Modifying Oil Pumps

[huskyboy]

From my experience on modafying pumps is sometimes you only need to modify one or the other to increase output it all depends on brand and make sometimes you just have to mod both pole one apart and study it really good watch where the to meet up sofar I've seen nun of them are perfect and while modify one baby steps are key otherwise you're just wasting time and money.

I agree, I’ve seen wide variations in the stihl control bolts. The ramps seem pretty consistent. The button can vary by as much as .010 thousandths. I found with a 460/461 pump .83 on the control bolt button size (stock they are about .100-.110) and about .020 off the ramp low side to work well in most cases. I just try to aim for one tank of oil to one tank of gas used with the oiler on max. Match up the bolt to the ramp on the “max” setting and see if they touch. If they don’t, you need to make the control bolt button smaller. Being careful is what I advise, less is more... you can’t put back what you take. The oilers are expensive...

 

[MG porting]

I agree, I’ve seen wide variations in the stihl control bolts. The ramps seem pretty consistent. The button can vary by as much as .010 thousandths. I found with a 460/461 pump .83 on the control bolt button size (stock they are about .100-.110) and about .020 off the ramp low side to work well in most cases. I just try to aim for one tank of oil to one tank of gas used with the oiler on max. Match up the bolt to the ramp on the “max” setting and see if they touch. If they don’t, you need to make the control bolt button smaller. Being careful is what I advise, less is more... you can’t put back what you take. The oilers are expensive...

Exactly. funny the oil pump on the ms460 I built that thing turned up all the way will empty the oil tank before running out of fuel and I didn't even touch that pump sometimes a guy can get lucky.lol

 

[Walter Glover]

Thanks fellas. Will go look mine over again real close. Get some numbers if I can.
I look at the pump this way:
Maximum displacement of the piston is dependant on cam surface angle.
Limiting of displacement is done by the adjuster.
With this in mind I need to look at the pumps again......
Cheers

 

[Terry Syd]

Also remember it is a positive 'displacement' pump. In other words, it can only pump out what ever oil is IN the pump.

Check the inlets for flow and you may want to shim the return spring to 'suck' in more oil between the strokes.

 

[Wonkydonkey]

I was going to add about the spring...... firstly oil can be a bit thick when cold, and less viscous when warm. It’s the spring that sucks it into the pump. so with that said.. the AM pumps generally have weaker springs... add it together and a oil pump may not oil very well in the colder times of the yr..

I always keep a check on how much oil is being used with every tank of fuel

 

[Terry Syd]

You can also add a bit of pre-mix to the first tank (or part tank) of oil for the day. Don't worry, it won't catch fire on the bar.

The pre-mix will thin the oil to get it flowing. As the bar warms up the pre-mix will evaporate and leave the thicker oil on the bar. Once the saw is warm, then go to your regular oil.

Think of it like motorcycle chain oil, the stuff you spray on and then the lighter elements evaporate and leave the thicker oil on the chain.

 

[huskyboy]

Exactly. funny the oil pump on the ms460 I built that thing turned up all the way will empty the oil tank before running out of fuel and I didn't even touch that pump sometimes a guy can get lucky.lol

I had a 440 here like that. Stock pump and it was using 1 tank oil to one tank of gas. Then I had two 044 here with the same pump that were stingy. 20” bar saw. They can vary. Which is why it’s important to see how much they oil before you tear into it. As a rule I found most stihls benefit from a oiler mod.

 

[MG porting]

I had a 440 here like that. Stock pump and it was using 1 tank oil to one tank of gas. Then I had two 044 here with the same pump that were stingy. 20” bar saw. They can vary. Which is why it’s important to see how much they oil before you tear into it. As a rule I found most stihls benefit from a oiler mod.

Yea Stihl are pretty much the only ones I've ever had to mod as well Husqvarna not so much they seem to oil pretty good as is.

 

[CR888]

Also remember it is a positive 'displacement' pump. In other words, it can only pump out what ever oil is IN the pump.

Check the inlets for flow and you may want to shim the return spring to 'suck' in more oil between the strokes.

You think say drilling out the intake stub a bit would help. The little barbed stub that the oil tank hose connects too. Also shimming the spring would that involve a little metal washer or something is the idea to compress the spring a bit to make it more responsive? I've had mixed results modding oil pumps, some have worked well others its hard to know whether ot made much difference.

 

[Terry Syd]

Also shimming the spring would that involve a little metal washer or something is the idea to compress the spring a bit to make it more responsive?

Yeah, a washer or two under the spring. It increases the pre-load on the spring, which is the most important force to get the piston to EXTEND further. If someone used a stronger spring (wire thickness and/or pitch) it would increase overall force, which although it may achieve the same extension also increases the friction on the ramp more than just increasing the pre-load.

 

[Walter Glover]

Have a Husky 372xp oiler and a Stihl 660 oiler here.
Both pistons are 0.235" diameter and both at max stroke on adjuster allow 0.025" of stroke.
The Husky pump gear has 13 teeth and the Stihl has 11.
So for the same saw rpm the stihl will pump more oil as found. The Husky design is flat out better and would be easy to mod. The Stihl is small intricate work to mod it for more.
Checked the Stihl for clearance between the adjuster and piston at full stroke and this one is good.

 

[Wonkydonkey]

Not sure what your saying about the stihl oil pump ,, it s documented with the std and the high out put in mm (the stroke), in the stihl Ipl on the 660...if you don’t have it google (stihl ms 660 ipl )

 

[Leafy]

What's the tpi of the screw on the crank?

 

[Walter Glover]

Crank worms are all one to one

I will check that ipl out. I just posted my measurements

Cheers

Edit, checked ipl and oiler is rated at 5 to 15cc at 10,000rpm. Doing the math with what I measured I get 16cc delivery. Not too bad

 

[huskyboy]

A 660 has a terrible stock oiler for a 90cc saw unless you have the HO pump, same oiler as a 460/461. A 372/390xp puts out quite a bit more volume on a 28” bar I found after using both. The hardest part of modding the stihl oiler is removing the tiny roll pins, which isn’t that bad with the right size punch. I filed one down to work. Then you have to have a understanding how the oiler works. Kind of self explanatory once you have it apart and study it.

 

[Walter Glover]

Do the 372 and 390 Husky use the same oiler?

 

[huskyboy]

Do the 372 and 390 Husky use the same oiler?

Yes. I found the later ones with the metal drive oiler put out a little more than the early ones with the all plastic drive wheel oiler.

 

[Walter Glover]

Pulled the pump on my 181se. Now that is one fine pump!
Drive gear is 22 teeth so pumps slower but the piston is 0.255” diameter and max stroke is 0.075”. This saw was set on number 2 setting which allows about 50% stroke. Running a 24” bar so will see how it oils when it sees some wood.

 

[Walter Glover]

Metal drive vs plastic? I thought they all were plastic drive gears? Is there such a thing as a drive gear that is a multi start thread? That would spin the pump faster for more oiling.

 

[Lightning Performance]

Does anyone know if Stihl chromed or hard surfaced the pump gear?

The control bolt is not coated that I can see but probably hardened.

1122 1128 take a different main gear. The control bolt looks the same but is listed as a different part number in my research. I might be wrong about the control bolt not being interchangeable. I don't mix pump parts when modding them, yet.

Can the 460 benefit from pump mods besides the gear, maybe. The 660 HO pump needs more to get past one to one tank use. Mine needs to put out more earl. The casting will need work along with a longer spring or shims. Prefer almost two tanks of oil to one tank of gas if it can be done... I'm all ears.