Vacuum leak caused by choke removal

[dcdoug]

Many of you experts out there may already know this, but I learned something last week that I thought I'd share for others.

I was recently watching a video on carburators and learned that if you remove the choke on a Holley 4150 carb, you need to replace one of the mounting screws and use thread sealer or you will likely have caused a vacuum leak.

I removed the choke on my 3255-1 quite a while ago (car always ran fine) but decided to investigate the claim from the video last night and found that indeed the center screw hole that was one of the choke mounting points is not plugged and goes somewhere into the center of the carb. So it seems to be true. My engine is out of the car right now and I couldn't run it to test if it actually is a vacuum leak, but it sure seems likely.

Here is a pic of the carb before the choke came off. It's the center hole of the three in this area when the choke is removed.