NGH 38CC 4 stroke
05-19-2014, 11:22 AM
#701
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Tks Carlwb & Tyor. I ALWAYS store my plane nose down, hanging from tail, my nececity due lack of space. whren hanged, the rocker cover is higher than the camshaft so the migration do not occur whren stored.
In a closer view, i noted the contact surface tween cam and lifter is virtualy zero, whren rizing the contact lifter/cam is an edge cut in the base of lifter ( may say virtual contact surface) , hence, extreme pressure...and the grooves.
I'll post some pics to try explain my obs. I smoothed the 'edges' to cilindrical surfaces couse I think that edge may not be the cause of damage but is an issue anywere.I'll also, using an 'T' connector, feed the crankcase AND camshaft with the same line from intake manifold.
This will: Improove the cam lub or spoil crank lub or balance the lub througout the engine
Fig 1, original lifter, fig 2 smoothed lifter.
In a closer view, i noted the contact surface tween cam and lifter is virtualy zero, whren rizing the contact lifter/cam is an edge cut in the base of lifter ( may say virtual contact surface) , hence, extreme pressure...and the grooves.
I'll post some pics to try explain my obs. I smoothed the 'edges' to cilindrical surfaces couse I think that edge may not be the cause of damage but is an issue anywere.I'll also, using an 'T' connector, feed the crankcase AND camshaft with the same line from intake manifold.
This will: Improove the cam lub or spoil crank lub or balance the lub througout the engine
Fig 1, original lifter, fig 2 smoothed lifter.
The edge of a flat tappet should never contact the cam lobe. That cam pictured above doesn't look like it was ever finish ground. The surface of the cam lobe is one of the most critical in a flat tappet engine as it operates under extreme pressure.
Last edited by SrTelemaster150; 05-19-2014 at 11:30 AM.
05-19-2014, 01:37 PM
#702
I was thinking that the engine wasn't lubricated well before it was test run. Thus the damage may have occurred mostly in the first engine run if the cam and lifters weren't oiled to start with. Hard to say now though as it is after the fact. But a number of people have had this happen with Saito and OS engines before though as the factory wasn't oiling the engines much if any. So maybe that was the problem.
05-20-2014, 07:44 AM
#703
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In this engine the lifter's edge DO CONTACT the cam between 10 up to 60 degrees.
Earlb, agree the damm damages did not occurred at once but, after 1 1/2 hs runing uppright the performance was so good i decided install the motor in the airframe, but i dont discard the possibility of the dammage started in the first run and got critical later.
If last is true, the problem is worse couse the three first tanks was run with oil 20:1, 100% sintetic, motor well primed and turning in rpm recomended by builder.
Thank you all.
Last edited by PARDAL; 05-20-2014 at 08:10 AM.
05-20-2014, 08:48 AM
#704
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Agree but I measured and skeched cam & lifter and only after 60° the cam do not contact the edge.
In this engine the lifter's edge DO CONTACT the cam between 10 up to 60 degrees.
Earlb, agree the damm damages did not occurred at once but, after 1 1/2 hs runing uppright the performance was so good i decided install the motor in the airframe, but i dont discard the possibility of the dammage started in the first run and got critical later.
If last is true, the problem is worse couse the three first tanks was run with oil 20:1, 100% sintetic, motor well primed and turning in rpm recomended by builder.
Thank you all.
In this engine the lifter's edge DO CONTACT the cam between 10 up to 60 degrees.
Earlb, agree the damm damages did not occurred at once but, after 1 1/2 hs runing uppright the performance was so good i decided install the motor in the airframe, but i dont discard the possibility of the dammage started in the first run and got critical later.
If last is true, the problem is worse couse the three first tanks was run with oil 20:1, 100% sintetic, motor well primed and turning in rpm recomended by builder.
Thank you all.
Please don't take offence to this question, and in no way am I trying to question your abilities. How did you calculate the 20:1 oil ratio, make sure you did not make a mistake
05-20-2014, 08:54 AM
#705
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05-20-2014, 09:20 AM
#706
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Pardal,
How are the lifters moving? I'm guessing that a lifter lockup could cause scoring. Spring pressure would be another area to look in to, I doubt it but still worth a check.
How are the lifters moving? I'm guessing that a lifter lockup could cause scoring. Spring pressure would be another area to look in to, I doubt it but still worth a check.
05-20-2014, 11:17 AM
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Pontiac_40, no offense at all, we are just chating trying to solve one problem i have, that is beyond my abilities, that may be of general interest.
The maker instruction says: 2. For break in use 2 cycle oil at a ratio of 25:1, and general use with 35:1.
I run a Saito 57t that maker recomends break in 20:1 and general 25:1. Users prefer use 20:1 allways in the saito, so do I.
Teoreticaly my NGH is still breaking in and i use 20:1 insteady.Whay? Less oil may dammage the engine and more oil tend to accumulate more carbon in the engine but too much oil just make a big oil mess.
Oil ratio. I use to buy 3.5 liter of high octane gas and add oil this way:
20:1 => 3500/20 = 175 cc of oil or say, oil content in % is (175/(3500+175)) x 100 = 4.76 % oil content. The oil is measured using an graduated test glass, no guess work.
Occured to me the cam surfases may had not been hardened properly. I'll wait my spare cam arrive and run it with the modified lifter i rounded the contact surfaces.
Lets see.
The maker instruction says: 2. For break in use 2 cycle oil at a ratio of 25:1, and general use with 35:1.
I run a Saito 57t that maker recomends break in 20:1 and general 25:1. Users prefer use 20:1 allways in the saito, so do I.
Teoreticaly my NGH is still breaking in and i use 20:1 insteady.Whay? Less oil may dammage the engine and more oil tend to accumulate more carbon in the engine but too much oil just make a big oil mess.
Oil ratio. I use to buy 3.5 liter of high octane gas and add oil this way:
20:1 => 3500/20 = 175 cc of oil or say, oil content in % is (175/(3500+175)) x 100 = 4.76 % oil content. The oil is measured using an graduated test glass, no guess work.
Occured to me the cam surfases may had not been hardened properly. I'll wait my spare cam arrive and run it with the modified lifter i rounded the contact surfaces.
Lets see.
Last edited by PARDAL; 05-20-2014 at 11:20 AM.
05-20-2014, 11:31 AM
#708
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After findings, I checked the lifter ( with an magnifyer ) for scores, not a single one. They were slipping in their sleeves freely.
Spring pressure were ok and iqual both sides. ( It is said the NGH 38cc valve springs are not that strong ).
Spring pressure were ok and iqual both sides. ( It is said the NGH 38cc valve springs are not that strong ).
Last edited by PARDAL; 05-20-2014 at 11:39 AM.
05-20-2014, 11:55 AM
#709
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Pontiac_40, no offense at all, we are just chating trying to solve one problem i have, that is beyond my abilities, that may be of general interest.
The maker instruction says: 2. For break in use 2 cycle oil at a ratio of 25:1, and general use with 35:1.
I run a Saito 57t that maker recomends break in 20:1 and general 25:1. Users prefer use 20:1 allways in the saito, so do I.
Teoreticaly my NGH is still breaking in and i use 20:1 insteady.Whay? Less oil may dammage the engine and more oil tend to accumulate more carbon in the engine but too much oil just make a big oil mess.
Oil ratio. I use to buy 3.5 liter of high octane gas and add oil this way:
20:1 => 3500/20 = 175 cc of oil or say, oil content in % is (175/(3500+175)) x 100 = 4.76 % oil content. The oil is measured using an graduated test glass, no guess work.
Occured to me the cam surfases may had not been hardened properly. I'll wait my spare cam arrive and run it with the modified lifter i rounded the contact surfaces.
Lets see.
The maker instruction says: 2. For break in use 2 cycle oil at a ratio of 25:1, and general use with 35:1.
I run a Saito 57t that maker recomends break in 20:1 and general 25:1. Users prefer use 20:1 allways in the saito, so do I.
Teoreticaly my NGH is still breaking in and i use 20:1 insteady.Whay? Less oil may dammage the engine and more oil tend to accumulate more carbon in the engine but too much oil just make a big oil mess.
Oil ratio. I use to buy 3.5 liter of high octane gas and add oil this way:
20:1 => 3500/20 = 175 cc of oil or say, oil content in % is (175/(3500+175)) x 100 = 4.76 % oil content. The oil is measured using an graduated test glass, no guess work.
Occured to me the cam surfases may had not been hardened properly. I'll wait my spare cam arrive and run it with the modified lifter i rounded the contact surfaces.
Lets see.
05-20-2014, 12:54 PM
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Pontiac_40, no offense at all, we are just chating trying to solve one problem i have, that is beyond my abilities, that may be of general interest.
The maker instruction says: 2. For break in use 2 cycle oil at a ratio of 25:1, and general use with 35:1.
I run a Saito 57t that maker recomends break in 20:1 and general 25:1. Users prefer use 20:1 allways in the saito, so do I.
Teoreticaly my NGH is still breaking in and i use 20:1 insteady.Whay? Less oil may dammage the engine and more oil tend to accumulate more carbon in the engine but too much oil just make a big oil mess.
Oil ratio. I use to buy 3.5 liter of high octane gas and add oil this way:
20:1 => 3500/20 = 175 cc of oil or say, oil content in % is (175/(3500+175)) x 100 = 4.76 % oil content. The oil is measured using an graduated test glass, no guess work.
Occured to me the cam surfases may had not been hardened properly. I'll wait my spare cam arrive and run it with the modified lifter i rounded the contact surfaces.
Lets see.
The maker instruction says: 2. For break in use 2 cycle oil at a ratio of 25:1, and general use with 35:1.
I run a Saito 57t that maker recomends break in 20:1 and general 25:1. Users prefer use 20:1 allways in the saito, so do I.
Teoreticaly my NGH is still breaking in and i use 20:1 insteady.Whay? Less oil may dammage the engine and more oil tend to accumulate more carbon in the engine but too much oil just make a big oil mess.
Oil ratio. I use to buy 3.5 liter of high octane gas and add oil this way:
20:1 => 3500/20 = 175 cc of oil or say, oil content in % is (175/(3500+175)) x 100 = 4.76 % oil content. The oil is measured using an graduated test glass, no guess work.
Occured to me the cam surfases may had not been hardened properly. I'll wait my spare cam arrive and run it with the modified lifter i rounded the contact surfaces.
Lets see.
05-20-2014, 01:29 PM
#711
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Alternative lub lines
Alfiev, it looks many fellows are flying the ngh38 inverted without issues.
My prime suspect is becoming the cam surface hardness, of course the poor contact cam/lifter is his partner in the crime.
By the way, what about that dam oil ring I heard was a mistake, just a mistake.
All recent ngh 38cc uses only two pressure rings.
What would You call me if I throw away the oil ring.
I must add an coment on lubrication of the camshaft. (bitten by snake are affraid of worms). I would not like to loose this engine.
I intend to lub the crank case as usual and the camshaft also. The vent niplle bellow the shaft connect directily to the cam gear and it seens a good idea to lub it .
See fig.
My prime suspect is becoming the cam surface hardness, of course the poor contact cam/lifter is his partner in the crime.
By the way, what about that dam oil ring I heard was a mistake, just a mistake.
All recent ngh 38cc uses only two pressure rings.
What would You call me if I throw away the oil ring.
I must add an coment on lubrication of the camshaft. (bitten by snake are affraid of worms). I would not like to loose this engine.
I intend to lub the crank case as usual and the camshaft also. The vent niplle bellow the shaft connect directily to the cam gear and it seens a good idea to lub it .
See fig.
Last edited by PARDAL; 05-20-2014 at 02:01 PM.
05-21-2014, 02:47 AM
#712
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BINGO - I tryed to saw and file the cam surfaces and found them as soft as an allen bolt read, by comparison.
The cams in my engine really came too soft. The lifter was properly hardened.
Let's wait the spare that is under way.
The cams in my engine really came too soft. The lifter was properly hardened.
Let's wait the spare that is under way.
05-22-2014, 06:56 PM
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Parts Needed!! I was running my NGH 38cc on the stand and because of the vibration the intake manifold broke at the flange that mounts it to the engine. Where can I get parts. Hi Model is always out of stock and another place in UK is very expensive. They want $30 for a $6 part. Any US parts houses for this engine.
05-22-2014, 07:27 PM
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Don't know about stockists in the US, perhaps AMR in Canada might be a better option for you? Also consider that, although Himodel doesn't show "in-stock" they may be able to source from NGH and ship to you quite quickley.
Well.... that was my experience anyway.
This is the second intake manifold I have heard of that has cracked through!
Good luck!
Alf
Well.... that was my experience anyway.
This is the second intake manifold I have heard of that has cracked through!
Good luck!
Alf
05-22-2014, 08:34 PM
#715
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Basil, I had the same thing happen to my engine (page 28). I bought my engine from AMR, they took care of me and I'm very happy with there customer service. You can try to see if they have the part in stock, there shipping to the USA is very reasonable. Try to contact them since they don't list parts for this engine on there website. The other guys would be agape racing, somebody mentioned them early in this thread. It is really frustrating, believe me, I know.
http://www.amr-rc.com/
http://www.agaperacingandhobby.com/index.php
http://www.amr-rc.com/
http://www.agaperacingandhobby.com/index.php
05-22-2014, 09:18 PM
#716
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Parts Needed!! I was running my NGH 38cc on the stand and because of the vibration the intake manifold broke at the flange that mounts it to the engine. Where can I get parts. Hi Model is always out of stock and another place in UK is very expensive. They want $30 for a $6 part. Any US parts houses for this engine.
Sorry, no intake manifold.
I thing the carb must be at first firmly fixed in the angle to the back plate and then the upper flange tightened to the head, to minimyze efforts in the manifold flange.
Last edited by PARDAL; 05-23-2014 at 01:07 AM.
05-23-2014, 08:12 AM
#717
HiModel was really good at getting NGH engine parts for me. Contact them. They may not show the parts in stock, but they are right down the street from the NGH engines facility. So they have a great knack at being able to get the parts for the engines.
05-23-2014, 09:01 AM
#718
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I called AMR they have the part shipped for $20. Is Himodel cheaper. The part is $6 at Himodel but what's there shipping cost for a small part like that.
I'm thinking it's better to order two of these.
Himodel just sent me an E-mail - there's a parts freeze on NGH 38cc right now.
Himodel just sent me an E-mail - there's a parts freeze on NGH 38cc right now.
Last edited by Basil Yousif; 05-23-2014 at 09:31 AM.
05-23-2014, 06:07 PM
#719
Well that is a bummer. Better to order more locally than overseas as I think the shipping may be less.
One could likely get a welder to weld the intake manifold back up. Then machine the flats for the mounting screws, etc. The welded repaired manifold might even be more strong than the original too.
I was wondering if the bracket holding the carburetor on became loose or not. If the carb came loose that would explain the intake manifold breaking then. Or does the bracket flex too much contributing to the failure.
One could likely get a welder to weld the intake manifold back up. Then machine the flats for the mounting screws, etc. The welded repaired manifold might even be more strong than the original too.
I was wondering if the bracket holding the carburetor on became loose or not. If the carb came loose that would explain the intake manifold breaking then. Or does the bracket flex too much contributing to the failure.
05-23-2014, 09:27 PM
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I called AMR they have the part shipped for $20. Is Himodel cheaper. The part is $6 at Himodel but what's there shipping cost for a small part like that. I'm thinking it's better to order two of these.
Himodel just sent me an E-mail - there's a parts freeze on NGH 38cc right now.
Himodel just sent me an E-mail - there's a parts freeze on NGH 38cc right now.
05-24-2014, 06:32 AM
#722
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If you guys remember in the beginning of the thread, somebody discovered that one of the engine stand-offs was touching one of the carb bolts, it actually touches the carb venturi as well. The point is, that if correct clearances are not achieved by grinding the stand-off etc,, the vibration could cause the stand-off to put pressure on the carb pate (by slapping against the carb venturi) making it loose and then eventually transferring the stresses to the manifold.
05-24-2014, 03:50 PM
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Here's what Hi Model Responded to me about the NGH 38cc engine parts:
[TABLE]
[TR="bgcolor: #DCEDFC"]
[TD]2 HiModel, Fri May 23 14:47:43 2014
[/TD]
[/TR]
[TR="bgcolor: #EDF8FF"]
[TD]Hi,
Due to factory supply problem, those parts are not available currently.
Regards,
Wang
HiModel.com
[/TD]
[/TR]
[/TABLE]
Maybe the manufacturing crew all went on vacation!!
I hope this isn't the beginning of the end for this engine!!
[TABLE]
[TR="bgcolor: #DCEDFC"]
[TD]2 HiModel, Fri May 23 14:47:43 2014
[/TD]
[/TR]
[TR="bgcolor: #EDF8FF"]
[TD]Hi,
Due to factory supply problem, those parts are not available currently.
Regards,
Wang
HiModel.com
[/TD]
[/TR]
[/TABLE]
Maybe the manufacturing crew all went on vacation!!
I hope this isn't the beginning of the end for this engine!!
Last edited by Basil Yousif; 05-24-2014 at 03:53 PM.