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-   -   Cap and Comp Jet Helicoil repair (https://www.fordbarn.com/forum/showthread.php?t=275626)

TinCup 01-19-2020 02:45 PM

Cap and Comp Jet Helicoil repair
 

Both of these are 5mm 75 pitch threads. Checked local auto parts and no luck there. Trying to repair Zenith 3 bottom that I found in a box at an antique store. All I can find is M5 .08.

F.M. 01-19-2020 04:36 PM

Re: Cap and Comp Jet Helicoil repair
 

Call Berts.. Brattons has it listed in its parts book..

wmws 01-19-2020 04:55 PM

Re: Cap and Comp Jet Helicoil repair
 

Can you find a SAE 10-34. It is only .00012 less in pitch and .007 smaller in diameter.

Gary WA 01-19-2020 05:32 PM

Re: Cap and Comp Jet Helicoil repair
 

Go online found some on Amazon years ago .local club members

TinCup 01-20-2020 01:05 AM

Re: Cap and Comp Jet Helicoil repair
 

Quote:

Originally Posted by Gary WA (Post 1843212)
Go online found some on Amazon years ago .local club members

No such luck spent all afternoon searching.

Synchro909 01-20-2020 05:00 AM

Re: Cap and Comp Jet Helicoil repair
 

Are you sure it is 5mm X 0.75 pitch? That is an odd thread. Metric coarse is 5 X 0.8 mm and metric fine is 5 X 0.5mm. A pitch of 0.75mm is very close to 34 tpi, again odd!

fuzes45 01-20-2020 08:56 AM

Re: Cap and Comp Jet Helicoil repair
 

Try McMaster Carr

1930 coupe 01-20-2020 10:08 AM

Re: Cap and Comp Jet Helicoil repair
 

Braze them closed then drill and tap to the proper size. Be very careful that you get them straight.

Gary WA 01-20-2020 11:16 AM

Re: Cap and Comp Jet Helicoil repair
 

1 Attachment(s)
Quote:

Originally Posted by Synchro909 (Post 1843339)
Are you sure it is 5mm X 0.75 pitch? That is an odd thread. Metric coarse is 5 X 0.8 mm and metric fine is 5 X 0.5mm. A pitch of 0.75mm is very close to 34 tpi, again odd!

Yes Zenith French Made!

Gary WA 01-20-2020 11:21 AM

Re: Cap and Comp Jet Helicoil repair
 

Quote:

Originally Posted by TinCup (Post 1843127)
Both of these are 5mm 75 pitch threads. Checked local auto parts and no luck there. Trying to repair Zenith 3 bottom that I found in a box at an antique store. All I can find is M5 .08.

Sent email may be able to help you out,

redmodelt 01-20-2020 11:56 AM

Re: Cap and Comp Jet Helicoil repair
 

https://www.snydersantiqueauto.com/P.../gaskets-parts


https://en.wikipedia.org/wiki/Zenith_Carburetor_Company
They are an American Co. The 2 jet design used was developed by the guy in the above posting and with more research would probable find that the two jet design was used under license, payed to the designer in France, so used some metric parts. The carburetors were made in the United States not France and used the same parts that Holley and Ford used in their carburetors.

Synchro909 01-20-2020 05:35 PM

Re: Cap and Comp Jet Helicoil repair
 

Hmmm, Made in France - strange threads! I wonder what threads I will find in a Japanese copy I have. I'd like to get it going and I've asked before if anybody know of them and did Zenith parts fit. I received no responses so I guess I'm on my own. It looks to my (non expert) eye that it was a double venturi type. Do they even make the uniquely double venturi parts for those now?
BTW, it is branded KTK.

The Master Cylinder 01-20-2020 06:04 PM

Re: Cap and Comp Jet Helicoil repair
 

Quote:

Originally Posted by Synchro909 (Post 1843626)
Do they even make the uniquely double venturi parts for those now?
BTW, it is branded KTK.

Snyder's has the '28 twin venturi but it is any bodies guess if it fits your carb. Only you will know for sure when you buy one. :p

F.M. 01-20-2020 06:07 PM

Re: Cap and Comp Jet Helicoil repair
 

The one from Brattons fits and works just fine.. I think its the same one Snyders sells..

TinCup 01-20-2020 06:36 PM

Re: Cap and Comp Jet Helicoil repair
 

I use the tap all the time to chase threads I have used it for years. The challenge is the threads are worn away and even cleaning up what's there isn't enough to hold the jets.
All I can find is a 5mm .08 helicoil and not .75.

redmodelt 01-20-2020 08:11 PM

Re: Cap and Comp Jet Helicoil repair
 

What about making some thin wall inserts using US thread but drilled and tapped for the 5m.75 thread.

TinCup 01-23-2020 04:45 PM

Re: Cap and Comp Jet Helicoil repair
 

Finally heard back for Steve at Bert's at as I was afraid they did not have a resource for the 5mm .75 helicoil for the repair. Because there is no way access the passage for the secondary well you cannot simply fill and retap. I had another old Zenith bottom that I tested using a 5mm .8 helicoil and it worked. It holds the jet and seals with no leak. Tends to chew up the threads a bit on the jet but is much better solution than JB Weld.

redmodelt 01-23-2020 08:00 PM

Re: Cap and Comp Jet Helicoil repair
 

The secondary well is a different size then the 5M.75 jets. So you need more then just the jets thread repaired to refurb this carb?

TinCup 01-23-2020 09:23 PM

Re: Cap and Comp Jet Helicoil repair
 

Quote:

Originally Posted by redmodelt (Post 1844688)
The secondary well is a different size then the 5M.75 jets. So you need more then just the jets thread repaired to refurb this carb?

The secondary well threads are not relevant here. Only the passage to the comp jet which cannot be reached if one was to fill the area with brass and cut new 5 mm threads.

CT Jack 01-23-2020 09:41 PM

Re: Cap and Comp Jet Helicoil repair
 

Take the jets to a plating shop and have a copper or nickel flash put on the fittings. This will easily add .0002" to the surface of the threads. Make sure you put wax in the orifice of the fitting otherwise it will get plugged.


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