1972 Merc 7.5 s/n 3624881 carb Venturi (plastic) need an expert

[bnurczyk]

Hi guys,
I got a brand new looking 1972 7.5 from a my friends dad, it's been sitting for 20+ years. The plastic venturi in the carb was broken, p/n 64247 which is obsolete.
I have found in another thread that they "think" that another venturi p/n 69764 will work. I have found parts diagrams that show both parts.
I got my hands on one and the I.D is the same, the O.D. is much smaller.
With more flow around the outside of the venturi I?m concerned it may run lean.

Does anyone know for certain if the two are interchangeable, or if the later number supersedes the other?
I want to bring this beautiful old motor back to life without burning it up!!

 

[bnurczyk]

Re: 1972 Merc 7.5 s/n 3624881 carb Venturi (plastic) need an expert

Well I put in the alternative part number venturi just to give it a quick try; it runs fine at low rpm’s but surges bad when given more than about 25% throttle.
But now for the good news; my local Merc. dealer ran a search on MercNet and found a half dozen dealers with the obsolete part, I’m having one shipped in. A lot of dealers won’t even tell you they can do that.