Venturi? '82, 50hp, 4cyl. Merc

[ednacutright]

I pulled my carbs apart for a rebuild and noted that neither has the "venturi" in place. These appear to slide into keyways in the throat of the carb casting, but haven't been in place since who knows when (perhaps day one) and the motor has been running w/o them.

Should I buy venturis and put them in? Were these omitted for some HP ranges? What effect do they have?

 

[WillyBWright]

Re: Venturi? '82, 50hp, 4cyl. Merc

Part # 64677. I don't know why they're there, or why yours are missing. They do call them venturis, but the ridge in the bore of the throat is what does the work. I really see no purpose for the plastic inserts, but there must be some reason or they wouldn't put them there.

If I'm not mistaken, they have a hole in the bottom to fit over the main fuel nozzle. I suppose it aids in atomization as the air being drawn in surrounds the center venturi and draws the gas along with it. On most carbs, that nozzle is near the bottom and I can see where it might not get quite the same degree of atomization that way.

 

[ednacutright]

Re: Venturi? '82, 50hp, 4cyl. Merc

THANX; I guess I'll buy them and stick them in. (Mercurypartsexpress lists them at $3.06 each)

I wonder if the originals disintegrated and got eaten by the engine...

 

[Laddies]

Re: Venturi? '82, 50hp, 4cyl. Merc

Willy, they claim that they help mid range and I know that on the 44XS engines they do seem to help, if they are missing the engines will stumble on hard acceration like a lean spot but about 1/3 of the carbs we tear down on fishing engine are gone. We replace them but I don't think that most would know if they were there or not

 

[imported_Voyager]

Re: Venturi? '82, 50hp, 4cyl. Merc

Found one of the missing venturis laying in the cowling, got another for ~$3 from the Mercury dealer. The mechanic assured me that the engine won't run right without these installed.

Be sure to install them with the tits on the end of the arms pointing toward the choke. In the diagrams at mercurypartsexpress, it looks like the tits are pointing away from the choke, this isn't correct.