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-   -   Mounting an engine inverted. (https://www.rcuniverse.com/forum/questions-answers-154/625283-mounting-engine-inverted.html)

radiocontrol 03-15-2003 02:28 PM

Mounting an engine inverted.
I will be mounting a Saito .91 4C to the GP UCD in the near future. The instructions call for mounting the engine inverted. This would be my first experience mounting an engine inverted. Are there any problems I could expect mounting the engine this way, vs. sideways or upright? Would the engine have more tendancy to "load up" while inverted? Can a new engine be "run in" while inverted? Any advice would be appreciated. Thanks!!


BingoFlyer 03-15-2003 02:41 PM

Mounting an engine inverted.
Some four stroke engines will benefit by using an on board glow driver when mounted inverted, also make sure that the spray bar on the carburetor is not below the pick up of the tank (if the plane is designed for an inverted engine this should not be a problem).

Make sure that you do not flood the engine when starting, if using an electric starter a flooded engine will cause damage to the engine (bent or broken connecting rod).

I have run my OS.91 Surpass inverted with out a glow driver and have not had any problems with loading up or flooding.

F.Ciccarello 03-15-2003 04:47 PM

Inverted engine
I run an O.S. .91 surpass II pumped in my P-51 Mustang, inverted as per the plan. So far the engine runs perfect. I have an on board glow system that is servo activated.

with my glow set up I don't have to stand on my head to hook up the igniter.

outssider 03-15-2003 07:00 PM

Mounting an engine inverted.
keep the center of the tank a little """BELOW""" the needle of the carb. The majority of the tank should be below the carb!! This is going to be tough with that plane because the tank is designed to go in a spot that is too high for that engine.
If the tank is too high, you will need to use either an on board glow system or a cline regulator if you want a nice reliable idle.

remember this........The higher the tank, the more the fuel will siphon into the carb while the engine is trying to idle....with the engine inverted the excess fuel has nowhere to go except into the combustion chamber ;)

radiocontrol 03-15-2003 09:35 PM

Mounting an engine inverted.
Thanks. I appreciate the input from everyone. I have seen one instance where a pilot mounted his engine sideways on the UCD. I assume the overall beauty of the plane would be better served if the engine is mounted inverted as intended. I will check the height of the tank vs. the carb very carefully. Can someone explain what an inboard glow system is? And what is a Cline regulator?


rc-sport 03-16-2003 04:44 AM

Mounting an engine inverted.
I run a Saito 56 inverted in a Sig Rascal. It doesn't have an on board glow driver and that engine is the sweetest running engine I have, at idle it ticks like a clock.

BingoFlyer 03-16-2003 03:25 PM

Mounting an engine inverted.
An on board glow driver is a battery that is turned on when the engine is at or near idle it can be turned on via mechanical or electronic means but in both cases keeps the glow plug hot, I use mine when starting also as the engine is completely inside the cowl.

coomarlin 03-19-2003 12:15 PM

Mounting an engine inverted.
I mounted a Saito 100 in a UCD and I put it in inverted. The carb ended up nearly 1 inch below the fuel tank which was not good news. That would lead to fuel loading and flooding and probably hydrolock. I ended up buying a Cline regulator which fixed all of those potential problems. My engine runs great with the cline. The cline is a demand regulator that only supllies fuel to the carb when it requests it. It slightly pressurizes your fuel tank and creates consistant fuel delivery throughout the entire run of gas which is great. You can find out more about the cline regulator at Jim Clines Website . It does cost $60.00 but it is worth it. There are also some threads here on RCU concerning Cline regulators and perry Pumps.

Cline Questions
Cline Regulator - Inverted Saito 100
Cline VS Perry Pump

The nice thing about the cline is that once you put it in there is really no adjusting to do other than the standard idle setting adjustments..

radiocontrol 03-20-2003 02:56 AM

Mounting an engine inverted.
Coomarlin, thanks for the info on the Cline regulator. I went to the website you mentioned and read the info. I'll be ordering one of these soon.

doctor jason 03-21-2003 09:39 AM

Mounting an engine inverted.
As far as I know it should not make any difference to the engine once it is running weather or not if it is upwright or inverted,all my four strokes are inverted and run tottaly happy.

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