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Engine basics => Engine set up tips => Topic started by: frank mccune on June 20, 2019, 01:26:12 PM
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Hi All:
While playing with my HP .40 BG equipped Ag Cat, I noticed a problem. The engine was impossible to start which is strange as it used to be very easy to start. The only change was that I had added a chip muffler with the muffler pressure line attached to the fuel tank. I removed the pressure line and it started instantly. While it was running, I attached the muffler pressure line to the fuel tank and the engine stopped. I am guessing that the muffler is too restrictive producing too much fuel going to the engine. This may explain why the engine and muffler were badly flooded with raw fuel. The muffler has twelve No. 43 holes drilled in it to release the exhaust gases. Perhaps there needs to be more holes drilled in the muffler.
Thoughts/suggestions,
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My provocative question:
Why do you want to use any pressure from muffler by a C/L stunt model?
If you have a good, carefully adjusted/positioned Uniflow tank you do not need any pressurizing.
The R/C is quite another world...
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i ALMOST NEVER RECOMMEND MUFFLER PRESSURE on CL stunt setups, Pressure makes everything worse, and makes the engine dumb where it does not respond to attitude change
If any leaks the become large problem,
if line slips off lean motor burn run
if line cloggs lean motor burn run
line slowly clogs makes for bad needling
trash burned carbon flake sand dirt etc can go thru the exhaust and ne put into the tank
you are filling the tank with massive bubbles, and hot gases, and burned fuel
there are many more
Randy
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Randy,
You forgot to say, how entertaining it is, when you fill up the tank, the smoke comes out from the overflow tube of the tank... ;)
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ARGH .
But if you get a bullet trough the fuel tank , the inert gasses mean it dosnt explode ! .
Muffler pressure can even the run where the airs really choppy , so the models bouncing all over the place , keeping the fuel up to the motor .
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Hello
I have used muffler pressure on many models over the years but normally on combat models where the venturi is to big to work on suction well especially on takeoffs where the fuel runs back to the tank or it just goes lean in maneuvers. We must use a muffler (unless it is a small diesel) so once you have sorted the back-pressure and tap outlet size it is a lot easier then crankcase pressure to work with. Just need to lean the needle over the suction setting like any pressure set up . Note muffler pressure taps vary wildly in size from about 1/32 up to about 3/16 id .
Regards Gerald
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Hi al.:
Thanks for all of the replies!
Rand’s post reflected my thoughts perfectly. It was suggested that muffler pressure would make an engine run much better. I have used a straight Uniflow system and never wanted for performance from a fuel system. Human nature dictates that we attempt to improve our lives in most cases. At times it may be well hidden.
Perhaps the idea of pumping dirty used oil into my fuel was the most repugnant. Any way, KISS is a good idea.