RE: gas fuel with glo plug no ignition  
View related threads: (in this forum | in all forums)

Tower Hobbies
Enter up to 4 keywords or Tower stock numbers
Logged in as Guest



Users viewing this topic: pdesotelle
  Printable Version
       


TurboHeader Muffler
Seller:  RC Specialties
Details:   $69.95   |  8/29/2008   |  Classified Ad
We will rotate YOUR AD in this spot if you select "Forum Featured" when placing or editing your ad!

All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Engine Conversions >> RE: gas fuel with glo plug no ignition
Page: <<   < prev  84 85 86 87 88 [89] 90 91 92 93   next >   >>  

Login
Message << Older Topic   Newer Topic >>
RE: gas fuel with glo plug no ig... - 7/17/2008 8:13:30 AM   
KI8FR


 

Posts: 836
Joined: 2/18/2004
From: Ovid, MI, USA
Status: offline 		I would like to see how you made the intake for the carb. and What did you make it out off. In the pics you got there it looks like to did a good job. I think I am going to give my ST 75 a shot at this just for fun.

Paul

(in reply to RysiuM)
       Post #: 2201

RE: gas fuel with glo plug no ig... - 7/17/2008 2:43:48 PM   
RysiuM



Posts: 1390
Joined: 4/22/2003
From: Elk Grove, CA, USA
Status: offline 		The adapter between the carb and the engine is made out of derlin (white plastic) but it is to soft for this type of mounting on the engine. I can turn the whole carb around in the engine. I'm going to use aluminium next time.

_____________________________

Mather Aerospace Modelers, Inc.
AMA Gold Leader Club, Charter #1243, Sacramento, CA

(in reply to KI8FR)
       Post #: 2202

RE: gas fuel with glo plug no i... - 7/17/2008 5:44:05 PM   
aero nut


 

Posts: 447
Joined: 11/10/2003
From: tijuanaBaja California, MEXICO
Status: offline 		I used 1/4 inch aluminum to make mine for a magnum 1.8

(in reply to RysiuM)
       Post #: 2203

RE: gas fuel with glo plug no i... - 7/17/2008 9:56:46 PM   
Jezmo



Posts: 805
Joined: 6/26/2006
From: Spring, TX, USA
Status: offline 		I used aluminum for the one on my ST90. I'll take a pic of it and post as soon as posible.

_____________________________

Raptor 50 V2 OS 50 Hyper, T-Rex 450XL CDE, Spektrum DX7, SuperTigre OS FOX Saito Enya Jett TT

(in reply to aero nut)
       Post #: 2204

RE: gas fuel with glo plug no i... - 7/19/2008 1:00:32 AM   
RysiuM



Posts: 1390
Joined: 4/22/2003
From: Elk Grove, CA, USA
Status: offline 		I have finished all the conversion, made nice adapter and all works fine but...and here I need some help from somone who knows Walbro.

The engine runs great on idle and the Lo needle works fine. But when I get more than 1/4 throttle now the engine goes lean and dies. Turning Hi needle doesn't change a thing. Fuel pump works well. So I tried something else: I attached the silicone tubbng to the pressure mettering tube and I blew into it simulating increasing outside pressure. I was able to make such pressure (not much) so the engine was runnign well. The same effect was when I put the end of this silicon tube to the exit from the muffler. Exhaust blowing from the muffler created enough pressure in the tune for engine tu run smooth through entire throttle range.


So there is something wrong in the fuel mettering. The valve doesn't open. Is there some special passage that creates vacum on the gasoline side of the membrane to open the valve but in my carb this passage is blocked? Or should I simple play with the sping or the the lever? I know something is wrong on that side even everything visually os OK, so how to fix that?

The Walbro number is WT-308-1

< Message edited by RysiuM -- 7/19/2008 1:01:23 AM >

_____________________________

Mather Aerospace Modelers, Inc.
AMA Gold Leader Club, Charter #1243, Sacramento, CA

(in reply to Jezmo)
       Post #: 2205

RE: gas fuel with glo plug no i... - 7/19/2008 5:00:55 AM   
aero nut


 

Posts: 447
Joined: 11/10/2003
From: tijuanaBaja California, MEXICO
Status: offline 		Try lifting the metering lever just a tad normaly it's level with the carb body just raise it a little bit this will make the diaphragm open the metering valve more and letting more fuel into the carb

(in reply to RysiuM)
       Post #: 2206

RE: gas fuel with glo plug no i... - 7/19/2008 6:41:24 AM   
RysiuM



Posts: 1390
Joined: 4/22/2003
From: Elk Grove, CA, USA
Status: offline 		I did that - Based on the information from Walbro it should be about 1.72mm below the surface, I think it was just a bit below. now it is about 1.7 Maybe this will help.

In the meantime I checked that the main nozzle is working fine so the problem is that it just does not create enough vacum to overcome the spring. So if rising the lever doesn't help I guess I will have to modify the spring. For ther last 24 hours I learned a lot about Walbro carbs

_____________________________

Mather Aerospace Modelers, Inc.
AMA Gold Leader Club, Charter #1243, Sacramento, CA

(in reply to aero nut)
       Post #: 2207

RE: gas fuel with glo plug no i... - 7/19/2008 5:32:11 PM   
aero nut


 

Posts: 447
Joined: 11/10/2003
From: tijuanaBaja California, MEXICO
Status: offline 		well let us know how it worked out, how much oil are you using on these babies?

(in reply to RysiuM)
       Post #: 2208

RE: gas fuel with glo plug no i... - 7/19/2008 7:01:21 PM   
RysiuM



Posts: 1390
Joined: 4/22/2003
From: Elk Grove, CA, USA
Status: offline 		Did not try yet.

Because the metering system is working fine (I mean the valve closes and opens), fuel pump is giving a pressure, and as soon as the metering valve opens I see a fuel dripping of the main nozzle then I figured out there must be two possible reasons:

1. metering spring is to strong - very unlikely as this is original one not modified by anyone.
2. at the venturi there is no enough vacuum to suck the fuel of the metering chamber. This vacuum is the one that presses the spring and opens the valve. So the reason for not enough vacuum must be either not enough airflow to the engine (kind of unlikely) or intake disturbance by the prop wash. It is possible that prop wash is pushing the air into venturi creating pressure instead of expected vacuum, and then the metering valve never opens.

To fix the second possible issue I installed my ugly velocity stack. This additional 1 inch of tube in front of venturi should smooth out the air flow and fix any pressure wave problem. I'm going to run the engine soon.

The last mixture I made was 9% of Red-line synthetic oil, and it was plenty of oil inside the engine. Now I mixed next batch of fuel this time 1:16 (6% oil) with Amsoil 100. After I run a couple of tanks of that through this engine I will check it again. As long as I have heavy oil spill on the fuselage I think I am OK with lubrication.


< Message edited by RysiuM -- 7/19/2008 7:02:18 PM >

_____________________________

Mather Aerospace Modelers, Inc.
AMA Gold Leader Club, Charter #1243, Sacramento, CA

(in reply to aero nut)
       Post #: 2209

RE: gas fuel with glo plug no i... - 7/19/2008 8:04:23 PM   
RysiuM



Posts: 1390
Joined: 4/22/2003
From: Elk Grove, CA, USA
Status: offline 		Bummer, the same thing. It should work, but it does not. Now I'm ready for major surgery. The worse case scenario is I will replace the body of this carb with another one (I have 4 of these WT308).

_____________________________

Mather Aerospace Modelers, Inc.
AMA Gold Leader Club, Charter #1243, Sacramento, CA

(in reply to RysiuM)
       Post #: 2210

RE: gas fuel with glo plug no i... - 7/19/2008 11:55:40 PM   
RysiuM



Posts: 1390
Joined: 4/22/2003
From: Elk Grove, CA, USA
Status: offline 		Now I think it's time to to major surgery. I reduced the spring to minimum but the engine dies on more than 1/4 throttle. Manipulating with Hi needle doesn't change a thing. So I started to play with Lo needle till I got full throttle rpm. The engine was running only on one needle (Lo end) almost full range so it is not the issue with fuel delivery to the metering chamber. And it looks like this carb size work good on this engine. As soon as I figure out the fuel problem.

Now I think that the Hi end just doesn't work. Maybe it is clogged or check valve doesn't work. Anyway this piece is going to have a major surgery. But before that I will try another body - maybe it will be better.

Of course any tips and comments are welcome.

_____________________________

Mather Aerospace Modelers, Inc.
AMA Gold Leader Club, Charter #1243, Sacramento, CA

(in reply to RysiuM)
       Post #: 2211

RE: gas fuel with glo plug no i... - 7/20/2008 2:00:55 AM   
captinjohn


 

Posts: 5602
Joined: 1/25/2002
From: Hesperia, MI, USA
Status: offline 		Some carbs have a fine screen under a welsh plug. Sometimes that welsh plug has got to come out and screen cleaned. You will need a new welsh plug also. This may not be the problem with yours though. Good luck Capt,n

_____________________________

I never met a engine I did not like!

(in reply to RysiuM)
       Post #: 2212

RE: gas fuel with glo plug no i... - 7/20/2008 2:56:53 PM   
nitro joe


 

Posts: 162
Joined: 12/15/2002
From: Chiburbia, IL, USA
Status: offline 		“Some carbs have a fine screen under a welsh plug.”

Interesting,I've never seen this.Please list an example or two.
Thanks.


_____________________________

Information on the Internet is subject to the same rules and regulations as conversation at the corner Pub -Author unknown.

(in reply to captinjohn)
       Post #: 2213