Nut driving me nuts

**KIRCHNER** · 12-03-2019, 01:59 PM

HAVE a 1987 220 efi. i lost the lock nut that goes on the stud that holds the throttle cam[black] that moves the rubber roller, opening the shutters. it takes a 3/8 wrfnch. ive tryed 6 or more nuts, none has the correct thread. even robbed fron a 150 carb, no good. could it be metric? sae fine? tryed to find it in linkage tech guide manuals, no luck. engine# ob211002. also the little plastic bushing that slides on first. goin nuts!

**Dave S** · 12-03-2019, 02:09 PM

HeeHee ya need a squirell.....Might be metric......but if it came off with a 3/8 then not....How much bigger was the 150 nut?

**KIRCHNER** · 12-03-2019, 02:47 PM

about the same, but wont thread on. mybe 10/32? if it was bolt, ide just go to hwd. store, but its in the block..

**gfinch** · 12-03-2019, 03:10 PM

If it isn't any of those it has to be......https://www.boltscience.com/pages/screw4.htm
Outside of nut who cares.... Could be a 2" spanner with a 1/2" hole. Hardware stores usually have a hole and stud size tool set where the nuts and bolts are. Owned a 1984 F250 with a 460cid engine. When replacing the water pump found 1 bolt that was metric. Fun trying to remember the correct hole it went in.

**Merc 2.5** · 12-03-2019, 04:30 PM

Is it the same on the 2.5? I have few nuts like that. got a pic of the stud?

**flabum1017** · 12-03-2019, 07:04 PM

3/8" wrench size will be either a 10/32 (fine) or 10/24 (coarse), most likely a 10/32 as I have never seen a 10/24 on an outboard.

**Merc 2.5** · 12-03-2019, 07:12 PM

Yall all mine is 7/16ths wrench. And looks fine thread. Did u get a odd ball on that stud? The 2.4 and 2.5 carb is same stud. or mite b a carb thang. Have u tried something like a switchbox nut for the connections? I think those 3_8ths mite b standard cant member. If 1 of those nuts would work u could match it up at hardware for 1 way

**SS Minnow** · 12-03-2019, 10:43 PM

The site I linked to has some very good diagrams with part numbers. Sometimes I order direct, sometimes the shipping is so much I take the part numbers to Ebay. Not sure if this is your motor in the link. If it is not, I am sure you will figure it out.

http://www.marineengine.com/parts/me...nd-shift-shaft

**tlwjkw** · 12-04-2019, 05:47 AM

from old time memory.. if its a 3/8 nut its gonna be 10/32.. if its 7/16 nut its gonna be 1/4 machaine thread.. only metric I remember ona 220 laser is tha two nuts on tha fuel pump stud connections???.. anything different is a screw up....

**DEN** · 12-05-2019, 09:42 PM

3/8" wrench would most likely be 1/4 -20 or 1/4 -28 bolt.
Measure the diameter, you will know from that measurement what it is.
Also, make sure the 1st two threads are not burred up or dented.
hope this helps.