mac84, water outlet hole

[XtremeRcBoats]

I've got a MAC84 I want to run in a rigger and I want to drill a hole in the cooling head for the water outlet. What size hole should this be for a MAC84?

Also want to close the exit hole with a allen type set screw. What size do I need (I'm not that familiar with US size screws)? I think it is 3/16"?

Tnx for the input.

 

[bermudadude]

drill the hole the same size as the hole in the included nipple to start with.if it over heats in your setup,providing youre not running lean u can go up a bit size. it should b 10/32 but if u take the engine to the store with you u can match the threads.tho it may be metric....cant remember

 

[Joe Warren]

I've got a MAC84 I want to run in a rigger and I want to drill a hole in the cooling head for the water outlet. What size hole should this be for a MAC84?

Also want to close the exit hole with a allen type set screw. What size do I need (I'm not that familiar with US size screws)? I think it is 3/16"?

Tnx for the input.

10/32

 

[John Knight]

10/32 set screw to close off the hole using blue locktite. I believe it is10/32 but may be metric. I no longer have any of the engines so I cannot measure one.

Drill a 1/16" hole in the top of the water jacket near the set screw for the water exit. Too large of a hole will not allow the head to heat up enough. I used the 1/16" hole for all my MAC 67 & 84's.

 

[moparbarn]

not a clue as to what size hole is needed, but listen to john . i would start small (1/16") as suggested, you can always enlarge the hole MUCH easier than making it smaller

 

[XtremeRcBoats]

Tnx for the help guys, I'll start with 1/16" and get some 10/32" inserts to replace the water nipple.

 

[timothy johnson]

CMB/MAC are 5mm

 

[XtremeRcBoats]

Tim, so it is normal metric thread?

 

[XtremeRcBoats]

I have been recalculating and I think 10/32" is a bit to big, but i'm not sure it's metric either. Problem is we have the metric system overhere in the Netherlands and these sizes are hard to get over here and can't try it in the hardware store.

 

[moparbarn]

You could solder the water nipple closed, or cut it off flush with the hex head & then solder it for a cleaner appearance........

 

[timothy johnson]

Sorry its a problem. In the US Lowes, Ace and most stores carry the metric set screws. The 10/32 will fit but its a sloppy fit, the real size is 5mm normal thread.

 

[XtremeRcBoats]

Hi Timothy,

checked it with 5mm and you were correct. I had expected to be US thread so didn't check metric thread. Tnx for the help.

 

[John Knight]

Hi Timothy,

checked it with 5mm and you were correct. I had expected to be US thread so didn't check metric thread. Tnx for the help.

No surprise it is metric since the MAC's were made by CMB.