rino

My Feedback: (121)

Anyone know what props I can use with an Irvine 72. I use a 12x6 but have tried a 13x6. With the 13x6 I couldn't tell how to set the top end because no matter how far out I turned the needle the rpm didn't change. Does this mean this is too much prop for the engine?

w8ye

My Feedback: (16)

I always thought it did. But some other day with different fuel or brand of prop, you may be able to set the mixture better. As time goes by, you will be better able to tell about the mixture if you keep trying.

Enjoy,

Jim

mgnostic

I have an Irvine Q72 ABC. The data sheet that came with it indicates that it will turn an 11X8, 11X10, 12X9, 13X9, 14X8, or 15X6 prop. I ran both the tuned muffler and a JTec box muffler and the engine would pull like crazy. I ran a 14X6 prop when I used mine on my Four Star Sixty. I was very pleased with the engine. I've only had two problems. One is that it will sometimes run backwards when started by hand flipping( it starts easily) and the other was a fule line stoppage. Some debris got in through the fuel and I had to completely disassemble the carb at the fuel knipple to find the blockage. My data sheet also indicates that one should "set the main needle at 2 and 1/2 turns open annd adjust (screw in) for optimum setting." I hope this info is helpful but bear in mind that my engine was manufactured in '93.

SwampFlier-RCU

I am currently breaking in a .72 which is inverted in a Swallow, it has a 13 x7 prop and works like a charm (same as my .53) i have in store a 13 x9 and a 14 x6 i haven't tried yet.
It seems to me that either you have a:
[X(] Dirt in the carb
[X(]a leak in the carburator O-ring
[X(]Air coming in to the cahmber.. check the bolts on the head and the crankcase

rino

My Feedback: (121)

What fuel/plug are you guys running? I think I am getting air when the engine heats up.

rik756

My Feedback: (12)

I have an Irvine .61 and a .72. You can find all the specs on the .72 [link=http://www.sigmfg.com/cgi-bin/dpsmart.exe/MainMenuFV3.html?E+Sig]Here[/link]

Unless I misunderstood you, you're turning the needle the wrong way. Turning it IN makes the engine run more lean. Turning it out of course makes it more rich. You should start with the needle about 2 3/4 turns OUT from being screwed all the way in. When I adjust the engine I give it full throttle and slowly turn the needle in (leaning it) until I reach the highest RPM. Once the rpm starts to drop I've gone too lean and peak it again. I find the *peak* Rpm then give it about 2-3 clicks back out to richen it just a little. A good way to check and see if you're close is to hold the plane straight up at full throttle. If it gags you might be to rich, if it speeds up and then sags allot you might be too lean.

Every glow motor I have ever seen has done this at some point. Unless you use an electric starter, it has or will happen eventually. If it becomes a real problem, try actually flipping it backwards.

pikebishop

sounds like you might have an airleak. I mentioned the carb O ring on your other post. this sounds suspicious to me because as the crankcase heats up the fit becomes more loose from expansion. 14/6 is an excellent prop for this engine 13/8 is great for speed. this engine has a lot of torque and is really not a screamer. but is excellent with the larger props.

rino

My Feedback: (121)

It sounds like an airleak to me too. See my next reply about turning the needle the wrong way.

rino

My Feedback: (121)

Actually, my statement wasn't clear. I can start at 3 turns and lean it out to gain only about 300 RPM on a tach at 2.75 or so. Then as I richen by tuning out the motor drops the 300 RPM's but that's it. It doesn't richen any more no matter how far you turn the needle out. I went out to 4.5 turns or so and got the same RPM as 3 turns. It doesn't do this with a either so it seems like when the motor is stressed it does some wierd things. No matter what prop is on it it seems like you should be able to richen it up so it blubbers. Not so with this one.

Thanks.

rik756

My Feedback: (12)

You have me at a disadvantage. I don't have a tach so I just do it by ear. Once it's at full throttle and running I just listen for the rpm change. I didn't go try it, but it seems that if it was already at full throttle giving more fuel just gets burned up. The places I have trouble with the mixture (especially if it's too rich) is the transition. I'm not sure how effective it is but I've heard another way to check your mix is to pinch the fuel line to the carb. If it dies immediately, you're too lean. If you pinch it and it keeps running for several seconds, you’re too rich. It should hold a couple seconds the *wind* down if it's close to correct. Again, that’s just something I've heard and haven't played with allot.

Few other things to check is that the low mix screw is right. On both of mine, the low screw sets almost flush. Also, check the O-ring on the main jet that the needle valve screws onto. One of my o-rings was cracked and it caused problems until I replaced it. Some guys will actually put fuel line over the needle valve to seal it. So much as a pinhole can cause problems. Try poking a hole with a t-pin in the feed line. You'll see some problems right away. Thus, if it's sucking air from somewhere else the result is the same. I think the two most common places are the needle valve and the o-ring the carb sits on. I put just a dab of rtv around the bottom o-ring and got a little fatter 0-ring for the needle valve.

Couple other notes - I heard it and I've really come to believe it with both of my Irvine engines. It seems that the "Sweet Spot" for an Irvine is in a 3-5 click range. So make your adjustments very small at a time. It's said that Irvine’s can run on Non-Nitro fuel. I've never tried it though. Justin VanDee at Sig Manufacturing is the Irvine tech. I called and asked him a few questions. He said they can run (I thinks it NAI fuel) non-nitro, but most people have had better luck running 10% nitro. He said the props listed on the chart are the recommended for Optimum performance, but most within the range will work. I ran a 14x6 on the .72 and it loved it. I usually run 12x6 or 11x9 on the .61.

As for fuel, I run the Sig or Byron 10%. I use the either OS or Thunderbolt long glow plugs with no idle bar.

I am no expert by any stretch of the imagination, but I do have two of these and I have had to do allot of troubleshooting. Hopefully something here might help you at least a little or at least get you on the right track.


Rick

DarZeelon

[email protected],

The Irvine .72 is a big engine.
Could it be that a long, small diameter fuel line you are using, is overwhelmed, by the demand from the open needle valve and simply cannot cope with the greater flow? Are you sure there is no other restriction in your fuel system (dirt, maybe)?
Does it do it with and without exhaust pressure?

Prop sizes between 11x8 and 14x6 should be a correct load on this engine. This engine has a less restrictive silencer than does the .72Q, so slightly smaller props are in order.
Only if you prop it very heavy, so it spins below 9,000 RPM, should the venturi suction become so small that the needle could become ineffective.
According to your previous posts, you have not done that.

rino

My Feedback: (121)

Thanks everyone,

I'm going to go out Sunday with someone from a local hobby shop that sells Irvine. I will tach it with a 13x6 and let you know how the numbers come out.

Harrymntncs

Hi everyone, from what I see this thread has been quiet for almost 19 years, wow.
I have an interesting question to ask on my Irvine .72, mildly used - just ran in, went into my ARC / Modelfly Jupiter. Real powerful for her, and practically vibration-free. However the following weird thing happens:
At first she completed her first flight with the slow-run needle almost flush with the carb - no issue whatsoever. Then, out the blue, while preparing for the next flight, in order to get it to throttle up properly on the ground, it needed me to open (screw out) the slow run about 3/4 of a turn! It does spool up fine on the ground, but this same mixture seems & sounds excessively rich for flying (engine's literally gurgling) - when I tried a "moderate" throttle up it died in the air, was able to glide the Jupiter back with only minor damage (caught one wheel in a haystack, U/C torn off).

So the question is this: should I re-apply the "old" (leaner slow run) settings even though the engine won't spool up properly (but only if I throttle it slowly) on the ground, in case it's fine in the air? The thought it may just be overheating on the ground (necessitating the richer mixture) hasn't left me for a single moment.

If anyone wants to see / hear the engine in action you can in my YT channel (cannot post URLs still): Irvine5312x6ma , first video by date.

Any ideas / tips / help very welcome indeed, thank you in advance!

mgnostic

I've still got the Irvine I posted about earlier. Since then I've had to disassemble and clean the carburetor twice to get the lint out of the needle valve. Even with a filter it will eventually collect what looks like fine dryer lint. It will pass enough fuel to start but makes for an erratic needle when trying to fly. When it is clean I seldom have to touch the needle.

1967brutus

A felt clunk will solve that issue...

Harrymntncs

Thank you for your advice, indeed I took the carb apart, then soaked it for 2 days in pure alcohol (needles / O-rings etc removed of course). Couldn't quite believe how much of this "fine dust" and similar crud came out of it into the container! Bear in mind it was last used 14+ years ago, but only for running in. Whatever residue was into the carb (I always re-start my engines dry of fuel to burn any fuel residue at all times) probably accumulated, hardened and as soon as the engine reached proper temperatures in the air likely loosened up and partly blocked the carb's jet? Does this seem like a reasonable explanation?
Also replaced all O-rings - including the engine backplate one, with same brand new ones. Fingers crossed I should be good to enjoy the 72's power & transition now. I read in another thread here that's where this engine really excels at, transitions. Re-fitting the engine on the Jupiter tomorrow.

1200SportsterRider

A bunch of us decided in 2003 that you could treat the Irvine 72 as if it were a 91. Watch the head bolts closely, they will loosen up at least once.

Harrymntncs

Thank you for your feedback, indeed I checked the head bolts after the first engine runup and they all needed slight tightening - I'll be keeping an eye out for any further loosening in the future.

Harrymntncs

Hello all,
Just writing back to say that the very thorough carb cleaning did have a huge effect on the way this great engine works, re-installed it on my ARC / Modelfly Jupiter, it transitions absolutely perfectly now, the thing has become ballistic, even 80% power is too much, just keeps on climbing vertically & nearly lost sight of it once. Full power on take off sees the aircraft off the ground in 2 seconds flat and she slows down nicely to land, but I do have to use the least possible (reliable) revs on the ground (~ 1,300 rpm idle on 10% nitro content & 18% oil fuel).
I wish I could post a link to a new onboard video I've made, if anyone's interested visit my YT profile "Irvine7214x6apc", first video by date is that last 6-flight session one. A bucketload of fun, I'd say the 72 and the Jupiter are "a marriage made in heaven". Only difference is, on that video I used an MA 14x6 prop (10k revs on the ground easy), now I've installed an APC 14x6 prop on her - should perform even better, RPM are pretty much identical.

mgnostic

Glad to hear that things are working well. The only other thing of note, at least regarding my Q-72, is a tendency to want to run backwards when hand starting. Flipping the engine backwards against compression gets it going every time. Of course, this isn't a problem if you use an electric starter.

Harrymntncs

Thank you, indeed that isn't an issue for me, who uses a starter all the time. She fires up on the first revolution of the starter every time, given the correct priming beforehand. I do love this engine, mine was made I think in 2006 or 2007, but was only used for running in, then stored "drowned" in after run oil for all those years. When did Irvine Engines go bust? It has to be around 2008 or something..

mgnostic

It looks like O.S. bought Irvine around 2010. From what I have read Irvine production in England continued for at least a while with the carbs and other parts being changed to the O.S. design. It probably just fizzled out due to lack of profitability.

Harrymntncs

I see, so Irvine went on for a little bit longer than I thought. Limping their way through, as it seems. A great shame they were even bought by OS - simply because on their very own they were building fantastic engines - not only reliable, but also smooth, powerful, and with amazing - super linear power transitions. Now my 72 is -thankfully- working fine, I'm enjoying its power transitions just as much as its power - which, for a 72, is definitely on the very high side.
I also own an original Irvine 53 (also Jetstream carb, like my 72) which was formerly on the Jupiter, fantastic too. My OS-Irvine 53's 2 of them, were working quite fine too, but they wore out quickly in comparison. The older, original, harder- used 53 still goes on quite strong. Changed its bearings recently as a precaution, not because it was really needed.

1200SportsterRider

When Ron Irvine passed away his son wasn't very interested and let the place wither away.

Harrymntncs

That's a crying shame, especially since they were such brilliant engines with all the aforementioned qualities.
There are still some original Irvines available through Ebay -funny enough that's where I bought my original 53 from (accompanied by a warranty from the then owner no less), over 10 years ago, and it has turned out a proper gem as mentioned above - there's also a .61 available yesterday that I checked! Generally though I think one should avoid getting engines from Ebay - have heard & witnessed all sorts of horror stories.