Bleed line function?

[mercrazy]

Can someone please explain how the bleed system works?
Here is my understanding. The fuel vapor passes through the reeds. At low idle, not all the vapor is taken into the cylinder and collapses in the crankcase. It puddles up and drains down to the check valves. When crankcase pressure increases, it pushes this fuel into the bleed lines which carry it to the cylinders. When crankcase pressure increases, it pushes it to a low pressure cylinder on the downstroke. Is this why it’s critical to have lines connected to the right places? Is this right?

[Jim Speros]

If you really want to confuse yourself look at early 3.0 manual with all the check valves. Early 2.4 didn't use check valves and diagrams did not include arrows.Early 3.0 liter charts include arrows and there are enough different versions to make your head spin.

Yes, generally the fuel moves away from reeds to transfer ports. Yes, it is important hoses are routed correctly.

[Jim Speros]

Now that my head is circling the drain, There are transfer hoses that are not bleed hoses. I think of the ones the create a vacuum in mains to draw fuel from crankcase and ultimately to front side of reeds or 2.4 carbs. The bottom main gets lubes from crankcase residual fuel and transfers to top bearing.

[skialot2]

On a carb motor, the bleed system takes puddling fuel from the crankcase and pushes it to the boost ports in the cylinder to be burned. On an EFI motor the bleed system takes the puddling fuel and pumps it back into the VST. They also pump Fuel/ oil from the bottom main bearing to the top main bearing to help keep it lubricated.

I found a description in the manual for an EFI but not a carb motor.

[mercrazy]

So am I right for a carb engine?
Does crankcase vacuum suck fuel to lubricate center mains bearings?

[Jim Speros]

Lower left most image shows that. The hose from center mains to intake behind top too carbs

[mercrazy]

Lower left most image shows that. The hose from center mains to intake behind top too carbs

But what force pulls it to bearings. Seems there would be negative pressure behind carbs?

[Jim Speros]

Negative pressure = vacuum

Seems to me the fuel mix in crankcase is intermittently under pressure and the vacuum helps move mix thru bearing

[Merc 2.5]

On a carb motor yes the top and bottom bearings get lubed from the bleed line (unburnt fuel/oil) but I wanna say its by pressure but don't quote me , also I believe if u pull line off and start ur motor u could easily find out

[mercrazy]

On a carb motor yes the top and bottom bearings get lubed from the bleed line (unburnt fuel/oil) but I wanna say its by pressure but don't quote me , also I believe if u pull line off and start ur motor u could easily find out

I did that years ago. At low idle it squirts, if I raise idle over 1200rpm, no squirting. I remember back then, people would let their engine warm up at low idle and it would chug and smoke and foul plugs.

[tlwjkw]

I remember back then, people would let their engine warm up at low idle and it would chug and smoke and foul plugs.

learned early on ta have tha motor trimmed at least level or a tad positive that helped quite a bit with tha fat idle...

[Glastron1987]

I've always kind of hated that seemingly silly bleed system and wished there was a simpler alternative. Why does that pooling occur, are the reeds not designed properly or something? Any chance you could do away with it if you use some CCMS reeds?