Please Help ??? on Pipe

[Richard Mancilla]

Hi Guy's,

I have an old SG 80 rigger running a modified Mac 84 for X class. What pipe works best for this set-up? What do you guys think about a parabolic pipe?

I am using an AB Black pipe now set at 12" my Bob Violet set at 3 1/2 turn I know it's fat but still keeps blowing plugs. I tried 3 turn on my needle but still burning plugs in every heat. Pipe is really set long cuz this is the only length that seem to work. Tried 11 1/2" but will not get on pipe fast enough. Your help is greatly appreciated.

Thanks,

Richard M

 

[Don Ferrette]

Hi Guy's,
I have an old SG 80 rigger running a modified Mac 84 for X class. What pipe works best for this set-up? What do you guys think about a parabolic pipe?

I am using an AB Black pipe now set at 12" my Bob Violet set at 3 1/2 turn I know it's fat but still keeps blowing plugs. I tried 3 turn on my needle but still burning plugs in every heat. Pipe is really set long cuz this is the only length that seem to work. Tried 11 1/2" but will not get on pipe fast enough. Your help is greatly appreciated.

Thanks,

Richard M

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Richard what prop are you using?? Set either the AB or parabolic pipe @ 11" & prop the boat to the pipe setting. An H38 cupped to about 5.6 or a 1667 cut to 64mm & cupped to about 5.6 should get it done. B)

 

[AndyBrown]

Richard,

The AB 67 is a great pipe for the MAC 84. 12" is long, so if it's not getting up well and blowing plugs there is another problem. We run that pipe at 11".

Give as many more deails about your set-up as you can think of.

 

[Richard Mancilla]

Hi Don, and Andy,

I'm using an Andy Brown 1667 with 5.6 cup on this rigger now. Modified Mac 84 from you Andy. 50% Redmax, and MC 9 plugs.

All ready tried to run this boat at 11 1/2" from the plug to the biggest part of the pipe and still will not go on fast enough.

Thanks,

Richard

Richard,
The AB 67 is a great pipe for the MAC 84.  12" is long, so if it's not getting up well and blowing plugs there is another problem.  We run that pipe at 11".

Give as many more deails about your set-up as you can think of.

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[AndyBrown]

Where do you run? Altitude? Is the boat runing clean? Large fuel lines? Do you pull the glow plug wire down? Two rear sponson SG or three rears? Shaft angle?

If you have two rears the full blade 1667 is just a little too much for 50% nitro.

Is this an engine I modified.

 

[Richard Mancilla]

Hi Andy,

Yes, the engine was modified by you. I run here in the bay area with District 9 along with Roger Hook. Large fuel lines. No I don't pull the glow plug wire. I have the 2 rear sponson SG. Shaft angle is neutral. The prop is one of your 1667 with a 5.6 cup.

What size prop do you think I should run? By the way we have a lot of little parts on order right now from you. If you have any prop that will work please just send it to use.

Thanks,

Richard

Where do you run?  Altitude?  Is the boat runing clean? Large fuel lines? Do you pull the glow plug wire down?  Two rear sponson SG or three rears?  Shaft angle?If you have two rears the full blade 1667 is just a little too much for 50% nitro.

Is this an engine I modified.

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[Don Ferrette]

Hey Richard sounds like all you need is a cut down prop or have Andy cut that one down to 64mm. The MACs will fool you & pull a bigger prop off the shore but they like to REV.

 

[gil sonsino]

Pipe set at 12", fat needle,large fuel lines and still burning plugs :huh: lead me to think of wrong head clearance or bad bearings once the rest sounds reasonable.

Is this a new engine?

Gill

 

[Buckshot]

Hey Richard,

Are you going to run this weekend and where?

If I come back to NorCal this weekend I might be able to meet ya'll at the pond and I've got some props you could try.(cut down 1667's)

-BUCK-

P.S. How was the race at Riverside last week. I was stuck in North Texas.

 

[AndyBrown]

Hi Andy,
Yes, the engine was modified by you. I run here in the bay area with District 9 along with Roger Hook. Large fuel lines. No I don't pull the glow plug wire. I have the 2 rear sponson SG. Shaft angle is neutral. The prop is one of your 1667 with a 5.6 cup.

What size prop do you think I should run? By the way we have a lot of little parts on order right now from you. If you have any prop that will work please just send it to use.

Thanks,

Richard

Where do you run?  Altitude?  Is the boat runing clean? Large fuel lines? Do you pull the glow plug wire down?  Two rear sponson SG or three rears?  Shaft angle?If you have two rears the full blade 1667 is just a little too much for 50% nitro.

Is this an engine I modified.

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Richard,

The full 1667 is too much, I'll send you something a little smaller. We always used small blade area with the two rear sponsons, like H-30, H-32. The strut needs to be set about 1 to 1 1/2 degrees negetive. This will clean up the back end. Make sure the strut is the right depth. With the boat sitting on the flat surface only the back of the strut will be sitting on the surface and the rear sponsons will be about 1/32" off the surface. Raising the strut higher will NOT free up the prop. It will only cause the rears to drag and over load the engine.

 

[Richard Mancilla]

Hi Guys,

You’re probably right Don. I will call Andy too see if I can get a good prop for this set-up.

Gil I have half a season on this engine. Bearings feel OK to me.

Buck sorry I not sure who you are. I will be running this boat in Fremont this Saturday for a race on Sunday at Seaside. The race at Riverside was cancel and moved to Seaside. We had good weather until after 2:00 pm when the wind start blowing pretty bad.

Thanks,

Richard

 

[Richard Mancilla]

Hi Andy,

Yes, please just send us a prop that you think will work better on this set-up.

I will call you today.

Thanks,

Richard

 

[Buckshot]

Buck sorry I not sure who you are. I will be running this boat in Fremont this Saturday for a race on Sunday at Seaside. The race at Riverside was cancel and moved to Seaside. We had good weather until after 2:00 pm when the wind start blowing pretty bad.

Thanks,

Richard

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I'm William Shackelford. The guy that ran with ya'll from Texas. B)

I drive the orange w/ flames 1.0 SGX and the yellow 20 hummingbird.

Who came out on top in X-hydro last race?

-BUCK-

 

[gil sonsino]

Hi Richard

Are your sponsons flat are stepped in this rigger?The very first SG(two rear) had non stepped sponsons maybe it is your case?

Remember a similar problem with a SG 67 two rear(1997) sponsons that we solved adding a step in the front/rear sponsons.A piece of 2mm plywood thick per 1 1/4 " wide was glued to the inner side on the botton of front sponsons and the boat literally spun heavier props.Same was done to the rear to keep the boat leveled and it worked great.Take a look to the new SGX sponsons and you will see what I'm saying! If you want to make a simple test use 3M double face for a trial. With the stepped sponsons your boat will run less wet,with less drag and will turn the 1667 cup 5,6 with less effort.

Just a suggestion!

Gill

 

[Terry Flynn]

I had a problem last year I was going through MC9 plugs like craze in my MAC 21 I only had about a gallon of fuel through it and thought that it was bad bearings so I replace them

new bearings same problem. tried diffrent glowplugs K&B HP and the problem was solved.

I don't know it I just got a bad batch or what but it sure was expensive changing bearings for no reason not to mention the cost of all the glow plugs.

 

[jasonspeedy]

I was having similar problems. Based on my experience, I'm not sure the problem is drag or load related, which encompasses all of the strut angle, AOA, sponson, etc...

I had a MAC 67 that would eat plugs and "go lean" every run, regardless of hull type or prop. I went through the whole large fuel line, change plug brands, change needle valves routine. This motor would even go lean under full rich conditions.

With Andy's help, I figured out that I simply was not keeping enough fuel in the combustion chamber. Sound simple right? Not enough fuel=lean. What did I do? I stingered the pipe to .410" ...and the sprint cat was on fire!!!

I was running the same pipe (black AB @ 11.5"). I was doing all of this in the dead of winter, so depending on where you are, you may or may not need as much stinger.

Of course a load issue could cause the problem, but this is one more thing to consider.

Best of luck.

 

[AndyBrown]

I had a problem last year I was going through MC9 plugs like craze in my MAC 21 I only had about a gallon of fuel through it and  thought that it was bad bearings so I replace themnew bearings same problem. tried diffrent glowplugs K&B HP and the problem was solved.

I don't know it I just got a bad batch or what but it sure was expensive changing bearings for no reason not to mention the cost of all the glow plugs.

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Terry, Did you get it worked? If not what needle valve are you using? Pipe, fuel tanks, boat, prop, fuel?

 

[AndyBrown]

I was having similar problems.  Based on my experience, I'm not sure the problem is drag or load related, which encompasses all of the strut angle, AOA, sponson, etc...
I had a MAC 67 that would eat plugs and "go lean" every run, regardless of hull type or prop.  I went through the whole large fuel line, change plug brands, change needle valves routine.  This motor would even go lean under full rich conditions.

With Andy's help, I figured out that I simply was not keeping enough fuel in the combustion chamber.  Sound simple right?  Not enough fuel=lean.  What did I do?  I stingered the pipe to .410" ...and the sprint cat was on fire!!!

I was running the same pipe (black AB @ 11.5").  I was doing all of this in the dead of winter, so depending on where you are, you may or may not need as much stinger.

Of course a load issue could cause the problem, but this is one more thing to consider.

Best of luck.

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The stock stinger bore of the AB 67 pipe is perfect for the MAC 84 in almost all conditions. No problem there!

Just a prop issue I'm sure.

 

[Terry Flynn]

I had a problem last year I was going through MC9 plugs like craze in my MAC 21 I only had about a gallon of fuel through it and  thought that it was bad bearings so I replace themnew bearings same problem. tried diffrent glowplugs K&B HP and the problem was solved.

I don't know it I just got a bad batch or what but it sure was expensive changing bearings for no reason not to mention the cost of all the glow plugs.

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Terry, Did you get it worked? If not what needle valve are you using? Pipe, fuel tanks, boat, prop, fuel?

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Andy, The engine is all stock I'm running a cmdi needel valve fine a parobolic pipe set at 8.3 a 12zo sulliven main tank and a 2oz bump tank it's running in a older micro burst with a x440-3. fuel is byron 60%