Stripped Breather Mounts, common problem?

[FiatBen]

It seems like every Fiat I have is suffering from this in one form or another.
The mounting studs that hold the air filter assembly to the top of the carb are either stripped or missing (because they've stripped). What solutions have you guys come up with?

[johndemar]

J-B Weld is the first thing that comes to mind

[nibbes123]

Best thing to do is tap it and install fresh studs.

[Ramzi]

JB Weld generally wont hold up to the torque. And the last thing you wand is to drop a nut or stud down the intake... It can make a nasty mess of the valve train.

Weber used to provide studs (which were oversized on the base) for just such an occurrence. Id recommending re-threading to a larger size.

(we might have some of those studs.... I'll try to look later)

Ramzi

[So Cal Mark]

heli-coil thread inserts

[131]

heli-coil thread inserts

X2.

Helicoil was a common repair we used to have to do. People over tighten the nuts and simply pull the stud out. I had one that another workshop had diagnosed as a big end failure, they pulled the sump and found nothing. The owner brought it to us, my boss asked me if there were any carb air filter studs missing, when I said yes, he said I'll find it in the combustion chamber, embedded in the head. That's where I found it.

[FiatBen]

Anyone happen to recall what size this is?

Note to Self: I really gotta get me a metric thread gauge.

EDIT: 5mm x 0.8
HeliCoil available at local parts stores (12/$5.89)
Tap & Die cheap at Harbor Freight ($16)

2nd EDIT: or not, no one locally had M5x0.8 heli-coils even though the website says they do

BTW: anyone know what size of tap you have to use for an M5 x 0.8 heli-coil insert??

[FiatBen]

Well, my "heli-coil" kit came in and I could finally finish up the carb. Thought I'd share pics of the process for people like me who are pretty new at most repairs.

The problem was two of the four holes for the breather mounting posts were stripped:


The solution is to retap and repair the threads. This kit costs me $16 and took about a week to get:


The kit includes the correct size drill bit to clean out the hole. For those who haven't drilled metal before (and this is VERY soft metal), go slow and use cutting oil (or any oil lubricant is better than none). I blew the hole and carb body with compressed air after drilling and after tapping to make sure nothing got in the carb itself.

The tap the hole: (kit includes tap, the handle is from my tap&die set)


Inset the heli-coil (thread repair insert, "heli-coil" is a brand name) with the tool provided in the kit:


The repaired carb body top piece:


Then I took out two posts from old carbs laying around. The lesson learned here is that the carb bodies are such soft material that the threads on the posts will be filled. These have to be cleaned out before inserting into your new threads.


And there you go! Ready to go back on the car.