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Stripping a GPU

Hydroflight

Active member
I recently purchased a GPU 220 with all the covers and generator shrouds on it. I was told that the small generator attached next to the throttle control assembly is also the starter on this motor. The unit was purchased surplus over 20 years ago and the fellow that owned it replaced the oil in it regularly and turned it over a few times a year. The owner passed on last year he was an avid pilot and stored the 220 in one of his hangers. It looks like it was never run, i have not pulled a barrel yet to see. I was hoping one of you fine gentlemen could inform me if it true the generator doubles as a starter? I am also confused with the two solenoids that go into the top of the carburetor. Would anyone know where I could get a conclusive manual on the unit? Is their any special concerns I should have with stripping this unit down as well? I sincerely appreciate any help.
 
my motor still had the silnoids on top of the carb.i used them to run the motor out of fuel after running it .i don't know about the gen.,duabling as a starter . i put an airtec starter kit on mine,witch includes a starter alt. prop adapter fly wheel all the brackets and hardwhere .the starter is a mini high torck the alt. is a small one wire ,the prop adapter is mechines bullit as well as the flywheel the bracket are nickeled .the best money i have ever spent on the boat .they run around 600 buck but i have never had any problems with it starting or charging .it is about 3 years old now been in the weither since i bought it.be carweful on some of the other srater kits because they sometime don't line up and tend to grind instead of starting .daany at sawgrass weildin makes a good starter kit for less ,he can also answer any of your question about the motor ,and get you a manual on it ,or parts .he is a real stand up guy his number i 772-571-1575 hope this helps give danny a call he will answer any of your quiestion and talk with you . like i said he is a stand up person and knows alot about these motors he also has a full machine shop there .
 
Doc, thanks for the lead on the manuals.
Woody, I appreciate the info on the solenoids, Do you use them to shut down the engine rather than to ground the magneto? Great lead on starter kit I will make contact.
Thanks for sharing your wisdom with me.
 
I just overhauled a 220 GPU that I took out of a MD-3. Taking it apart is pretty straight forward. Throw the Zenith carburetor away and get an adapter from Speed Wheelie and put on a 500 Holley two barrel carb with 76 or 77 jets and a 10.5 power thing. I can almost guarantee the cylinders are rusted and need replaced. Speed Wheelie will sell you a new set at $250 each. That includes rebuilt chromed cylinders with the valve work done to perfection and a new set of steel rings.

That starter is heavy and will not work. Get the Air-Tec starter and generator set for $600. It includes the prop adapter, starter and generator and the necessary brackets. The parts and overhaul manuals can be purchased from Essco. You need both. If the crank has been turned you need to have it re-nitrated to harden it. If you overhaul it you should measure the cam to limits as well as the crank and have the lifters rebuilt. Rebuilt lifters and cam followers is $500 from Aircraft Specialties in Tulsa Oklahoma.

You've got a great engine if you take care of it. Get your magneto overhauled and get a new harness from Mike Thurman.
 
des where did you get your crank re nitrated. and is that when it makes it very strong? hydra i used the mag to shut the motor off when i was runing the boat,but after i put it on the trailer i would use the solenoids to run the carb out of fuel for storage in between runing .i ran the zenith the hole time i ran my 220 .never had any problems out of it.i got better fuel econ. with the zenith than my buddy got with the holly.but that is ford vrs. chevy a/c vrs. c/m thing going on. best thing i can say is run both of them and see witch one u like better and sell the other. run the zenith and see if you like it,you already have it ,and it will not cost a thing if you do.
 
To: Doc, Woody, Flordacrakr0470, and Des Moines boater. You guy's are champions willing to give your wisdom so freely. I appreciate all the leads, and look forward to a first class rig due to your help. Any other helpful hints are more than welcome.
 
woody ,
you get more oil splatter on the front unless you put a plug where the old gear was by putting it on the oil filler neck removes that little bit. a single vent is ok bu those 220 really should have a double vent one on the back and one on the front to let it breath
 
I BELEIVE that there is a small high torque starter that is made buy toyota that you can buy of the shelf @most part stores , dont know the part # . but that starter is a Toyota starter. A buddy of mine gets his at napa auto parts store in Okeechobee,FLA . I apologize that i dont have that # .
 
Plum, Woody, and Goldhunter: Thank you for the breather info, I am confused as to what the acs case is? I will weld the half inch pipe as recommended. Where should I vent the rear of the engine?
Cowboy are you talking about a direct replacement starter for the 24 volt unit that is presently on the engine?
Thanks again gentlemen for all your wisdom.
 
Hydro,
where everyone vent the asscory case is they remove and junk the 24v gen in the top center hole make a block off plate for that hole and put a vent there. if you put the 3/4" vent tube on the oil filler neck like plum said that is good for the back of the case. on the prop end of the motor you will see either a plate or a 2.5" butterfly vent on top the motor case remove the butterfly vent make a solid plate an drill and tap for 3/4 pipe nipple for your second vent
 
continental cracker, I have all my aircraft machine work done by Aircraft Specialties in Tulsa, Oklahoma. Any overhaul place should be able to re-nitride the crank and it does harden it. I like the Holley 500 but it seems some people like the Zenith. I haven't tried the Zenith, so, I shouldn't make a judgment. I have a spare if anyone wants one.

The accessory case is the back of the engine where the oil screen and magneto go. It contains the oil pump too. For airboat folks they refer to that as the front of the engine since it is to the front of the boat. The prop end is the rear for airboat purposes.

You do need to make a plate to cover the back top of the accessory case and one for the front vent. You can remove the oil pressure valley assembly and tap the oil holes and plug them. A filler neck vent is a good idea.
 
Hydro here are a couple pictures that hopefully will be easier then "OUR" (happy des:) ) descriptions

Oil filler neck vent and block off plate (black)

Vent_oil_filler_neck_jpg.JPG


PE-90 /520 conversion front vent plate

vent_front_pe-90_520_conversion_jpg.JPG


220 front vent plate

Vent_front_220_jpg.JPG
 
Goldhunter,, Thank you!! This is way more than expected. I appreciate all the time and effort that went into getting those pictures for me. It is true a picture is worth a thousand words in this case.
You gentlemen are exceptional people, and you have my deepest gratitude.
Hopefully one day I will be able to mentor someone on this subject like you are mentoring me now.
Thanks again from the Northwest.
 
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