Willys Flathead Idle Timing

[wkuran]

Is it possible your combination of cam overlap and the intake plenum design just don't want to work together at idle?

Yes, certainly possible.

[Tuner]

Hiya's,
7 lbs/hour is wayyyyyy too much fuel for that engine at idle, probably at least 2x. Forget the wideband for now and use the MAP sensor reading as a vacuum gauge of sorts, keep pulling fuel in those cells 'till it gets happy.

If you are thinking the usual .5 lb per HP/hr, that only represents 14 HP. .5 lbs hp/hr is more efficient than an idling engine will be, and particularly a flathead side-valve, because of overlap EGR, etc. Supercharged engine BSFC is commonly .6 or .65 or so, because of the additional power required to turn the compressor(s). 7/.65=10.8 HP to idle, well within reason. Do you think a 5 HP Brigs will turn all the machinery and two superchargers at idle speed? Not likely.

The fuel required to idle must supply the power to make the basic engine rotate against friction (don't overlook the stiff valve springs increase fiction) and pumping loss, plus turn the two superchargers, so the high fuel flow represents the total power required to idle and the superchargers don't turn for free.

I would turn off the O2 feedback and adjust the idle A/F and timing by ear and then morph the advanced idle timing into the timing table set as the engine requires for normal load conditions and boost.

You can leave the timing up, headers run cooler.

Yes, set the idle initial advance to the happy spot. However, that requires modifying the distributor centrifugal to limit the total. Flatheads do not like much total advance.

This exactly. Find whatever minimum timing makes best combustion for best torque in the particular load conditions, idle, level road, part-throttle light and moderate acceleration, WOT and WOT W/Boost, every different condition of load and RPM may want a large difference in timing for best combustion, and your custom cylinder head may have significant influence which requires different timing than the original head.

Flathead Fords have a problem with this because there are several different cylinder heads available for them and depending on year original Ford heads are not alike. Some early V8s only need 17 total and will not tolerate more. The later motors use 25-26 total. When I repair and set up a distributor for a Flathead Ford I need to know these details and make sure the right advance mechanism is used to avoid problems with knock or overheating. Hudson Hornet uses 17 total.

[wkuran]

If you are thinking the usual .5 lb per HP/hr . . .

I should have considered BSFC earlier. Here are some measured loads and extimates.
Water Pump: 0.15 hp (call it 0.2) This was measured when doing water pump impeller testing (see Figure 8.0). https://drive.google.com/file/d/1LMdb7V ... wVyMB/view
Crankcase Vacuum Pump: 0.15 hp (call it 0.2) This was measure when doing vacuum pump testing (see Figure 34). https://drive.google.com/file/d/1nsF95b ... 81uUQ/view
Paxton SN60 Supercharger 2 hp x 2 units = 4 hp (call it 5.0) I got this from the VS57 compressor curve. The SN60 and VS57 have identical planetary drives, rotors, scroll, etc. The compressor curve does show data at idle speed (about 7000 rotor rpm) so this is really a guestimate.
Engine Friction: I'm guessing at 5 hp.
That adds up to 11 hp. 11 hp X 0.65 BSFC = 7.2 lbs/hr. The same as your estimate.

However . . .
It is running well on 4.9 lbs of fuel with the following
CLT Temp: 163 (180° thermostat is installed but the head has a bypass (set at 5 percent) so it doesn't see 180 degrees unless making power)
MAP: 52 - 56 KPa
IAC: 2 - 4 percent open
Timing: 30 degrees
A/F Ratio: 15 - 17 (learn is not on)
EGT: 600 - 800 degress (No. 3 is around 350 - it is always low - why?)
Estimated VE: 57 percent

If this looks to be okay and I were to leave the timing and fuel maps as is, how do I transition out of the idle area (about nine cells)? If you look at the attached maps you'll see that as soom as the rpm and/or load increases the table values are significantly different (much higher for the fuel and much lower for timing.
Timing Map https://photos.google.com/search/_tra_/ ... MMxfzDWuWz
Fuel Map https://photos.google.com/search/_tra_/ ... ECE7hRNr2_

Thanks . . .

[Tuner]

I don't think anybody will sign in to ghooghul anything so you will have to post the images here.

The odd EGT, have you tried moving the injector to a different cylinder to see if the EGT follows it?

[wkuran]

I'm happy with the results. The engine starts easily, no more rich idle, and plugs are clean. This is what I did based on suggestions, etc.

Added 15 degrees (was 15, now 30) of timeing at idel (800 rpm)
Reduced fuel flow at idle for 7 to 5 (40% less).
Replaced heat range 9 plugs with heat range 5 plugs.
Figured out how to transition out the high idle advance to normal driving conditions.

The tune is good for what I call around town driving (800 to 3000 rpm with up to 2 psi boost). For racing (3000 to 5500 rpm and up to 10 pounds boost) I'll have to modifiy the tune. For now I'm happy to take it to the grocery store and show off at the local coffee and cars meet up.

Cold Plug: https://www.willysutilitywagon.com/wp-c ... scaled.jpg
Hot Plug:https://www.willysutilitywagon.com/wp-c ... scaled.jpg

Thanks again . . .

[PackardV8]

Glad you found your way out of the woods.

Learn something every day. That 30 degrees of advance at idle may only be applicable to highly modified Willys six-cylinders w/EFI; I'd never have thought to try that much initial advance on a flathead.