees BTDC 30 degrees dwell angle
distributor original 1111480 set at (9 degrees) 18 at crank mechanical from 1200 to 2600, advance 7 inches mercury limited to 10 degrees stop.
Valve lash .028 cold stocked stamped "O" units Crower poly-lok's




Car ran ok hears first results after initial AFR install
So gauge installed results were kind of surprising:
1) Idle 900 RPM AFR ~13-14 so looks like I'm pretty close on the secondary opening was rich before adjustment
2) Idle to 2500 RPM 13.5-15 with lean spots on accel (probably needs a more aggressive cam on the accel pump)
3) cruise 2800-3500 RPM 11.2-12.3 jets are 72-76 so probably need to go to 70’s?

What elevation and DA conditions are you working in? 2497 Quartz Hill Ca it was 4408 on the density calculator this morn.

[TODD]

Update to tune
pulled carb checked transfer slot perfectly square.
Threw in two new 6.5" power valves.
Carb back on recheck dwell timing: 30 degrees dwell 12 degrees BTDC
adjust idle trims for best afr
1) Idle results Left ~13.2-14.0 Right 13.5-14.2 AFR engine at operating temperature
2) Idle to 2500 RPM 12.5-13.5
3) cruise 2800-3500 RPM 12.2-12.6

Car is crisper on the takeoff with 6.5 power valve
will keep driving and report back on current tune.

[X33RS]

Those numbers look pretty good considering the DA you're dealing with.  I'd probably drive a while and see how your plugs look.  If they are too black for your liking you're close enough on the tune that you could simply step up a heat range or two and leave it alone as long as WOT AFR's are safe.

I think I mentioned the 6.5 power valves seem to work better in these 4053's on 302's.    You have your cruise AFR in the mid 12's which is right where my 302 is happy as well.  I've run mine leaner but it just starts to feel lazy, more throttle angle required to climb grades, etc...and mine never liked a really lean idle either.

You'll get to a point where you can pay less attention to the AFR's and more attention to the drivability aspect and see how the AFR's compare to how well the car drives in all conditions.  Best drivability is most important, just as you found car is crisper on take off with 6.5 power valves, even though that may have fattened up the "under load" area. 

Depending on how deep you want to get involved, You can start getting more in depth with changes if searching fuel mileage, such as smaller primary jet and then enlarging the power valve circuit to cover under load, some other changes that would require modifications that some may not want to do on an original 4053.

[TODD]

Took it for another spin this morning definitely have to feather the clutch at takeoff, or it falls flat.
I'm at 12 degrees advance right now. I am going to try and bump that up to 14-15 to see if it goes away.
Getting close to a excellent tune. 

[X33RS]

You're on the right track.   Mine likes more timing.   I'm running 16 initial, 20 centrifugal for a total of 36.  I found mine also likes to run the vacuum advance off manifold vacuum.  Part of the reasoning is because of the elevation here.  Mine responded to better idle quality and a little more engine vacuum at idle, which is at a premium up here at 5,000 feet where engines typically make 3-4 inches less vacuum than at sea level.   I run nearly the same vacuum setup you're running, which adds 10 degrees and it's all in with just 7-8 inches of vacuum.   It now makes about 9-10 inches of vacuum at idle up here (1,000 rpm) and down at sea level it's 13-14 inches. 

[TODD]

Ok changed the jets to 70 Pass/72 Driver, 76 rear Pass/78 rear driver
35 squirter with high flow screw/blue accelerator cam, 18 degrees advance.
Car runs fantastic best tune yet

Hint of peen lugging, probably 16 degrees is it will pull it back a scosh to~16-17

[X33RS]

Good to hear Todd

[ban617]

What are you running for fuel ?

[TODD]

unfortunately the highest octane here is 91

[X33RS]

91 is all we have here as well.  Not the best, but my DZ with 11:1 is running fantastic on it with the tune I mentioned above.  Been daily driving it for about 2 years now.  I'm running mine at 36 degrees of total timing (no vacuum advance) and all in by 2600 rpm.  I'm adding an additional 10 degrees of vacuum advance at part/light throttle conditions.  The factory cam has so much overlap it bleeds off a ton of low speed cylinder pressure making the compression ratio manageable, as long as the cam isn't installed really advanced. 

     This tune has gotten me a pinch over 17 mpg on the last 300 mile cruise on Rt 66, holding a steady 65 mph with 3.55's out back.  It routinely gets 14 mpg driving around town in traffic on 25-45 mph streets.

If you feel you're hearing some detonation, pull the plugs and look closely (I use magnifying glass) at the porcelain for black speckles (like pepper)   May take a fresh set of plugs and a couple of WOT pulls to see anything, if there is detonation.

I have my timing coming in fairly quickly with no issues.  If yours has a similar curve, and you feel like it's necessary to pull timing or you think you may see something on the plugs, a simple change would be to just slow the curve down a bit with a stiffer spring, rather than pull initial out of it which would affect idle quality, vacuum, and your overall total timing.   Just some thoughts.