OMG it arrived - Profi speed .049
#26
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I think it's the tight ones that you want to buy [if you are lucky] and just figure that you will need to spend time to get it just right. It's tough to determine what is "just right" if you aren't very experienced, if if you don't have a "GO - NO GO" method to know when to stop honing.
I have had success with using a steel handle fitted to the piston [using the piston as the honing tool] and fine sink scrub powder mixed with oil as the abrasive.
Fox used to sell a powder called Lustrox to dump into the old iron engines to polish them while they were more or less broken in. It might have done some magic microscopically to fill the pores. I don't know what the ABC or AAC equivalent of that process is.
I have had success with using a steel handle fitted to the piston [using the piston as the honing tool] and fine sink scrub powder mixed with oil as the abrasive.
Fox used to sell a powder called Lustrox to dump into the old iron engines to polish them while they were more or less broken in. It might have done some magic microscopically to fill the pores. I don't know what the ABC or AAC equivalent of that process is.
#27
I have 3 CS engines the Sport RC and CL .061's seem to be reasonable for a new engine with flipping over with some after run oil.
Ran up the RC sport version with a 1/2A starter no problems. The ABC speed engine is very snappy when turned over with a bit of after run oil.
The material used to polish / clean car light lenses or plan cream tooth paste should work too.
Ran up the RC sport version with a 1/2A starter no problems. The ABC speed engine is very snappy when turned over with a bit of after run oil.
The material used to polish / clean car light lenses or plan cream tooth paste should work too.
#28
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We used to break them in with no pipe so it would not get too hot. I think that nowadays the plan is to break them in at the operating temps, but well on the rich side. That CS was nasty tight. Not even heat would do much there. It is good now, just a manufacturing "defect" The CS is more of a kit motor that you have to fit yourself. I am sure the Profi is much closer to being right. The pipes on the F2A stuff sometimes have adjustable outlet sizes that screw in. I think 4.__ mm is about average for them. Quite small really, as the F2D is more like 6mm, which is down from the older 8mm.
Yup, 4mm on my Profi F2A - I was advised that for extended runs or 10% fuel, to open it up a little to scavenge more heat. It does not have stinger inserts. The small outlet diameter on a resonant exhaust doesn't surprise me, nor does a more open outlet on a non-piped engine where scavenging is the goal.
I would have bench run the F2A by now but I can't put it in a regular mount, I'll make an Al plate for it sometime soon. The airframe arrives today or Monday, then I gotta get my butt in gear on the rework.
Open pipe to avoid heat buildup makes all the sense in the world - the F3 speed guys do this all the time. But I was also told that - regards the current good speed engines - in most cases you just go out and fly 'em.
#29
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For a McCoy Red Head, sand or fine gravel should be about perfect.
#32
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Some pistons look even worse, but I think what you show is "State of the Art".
My local "mentors" taught me to make a sonic cleaner with either a denture cleaner or an orbital sander and place new or reworked engine parts in solvent, then give everything a good shaking until you feel that it's good enough. One guy would leave the parts buzzing away over night in a denture cleaner. He was one of the Top Dogs around here when it came to this stuff, so nobody questioned his swarfaphobia.
My local "mentors" taught me to make a sonic cleaner with either a denture cleaner or an orbital sander and place new or reworked engine parts in solvent, then give everything a good shaking until you feel that it's good enough. One guy would leave the parts buzzing away over night in a denture cleaner. He was one of the Top Dogs around here when it came to this stuff, so nobody questioned his swarfaphobia.
#34
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First starts - clipped combat prop 4.5x2.75 - too much shaft load I think, can't get it past overrich low speed or starving for fuel.
Just returned from the basement - now it's 3.8x2.75 (and carefully balanced).
I am not really sure how to mentally equate 1 blade to 2 blade shaft loads. These would normally run a SB 2.875 x 4.0-4.5 or so, that means it scribes a 5.25 diameter circle.
Just returned from the basement - now it's 3.8x2.75 (and carefully balanced).
I am not really sure how to mentally equate 1 blade to 2 blade shaft loads. These would normally run a SB 2.875 x 4.0-4.5 or so, that means it scribes a 5.25 diameter circle.
#36
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I am not really sure how to mentally equate 1 blade to 2 blade shaft loads. These normally run a SB 2.875 x 4.0-4.5 or so, that means it scribes a 5.25 diameter circle.
First starts - clipped combat prop 4.5x2.75 - too much shaft load I think, can't get it past overrich low speed or starving for fuel. [UPDATE] no I think way too much fuel pressure is the problem. Pipe tap time. Will have to rob a small pressure fitting from a Norvel for now.
First starts - clipped combat prop 4.5x2.75 - too much shaft load I think, can't get it past overrich low speed or starving for fuel. [UPDATE] no I think way too much fuel pressure is the problem. Pipe tap time. Will have to rob a small pressure fitting from a Norvel for now.
#40
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I am pretty sure Fox supplied Lustrox with one or two of my combat engines. Some of my old CL buddies said that Jewelers rouge works for a lapping compound.
One of these days I need to break down and get a couple of Fora CL combat .049's. Kinda sad, I will be at the AMA Nats this summer, at the same time as combat, but will be flying another event. Last year an old buddy let me fly one of his FAI Fora .15 powered combat models. What a treat that was. Right before I left to head home as well. That made me smile for the trip home.
One of these days I need to break down and get a couple of Fora CL combat .049's. Kinda sad, I will be at the AMA Nats this summer, at the same time as combat, but will be flying another event. Last year an old buddy let me fly one of his FAI Fora .15 powered combat models. What a treat that was. Right before I left to head home as well. That made me smile for the trip home.
#42
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First starts - clipped combat prop 4.5x2.75 - too much shaft load I think, can't get it past overrich low speed or starving for fuel.
Just returned from the basement - now it's 3.8x2.75 (and carefully balanced).
I am not really sure how to mentally equate 1 blade to 2 blade shaft loads. These would normally run a SB 2.875 x 4.0-4.5 or so, that means it scribes a 5.25 diameter circle.
Just returned from the basement - now it's 3.8x2.75 (and carefully balanced).
I am not really sure how to mentally equate 1 blade to 2 blade shaft loads. These would normally run a SB 2.875 x 4.0-4.5 or so, that means it scribes a 5.25 diameter circle.
I found that a 4.2 x 4 was marginally too much for a piped .061. It was better for the engine with the airfoils thinned out. If you take 4.2 x 4.2 x 4 =70.56...that gives you a load factor that I'd say is too much for a new engine that you are playing with. Consider the 4.2 x 4 "swinging for the fence".
I could have been using too much compression and nitro...I don't remember those details. I wasn't using any more than 10 or 15% nitro, but I wasn't being very careful about my approach.
#43
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Yes, piped. I'm changing over to pipe pressure tonight. Pressure was a nightmare on the MDS, pipe pressure fixed everything. Could just be my learning curve.
The engine never got hot or complained, it amassed 2 minutes or so of gurgling, frantic pinching, and eventually some steady running in the teens. Squeaky fit still. The workmanship is really good on these Profis.
The engine never got hot or complained, it amassed 2 minutes or so of gurgling, frantic pinching, and eventually some steady running in the teens. Squeaky fit still. The workmanship is really good on these Profis.
#44
Too much in the air or on the ground?
If you put the pressure tap at the apex of the pipe it is the most constant correct?
If you put the pressure tap at the apex of the pipe it is the most constant correct?
Last edited by Pond Skipper; 04-18-2015 at 05:33 PM.
#45
Pond Skipper, I would rub the top of the AP piston on some 600 sandpaper first to get rid of the nasty machining marks. Isn't it an .06 or .09? I didn't know that they made an .049. I lap my motors with Brasso or Silvo. Can't wait for the numbers on the Profi. I think I will run up my piped CS and Fora .049 soon, as soon as I get some time. Got some building construction and a move coming up.
Last edited by aspeed; 04-18-2015 at 05:35 PM.
#47
I don't think it would matter much, maybe the carbon may stick a bit easier. I have an AP .15 with chatter marks and grooves on the piston, but it seals well, and fits well and runs great. The grooves may hold the oil better, or cool things better, who knows.
#48
Yes thought about distribution but then the grooves are great way to collect hard deposits.
It's possible the cylinders could have been milled to level them off without the added cost to remove the tool marks.
It's possible the cylinders could have been milled to level them off without the added cost to remove the tool marks.
Last edited by Pond Skipper; 04-18-2015 at 06:52 PM.
#49
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According to Nelson, pipe pressure is the best was to get proportional fuel delivery.
He does not approve of bladders, since the bladder has no way of "ramping up" for a huge unloading.
This engine ought to turn a 3.8 x 2.75 with ease, even with open exhaust.
If the engines runs balky and dies unexpectedly, look at the glow plug to see if it's wet or not.
He does not approve of bladders, since the bladder has no way of "ramping up" for a huge unloading.
This engine ought to turn a 3.8 x 2.75 with ease, even with open exhaust.
If the engines runs balky and dies unexpectedly, look at the glow plug to see if it's wet or not.
Last edited by combatpigg; 04-18-2015 at 07:33 PM.
#50
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It became very obvious that pressure doesn't work worth beans, for exactly that reason - does not respond to the widely varying fuel demand. I already dropped a 2.5mm pressure tap on the pipe - later today will try out,