twin mac 84 problems

[Drew St. Amant]

We are definitely planning on being at as many district 13 races we can make it to look forward to seeing you there too man! I've got some solid info on what to look for in the boat once I've got some of those things tested I'll post an update of what I've found

 

[Bill Eilers]

Your fule AND pressure systems must not and cannot leek. Don't screw with it. Just replace all lines. Back flush all lines and needels with isopropyl alcohol in a good spray bottle. (Can set it up with a fule nipple in front.) Clean your pressure tap. I filter my fule going in and Have a CORSE screen filter in the pressure line. (That's where the crap comes from) new o rings in the needels. There right ANY air in lines running will have you pulling hair. Your pipe to eng can't loose press eather

 

[Drew St. Amant]

All the fuel system is new with the exception of the tanks orings in needles and everything I replaced all that earlier in this thread chasing another issue I don't have filters on the pressure line going into the tank though

 

[Bill Eilers]

Another thing I heard of is that a cut water jacket o-rings will pump water into eng compartment. It will end up in carb and put the fire out

 

[Drew St. Amant]

Alright so I did the test that Rick recommended with the tanks I filled them full put them on the table with a long hose and blew in the pressure for just second to get them started they both drained all the way without any bubbles whatsoever no trash or any came out either I checked the radio components under a load by trying to resist both steering and throttle and moving them both while doing this it all functioned perfectly I then looked at the motor mounts now don't ask me how we didn't see this at the pond we aren't the kind of people that don't look at our boats while we run them but one motor mount screw was like 3 threads from falling out it was the front screw on the outside mount of the outside motor the rest of the screws weren't loose just that one so my question is could this be causing the whole issue I meant obviously that is something you guys mentioned to look at so it must be important but important enough to not let the boat run more the 10 feet with both engines running but yet unimportant enough to let them run separately just fine?

 

[Bill Eilers]

Alright so I did the test that Rick recommended with the tanks I filled them full put them on the table with a long hose and blew in the pressure for just second to get them started they both drained all the way without any bubbles whatsoever no trash or any came out either I checked the radio components under a load by trying to resist both steering and throttle and moving them both while doing this it all functioned perfectly I then looked at the motor mounts now don't ask me how we didn't see this at the pond we aren't the kind of people that don't look at our boats while we run them but one motor mount screw was like 3 threads from falling out it was the front screw on the outside mount of the outside motor the rest of the screws weren't loose just that one so my question is could this be causing the whole issue I meant obviously that is something you guys mentioned to look at so it must be important but important enough to not let the boat run more the 10 feet with both engines running but yet unimportant enough to let them run separately just fine?

Alright so I did the test that Rick recommended with the tanks I filled them full put them on the table with a long hose and blew in the pressure for just second to get them started they both drained all the way without any bubbles whatsoever no trash or any came out either I checked the radio components under a load by trying to resist both steering and throttle and moving them both while doing this it all functioned perfectly I then looked at the motor mounts now don't ask me how we didn't see this at the pond we aren't the kind of people that don't look at our boats while we run them but one motor mount screw was like 3 threads from falling out it was the front screw on the outside mount of the outside motor the rest of the screws weren't loose just that one so my question is could this be causing the whole issue I meant obviously that is something you guys mentioned to look at so it must be important but important enough to not let the boat run more the 10 feet with both engines running but yet unimportant enough to let them run separately just fine?

I can see u wanna keep a motor in its rails... but . Was that screw holding up a linkage

 

[Timbo Whalen]

Alright so I did the test that Rick recommended with the tanks I filled them full put them on the table with a long hose and blew in the pressure for just second to get them started they both drained all the way without any bubbles whatsoever no trash or any came out either I checked the radio components under a load by trying to resist both steering and throttle and moving them both while doing this it all functioned perfectly I then looked at the motor mounts now don't ask me how we didn't see this at the pond we aren't the kind of people that don't look at our boats while we run them but one motor mount screw was like 3 threads from falling out it was the front screw on the outside mount of the outside motor the rest of the screws weren't loose just that one so my question is could this be causing the whole issue I meant obviously that is something you guys mentioned to look at so it must be important but important enough to not let the boat run more the 10 feet with both engines running but yet unimportant enough to let them run separately just fine?

Drew, this is getting a bit long of tooth. Nobody here has a crystal ball and magic wand. Your queries are becoming peculiar, too....

Tighten the damn screw, go run the boat. If you can't troubleshoot and tune one of these boats maybe stamp collecting is in your future.

You should've had this solved in half an hour, seriously. The majority of replies here are just plain ludicrous, which seems to be the trend these days.

You say you don't want to take an engine out, this, that, and the other...well, that's just part of this deal. I told you the problem yet you keep chasing your tail with all this nonsensical ******** being thrown at you.

If you're going to keep chasing your tail and not applying some of the suggestions, well, one of two things needs to happen- Ferrette needs to shut this thread down, and/or you need to book an appearance on the Dr. Phil Show.

Sorry to be the one to tell you, but obviously you're in over your head with this boat.

I wish you the best, but my phone blowing up with notifications on this has way surpassed ridiculous.

GOOD LUCK!

 

[JRXHydros]

Replace the rubbers on your engine mounts,if you have vibration problems. How old are the rubbers on your mounts? What kind of twin do you have,seen no pictures of this boat? Go put one engine at a time in a single engine outrigger & see if you can make each engine run like a bat out of hell!! GOOD LUCK!

 

[Timbo Whalen]

Replace the rubbers on your engine mounts,if you have vibration problems. How old are the rubbers on your mounts? What kind of twin do you have,seen no pictures of this boat? Go put one engine at a time in a single engine outrigger & see if you can make each engine run like a bat out of hell!! GOOD LUCK!

 

[Drew St. Amant]

Glad to see when I ask questions from people that are knowledgeable I get chastised for it of course I'm going to try it anyway but twins are complicated figured I'd ask for help and give as detailed responses of what's going on as I could I'm a 23 year old you guys wonder why the sport is fizzing out if you are tired of replying don't reply being smart just makes people mad and not want to do the hobby

 

[Drew St. Amant]

Also timbo I have tried every suggestion that has been made the only one I haven't yet is putting the engines in a single engine boat to test them and that's only because we haven't been to the pond again since I was given that suggestion we plan on trying that tomorrow I was simply asking if you think the motor mount was possibly my whole issue or not mainly I was just curious but I guess that what I get for being interested

 

[FloridaScaleBoater]

Also timbo I have tried every suggestion that has been made the only one I haven't yet is putting the engines in a single engine boat to test them and that's only because we haven't been to the pond again since I was given that suggestion we plan on trying that tomorrow I was simply asking if you think the motor mount was possibly my whole issue or not mainly I was just curious but I guess that what I get for being interested

Hey Drew, screw the "blow hards" take them for what they are, and truck on buddy.
And you are absolutely correct!
Attitudes like that are why our hobby is in the crapper.
Get it figured out and we'll see you next year at the pond.

 

[Danny King]

I have not read this whole post.
Have you changed the bearings in both engines? Have you checked the orings in both engines?
Have you tried 2 brand new plugs?

 

[Drew St. Amant]

We have disassemble the motors and looked at the inside and the orings and gaskets all look great to me the bearing feel smooth and seem to be in good shape earlier in the thread I was looking into putting in cmb 80 pistons and liners and using those to do a full rebuild but we came to the conclusion that a better option would be to buy new motors entirely I'm using that as a last resort which is why we wanna try both motors individually in a boat like they were saying to confirm if the motors are in fact bad we also have tried several plugs to no avail

 

[Drew St. Amant]

But you could very well be right that something internally such as bearings is my issue hopefully this weekend will tell us

 

[Brandon Atwell]

Hey Drew!
Any luck today?

 

[Drew St. Amant]

Both motors did run and could a run a full tank completely out if fuel but one engine was definitely down on power and didn't sound right almost sounded clacky or tinny we are planning to disassemble that motor again and give it a closer look but as of now we are thinking hurt motor

 

[Buckshot]

I’ll be at the race this Friday and willing to help in person if I can.

 

[Will Gallagher]

Hey Drew,

Don’t get discouraged. If you have the opportunity to have Buck look at your setup that would be great. Both of us have been running twins for a long time and I know he can help with the set up.

So here’s my 3 cents. It sounds like a fuel delivery issue.

In post #18 you mentioned that the fuel line from Needle Valve to engine is smaller than the supply line. You need to use Large Fuel line all the way and each of sections (both right and left) needs to be the same length.

The MAC 84 spray bar should be drilled to .110

Head clearance .012 /.015

Pipe length 11 / 11.5 plug to weld

At idle, the carb barrel should be 30% open. Adjust the needle so the engine runs rich on shore with an occasional tap of the throttle to clear it out.


Once you get the engines to run consistently, then work on pushing the pipe in and such.

Wise man once said; it might not run good rich, but it doesn’t at all Lean….

Hope this gives you some insight

 

[Drew St. Amant]

I was actually about ask about head clearance so I guess you read my mind! Thank you! Also I'd very much appreciate that buckshot that would be extremely helpful!!