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Gso 480 newbie questions

Posted: Tue Jul 21, 2020 10:17 am
by 12ftgso480
Hello airboat community. Out of northern Oklahoma right on Arkansas river. Just bought my first boat that sits on a 13' sled and has gso480. Being brand new thought I could ask some real rookie questions like what my oil temp and oil pressure should run after warm up and idle. It appears we have a 750 double pump feeding it with 1/2". Forgive me for I have not a clue about aircraft engine and am trying to work my way in. Notice a little smoke at start up but performed well. Would take off dry sand bar with half throttle ? Seemed like oil pressure was around 50-60 @2000rpm and oil temp was 200ish? Oil sump was half full on sight? I've tried to read through post and was finding spefic info I was looking for. I've got a manual downloaded hopin it will help with general maintenance, also we only ran it with one mag switch on and thought I read somewhere on here that someone was running both? Can you guys please help me with a check list before I put too many hours on it and break something that could be easily avoided. Posted a couple pics below to help describe my setup. Thanks!! :old_glory:

Re: Gso 480 newbie questions

Posted: Tue Jul 21, 2020 10:29 am
by 12ftgso480
Ps noticed it would burp ( not quite a back fire but sounded kinda loaded ) when shutting engine off after each run we made.

Re: Gso 480 newbie questions

Posted: Tue Jul 21, 2020 11:05 am
by Bonefish
GSO, normal operation is to start on the impluse mag then switch on second running both all the time. With that you will get better performence and I suspect your oil temp will drop some.

Re: Gso 480 newbie questions

Posted: Tue Jul 21, 2020 4:10 pm
by kwanjangnihm
12ftgso480 welcome to SA!

There are no rookie questions here bro, asking is the only way we all learn. :salute:

Do you know any history about the motor? (hours, builder, etc)

Good luck & slide safe!

Re: Gso 480 newbie questions

Posted: Wed Jul 22, 2020 2:24 pm
by 12ftgso480
Looks like one of the middle cylinders has been worked or replaced. I'll look at hour meter this evening. All my airboat buddies told me not to go aircraft but was on tight budget and got a good buy at auction. I literally know nothing as far as taking care of it starting or running. I looked for an hour filter for 20 min :shock: I got operation manual printed off. Gonna read through it aswell.

Re: Gso 480 newbie questions

Posted: Wed Jul 22, 2020 7:36 pm
by unforgiven11B
I’m sure sliding gator or Kwan will chime in, also hit the search function on the site or just type in your questions in google like “gso480 Running temp southern airboat” “ gso480 oil temp or pressure southern airboat” you’ll get more information than you’ll want to read in one sitting. There’s a link here somewhere on the overhaul manuals that you should read up on. Good looking rig and welcome.

Re: Gso 480 newbie questions

Posted: Thu Jul 23, 2020 5:54 am
by Blownaway540
Welcome, how many quarts of oil does sump hold, have a good oil cooler, it it in a good position,clean? The supercharged motors have tremendous power but high head temps will kill it, burn pistons. I don't run for miles dry with mine in summer heat. I put a nitrous plate under my 750 carb, fuel only with its own fuel pump. If I'm running dry and see temps rising, hit the button for the nitrous plate (fuel only) fatten it up and can see temps drop. Run only AV gas, (100ll) at 16 pounds boost it kicks your compression to over 15-1. Great motors if you are old and lazy and are tired of getting stuck and having to get off and push/pull like me. Regards, Mark

Re: Gso 480 newbie questions

Posted: Thu Jul 23, 2020 9:12 am
by SuprchgedPalmBeach
25 psi at idle, 60-80 psi running with engine at temp. I typically see nothing greater than 180 oil temp but I run a 4 gallon oil sump with de-foaming baffles and a big cooling shroud. If you get foam in your oil it will also kill it over time and lower oil pressure. Keep cylinder temps low and this engine will perform as it should. The gso480 is a bulldozer but only if its set up correctly.

Re: Gso 480 newbie questions

Posted: Fri Jul 24, 2020 12:26 am
by 12ftgso480
So dad and I got on it tonight and installed a new set of gauges, all except tach. After all talk about running rich we pulled few plugs and noticed couple were oily while the other half looked healthy. We ran the boat with only one mag switch on the whole day, hoping that will cure oily plug issue. As for my oil cooler I didnt measure but guessing reservoir or sump what ever that thing is :lol: looks like it has to be 2 gallons or more. Took a peak inside with it half full I don't see baffles. Kinda curious at this point if we should run it full ? Half full on the site? It sat on half when we bought. Hr meter reads 80hrs for what that's worth. It has a new cylinder that was put on right before we bought. Also dad doesnt know what to think about our hood/cooler. Ours Is made of stainless do guys recommend aluminum? Gonna see this weekend how were looking after new guages and both mags running. Sorry for long post, I'm open for criticism or helpful info if you guys notice anything way off in our pictures. Thanks guys :old_glory:

Re: Gso 480 newbie questions

Posted: Fri Jul 24, 2020 4:25 pm
by kwanjangnihm
12ftgso480 wrote:
Wed Jul 22, 2020 2:24 pm
Looks like one of the middle cylinders has been worked or replaced.
If the cylinder was replaced, there is a break in period and typically lycomings run Aeroshell 100 Mineral oil until the rings set.

Re: Gso 480 newbie questions

Posted: Fri Jul 24, 2020 8:10 pm
by lariat
It is best to shut it down with fuel cut-off rather than with mags.

Re: Gso 480 newbie questions

Posted: Sat Jul 25, 2020 6:15 am
by Gary S
All aero shell 100 is mineral. Break in is straight mineral without ashless dispersants.

Re: Gso 480 newbie questions

Posted: Sun Aug 09, 2020 1:19 pm
by 12ftgso480
Was out today. Noticed after warm up at idle oil pressure was around 25,, at 2000 rpm I was around 55 and closer to 60 at 2300. Its around 85° here now. Engine got up to 190 after 2 to 3 miles of running on average around 2000 rpm in water no dry. Noticed my oil sump was a little low when we got back. Do you guys run yours completely full or half ? When I added some after warm I also noticed a little foam at top or oil. Not much.

Re: Gso 480 newbie questions

Posted: Sun Aug 09, 2020 6:19 pm
by Blownaway540
My sump holds about 3 gallons, I put 2 1/2 gallons in (10 qts).