Stripped Threads for Carb Choke Lever (Starter Lever)

[YL82]

Just about had my BS38 CV Carbs re-assembled and BAM! wouldn't you know it, I stripped out the little hole where the Carb Choke Lever (i.e., Starter Lever) fastens to the carb body.

After I initially stripped out the female threads (which aren't that far up into hole due to short screw), I went with a SST M4 x .70 Pitch x 13 mm socket head screw I had left over from my float bowl screws. This likely finished off what was left of the female threads further up into the cavity.

I've never done a helicoil thing before. Is this the way to go? If so, what do I need and where do I get it and how do I do it?

NEED HELP!

Thanks!

 

[weekendrider]

First locate a kit with the thread size you need to replace.
Most "kits" come the drill bit needed and a tap.
But it is through tap and you will need a bottom or blind tap since it has a bottom.
Ebay, Amazon, auto parts stores all should have helicoil kits.

 

[YL82]

Thanks, weekendrider.

I'll probably also check out any youtube videos that might be out there on how to do this (for any application).

 

[angus67]

didnt know they made them that small

 

[weekendrider]

A m4 X .7 is available.
OP if you aren't wanting to do this contact Oldskool carbs. Info in the shops section.
He will do you right.

 

[YL82]

Thanks, I will keep that in mind.

I appreciate the feedback/suggestions.

 

[YL82]

I found HeliCoil Kits available from O'Reilly Auto Parts and from Ebay and went with the one below from Ebay for about $57 in a "Fine" Kit. Fastenal ordered me one, but I'm not sure of brand or whether I'll even pick it up.

HEC-5546-4 Heli-Coil Metric Thread Repair Kit-Fine, Metric M4 x .7 x 6.0mm

The one from O'Reilly Auto Parts was a "Course". So for the same part# (5546-4), does one have to select from Fine, Medium or Course?

At any rate, I went with the Fine one.

 

[hobbes28]

Course Medium or Fine is based on the pitch (.7mm in this case). .7 is a course thread but some places call it fine because it's small. Either way, if you got the M4x.7 helicoil kit, you'll have the right one. The kit at O'Reilly Auto is the right one and a pretty good price. We usually pay close to $60 for kits at MSC.

The big thing to keep in mind is to not force the insert in because you can cross thread them and deform the hole. The insert tool should do a pretty good job with keeping it straight and help it into the right track. I like to turn the insert out from the tip two or three threads so I can see where it starts and I can turn it down until the inserting tool gets to the surface and keeps it straight. Make sure you get the tang out after you break it off too so it doesn't show up later on.

 

[YL82]

Thanks for your advice, hobbes28!

Yeah, that was confusing to me on the Fine & Course thing since I knew the thread pitch was 0.7. Looking at some of the crappy product images (e.g., Amazon, etc.) they oftentimes showed a different fastener size which didn't instill much confidence.... I coulda saved $20 by going with O'Reilly, but their incorrect/confusing product title header (online) made me look elsewhere even though I apparently would have gotten the same darn thing.

I may be off a little, but it looks like the available screw length on my stock screw and screw from the Mikesxs kit I bought was only about 3 mm (into the hole). Unless I've put the the carb choke lever kit together wrong, that seems like very little thread to secure the lever...

I plan to try a 16 mm long M4x0.7 socket head screw which will put about 8 mm of threads into the hole. The total deadend hole looks to be about 15 mm, so I thought I'd try an 8 or 10 mm insert (assuming the kit I ordered has one of those).

Am I on track here?

Thanks again!

 

[weekendrider]

I'd say you are. When you get the kit your tap is most likely going to be a through tap
meaning it will have a tapered end to start the threads. You lose the length of that taper. In this case because of the excess depth it may not be a problem.
You also don't have to worry to much about the tang retrieval.

 

[hobbes28]

If the insert kit you ordered has inserts that are too long, just snip it down one thread at a time until it's the right length. Snip from the end opposite the tang.

Food for thought about the original hole: 3mm of thread is 4 threads which is plenty to hold it all together. Just something to think about if your inserts are shorter than you thought they would be.

 

[YL82]

Good Stuff!

Thanks!