Trouble with idle and warm starts
Thank you for the time you spent explaining the technical issues with the carburetor. It'll take a bit to digest this info. I have some things to try and will reply after I have to chance to work on this.
I know that 2210 is lean from personal experience. All the circuits are lean.
However
Fix your idle speed, and that will go a long way to easier starts, and
Here's why;
If the high idle is caused by the throttle being too far open; Then the transfer slot exposure below the plate is too high. At 350 rpm cranking speed, the air passing by the throttle blade, fails to pull fuel from the transfers or at least not enough to produce a combustible mixture. In an effort to get the mixture right,when warm, someone may have closed up or reduced the Idle mixture screws. The "vacuum" at the idle mixture ports will now be too low to activate them, much less pull a combustible mixture.
So #!, is insufficient fuel being drawn in.
#2 is this; in a no-start situation,none of the fuel being "sucked" in is getting burned. Where is it going? Some is going into the exhaust but most is getting by the rings,and ends up in the oilpan. On it it's way, it is washing the oil off the cylinder walls and your compression goes away.
So, you gotta make sure that when the engine is warm, the throttles are off the fast idle cam, and in the right position relative to the transfer slots, so that the transfer slots are working properly; and then the mixture screws also have to be flowing.
But
if the high idle-speed is not caused by the butterflies being open too far, then NONE of the above applies. Find out why this is so and fix it. Check your timing; make sure the Vacuum advance can is plumbed to the spark-port, and NOT to the intake manifold or to any carb-port that has vacuum at idle. The Vcan signal has to be dead at idle.
If you are 100% certain that there are NO vacuum leaks, then
set your transfer slot exposure under the main butterflies to a little taller than wide, with the speed-screw, reset your mixture screws to 2.5 turns from lightly seated, and
set your idlespeed with idle-timing. Make sure the advancer is working smoothly. You can reduce your Idle-timing to as far as TDC if you have to, to get the idle speed to fall around 650(P) with a stock 360. If you have to retard it that far, then check that your balancer TDC mark is accurate.
You can work on the timing AFTER the engine starts and idles properly.
Now here's
a secret; The engine doesn't suck fuel out of the carb's bowl.
Actually, atmosphere pushes fuel out the bowl in response to the lower pressure at the discharge ports and slots. So if the atmosphere cannot get into the floatbowl, guess what doesn't happen.
And
another secret;
on a cold start with the choke blade fully closed and the floatbowl open to atmosphere, and the throttle-blades opened by the fast-idle mechanism; then;
the low-pressure created by the falling pistons, moves up from the intake-manifold, to under the choke blade. Now the atmosphere pushing on the fuel in the floatbowl, causes the fuel to gush out of every orifice that it is possible to gush from, escaping the bowl. So now you have a ridiculous amount of fuel spewing into the airstream, and more than the air can handle. So a lot of it just falls to the plenum floor, and just lays there, or some of it may get coaxed to run down the runners, but mostly it just sticks to the cold iron.
So lets say the engine gets a combustible mixture; the first thing that happens after the engine springs to life is that the choke blade gets opened by the pull off, to stop the spewing, to prevent the engine from getting flooded. Next,the engine revs up and cleans itself up, pulling some/most of that fuel up off the intake floor, and off the runner walls. Now, the engine has used up most of the lying-around fuel, and the rpm is settling down.
But, the transfers and the mixture screws still cannot always keep supplying the tiny droplets that are required for combustion, and a lot of the bigger droplets are going straight thru the engine and dripping out the tailpipes. And yes some is getting into the oilpan.(And that is why we have to change the oil more often on carbed cars than on injecteds.)
So at this time, the choke pull-off adjustment has to be already set and maintained to an opening that sorta keeps the boosters alive, to feed that hungry beast, especially when at the one to two minute mark, you tap the gas pedal and the idle speed falls, AND the transfer slot fuel becomes less.
But. the choke-butterfly has to automatically open over time, beginning at about one or two minutes, in order that the engine doesn't flood and die; but not so fast that it starves for fuel.
So what opens that choke, and how is the rate of opening controlled?
Well on a factory intake, you have the double whammy of the heat-crossover under the carb, and the thermostatic choke element protruding into it, and sometimes an electrical assist. These have to all be working, especially that heat-crossover, which is warming the carb to prevent icing, and to get those Too-big gas droplets lying on the plenum floor, to break up or let go of eachother, so they can be burned.And then things have to be adjusted by the tunner.
So fix the idle speed and you may incidentally fix your warm-start.
Ok so
when warm, IF
the T-slot exposure is set right,(a little taller than wide)
and the compression is up, (at least 140psi and less than 5% variance)
and the float-bowl is vented,
and has the correct fuel-level (a tad on the high of spec)
and the ignition system is decent with clean plugs,
and the timing is even half-way close, (5 to 12 degrees at idle)
and the Torque convertor is not seized, (don't laugh it happens)
if all that is right, then the 360 should spring to life in two revolutions or less with the mini-starter, with no gas-pedal input.. Click vroom. Not quite as nice as a 289/302, but hey, it's still a Mopar.
And that's my opinion[/QUOTE]
I know that 2210 is lean from personal experience. All the circuits are lean.
However
Fix your idle speed, and that will go a long way to easier starts, and
Here's why;
If the high idle is caused by the throttle being too far open; Then the transfer slot exposure below the plate is too high. At 350 rpm cranking speed, the air passing by the throttle blade, fails to pull fuel from the transfers or at least not enough to produce a combustible mixture. In an effort to get the mixture right,when warm, someone may have closed up or reduced the Idle mixture screws. The "vacuum" at the idle mixture ports will now be too low to activate them, much less pull a combustible mixture.
So #!, is insufficient fuel being drawn in.
#2 is this; in a no-start situation,none of the fuel being "sucked" in is getting burned. Where is it going? Some is going into the exhaust but most is getting by the rings,and ends up in the oilpan. On it it's way, it is washing the oil off the cylinder walls and your compression goes away.
So, you gotta make sure that when the engine is warm, the throttles are off the fast idle cam, and in the right position relative to the transfer slots, so that the transfer slots are working properly; and then the mixture screws also have to be flowing.
But if the high idle-speed is not caused by the butterflies being open too far, then NONE of the above applies. Find out why this is so and fix it. Check your timing; make sure the Vacuum advance can is plumbed to the spark-port, and NOT to the intake manifold or to any carb-port that has vacuum at idle. The Vcan signal has to be dead at idle.
If you are 100% certain that there are NO vacuum leaks, then set your transfer slot exposure under the main butterflies to a little taller than wide, with the speed-screw, reset your mixture screws to 2.5 turns from lightly seated, and set your idlespeed with idle-timing. Make sure the advancer is working smoothly. You can reduce your Idle-timing to as far as TDC if you have to, to get the idle speed to fall around 650(P) with a stock 360. If you have to retard it that far, then check that your balancer TDC mark is accurate.
You can work on the timing AFTER the engine starts and idles properly.
Now here's a secret; The engine doesn't suck fuel out of the carb's bowl.
Actually, atmosphere pushes fuel out the bowl in response to the lower pressure at the discharge ports and slots. So if the atmosphere cannot get into the floatbowl, guess what doesn't happen.
And another secret;
on a cold start with the choke blade fully closed and the floatbowl open to atmosphere, and the throttle-blades opened by the fast-idle mechanism; then;
the low-pressure created by the falling pistons, moves up from the intake-manifold, to under the choke blade. Now the atmosphere pushing on the fuel in the floatbowl, causes the fuel to gush out of every orifice that it is possible to gush from, escaping the bowl. So now you have a ridiculous amount of fuel spewing into the airstream, and more than the air can handle. So a lot of it just falls to the plenum floor, and just lays there, or some of it may get coaxed to run down the runners, but mostly it just sticks to the cold iron.
So lets say the engine gets a combustible mixture; the first thing that happens after the engine springs to life is that the choke blade gets opened by the pull off, to stop the spewing, to prevent the engine from getting flooded. Next,the engine revs up and cleans itself up, pulling some/most of that fuel up off the intake floor, and off the runner walls. Now, the engine has used up most of the lying-around fuel, and the rpm is settling down.
But, the transfers and the mixture screws still cannot always keep supplying the tiny droplets that are required for combustion, and a lot of the bigger droplets are going straight thru the engine and dripping out the tailpipes. And yes some is getting into the oilpan.(And that is why we have to change the oil more often on carbed cars than on injecteds.)
So at this time, the choke pull-off adjustment has to be already set and maintained to an opening that sorta keeps the boosters alive, to feed that hungry beast, especially when at the one to two minute mark, you tap the gas pedal and the idle speed falls, AND the transfer slot fuel becomes less.
But. the choke-butterfly has to automatically open over time, beginning at about one or two minutes, in order that the engine doesn't flood and die; but not so fast that it starves for fuel.
So what opens that choke, and how is the rate of opening controlled?
Well on a factory intake, you have the double whammy of the heat-crossover under the carb, and the thermostatic choke element protruding into it, and sometimes an electrical assist. These have to all be working, especially that heat-crossover, which is warming the carb to prevent icing, and to get those Too-big gas droplets lying on the plenum floor, to break up or let go of eachother, so they can be burned.And then things have to be adjusted by the tunner.
So fix the idle speed and you may incidentally fix your warm-start.
Ok so when warm, IF
the T-slot exposure is set right,(a little taller than wide)
and the compression is up, (at least 140psi and less than 5% variance)
and the float-bowl is vented,
and has the correct fuel-level (a tad on the high of spec)
and the ignition system is decent with clean plugs,
and the timing is even half-way close, (5 to 12 degrees at idle)
and the Torque convertor is not seized, (don't laugh it happens)
if all that is right, then the 360 should spring to life in two revolutions or less with the mini-starter, with no gas-pedal input.. Click vroom. Not quite as nice as a 289/302, but hey, it's still a Mopar.
And that's my opinion
