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Author Topic: Merco 35 break-in  (Read 1304 times)

Offline Michael Millard

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Merco 35 break-in
« on: August 24, 2021, 11:56:24 AM »
 I picked up a Merco 35 R/C about eight or nine years ago, put a super tigre needle and spraybar  and Delrin  venturi with .275 opening in this  engine. I'm finally getting around to running it. The operative word is trying to run it. I have a new merlin 2003HD glowplug  in it fresh Sig 5% 25% castor  and am  getting nowhere with it.  Originally tried an 8x4  on it but couldn't get enough flywheel effect to get more a few pops out of it when extremely rich. I switched to MA 9x4 , basically the same thing. Any help would be greatly appreciated. Michael Millard

Online Dan McEntee

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Re: Merco 35 break-in
« Reply #1 on: August 24, 2021, 12:37:13 PM »
  Well, the 9X4 should get you started. How many turns is the needle valve opened?  It should be at least three turns. Make sure that fuel is getting to and through the spray bar. If you have any doubts, pull the spray bar and physically check it by flushing it with fuel and or sighting through it. Install the needle , open it three turns and make sure you get some flow. Put the spray bar back in and make sure the hole is pointing down the venturi and not visible when you look down the throat of the venturi. The plug should be good for bench running, but check it's operation by connecting it to a glow ignitor to make sure it's glowing. Prime the engine with a small charge f fuel down the venturi and see what happens. Do not run a muffler during break in. Let all the crap and heat out of the engine.
  Type at you later,
   Dan McEntee
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Offline BillP

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Re: Merco 35 break-in
« Reply #2 on: August 24, 2021, 01:27:09 PM »
Did you check all screws for tightness? A fast and easy way to check the NVA is to blow through it using a piece of fuel line. Adjust the needle while blowing and that will give a hint on being blocked or needle not open enough.  I would start with a 9/6 or 10/6 nylon MAS. Neither will hurt the engine to get it started and needle tweaked...but the weight may help for the initial flip start. Glow plugs can glow but still not be ok so a new plug is worth a try. Last resort is put a spinner on and use an electric starter.
Bill P.

Offline Michael Millard

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Re: Merco 35 break-in
« Reply #3 on: August 26, 2021, 03:51:52 PM »
 Hi everyone, I finally got the Merco to run  at about 2 turns open on first tank  running extremely rich, had to restat four times first tank. When I disconnected the glow igniter the rpms  dropped at least 100 rpm with either Merlin 2003 HD or glow devel glow plugs. I ran almost a quart of fuel after leaning out to a turn and half open. It's running well enough to fly to finish break-in. The question now is where do I get glow pugs that are hot enough, and how much of a national war debt are they going to cost me. Michael Millard

Online Dan McEntee

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Re: Merco 35 break-in
« Reply #4 on: August 26, 2021, 08:46:36 PM »
   The Glow Devil should do the job, and are only available direct from Sonic-Tronics.  I use the Glow Devil R/C long and do a lot of others. The Thunderbolt plug is available from Mikegoesflying.com, I think it's called. You may find out for sure by searching this forum. get on the Sonic-Tronic website and sign up for an account as they sometimes email out discount codes that are almost like buying wholesale. Make sure of the spray bar hole at this point and put another quart through it if necessary. Flight loads from airplane weight, drag, and a bigger prop with more pitch will affect it. If still on a test stand it should start easy, lean out a bit if fuel line is light pinched and go back to the setting immediately, and should lean out and quit quickly and cleanly when the tank empties. If the engine stops with the piston at the top of the stroke consistently, run it some more. I have been working with a OS.35S to put in a Nobler ARF and thought it was a low time used engine, but in reality I think it had never really been run and had similar difficulties as you have experienced, and it just took about 6 or 8 tanks of fuel to get over the hump. Starts easy and quits cleanly  now so beck in the model it goes!
   Type at you later,
    Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Offline Robert Zambelli

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Re: Merco 35 break-in
« Reply #5 on: August 27, 2021, 06:50:59 AM »
I picked up a Merco 35 R/C about eight or nine years ago, put a super tigre needle and spraybar  and Delrin  venturi with .275 opening in this  engine. I'm finally getting around to running it. The operative word is trying to run it. I have a new merlin 2003HD glowplug  in it fresh Sig 5% 25% castor  and am  getting nowhere with it.  Originally tried an 8x4  on it but couldn't get enough flywheel effect to get more a few pops out of it when extremely rich. I switched to MA 9x4 , basically the same thing. Any help would be greatly appreciated. Michael Millard

Michael - I believe there were two versions of the Merco 35 RC.
Please post a photo of yours.

Bob Z.

Offline Robert Zambelli

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Re: Merco 35 break-in
« Reply #6 on: August 27, 2021, 07:04:08 AM »
There were two versions:
One had a one-piece crankcase and an orange head,
The other had a removeable steel finned liner and, as I recall, a black head.

I've owned them both and a 10-6 prop and Brodak 10/23, 50-50 fuel worked perfectly for break-in.
The one-piece version performed much better and was similar in performance to the Max-S 35.

Bob Z.

Offline Michael Millard

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Re: Merco 35 break-in
« Reply #7 on: August 27, 2021, 05:55:19 PM »
 It's the two piece crankcase. The picture is to large a file.


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