LOOSE CARB ON 21MAC

[NOVALTD]

Does anybody have any experience with a carb that won't stay tight in the engine case? I have a mac 21 with a nr 21 carb that will not stay tight to the engine case.

I have changed clamps ,nuts, washers and o-rings and nothing holds when operating. Have you guys used epoxies or loctites that work AND IS A PERMEANT CURE.

Your help is appreciated ---- DAN

 

[P THOMAS]

Is this an OB motor? you can use some long set epoxy on the carb or some quick set that will get real hard, not the gummy minute stuff. I had some black quick set epoxy for loose carbs. If you have a tight fit on the carb loctite may do the job too.

 

[dwilfong]

use the K&B 7.5 carb clamp nut it will not move with this in place.

I had the same problem with my Speed master carb this fixed it for good.

 

[Robert Pickard]

Dan didnt you tell me at one time to use JB weld it works

 

[brad nichols]

I have used JB weld and it does work and like any epoxy it will come off with heat.

Brad

 

[NOVALTD]

Thanks for all the replies. No Phil this is a inboard . Has anybody tried green loctite? And can you remove the carb with heat or is it permanently in the case? Also what QUALITY EPOXY can be used to glue the carb in place and last? A garbage glue will crumble and break apart under heat and vibration. A friend of mine suggested sig two part epoxy,but the hobby shops around me are closing down

or don't carry sig. Can JB weld be used and last? Can you remove the carb with a torch? Thanks DAN

 

[mark ham]

Loctite 11c hysol epoxy patch, best epoxy out there, used it for many years. and yes you can break it down with a torch.

 

[Robert Pickard]

I used the JB Weld on a OS carb just heated it up to break it loose and yes it will last

 

[Brian Sorgente]

I would not recomend using epoxy to hold the carb on. If it does come loose or start to leak air you've got a whole new set of problems that could come with it...

I had the same issue with my Mac 21 OB engine (same method of clamping carb). The reason it happens is because the clamp rod only pulls on one side of the carb neck ( instead of both like a nova) and the clamp rod starts to divot the carb neck due to vibrations and the fact that a sharp edge is putting a lot of force on a very small area. As the divot gets deeper into the carb, this causes the nut holding it tight to come loose and vibrate off (because the neck of the carb basically got smaller and the nut didn't get tightened to compensate).

So what I did (after mine came loose at least 3 or 4 times lol) was, tighten the carb a little more than normal so the divot in the neck gets a little wider. Tighten and loosen it a few times and check what it looks like. Make sure your not deforming the inside of the carb while doing it...This will spread the load of the clamping rod onto the carb neck and stop that sharp edge from jackhammering itself into it any deeper. After it has a good divot, put some blue locktite on the threads, throw on a lock washer, then tighten it up like normal.

Kinda long winded but hope it helps,

Brian

 

[happybradboating]

I have tried silicone as well and it helps hold it in place and generally comes loose by hand or pliers no heat required. One time I had a motor that someone used epoxy on and I could NOT get it loose with heating it up to 350 in the oven.

Brad

 

[JRXHydros]

Does anybody have any experience with a carb that won't stay tight in the engine case? I have a mac 21 with a nr 21 carb that will not stay tight to the engine case.

I have changed clamps ,nuts, washers and o-rings and nothing holds when operating. Have you guys used epoxies or loctites that work AND IS A PERMEANT CURE.

Your help is appreciated ---- DAN

I take the o-ring & throw it in the trash & used automotive high temperature red silicone & never had a problem holding & sealing carbs. Make sure you clean your parts & have no oil resedue on them....I use denatured alcohol for cleaning.

 

[Tom Foley]

Anyone who has ever run OPS engines over the years has had this problem and dealt with it one way or the other . The epoxy and JB weld or similar , PC 7 etc method works . Super clean both parts , apply sparingly to the neck of the carb and assemble and tighten . Done . Engine can still be disassembled as well as the carb if necessary . The drawbar method of carb attachment truly sucks !

 

[Al Hobbs]

Tom Foley is right!

Al Hobbs

 

[Rudy Formanek]

I have used slow JB Weld on carbs and it holds well and is not too difficult to remove when wanted. It worked where people said Loctite would work and didn't. I didn't especially like having to use it, but it worked so well and came off when I wanted it to, I now consider it the first solution for holding carbs on that don't want to cooperate. I just put it on the top of the neck, I don't coat the whole neck and socket. It must be redone everytime the carb is removed. I have found that heating slow JB Weld with a heat gun will get it to cure in 15 min. works best on metal parts that can take the heat.

 

[Terry Keeley]

I used to add a couple of set screws to the OPS backplates, done!