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Old Jan 13, 2013, 12:18 AM
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farmington, mn
Joined Sep 2003
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Any Fuel pumps for twin 4-stroke engines?

I have a PBY Catalina that has twin 4-stroke .30 OS engines. My current set up is small primer tanks behind the engines then a large tank in the belly, I need the primer tanks since the engine can't pull the fuel out of the belly fast enough. Due to a crash I need to rebuild her. I want to remove the primer tanks and ad a fuel pump. Are there any electric fuel pumps that I can add? I know there are some mechanical pumps that don't work on 4 strokes so I was thinking of electric but can't see to find any. Anyone have any ideas? Weight really isn't an issue since the plane is huge and has lots of space
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Old Jan 13, 2013, 09:26 AM
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earlwb's Avatar
USA, TX, Grapevine
Joined Dec 2008
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You can get the Perry pump for four stroke engines. It uses the engine vibration to operate the pump mechanism. But I have never tried using it on a small .30 size four stroke engine.

They do not make small electric fuel pumps for model airplane engines. One could likely use a electric pump like you use to fuel up the plane with, but these pumps aren't designed for continuous duty though. So I don't know for how long they might last in this case.

You'll need to use a Cline regulator on each engine for the pumps in any case.

Usually people put the fuel tank right behind the engine, as the engines were designed for that. But with the PBY plane I can see that being a problem of course.
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Old Jan 13, 2013, 03:42 PM
I HATE GLOW PLUGS!
SrTelemaster's Avatar
United States, NY, St Lawrence
Joined Feb 2012
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Quote:
Originally Posted by jeff262 View Post
I have a PBY Catalina that has twin 4-stroke .30 OS engines. My current set up is small primer tanks behind the engines then a large tank in the belly, I need the primer tanks since the engine can't pull the fuel out of the belly fast enough. Due to a crash I need to rebuild her. I want to remove the primer tanks and ad a fuel pump. Are there any electric fuel pumps that I can add? I know there are some mechanical pumps that don't work on 4 strokes so I was thinking of electric but can't see to find any. Anyone have any ideas? Weight really isn't an issue since the plane is huge and has lots of space
You can use crankcase pressure to pump fuel by installing an inlet check where the crankcase breather is located, then finding a spot (preferable in a removable part) where you can D&T for an outlet check like a rocker covers perhaps.



Then you route this positive pressure to a bleed off that can be fashioned from a spray bar. This will also force oil through your valve train for better lube.

Or you can buy the whole set-up from Saito.http://www.horizonhobby.com/products...SAIE300TTDP#t4



This is what Saito uses on the twin carb FA300TTDP.
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Old Jan 14, 2013, 07:30 AM
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USA, MA, Weymouth
Joined Mar 2004
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The Perry SHAKER pump is the one for the four-stroke mills...

Dear Jeff262:

The PIPE Here...the sort of Perry pump that EarlWB was recommending for use with your pair of OS FS-30 four-stroke mills looks like THIS...



...and with the blue anodized outlet hex fitting, it's called the VP-20 that's meant solely for glow fuel, and with a gold anodized outlet hex fitting instead, that's the gasoline version, known as the VP-22SG.

I've also included a PDF copy of the general instruction sheet that comes with each Perry "shaker pump", as I've always called them, to give you a better idea of how it's properly installed. I've used them on both of my OS single-cylinder four-stroke mills (FS-40 and rear camshaft FS-90), and they've worked quite nicely, "never missing a beat" from the early 1980s through to when I had to stop flying for a while a decade ago.

Here's hoping that the VP-20 glow fuel version of the Perry "shaker pump" is what your FS-30 four-stroke mills can use - one per engine, of course - to give each of them a decent fuel flow for reliable running.

Yours Sincerely,

The PIPE....!!
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Old Jan 14, 2013, 09:26 AM
I HATE GLOW PLUGS!
SrTelemaster's Avatar
United States, NY, St Lawrence
Joined Feb 2012
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Quote:
Originally Posted by The PIPE View Post
Dear Jeff262:

The PIPE Here...the sort of Perry pump that EarlWB was recommending for use with your pair of OS FS-30 four-stroke mills looks like THIS...

While I have used the Perry "shaker" pump W/great sucess on a Saito FA150, I fear the size will be too large when applied to the .30 size OS in the Catalina nacelles.

The case pressure pumping system adds almost nothing as far as weight/bulk. Both engine would be used to generate pressure W/1 regulating valve near the tank.
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Old Jan 14, 2013, 10:54 AM
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tacx's Avatar
United States, MI, Macomb
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What about one of these

http://compare.ebay.com/like/3707314...Types&var=sbar
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Old Jan 14, 2013, 12:11 PM
I HATE GLOW PLUGS!
SrTelemaster's Avatar
United States, NY, St Lawrence
Joined Feb 2012
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Quote:
Originally Posted by tacx View Post
That particular one is for gas/oil, not glow fuel.

Besides, why add weight/complexity when you have crankcase pressure that will do the job?

I mount my tanks over the CG if I can & although I have used the VP-20s in the past, since I have discovered how to use crankcase pressure that option has less apeal to me.

Also, the shaker pumps are too large for this application as they must be mounted directly to the back plate of the engine.

Crankcase pressure is dependable, it adds no significant wieght & it takes up very little room, just a place to mount the regulator valve which is not very large.
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