Go Back  RCU Forums > Glow Engines, Gas Engines, Fuel & Mfg Support Forums > Engine Conversions
Reload this Page >

Glo to Gas conversion: how to get it right fast !

Notices
Engine Conversions Discuss all aspects of engine conversions in this forum

Glo to Gas conversion: how to get it right fast !

Old 01-21-2023, 02:30 AM
  #26  
AA5BY
 
Join Date: Sep 2006
Location: White Oak, TX
Posts: 2,395
Likes: 0
Received 2 Likes on 2 Posts
Default

A short piece of silicone is what existed and did finally split but it lasted a long time.I'll likely go back with another.
Old 01-21-2023, 02:56 AM
  #27  
1967brutus
Senior Member
 
Join Date: Oct 2021
Posts: 747
Received 42 Likes on 41 Posts
Default

Like I said, they have never lasted shorter than 2 years for me. Even a 2-yearly replacement would not be an issue, but I have several that are still "OEM" and are allready in place for about 5 years.

No need to change something as simple replacable as that...
Old 01-21-2023, 02:08 PM
  #28  
AA5BY
 
Join Date: Sep 2006
Location: White Oak, TX
Posts: 2,395
Likes: 0
Received 2 Likes on 2 Posts
Default

Ya never know.

My Saito 125 died at the top of a loop and I thought it went lean and quit as I found the muffler pressure line split and off the tap. It was due, so given a fuel system overhaul but wouldn't start after completion, in fact not a single fire could be coaxed from it..

Timing ok.
Spark ok.
Valve train ok.
Compression ok.
Primed with methanol and still wouldn't fire, even spinning over with a starter. Hooked up a spare ignition, and it started on second flip.

This is the second RcExl ignition failure I've experienced in ten years and the first that would spark the plug out of engine but fail to fire the engine. The spark boot is a suspected problem having gotten oily.
Old 01-22-2023, 12:42 AM
  #29  
1967brutus
Senior Member
 
Join Date: Oct 2021
Posts: 747
Received 42 Likes on 41 Posts
Default

I have now ten or so in operation, and only one, a very old one with the pre-laserwelded plug cap, has a bad cap (the soldering broke). It still works for testbed running, but better not touch the cap while running (have to admit, it is not near as "shocking" as 10+kV would lead to expect, but still not pleasant...
I had two suspect failed ones, that turned out to be borderline worn out ignition batteries that would not maintain voltage under load. Among them the 5-lead radial ignition. A new battery with one cell more (5S NiMH instead of 4) completely cured the issue.
Old 01-23-2023, 05:08 AM
  #30  
AA5BY
 
Join Date: Sep 2006
Location: White Oak, TX
Posts: 2,395
Likes: 0
Received 2 Likes on 2 Posts
Default

Got the ignition out and it can be heard sparking internally.
Old 01-23-2023, 05:33 AM
  #31  
AA5BY
 
Join Date: Sep 2006
Location: White Oak, TX
Posts: 2,395
Likes: 0
Received 2 Likes on 2 Posts
Default

Bert,
When rebuilding the fuel system after the 213 flights, the muffler pressure tap was about 80% clogged. The interior of muffler was relatively free of deposits. The tank had a few small carbon floaties. the felt clunk was dirty but not encrusted. No crap trap or vent line filter was used.

Others have reported choking deposits, which leaves me wondering about the comparisons and the question of whether deposits are primarily left by the oil and if so, what might be the comparison between oil based and synthetic. Another is the mix ratio.

I've not used synthetics in this engine and the ratio has been 20:1

What are your thoughts?
Old 01-23-2023, 11:28 PM
  #32  
1967brutus
Senior Member
 
Join Date: Oct 2021
Posts: 747
Received 42 Likes on 41 Posts
Default

I am using a full synthetic, and I do have near to nothing experience with non-synthetics and gas. So far, I have seen zero tendency to clog up the muffler nipple with the Oil I use (Castrol PowerRS 2stroke), but in the pre-solenoid days, the "blackening" of the fuel in the tank was a serious problem.
If I would go to the field with half a gallon of fresh fuel, do 2~3 10 minute flights and defuel the plane back in the fieldcan, that fresh, bright red fuel would already darken significant. Two afternoons and the fieldcan would be black. And consequently, running that blackened fuel through a feltclunk would restrict flow within a gallon or two per clunk. Not encrusted, just a discoloured clunk that would not pass sufficient fuel anymore. The craptraps were not installed to protect the fuel tank of the plane in question: their purpose is to keep the fieldcan clean, because for me it is imperative that I can defuel my planes (otherwise they stink up the house). Otherwise the "blocked clunk syndrome" would spread over my other planes like the black plague.

Post-solenoid, the blackening is less, but there is still the issue with the condensation of water from the exhaust gas in the fuel tank of the plane, and that appears to worsen a bit from the solenoid, since leaner mixtures cause the muffler to remain cooler (I have seen liquid water come from mufflers at idle).

For reasons I cannot explain, the few customers I had that were running Stihl alkylate fuel and Stihl oil, I never managed to get the engines adjusted consistent, not with and not without the solenoid. Same for premium fuels (98 RON rating)
That could be me, but I have consistenly had the best results with the simplest pumpgas (95 RON, comparable to your 91 MON. Over here it contains up to 10% Ethanol, which still has to show its first disadvantageous property yet, I haven't noticed any***) and this Castrol oil. I have tried Motul, and the engine runs satisfactorily, tunes well, but the residue is markedly different (gummier), and I have used the full synthetic sold under the brandname Q8, which behaves very similar to the Castrol.

As for mixing ratios, I have myself only experience with 10:1. I have tried 15:1 in the smaller engines, and it somehow "did not feel right"... Hard to explain, but I only used that for 2 afternoons or so, and my impression was that the engine was less well overall lubricated, did not feel as "wet" and I thought "this can't be right"

I have seen a few engines that were operated on 20:1, and I was not impressed. Internal inspection revealed that lubrication absolutely was adequate, but the dirt on pistoncrown and valves suggested less than stellar detergent action.

It is very possible that the clogged nipples you encounter are due to the relatively low oil content, but that is a total guess. But since I am not seeing ANY of that at 10:1 ratio supports that guess. But I do know that anyone that had issues with the special fuels or the lean ratios, would see improvement from using a good full synthetic at 10:1 in regular unleaded. It simply works better. Sure, there are people that get 20:1 working, or that have good results with alkylate fuel, and that's OK. But IF someone encounters issues, my goto-advise is a a craptrap, a clean feltclunk, a viton clunkline IN the tank, full synt oil 10:1 in regular unleaded, and start from there.

I think a (partly) blocked nipple and feltclunk after 200 flights (which is what? 4 gallons of fuel?) would qualify...

The one thing that leaves me baffled to this day is that you manage to achieve decent needle settings on standard carbs. I never managed that. A few of my engines were "flyable" but the poor throttleability of the engine spoiled the fun. The rest of them simply were "unflyable", because it becomes very hard to land if the engine won't follow the throttle with at least some consistency.

*** E10 fuel HAS shown very detrimental effects in my old carburated Ducati, both WRT throttle response and adjustability, as well as with corrosion and deposits in the floatvalve, acccellerator pump and carb jets. I can completely negate that with a relatively very cheap fuel additive (less than 3 cents per treated litre), and that seems to cancle all the negative effects completely, but the converted glow engines never needed that additive and do not seem to benefit from it either.

Last edited by 1967brutus; 01-23-2023 at 11:56 PM.
Old 01-23-2023, 11:58 PM
  #33  
1967brutus
Senior Member
 
Join Date: Oct 2021
Posts: 747
Received 42 Likes on 41 Posts
Default

Originally Posted by AA5BY View Post
Got the ignition out and it can be heard sparking internally.
That would suggest to me your plugcaps are somehow fouling up internally, leading to bad contact and higher discharge voltages.

I use the contact springs in all my caps, and so far haven't had that issue.
Old 01-25-2023, 06:05 AM
  #34  
AA5BY
 
Join Date: Sep 2006
Location: White Oak, TX
Posts: 2,395
Likes: 0
Received 2 Likes on 2 Posts
Default

After exciting the ignition with signal generator, spark breakout was visually noted to be about an inch from the ignition in the HT lead. Opening the shield and inspecting, the center conductor has a horse shoe bend of about 1/8" hump and placing it thus very close to the braided shield where it ruptured through the dialectic.

Who knows why it exist, shrinkage of the dialectic, manufacturing anomaly, or perhaps installation to the ignition error, by soldering the conductor within the ignition and then forcing the dialectic and braided shield into the housing crimp and thus compressing the center conductor causing it to buckle into the horse shoe.

I will try some kind of repair but am unsure of success.
Old 01-25-2023, 09:23 AM
  #35  
1967brutus
Senior Member
 
Join Date: Oct 2021
Posts: 747
Received 42 Likes on 41 Posts
Default

Originally Posted by AA5BY View Post
After exciting the ignition with signal generator, spark breakout was visually noted to be about an inch from the ignition in the HT lead. Opening the shield and inspecting, the center conductor has a horse shoe bend of about 1/8" hump and placing it thus very close to the braided shield where it ruptured through the dialectic.

Who knows why it exist, shrinkage of the dialectic, manufacturing anomaly, or perhaps installation to the ignition error, by soldering the conductor within the ignition and then forcing the dialectic and braided shield into the housing crimp and thus compressing the center conductor causing it to buckle into the horse shoe.

I will try some kind of repair but am unsure of success.
If the spark is outside of the box, it is "repairable", in the sense that the electronics are not shot, and if you find a way to either shorten the existing cable or replace it, it will near 100% sure function again.. Most likely cause is that there was some torque on the HT lead, and if so, it will usually fail at the tightest bend, or so I am told. No personal experience, as I always took great care to route the HT lad in such a way and if necessary rotate the ignition box such that there would be no or minimal torque tension on the lead.
All my ignitions are built in different because of this.
Usually, I coil the lead up one or two turns, or if possible I route the lead rearwards then through the fuselage wall, then back forward to the engine. Routing is done backwards from engine (plug capped) to box, and the way the HT lead wants to turn the box, is how the box will be placed. This method has served me well over the last 9 or so years.
Old 01-27-2023, 12:12 PM
  #36  
AA5BY
 
Join Date: Sep 2006
Location: White Oak, TX
Posts: 2,395
Likes: 0
Received 2 Likes on 2 Posts
Default

I've made an attempt at repairing the HT cable and so far its been on the signal generator at an idle speed for a couple of hours and hasn't missed a beat. We'll see.

The cable got shortened to insure that the shield would be long enough. Silcone was used to seal up the dialectic splice and it given heat shrink.

Nothing ventured, nothing gained.
Old 01-27-2023, 12:23 PM
  #37  
Raleighcopter
Senior Member
 
Raleighcopter's Avatar
 
Join Date: Jan 2022
Posts: 173
Received 3 Likes on 3 Posts
Default

that's my attitude when it comes to fixing broken stuff. It's already broken. What do I have to lose.
Old 01-27-2023, 01:42 PM
  #38  
AA5BY
 
Join Date: Sep 2006
Location: White Oak, TX
Posts: 2,395
Likes: 0
Received 2 Likes on 2 Posts
Default

Fortunately the engine is powering a Cub that will float and glide back to the runway from about anyplace in the pattern it is flown.
Old 01-27-2023, 08:33 PM
  #39  
1967brutus
Senior Member
 
Join Date: Oct 2021
Posts: 747
Received 42 Likes on 41 Posts
Default

Originally Posted by Raleighcopter View Post
that's my attitude when it comes to fixing broken stuff. It's already broken. What do I have to lose.
that depends on the possible chain of events

Fully agree on the "allready broken, what's there to lose" part, but one has to keep in mind that a 50 or 75 bucks ignition system keeps a much more expensive aircraft up...
There are planes in my collection that for peace of mind's sake would just get a new ignition if the old one only so much as looked back at me the wrong way. Then there are those where a repaired ignition would not keep me wake at night
Old 01-28-2023, 07:07 AM
  #40  
AA5BY
 
Join Date: Sep 2006
Location: White Oak, TX
Posts: 2,395
Likes: 0
Received 2 Likes on 2 Posts
Default

I confess mental and fiscal fiber to keep mechanical things working with admittedly wins and losses. My conclusion is that this repair has minimal risk after contorting and pulling on the HT cable repair during a several hour test without it missing a spark.

And... as mentioned... the plane it will go back in is at minimal risk to making it back to the runway. It quit near the edge of its pattern and landed safely with ease. I agree with Bert once again, there are planes in the fleet where a concern factor would be in play.


Old 01-28-2023, 07:39 AM
  #41  
1967brutus
Senior Member
 
Join Date: Oct 2021
Posts: 747
Received 42 Likes on 41 Posts
Default

Keep in mind, that an electrical faillure of the HT lead OUTSIDE the ignition box, CAN cause severe interference, especially if the faillure is not immediately killing the engine. So make sure you have your failsafe set such that it kills the engine at the minimum, and neurtalized rudders if possible. This will allow regaining of control to bring in the plane in a deadstick. Because if the lead or cap are arcing outside but the engine keeps running, the plane is toast...
Old 01-28-2023, 12:12 PM
  #42  
AA5BY
 
Join Date: Sep 2006
Location: White Oak, TX
Posts: 2,395
Likes: 0
Received 2 Likes on 2 Posts
Default

Perhaps I should detail how the splice was performed.

First, the cable was cut at the bad spot.
Sliding the shield toward the plug boot, the cable was shortened about two inches to insure there would be adequate braid to recover the repair.

The center conductors were provided 1/4" leads from the dialectic.

To couple the center conductor, a 2-56 threaded coupler for 1/16" wire was cut off leaving a 1/2" sleeve to use as a coupler. A piece of dialectic from RG-8 cable was cut to the length of the center conductor splice length and then split open to fit onto the center conductor. It was slightly larger than the HT dialectic and thought to be needed to keep distance over the now slightly larger splice collar.

The seam and ends were given silicone and the piece of heat shrink prepared on the cable was slid over and shrunk.

The braided shield was was returned in place and soldered and finally the last piece of larger heat shrink that had been prepared on the cable was slid into place and shrunk.
Old 01-28-2023, 08:20 PM
  #43  
1967brutus
Senior Member
 
Join Date: Oct 2021
Posts: 747
Received 42 Likes on 41 Posts
Default

That sounds like it should do it!
Old Yesterday, 05:01 AM
  #44  
Sokat
Junior Member
 
Join Date: Feb 2023
Posts: 2
Likes: 0
Received 0 Likes on 0 Posts
Default

Hi aa5by
Did you modify the carb or just converted with spark ignition only. Are you still using glow carb. How did you convert it to gas.
I have never converted any engines so I am looking for easy way.
Thanks.
Old Today, 06:22 AM
  #45  
AA5BY
 
Join Date: Sep 2006
Location: White Oak, TX
Posts: 2,395
Likes: 0
Received 2 Likes on 2 Posts
Default

Originally Posted by Sokat View Post
Hi aa5by
Did you modify the carb or just converted with spark ignition only. Are you still using glow carb. How did you convert it to gas.
I have never converted any engines so I am looking for easy way.
Thanks.
Using the stock carb with a throttle servo slow down of .7. Conversion requires adding ignition and providing gas fuel tank disciplines including gas stopper in tank, felt clunk pickup, and fuel lines that will survive gas.

I've a lathe so make my own timing rings and fabricate my own pickup mounting and purchase ignitions on Ebay. Commercial conversion kit packages are available from Adrian at CH Ignitions. There is a short list of pros and cons to conversions, and if needed the list can be repeated.

Arlyn



Old Today, 06:53 AM
  #46  
AA5BY
 
Join Date: Sep 2006
Location: White Oak, TX
Posts: 2,395
Likes: 0
Received 2 Likes on 2 Posts
Default I'm snake bit

Originally Posted by 1967brutus View Post
That sounds like it should do it!
Embedded the ignition back into the bowels of the plane and to my horror... not a single pop when attempting to start. What the hell now?

Pulled the HT of the plug, inserted a new plug and the spark was completely intermittent. Rocking the prop might produce one spark out of ten passes so the signal generator was hooked to it and the plug would fire maybe 1/10th of the time. On the bench it hadn't missed a spark. No prodding or pulling on the boot end affected the intermittent spark. A good battery was plugged directly into the ignition power lead with no change. A ground wire was hooked to the plug and made to the battery ground... no change.

So, I don't know what changed between the bench testing and reinstall to the plane. The prime suspect is a cold solder connection on the center conductor coupler. If so, the ignition itself may now be damaged.
At any rate, two new ignitions were ordered a couple of weeks back and the plane will get one.
Old Today, 08:02 AM
  #47  
1967brutus
Senior Member
 
Join Date: Oct 2021
Posts: 747
Received 42 Likes on 41 Posts
Default

If the center lead was the initial issue, making an extra ground to battery would not show any difference. But it is very possible that the internals somehow were overloaded and more damage than initially visible was done.

Whatever the case, those 75 or so bucks won't break the bank I take it, and peace of mind is worth a lot of money

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information -

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.