Weber carb rebuilding, help!!!

[tweety]

Hi,
I have a 40IDA with almost stripped main jet threads on the body.
The jets bolt in alright, albeit with some play but some fuel leaks through the copper washer.
I dare not apply anymore force to tighten the jet because it feels soft... and I think that whatever thread there is left it will be stripped completely.

This, obviously, is not tight enough to completely seal the two sides of the jet and fuel probably leaks through into the emulsion tubes.
The engine pops and backfires a lot, as a result of the above and the λ sensor shows very confused readings.

I tried using a small amount of teflon thread seal tape (the plumbing type) and it improved things a little but not enough.
And I am weary it will eventually fray and block the jet.

I also made paper jet gaskets to replace the copper ones and fuel leakage outside is now under control but still not good enough (it sweats)

Question.
Can the bodies be rethreaded?
If not, is it an option to use thread sealant and gasket sealant?


Thanks in advance for enlightening me!

[1QuickS]

I've seen a lot of stretched main jet holders and jet holders broken off in the body but have not seen stripped threads in the body. Are you sure it is the body that is bad and not the jet holder? Also, only the threads make a seal with the fuel being delivered to the emulsion tube well as is evident from the sectional view.




Paul Abbott
www.PerformanceOriented.com

[tweety]

Thanks Paul,
The body is shot... the threads are partially pulled and I have no option but to use thread sealant to have some seal between the jet and the fuel bowl.
Also I will use a paper gasket with some gasket glue and see if it seals the outside leak.
Your site is awesome and I just wish I could have someone as knowledgeable as you here in Greece to help me tune the carbs.
Well c'est la vie...

[1QuickS]

Best chance for a repair of the threads is to use a Time-sert insert. The outside threads are "timed" at the same pitch as the internal threads to minimize the new threads in the body for minimum material removal which is needed for the thin wall of the main jet holder. I did a quick search and carbon steel inserts are available (no stainless ones available) so they would need to be zinc plated before installation. The inserts require purchase of a special tap and installation tool...expensive for a one time use but cheaper than a new throttle body.

http://www.timesert.com/

Paul Abbott
www.PerformanceOriented.com

[tweety]

I finally used some thread sealant on the jet carriers and it worked.
I could tighten the carrier adequately, using the above mentioned paper gasket instead of copper, there is no leakage and the fuel metering is now controlled precisely by the jets.

I cannot vouch on how this will hold over time but if any problem occurs I will keep you posted.

By the way I also removed the lead plugs and unblocked the idle passages...
A world of difference.
I am now ready to start tweaking the carbs to match my early S cams and 9.5JE pistons.
Here comes a fast 2,7.

Paul I am obliged by your interest. If ever you find yourself in Greece I'll be delighted to help you see the best my country has to offer.
And we will certainly take tweety out for a spin.

[Walt Fricke]

Tweety's owner:

What are the three black dots above each headlight? Sheet metal screws to insure the headlamps don't fall out?

Walt

[RWebb]

the thread sealant makes me nervous but I guess it won't put you in a worse spot than now if it fails and goes down the hatch

[Walt Fricke]

More for Tweety's owner:

Have you ever forgotten to tighten one of a Weber IDA 3 barrel's main jets?

I did once. Ran out of gas on the track. Very lucky that was the only clue, as I must have pumped five gallons at least out that hole in a fairly short time.

What I am suggesting is that you fashion something external to hold your ailing main jet in place. Perhaps something like the holders for the lower spark plug connectors on factory twin plug setups. You could attach it with the float level screw/plug. Or to one of the studs which hold the carb to the intake manifold. Or something even cleverer, once you look at with an idea of how to press the jet holder in toward the carb body.

Just a safety precaution, even if it looks like the paper gasket gained you enough threads to hold the thing in place.

Walt