MAC Troubleshooting

[Wasted wages]

Guess you're the expert then. Still want to know who you are.......

"Still want to know who you are".......I'm someone who likes to deal with facts,, not B/S,,,no one you would know,,,although I have thrown a boat or two into the water,,

"Guess you're the expert then."........"I" never made this claim,,,

 

[DON MAHER]

Hey, WW ( WASTED WAGES)

I must agree, facts dont lie. Your 100% correct.

Don

 

[Don Ferrette]

"Still want to know who you are".......I'm someone who likes to deal with facts,, not B/S,,,no one you would know,,,although I have thrown a boat or two into the water,,

Whatever. It's nice to know who we're chattin' with, adds a dash of credibility to the mix.

So do this, take a motor & needle with 1/8" line between & set a good running needle. Do this on an application that runs well & has no "issues". Now swap out to 5/32" & change nothing else. Will it run exactly the same?

 

[Dan_Cousin]

If you look in a MAC .51" carborator, that spray bar is squirtin fuel like a firehose!!! More fuel than I've ever seen. If you look too close it will spit some at you :lol:

Russell and I run together so I'm interested in the answer too so I don't break my back tossing that 15lb boat (bowling ball)!

On toss in the boat get us pretty good even with the larger props. once on the pipe after 1,2,3 it runs OK (on the pipe) but isn't making quite as much speed as it could. then engine doesn't sound like it is revving even with the X455/3. if oyu lean on it a little you get treated to a sag (classic symptom). If you richen it a click or two, you also get a bog (hmmm??). Once bogged for too rich oen ot two clicks lean and it gets back up (really sensitive to the needle)

As was said before, it is a bear to start. We have been fogging the engine, punche the line to get it to pop off then ease off of thepinch so it takes the fuel. If you let off too fast it will flood. Fuel/Oil coats the back of his boat stand and table during startups. WAY more rich than the OPS, Picco and CMBs I've run.

Looks like the stinger reduction may be a good idea. Then engine is cool enough to keep my hand on it after we bring it in fron a run so the extra heat may be a good thing.

Do all you MAC runners go through that much trouble to start your MAC 67s?

 

[Wasted wages]

"Still want to know who you are".......I'm someone who likes to deal with facts,, not B/S,,,no one you would know,,,although I have thrown a boat or two into the water,,

Whatever. It's nice to know who we're chattin' with, adds a dash of credibility to the mix.

So do this, take a motor & needle with 1/8" line between & set a good running needle. Do this on an application that runs well & has no "issues". Now swap out to 5/32" & change nothing else. Will it run exactly the same?

No,,because now you have changed the "VOLUME " of the line DOWNSTREAM of the pinch valve.

Increased volume DOWNSTREAM of the valve will reduce the amount of flow to the carb (again all things remaining equal) as the fuel must now expand to fill this "extra space"

EVERYTHING I have been talking about is BEFORE THE VALVE.

 

[Don Ferrette]

"Still want to know who you are".......I'm someone who likes to deal with facts,, not B/S,,,no one you would know,,,although I have thrown a boat or two into the water,,

Whatever. It's nice to know who we're chattin' with, adds a dash of credibility to the mix.

So do this, take a motor & needle with 1/8" line between & set a good running needle. Do this on an application that runs well & has no "issues". Now swap out to 5/32" & change nothing else. Will it run exactly the same?

No,,because now you have changed the "VOLUME " of the line DOWNSTREAM of the pinch valve.

Increased volume DOWNSTREAM of the valve will reduce the amount of flow to the carb (again all things remaining equal) as the fuel must now expand to fill this "extra space"

EVERYTHING I have been talking about is BEFORE THE VALVE.

Precisely. In this application there is no needle at the carb, you can look straight thru the spraybar. Anyone who knows these engines knows this. These engines consume alot of fuel, anyone who runs these knows this also. So for this topic titled "MAC troubleshooting" in this application it is about volume & ability to deliver it.

It's been fun.

Maybe someday you'll tell us who you are. B)

 

[Wasted wages]

"Still want to know who you are".......I'm someone who likes to deal with facts,, not B/S,,,no one you would know,,,although I have thrown a boat or two into the water,,

Whatever. It's nice to know who we're chattin' with, adds a dash of credibility to the mix.

So do this, take a motor & needle with 1/8" line between & set a good running needle. Do this on an application that runs well & has no "issues". Now swap out to 5/32" & change nothing else. Will it run exactly the same?

No,,because now you have changed the "VOLUME " of the line DOWNSTREAM of the pinch valve.

Increased volume DOWNSTREAM of the valve will reduce the amount of flow to the carb (again all things remaining equal) as the fuel must now expand to fill this "extra space"

EVERYTHING I have been talking about is BEFORE THE VALVE.

Precisely. In this application there is no needle at the carb, you can look straight thru the spraybar. Anyone who knows these engines knows this. These engines consume alot of fuel, anyone who runs these knows this also. So for this topic titled "MAC troubleshooting" in this application it is about volume & ability to deliver it.

It's been fun.

Maybe someday you'll tell us who you are. B)

all of my carbs are set up this way,mono and hydro, the spray bar is nothing more than a piece of brass sticking into the venturi,no low end needle, the point I was making was that the lines upstream of the valve do not have to be 5/32's if they can supply the required amount of fuel to the needle,,downstream of the needle is a whole 'nuther subject.

It has been fun grasshopper,,,,,,,

 

[scott bouchie]

Heres somthing also to think about,this is a scale boat and probley has a cowl covering the pipe and motor.Y ou need some air flowing around the pipe to keep it some what cool cause if it gets to hot it will act short.I have had this problem before,this may not be the problem but keep this in mind.Maybe try it without the cowl? and shim down the stinger like Andy said.

 

[AndyBrown]

I covered all the bases in my previous answer for Russell.

Once he gets the boat set up that way there will no longer be any issues to worry with.

Don and Speedy Jason where chasing the same "issues" with Jason's MAC 67 powered Cat.

A short phone call from them to me while at the pond had Jason's Cat hauling the mail in no time.

They got the same answers I gave to Russell.

WW,

You have not covered all the bases and therefore still miss the reason for the "correct" size fuel line.

I say "correct" because it can be too big also.

Try thinking a little more outside the box.

P.S. The answer is backed by solid physical principles.

 

[Tom Foley]

I think the wage man needs to go to the lake a little more often with some current motors and setups to get a feel for whats actually going on . Good luck Mr . Secret Agent Man .

 

[Glenn 787]

Do all you MAC runners go through that much trouble to start your MAC 67s?

I'm running the .510 carb, slightly modified motor, 5/32 lines and black AB pipe set at 11 1/2.....any longer and the rpm's start dropping off. As for starting I need to have it at least at 1/2 throttle and keep the revs fairly high until it hits the water. As long as the plugs good and it's got enough juice going to it flooding is never a problem. Currently running a modified X465.

No problems, a very happy MAC owner.

 

[Don Ferrette]

Do all you MAC runners go through that much trouble to start your MAC 67s?

Nope. B)

 

[Russell Bear]

I covered all the bases in my previous answer for Russell.

Once he gets the boat set up that way there will no longer be any issues to worry with.

Don and Speedy Jason where chasing the same "issues" with Jason's MAC 67 powered Cat.

A short phone call from them to me while at the pond had Jason's Cat hauling the mail in no time.

They got the same answers I gave to Russell.

Yep, thanks Andy for having the talk with me this morning. I have everything set as you described and as soon as the package from Megan comes I will add the bushings to the pipe and then I'm ready for the pond. The weather is REALLY COLD!!! here this week, expecting mid to upper 50's this weekend.

Hopefully get a chance to run again soon.

Dan, what's up?

 

[RaceCraftBearings]

Do all you MAC runners go through that much trouble to start your MAC 67s?

Nope. B)

Nope, mine starts so easy sometimes I dont even need the starter just turn on the radio apply glow starter and she fires up. No not every time but its happened several times lately.

Ron

 

[Dan_Cousin]

Do all you MAC runners go through that much trouble to start your MAC 67s?

Nope. B)

Nope, mine starts so easy sometimes I dont even need the starter just turn on the radio apply glow starter and she fires up. No not every time but its happened several times lately.

Ron

Thats what I Like!!!! My CMBs are like that once they are properly fogged. Start on the first bump almost every time.

Russell,

If you're ready I can meet you out there. As you know there is another project X on my setup bench.

Andy,

I believe the on the water accounts of needing larger fuel line for the MACs but I don't under stand why. Would you care to go into the theory choosing the correct size fuel line so we can all understand (go as techical as you want, I'll catch up. )?

thanks.

 

[Wasted wages]

Do all you MAC runners go through that much trouble to start your MAC 67s?

Nope. B)

Nope, mine starts so easy sometimes I dont even need the starter just turn on the radio apply glow starter and she fires up. No not every time but its happened several times lately.

Ron

Thats what I Like!!!! My CMBs are like that once they are properly fogged. Start on the first bump almost every time.

Russell,

If you're ready I can meet you out there. As you know there is another project X on my setup bench.

Andy,

I believe the on the water accounts of needing larger fuel line for the MACs but I don't under stand why.

Would you care to go into the theory choosing the correct size fuel line so we can all understand

(go as techical as you want, I'll catch up. )?
thanks.

"Would you care to go into the theory choosing the correct size fuel line so we can all understand"

Yes,,,we WOULD like to hear YOUR theory of flow and fluid dynamics,,,,,

 

[Don Ferrette]

Do all you MAC runners go through that much trouble to start your MAC 67s?

Nope. B)

Nope, mine starts so easy sometimes I dont even need the starter just turn on the radio apply glow starter and she fires up. No not every time but its happened several times lately.

Ron

Thats what I Like!!!! My CMBs are like that once they are properly fogged. Start on the first bump almost every time.

Russell,

If you're ready I can meet you out there. As you know there is another project X on my setup bench.

Andy,

I believe the on the water accounts of needing larger fuel line for the MACs but I don't under stand why.

Would you care to go into the theory choosing the correct size fuel line so we can all understand

(go as techical as you want, I'll catch up. )?
thanks.

"Would you care to go into the theory choosing the correct size fuel line so we can all understand"

Yes,,,we WOULD like to hear YOUR theory of flow and fluid dynamics,,,,,

I think before WE go any further WE would really like to know who YOU are. You seem very well versed in this topic so how about a name, we're all one big family here ya know. Besides, a name would sound alot better than "hey Wasted"

 

[jeff baham]

don, wasted, is tim the toolman's neighbor, you know, the guy that just show his eyes. lol

 

[Don Ferrette]

don, wasted, is tim the toolman's neighbor, you know, the guy that just show his eyes. lol

Wasn't that Wilson, even he had a name.

 

[AndyBrown]

Do all you MAC runners go through that much trouble to start your MAC 67s?

Nope. B)

Nope, mine starts so easy sometimes I dont even need the starter just turn on the radio apply glow starter and she fires up. No not every time but its happened several times lately.

Ron

Thats what I Like!!!! My CMBs are like that once they are properly fogged. Start on the first bump almost every time.

Russell,

If you're ready I can meet you out there. As you know there is another project X on my setup bench.

Andy,

I believe the on the water accounts of needing larger fuel line for the MACs but I don't under stand why. Would you care to go into the theory choosing the correct size fuel line so we can all understand (go as techical as you want, I'll catch up. )?

thanks.

Dan,

The explaination of how and why is really simple. If I explain it, there will be a few guys on here that will pop up and say, "I knew that". A few others will get on here in the near future and explain how THEY DISCOVERED the importance of fuel line size. And about a year from now I will have someone on the phone telling me the same thing.

Let's just leave it as being important. Those of you who are interested will go to the pond with three different sized fuel lines and learn something. The Naysayers will not......or at least not admit to it.

Just like knowing the cold hard fact of Gravity weather or not the theory of Gravity is understood.

I will throw something out here to help boaters in general. Prather medium fuel line has normally been supplied with a .093" I.D. Last Summer we received a case of Prather medium fuel line that had the same O.D. as always, but the I.D. was .078". That will definatly change the perfomance of the engine if you were previously running the .093" line.

BTW- We did bring this to the attention of Prather and luckily we had not sold much before we discovered the small I.D.

O.K. one Hint! Phil Thomas mentioned that he completly removed the needle assembly from his med. fuel line and the engine still went lean. Think about that WW!