rlmcnii

My Feedback: (3)

All,
I am assembling a Kange Waco UPF-7. The book says to anticipate o weight of 12 to 15.5 pounds. This one will probably be near the middle of that range, depending on the response to this question.

As I have no experience with the big-block Saitos, I need to ask: Do you big-block-experience people think that a Saito 1.50 would be ample for this airplane. It will be used for sport and basic IMAC style flying, no 3-D. On the other hand, dragging a model around at 75 or 80 percent power is no fun (at least for me) either. Level flight at 50 or 60 percent with the ability to enter elements of the basic sequence from level flight would be sufficient. Indeed, that power would probably be fine.

Originally, a 40cc gasser was under consideration. But, I do love those Saitos!

Any thoughts would be welcome; and, thank you in advance. rlmcnii

skillet92

What kind of fuel do i have to run. I have broke my 125 in on cool power 4c that is 15% i want to know if i can use my regular 15 cool power that i use in my 2c??

William Robison

My Feedback: (3)

rlmcnii:

Sorry, I read your post earlier and somehow thought I had answered it. An FA-150 with a Zinger 18x6 should give about 15 pounds thrust at 8500 rpm, more than sufficient for your WACo bipe.

Skillet:

15% nitro is fine, but why do you reject the safety and insurance offered by castor oil? Stay with Morgan Fuels, but switch to Omega. Your engines will thank you for the castor in the oil blend. This is the two strokes as well, but �specially the cam and tappets in the Saito.

Bill.

skillet92

Don't reject the safety of the caster just the mess and stains that it leaves on the beautiful engine! I do believe that the cool power that I have for my 2c has some caster in it just not the amount as the cool power that i bought for the 4c. BTW I installed that cowl with some more cut outs and at full throttle it will do 8800 on a 16x6 MAS and after twenty minutes at full and half settings I have no loss in power. I still do not have the best midrange that I would think it should have, but I think I can live with that. I will know when I fly it next weekend.

PS I just looked at my fuel and it is Omega and it also says not use After run oil so i think what i have i can use in both the 2c and 4c!

JettPilot

My Feedback: (6)

Played for hours with the Saito 150 yesterday, and resulted in 5 minutes of flight time , 2 deadsticks, and one very sore wrist [:@]

I think the low speed needle might have been so far off, that the HS was in to far for it to run.

How many turns from closed does a Saito 150 GK LS needle usually run at ? I think I need to set the best adjustment for both the HS and LS and then adjust the fuel pump to get the engine running instead of turning the needles out of range [sm=idea.gif]

Thanks,

JettPilot

William Robison

My Feedback: (3)

JP:

Sorry, I thought I had made it clear. Adjust the pump pressure to get the high speed needle peaked at four to five turns open. If it’s peaked at three turns the pressure is too high. Lower the pressure and try again. When you get the HS mixture right with the HS needle four to five turns open all should be well. Try for 4½ or more if you can get it.

Skillet:

Fine. The Omega is the “Right” fuel for both the two and four stroke engines. But don’t stop using after run oil. Still needed in spite of fuel maker’s claims.

Bill.

J-3

Hi All,
I have a FA-30 that is looking for an airplane, and I have a FA-65 I am installing in a GP J-3 ARF. I have read up to page 17 and I have a long way to go to catch up, but I am learning and enjoying the read. Thanks...Brian

William Robison

My Feedback: (3)

Brian:

Welcome. I've put you in as number 312.

Any relation to Otto Kretchmer? Yes, I note you spell yours with an"A" instead of the "E" in his name. Still wondering.

Bill.

J-3

Hi Bill, No relation to Otto that I know of. My last name started out at Kretszchmar, then the z got dropped to Kretschmar, my dad dropped the s to Kretchmar. I have not dropped any letters and plan to keep it that way

skillet92

I usually fly every weekend and was wondering about the after run oil. Up until now I have used it everytime, but some of my club members have said that you only need it when you are not going to be flying for awhile. How long does it take for the engines to start get damaged from the fuel. I know that the fuel is bad. I ran cars for a long time, but I was running them 2 or 3 times a week and when I did lay off it was never more than 2 weeks. I know that it is better to be safe than sorry, but the for the saito it is a little trying to get the oil in the back breather hole. BTW the FW-190 weights 10lbs 3ozs and I hope that the 125 is going to be enough. This is my first plane this heavy, all my others are in the 5 to 7 range.

William Robison

My Feedback: (3)

Skillet:

As the engine runs acids are formed in the combustion process. Most of the acids are blown out the exhaust, but some also blow by the piston along with the oil for the bottom end. Some of the acid and other corrosives go out the vent, but just as with the oil, a lot stays in the engine. Some unburned methanol and nitromethane also get in the crank case. There is no way to avoid this contamination. The same thing happens in your car engine, one of the main reasons for regular oil changes.

There is nothing we can do to prevent these acids working while the engine is running, but they are not in a high concentration so their effect is minimal. If left in the engine after running though, they will continue to eat away at the internal metals.

The easiest way to prevent short term damage is using an oil with a high film strength. Synthetic oils do not have this high film strength, they tend to drain off surfaces quickly, and the acids remain, starting their damage. Castor oil on the other hand has an extremely high film strength. This not only makes your airplane harder to clean after flight, it leaves a coating on the internal parts that is resistant to penetration by the acids and other corrosives. An added benefit of the high film strength of the castor oil is decreased wear of the cam lobes and tappets.

We can also flush the engine, and neutralize the acids. This is where the after run oil comes in. An ideal after run oil will have chemical buffers that not only will neutralize the acid, they will also counter any alkaline corrosives left in the engine. The ideal oil will have high “Moisture Displacement” qualities as well, lifting any water off the metal and replacing the water with an oil film. Dexron automatic transmission fluid has all these desired qualities.

So when your day’s flying is finished pump the tank dry, and spin the engine with glow heat applied, and run it dry also. Then pump a healthy slug of Dexron ATF into the crank case, turn the engine a few turns by hand to be sure it’s not too full and apply your electric starter to give the engine a good spin, get all the inside coated, and blow the excess oil out the vent.

The castor oil in the fuel, and religious use of after run oiling, will make your engine last a lot longer before any repair are needed.

Bill.

William Robison

My Feedback: (3)

Skillet:

From Saito Notes:
-------------------------
After run oil – how the #% do I get it in the crankcase?
Some few twins have two crankcase ports, but none of the singles do. As a result when you try to force the ARO in it tends to blow back out. No problem.

Got a plastic squeeze bottle with a tapered spout, the sort that you put your tomato catsup or mustard in. Best if you can see the level of the contents. If the tip is small enough to go into the vent hose you’re done. If not a short length of brass tubing can be forced in the tip, or you can cut the tip back to get a larger diameter that will let you push the vent hose inside.

Fill it about ½ way with your favorite AR oil, and you are ready.

Pull the vent hose out the top of the plane, or if not convenient turn the plane over, just be sure the hose is pointing up. Attach your new oil bottle to the hose. Then holding the bottle with the tip down turn the engine slowly.

While the piston is going down in the bore you’ll see bubbles in the oil bottle, then when the piston is going up it will draw oil back into the engine. Keep turning until you have drawn an ounce or so of oil in. Unhook the bottle, turn the plane back upright (Or the hose back out the bottom) and spin the engine for a few seconds with your starter. This last will make sure the oil is run everywhere inside the engine, and blow any excess out.

Simple, isn’t it?
-------------------------------

Bill.

JettPilot

My Feedback: (6)

The low speed seems to affect the HS needle greatly, I have the HS set to 5 turns open, but I beleive that my LS needle is so far off could be affecting the HS even at full throttle [X(]. I need to know more or less how many turns the LS should be open also so I have a place to start.

If it goes lean while I am running the engine up, is it going to ruin the engine ? The other day I gave it full throttle and it ran at 7200 RPM with no smoke comming out the exaust for about 10 seconds while I spun the HS needle like mad [:@]. How long will the engine tolerate a lean run at full throttle while I adjust it ? (No cowl, mounted upright in the open...) 16X8 APC Prop, Omega 10 % fuel...

JettPilot

William Robison

My Feedback: (3)

Jett:

Momentary lean wont hurt your engine, and ten seconds is short enough to be considered momentary.

The low speed needle, using suction or muffler pressure, is the main mixture control up to ½ throttle, and still has a great effect at ¾ throttle. This is why the HS must be adjusted at full throttle only.

Starting point for the LS needle is with the flat slotted end slightly below flush with the face of the throttle lever. This will be very rich. Starting point for the HS needle on your engine should be 4½ to 5 turns open, and close to the same position when tuned. This final position is the first indication of correct pressure when using a pump. If yu have to lean it more than a turn or so to reach peak rpm the pressure is probably too high.

After adjusting the HS AT FULL THROTTLE and setting the LS for good transition set the throttle ½ open or a hair more, and pinch the fuel line. If the rpm rises just a little you’re set. If it falls immediately raise the pressure and reset the needles. If it stays the same for a moment and then falls you are at the point of having the pressure too low. Best if the rpm rises just a bit. Same old thing, better safe (rich) than sorry.

Bill.

crazy4planes2000

Can you please tell me how i can decide if my 65 has the high lift cam or not.

Garry (crazy4planes2000)

w8ye

My Feedback: (16)

The high cam version has little brass guides sticking up out of the cam box. They are covered by the rubber pushrod boots but you can feel them under the boots.

rlmcnii

My Feedback: (3)

WR and JP:

I've been following this pump-adjusting post from a distance as there may be a pump in my future. It seems as if one needs to adjust one's pump to establish a nominal fuel-flow. That is, the pump pressure shoud compensate for the positioning of the tank (high, low, or too far from the engine) and return the flow to that of a fuel system with a normally positioned tank and no pump. Or, perhaps just a bit more flow than in an unassisted system. Is this correct??

Too much pressure, i.e. too much flow results in a situation where the needles become difficult - or perhaps impossible to adjust. I suspect this is why WR recommends setting the pump so that the HS needle will be properly adjusted at 4 to 5 turns out. This adjustment of the HS needle will maintain a workable, spatial, relationship between the HS and the LS and thereby permit one to tune the LS after the HS has been adjused at full-throttle. This is the standard Saito set-up drill. (In my limited Saito experience it seems as if the HS needle usually does not need to be leaned too much from the beginning setting and if it is set up too lean, it becomes very difficult to tune the LS needle. I think, perhaps incorrectly, that this is because of the loss of the workable, spatial, relationship between HS and LS needles. Not too mention, the engine will not run properly, if at all, at wide-open throttle. Further, from reading many of these posts, I believe that many Saito tyros mistakenly adjust the HS needle at other than wide-open. I did.)

What if one were to set the HS needle at 4, 4.5, or 5 turns open (choose your setting) and, at wide-open throttle, ADJUST THE PUMP to max rpms?? One may have to increase or decrease the fuel-flow, but the result would be stoichemetric combustion; i.e. max rpms. Would not a proper. nominal, fuel-flow thereby be established? Further, since a nominal (or normal) fuel flow had been established, would one not be able to then tune the engine as if the pump did not exist?? In the final tuning one would be dealing with only one, collective, variable..the needles.

Any thoughts? Or, tell me what I don't know!! Thanks, rlmcnii


P.S. I was thinking about this a little more. What if one just set up the engine on a test-stand first? Break it in, adjust the needles, etc.. Then, put it in the plane with the pump, go to wide-open throttle and adjust the pump for max rpms, or a bit rich of max if you had set up the HS needle on the rich side with no pump in use. That way, one could be fairly certain that the pump was doing nothing more than compensating for the fuel-system installation and not creating an unmanageable fuel-flow condition. Again, tell me what I don't know (just about pumps and Saitos, please!).

William Robison

My Feedback: (3)

Jim:

You're right on current production, but an older mid block engine with the lower tappet guides could still have the "S" cam installed at an overhaul without changing the cam box.

Bill.

William Robison

My Feedback: (3)

rlmcnii:

Quote:

ORIGINAL: rimcnii

It seems as if one needs to adjust one's pump to establish a nominal fuel-flow. That is, the pump pressure should compensate for the positioning of the tank (high, low, or too far from the engine) and return the flow to that of a fuel system with a normally positioned tank and no pump. Or, perhaps just a bit more flow than in an unassisted system. Is this correct??

That’s pretty much correct, there’s some leeway on each side of that setting though.

Quote:

Too much pressure, i.e. too much flow results in a situation where the needles become difficult - or perhaps impossible to adjust. I suspect this is why WR recommends setting the pump so that the HS needle will be properly adjusted at 4 to 5 turns out.

This is true, see more comments below on “Sleeve” metering.

Quote:

What if one were to set the HS needle at 4, 4.5, or 5 turns open (choose your setting) and, at wide-open throttle, ADJUST THE PUMP to max rpm?

This is, effectively, the way I recommend doing the adjustment. Many pump installations don’t allow easy access to the pressure adjustment, with them it’s usually safer to run the engine, find where the HS setting comes in, shut the engine down and adjust the pump, then restart for another check. If you have access to the regulator screw on the pump I see no reason why your method would not work just as well. Always being sure, of course, to allow enough time for the engine rpm and pump pressure to stabilize between adjustments.

The later Saito carbs do not have a true low speed needle. They instead use a sleeve that covers the end of the spray bar in the mid block engines, and covers the fuel orifice in the spray bar on the big block engines. This is why the LS “Needle” has such a great effect up to about ¾ throttle. And part of the reason why they are so sensitive to high fuel pressure.

Bill.

rlmcnii

My Feedback: (3)

WR,

Thank you for the reply. If there is, indeed, a pump in my (or anyone else's) future your guidance will be of great help.

I was aware of the spray-bar and sleeve mechanism within the carburetor. The spatial relationship between those two was the spatial relationship to which I was referring. I suspect if the HS needl has to be leaned (turned in) too much that the workable relationship will be destroyed. That is, the needle will be adjusted beyond the limits of function of the carburetor and one will never be able to properly tune the engine.

Your point about access to the pump is well taken. rlmcnii

JettPilot

My Feedback: (6)

I just ran my Saito 150 with the settings you specified (low needle just below surface and HS at 5 turns). I adjusted the screw on the Perry pump so far back it was almost to fall out and there was still to much pressure [] HS ran great at about 2 turns out... And good idle resulted in very rich midrange. I have the T fitting right against the crank vent and the crank pressure goes straight out to atmosphere while the perry pump hose is on the bottom of the T. I tried it with 4 inches of hose on the top of the T and also with no hose, so that it vented to atmosphere with less than 1/2 inch total restriction. The fuel pressure was to high no matter what I did....

I am starting to think that I need to do something like the Helicopter guys do, which is to put another T between the output of the Perry pump and the carburetor, with the bottom of the T returning fuel to the fuel tank. Its a bit more complicated that way, but the fuel pressure against the carb would be about zero... Any thoughts on this idea ?

JettPilot

Thunderchild

Bill Robison - Assistance please!!

Hi Bill,
I managed to stick an intake valve in my 82 yet again on the weekend. After disassembly, rectification and re-assembly, I put the plane on a test stand and thought I would do some serious tuning to try and improve my fuel burn (I've been running it rich since new) and want to get it right now that I have the velocity stack in place.

Now here is where it got interesting. I peeked the RPM on the HS needle, but it wouldn't go much past 7,500 (10% nitro, 11 X 10 prop). I removed the pressure feed to the tank and immediately saw a 1,000 to 1500 RPM jump in speed and the engine smoothed out.

What's the deal Bill? Why is my engine running like a hairy goat on pressure and then like a sewing machine without it?

What have I stuffed up?

BTW, took the opportunity to inspect the internals of the engine (only had the head off to do the valve) and she looks like she was just out of the box. That castor in the fuel and the after run oil is sure doing its job!

TC

rlmcnii

My Feedback: (3)

JP,

Could the Tee be too close to the crankcase vent. Perhaps a length of tubing would dissipate the pressure impulses a bit. Just a thought.

Also, does anyone know why the Perry Pump website specifically recommends the VP-20 for four strokes? Just another thought.

William Robison

My Feedback: (3)

Jett:

rimcnii mentioned the hose length between the case vent and the tee. Lengthening this hose will also lower the pump pressure. Or if you are using the hard hose that came with the pump you can use ordinary silicone hose in its place. That will lower the pressure too, as will lengthening any of the hoses except the vent from the tee to the air.

Your suggestion of the tee and fuel return is a good idea as well. I had forgotten about it.

TC:

I can offer no suggestion to explain your FA-82 valve sticking again, unless maybe you’re a victim of tolerances – the valve stem is at max size, and the guide is at minimum. If this is the problem it will go away as the engine runs.

I can also offer no explanation for picking up 1–1.5 K rpm when you disconnect the pressure line, unless you had a false peak on the HS. It does happen. Was the HS needle about 2½ turns open? If no put it back together with the pressure connected and get your 7500 peak again, then turn the HS needle in further and see if you reach a second, higher, peak with the needle further shut.

rimcnii:

Perry seems to consider the sometimes bothers with the piping of the VP-30 with a four stroke isn’t worth the effort, using the shaker VP-20 is just easier.

Bill.

Thunderchild

Thanks Bill,

I'll try again and let you know.

Cheers,

TC