Slip it all day long. It's not a Cessna.
The IO-360 has it's own pecularities & not a lot of people take the time to figure them out. It's worth it though, sweet little engine until you get to rebuild it. Butch is right (Hey Butch! ) There's a few rules here. Don't baby it, run it at 23-24 squared like James said (Hey James! ) Make damn sure your baffling is good. This engine doesn't suffer overheating well at all and was the reason it suffered in the rear spot of the 337 to begin with. There's a nasty off idle stumble that'll add some gray hairs to your head if your'e not warry of it on short final. Sorry, no experience with GAMI's, herard they're great, willing to accept sponsorship though....
Flight: We covered slips, the M-5 wings are the same length, have the ailerons moved out board and about 18" more flap. The big advantage is that most -5 wings have the aux tanks which I can't really see myself ever being able to without here. (I have the -4 wings with aux tanks) The -4 slips great, arguably has a better crosswind component and is ~100-120# lighter than the -5, -6 & -7's. They are well balanced on the controls and with experience, will do some pretty amazing things.
I have 31's and cruise ~125 or so. The gap seal is the best $50 you'll ever spend. The VG's won't lower your stall much if at all but will give you a tremendous increase in aileron authority. Worth it in my book if you spend much time on the backside of the power curve. Oh yeah, spend a lot of time in this region at altitude, get real familar with it. It will keep you alive.
Your best mod is a lot of gas. Have fun with it

YELLOWMAULE wrote:Slip it all day long. It's not a Cessna.

The IO-360 has it's own pecularities & not a lot of people take the time to figure them out. It's worth it though, sweet little engine until you get to rebuild it. Butch is right (Hey Butch! ) There's a few rules here. Don't baby it, run it at 23-24 squared like James said (Hey James! ) Make damn sure your baffling is good. This engine doesn't suffer overheating well at all and was the reason it suffered in the rear spot of the 337 to begin with. There's a nasty off idle stumble that'll add some gray hairs to your head if your'e not warry of it on short final. Sorry, no experience with GAMI's, herard they're great, willing to accept sponsorship though....

I have the Cont IO-360 in my 170B, so I've been following this thread. Setup and plumbed like a Hawk XP.

The 'nasty off idle stumble' you mention - could you describe that a little more? any idea of the cause? mine does that a little, only on short final at idle. Doesn't bother me, I have almost 800 hours flying it.

Agree on the 23-24 sq, with exceptions. I used to commute in the airplane from KCCR to KPAO a fair amount. Right over some of the worst traffic in the San Francisco Bay Area. I would usually climb out at 24 sq to about 2500 and then throttle back to 20" and 2100 and lean it to about 6 gph, and just loaf the rest of the way. Cost me about 4 minutes roundtrip and saved a gallon+ per trip. I have an engine monitor though, not sure I would do that wihtout.

HAVEN'T EXPerienced any problem off idle.. It is a rather rough running engine at idle and on the ground though... Give it a little throttle and it smooths right out... at cruise it's a smooth running son of a gun and I once got 7 gals per hr on a trip home from Idaho at 23 squared between Caldwell and Tonopah....so it's doable if you lean it out at altitude and aren't in a hurry....

YellowMaule, thanks for the info. I've been climbing at 25 squared, cruising at 24 squared (is that doing it right?). Baffles are brand new, and I keep an eye on the temps on the JPI. I plan to get the VGs and gap seal soon. You're absolutely right, spending money on gas is one of the best "mods" for me with my new-to-me bird. And believe me, I'm having fun with it.

I get a little exaust popping with the power all the way off, but it has been quick to respond and hasn't stumbled when I add throttle back. Is this when the stumble occurs that you are talking about?
As far as idleing rough on the ground...sounds kinda like a hotrod . I pull the mixture back a good bit on the ground and it smooths out a little.

My left fuel tank vent seems to puke fuel out of it more than it should. In flight, on the ground, at any time when the left wing is low, I brake aggressively, or turn right on the ground. I get a little spill out of the right vent also, but not as regular as the left. Happens at all fuel levels too, not just full. Any ideas??

Do y'all ever run a fuel tank dry in the air before switching tanks? I used to do that in my 182 and have done it successfully a few times in the M4. However, (after I had done this a few times) a pilot with a lot more years of experience than me told me that some fuel injected engines won't pick back up after you switch tanks, even with boost pump on. He has put 2 on the ground as a result of this. Is it vapor lock? In mine, as soon as I get the rpm drop, switch tanks and boost pump on and the engine comes back to life. Is this is a risky practice...something that may not work every time? I'll quit doing it if there is reason to believe that it won't pick up every time. I like off airport landings, but I like to decide when and where I do it.

Oh ya, one more thing. What oil change intervals do you use. Oil at 25 and oil and filter at 50? Or just do both at 50? What do you think is best?

Thanks for the help guys!

YELLOWMAULE wrote: Slip it all day long. It's not a Cessna. ....

Haven't seen you post in a long time, Kurt-- how are you & the Mac clan doing? Just thought I'd say hi....

Eric from PT

I ran one dry on a return from Johnson Creek one year and didn't have a problem switching but I must admit it makes the pucker factor higher even though you know it's gonna run dry...Don't slip it so much here at home but Up in Idaho I use slips more for the short strips and dicey approaches.....are you sure it's your vent that's leaking... I had same problem on my left and I got a new gasket for the cap... Problem solved...and your description of idle on the ground is spot on... sounds like a hot street rod...I don't have a filter so I change oil every 25 and I use straight 50 weight....and yeah Kurt.. where u been... miss your fantastic pix...

This is not a slip by the way. Playing around with a couple of other Maulers at 9,000'
What I meant earlier about the low RPM stumble, is that immediaely off idle there is an initial stumble or hesitation that is in my opinion, a design issue in the engine. You have a relatively long plenum run, a large air valve and the two combine to briefly lower the velocity allowing a great deal of air in at one time. Nothing wrong with it, just learn it. Oil changes, - 25 hours, 20/50 year round.
Butch, just been laying low, staying away from the Federales. Last cabin trip this weekend until breakup I'm afraid. But then, we can start fishing soon too!
Eric, We're doing good! Give everyone at PT our best, sure miss the breakfast runs on the weekends. Keep that nose wheel straight!

I also get that light exhaust popping on final at idle power. That goes away if you lean it just a little bit.

YELLOWMAULE wrote:......Eric, We're doing good! Give everyone at PT our best, sure miss the breakfast runs on the weekends. Keep that nose wheel straight!

Nosewheel ?? You know better than that! C150 tailwheel conversion with 150hp Lycoming.

ok now I know what you're talking about.. Mine does the same... I figured it's nature of the beast.. Changed all 12 plugs today and glad I did... hadn't done that since I brought the plane home about 8 years ago and boy were they about worn out... seemed to start easier and not as many turns of the prop before it lit off..should have done that long ago.,..you cannot take a bad picture with Yellow Maule in it.. especially in Alaska with either a white or blue background...if any of you reading this haven't visited Kurts photo gallery do so .. it's a treat....

iceman wrote:..Don't slip it so much here at home but Up in Idaho I use slips more for the short strips and dicey approaches...

I only need to slip every now and then. Mostly because I get caught too high on a short strip and don't want to add any speed, yet have to drop it down on final. This thing will float and/or bounce if I try to land it too fast! At two places I land regularly, I do come over power lines, so the slip is handy there.

iceman wrote:..are you sure it's your vent that's leaking... I had same problem on my left and I got a new gasket for the cap..

Well, I say vent...the small tube that comes down out of the bottom of the wing. There's one on each wing. This is where the fuel spills out.

YELLOWMAULE wrote:

Damn! That looks like fun!

YELLOWMAULE wrote: a design issue in the engine. You have a relatively long plenum run, a large air valve and the two combine to briefly lower the velocity allowing a great deal of air in at one time.

...and uh, ya...that's what I was gonna say...