Holley 4346 question

clayran · #1 03-21-2020, 06:06 PM

Need some advise on my Holley 4346 carb issue. Getting the car ready to start for the summer I had the air cleaner off and I noticed the boss that the rear vent is pushed into had 2 cracks running down the sides. The vent tube is not loose and not sure if this causes any issues with the carb’s operation. Was thinking of putting some JB weld on the cracks but thought I would seek some other opinions.

**Maxsg1973** · #2 03-21-2020, 06:56 PM

Pictures would be helpful. If you have access to a smoke tester you could determine if its leaking, possibly without disturbing it. Hard to advise without eyes on it. Sounds like it may cause a vacuum leak.

rszmjt · #3 03-21-2020, 08:13 PM

It won’t cause a vacuum leak, it is just a vent for the bowl & metering block cavity.
However it can be catastrophic if it falls out into rear carb throat as it can go into engine upon WOT. I Personally would either JB weld it in and the cracks or drill it and put a cotter pin rite through the boss to stop it falling out. Lots of Nascar & race carbs are done like that.

Use the original JB weld that takes 24 hr cure time, it’s gas impervious once it’s cured. I have Q jets & Holleys out there 30 plus years old with JB welded Welch plugs and no lifting or deterioration

**SuperNovaSS** · #4 03-21-2020, 08:14 PM

I think he is talking about a cracked vent tube boss like the one shown here. JB weld or other reinforced epoxy is not a bad option. Tightening the cracks together with a small hose clamp during the epoxy process helps provide a cleaner and better repair. Many shops simply cut the cracked portion off complete at about the position of the hack saw in the last picture. There are also shops that “weld” this pot metal but that would be an extreme option.

Jason

rszmjt · #5 03-21-2020, 08:22 PM

Bodies are made of zinc & very hard to weld, just JB weld it

**Maxsg1973** · #6 03-21-2020, 08:55 PM

Now that I read the description again I understand. I was picturing the throttle plate vacuum port. Pictures would still be helpful.

**WILMASBOYL78** · #7 03-21-2020, 08:58 PM

I would suggest reaching out to Eric Jackson....Vintage Musclecar Parts. He is the best in the business on these carbs

http://www.vintagemusclecarparts.com/

937-836-1885

-wilma

clayran · #8 03-22-2020, 04:26 PM

Hi and thanks for the replies, the picture shows my problem except mine isn't split, just has the cracks in it. Your suggestions really were helpful, especially the drilling or using a small hose clamp, I never gave that a thought for containing the boss metal. I even have a corbin clip that is the right size. I knew I could count on this site for useful suggestions. I have one more question, that air vent is in a low stress area so what could cause the metal to crack?

**SuperNovaSS** · #9 03-22-2020, 04:38 PM

The cracks usually happen when the carbs are shipped with insufficient packaging or moved around and the vent tube knocks into something. It’s not a critical area but you don’t want the tube or chipped piece falling into the engine.

Jason

**earntaz** · #10 03-22-2020, 04:58 PM

FWIW -- most of those damaged areas measure approx 7/16" OD. In the past I have fashioned a "collar" out of 7/16" ID tubing and pressed the collar over the damage. Got the tubing from a hardware store. TAZ