63 F.I. calibration

[Rainer S.]

I would like to comment again, in reference to the problem I ran into, during the cam run-in session Jan 3, 04.
I finally found the root cause of the problem, running too rich and burning too much fuel and consequently running rough.
The problem was a bad cranking signal valve. I followed Bill Clubber's and Mike McKowen's advise, pinched-off the signal line, therefor elimination the vacuum feedback. The engine cleaned-up beautifully and runs smooth. Still have to adjust a few things to make it run better, but needed to drain the oil (for the 3rd time) to be sure that gas was not present in the oil.
I also got some help from John DeGregory (F.I. restorer, unfortunately not the one that restored mine). will order a replacement cranking signal valve from him tomorrow.
One observation I had, when I ran the motor from cold. After a short time, white smoke was coming out of the tailpipes, like you see on todays new cars, except a lot more. Almost as if I was burning coolant. It did not smell, and evaporated quickly, like steam. The white smoke would stop, as the engine would warm up. Is that normal ? Or is it also related to running out of specs still (too rich ?)I am sureI will have to do more tweeking.

Rainer

[Tracy C.]

Re: 63 F.I. calibration

Rainer,

Is it winter where you live? What you describe sounds like normal condensation in the exhaust pipes turning to steam and evaporating.

I'd say if the temperature is 50 degrees or below what you see is normal.

If you hold your hand to the outlet pipe, does it become moist?

tc

[Roy B.]

Re: 63 F.I. calibration

Even thou there are people that are vary good at rebuilding FI units and calibrating them up to specks a person's engine depending on how many miles of ware it has MAY read a different vacuum readings. (The FI runs on engine vacuum) I seen many FI just rebuilt that still run rich or lean . So understanding how to fine tune the unit a little better is why I'm putting this pic. on.
The Ratio lever works like the (carb metering rods.)
By adjusting the travel of the lever you (increase or decrease) fuel flow.
While at idol if the engine is running to rich or gas mileage is really poor you increase or decrease the economy lever.( while driving at a stady speed the lever sets on the economy lever.)
When ex-celerating the engine stumbles or blows black smoke , you increase or decrease the power lever.( lever moves to the power side)
Only if needed for farther adjustment do you adjust the enrichment diaphragm.
I have had many FI units and rebuilt them ( in the old days when I was poor) then driving I would play with the ratio lever to get my Corvette running just the way I liked it.

[Ed Jennings]

Re: 63 F.I. calibration

If you set your economy stop by trial and error, do so in 1/4 or 1/2 turn increments so you can return to a known setting. At some point it will develop a lean surge or stumble. Then you need to richen a 1/2 turn or so. Be absolutely certain you have no vacuum leaks. As Roy states, it operates on vacuum, and a leak screws up the whole works.

[Duke W.]

Re: 63 F.I. calibration

The primary combustion products of hydrocarbon fuels and oxygen are CO2 and H2O. Both are in a gas state exiting the engine and are colorless and orderless. In cool weather, when the engine and exhaust system are cold, the exhaust will cool
enough for some of the water vapor to condense into tiny droplets before it exits the tail pipe, which is what the "white smoke" is - like clouds in the sky.

Once the engine and exhaust system are fully warmed up, the exhaust is hot enough at the tailpipe exit for the H2O to still be in a gas state, and the "white smoke" disappears.

H2O condesation is also what rusts out the exhaust system from the inside, and short trips that don't get the exhaust system hot will do it in quite quickly. The heat riser on carbureted cars will tend to rust out the right hand side, even if it is functioning properly because most of the exhaust is routed through the heat riser passage to the LH side until the heat riser opens, so the RH side takes considerably longer to warm up.

Duke

[Rainer S.]

Re: 63 F.I. calibration

Thanks everybody for the accurate description of the cause of the vapor and why its happening.
Its indead winter here in Michigan and what i see, is obviously condensation. I just didnt expect so much. Will cont. to calibrate the ratio lever, but some of it may have to wait, when the car can be driven...

Rainer

[Ed Jennings]

Re: 63 F.I. calibration

You can get a good approximate starting point using a MityVac. Set the power stop where the lever will just touch at 3" Hg and will go fully against the economy stop at 9" Hg. This will get you close enough that the engine should run reasonably well. You can check and see if your present settings are at least close to these readings prior to any tweaking.

[Michael H.]

Re: 63 F.I. calibration

Setting the lean/power stops without running the unit on an engine with a manometer is not possible and the vacuum readings at which the lever leaves the stop must only be set once the stops are set for the correct fuel flow. The angle of the ratio lever, or the position of the pivot at the end of the roller on the axle/link assy determines the ratio of leverage that the main control diaphragm has against the spill valve. When the engine is running at idle and the ratio lever is at the lean stop, the slight vacuum signal at the main control diaphragm pulls up on the axle/link assy which closes off the bypass inside forcing fuel to travel to the nozzle circuit. If the valve is closed further, more fuel is directed to the nozzle. If the adjustment at the ratio lever is changed, the same vacuum signal has more (or less) leverage, or mechanical advantage against the spill valve. Once these adjustments are made and the correct fuel flow ratio is obtained, the enrichment rod length should be adjusted so the lever leaves the stops at or near the desired vacuum readings. This is done by removing the enrichment rod and changing it's length, which changes the spring pressure that is acting on it, to change the readings at which the lever leaves the stop.
Adjusting these stops to change or adjust the point at which the lever leaves the stop is totally incorrect. It's only a final adjustment to be made once the stops are set correctly for fuel pressure/air volume ratio is set.

The stop adjustment screws are not part of a general tune up but are used for the initial calibration of the unit and should require little change over the years but because they are basically the only thing visible to fiddlle with, they often become totally out of adjustment.
Unfortunately, there's no way to even guess at a preliminary setting as the location of these stops seemed to vary quite a bit on brand new factory calibrated units.
On the lean side, at idle, the final adjustment is made with the small adjustment needle on the top of the air meter, which adds or restricts bleed air to assist the signal to the main control diaphragm.