Help With my Mac 45

[Heartbeat]

Here we go

At first I couldn't get it to pull the right props, In a thread last week we talked about

drilling the stinger. I drilled the stinger to .432

At the lake this week : Pulls the right props, Speed was great, good acceralition, But now I am burning plugs, every run.

We tried running the motor very rich. This is where we starting thinking the head clearance was off. It wasn't

When it burned the plugs, they were NOT pulled

Where do I go from here?

Thanks Mike

 

[Eric Canto]

Hello Mike. What boat are you running the engine in? What are the "right props" and what speeds are you running? What plugs are you burning? Is the element gone, or just broken? If it is just broken, is it shiny or dull? What fuel are you running?

Eric Canto

The Speed Shop

 

[nitro junky]

Here we go
At first I couldn't get it to pull the right props, In a thread last week we talked about

drilling the stinger. I drilled the stinger to .432

At the lake this week : Pulls the right props, Speed was great, good acceralition, But now I am burning plugs, every run.

We tried running the motor very rich.  This is where we starting thinking the head clearance was off.  It wasn't

When it burned the plugs, they were NOT pulled

Where do I go from here?

Thanks Mike

105175[/snapback]

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what version MAC are you running? Is it the newer sonic flow motor? I had the same problem. I am running the older version before the sonic flow. I was told to get the newer carb with the smaller bore. I did and no more burned plugs.

 

[Heartbeat]

Its the older version MAC

Roadrunner Extreme

Does it with all props, we started with a 1455,1453,1457 and last H-18

before I drilled the stinger it would only pull the 1453,1455

Fuel is 50% John Otto's

MC9 Plugs

Element is broken and Shiny

Thanks for the help

Mike

 

[Jerry Wyss]

This may be a little on the "stupid" side of a response, but is the edge of the "bubble" in your head button really "sharp"?? This has been known to blow plugs absent from any other reason. h34r:

 

[Dan_Cousin]

How are the bearings? lots of endplay?

What pipe length? Start at 10 1/2" from the center of the engine to the weld and move it in from there as testing continues. you'll probabley stop at 9 1/2" to 9 3/4"

You have a 1655?

 

[Don Ferrette]

This may be a little on the "stupid" side of a response, but is the edge of the "bubble" in your head button really "sharp"?? This has been known to blow plugs absent from any other reason. h34r:

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Not stupid at all. I take that edge off on all my head buttons for that very reason. Back when I ran Picco 80's this was always done as they would break plug windings every time if left sharp. All you need to do is place a piece of 400 paper over your thumb & turn head button against it. All you want to do is remove the sharp edge & no more.

 

[Heartbeat]

This may be a little on the "stupid" side of a response, but is the edge of the "bubble" in your head button really "sharp"?? This has been known to blow plugs absent from any other reason. h34r:

105250[/snapback]

​

Not stupid at all. I take that edge off on all my head buttons for that very reason. Back when I ran Picco 80's this was always done as they would break plug windings every time if left sharp. All you need to do is place a piece of 400 paper over your thumb & turn head button against it. All you want to do is remove the sharp edge & no more.

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Interesting The edge is VERY SHARP

Does this edge effect preformance other then plugs?

Thanks Mike

 

[Jerry Wyss]

This may be a little on the "stupid" side of a response, but is the edge of the "bubble" in your head button really "sharp"?? This has been known to blow plugs absent from any other reason. h34r:

105250[/snapback]

​

Not stupid at all. I take that edge off on all my head buttons for that very reason. Back when I ran Picco 80's this was always done as they would break plug windings every time if left sharp. All you need to do is place a piece of 400 paper over your thumb & turn head button against it. All you want to do is remove the sharp edge & no more.

105260[/snapback]

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oh,,really? well i guess i can stop looking thru this "mail slot" h34r: ,, :lol:

 

[Don Ferrette]

Interesting The edge is VERY SHARPDoes this edge effect preformance other then plugs?

Thanks Mike

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Nope. Just a by product of the machining process when head buttons are made. Removing that edge would mean another machining process (read additional labor cost) in the manufacture. There are many instances where motors run just fine with that edge but I have NEVER seen any performance loss by removing it.

 

[keith warham]

Don, would you do the same on the Mac 21 head button?

keith

 

[Don Ferrette]

Don, would you do the same on the Mac 21 head button?
keith

105266[/snapback]

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Sure. Just be sure to ONLY take the edge off which doesn't require much. This is why I do it by hand.

 

[Heartbeat]

Thanks Don

BTW what is a good heat racing speed for a 45 Rigger?

Mike

 

[Don Ferrette]

Thanks Don
BTW what is a good heat racing speed for a 45 Rigger?

Mike

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80+ B)

If you can run in upper 70's you've got a competitive boat. You'll just need to be in lane #1 & drive your a$$ off.

 

[Heartbeat]

Thanks

I am getting there

Mike