testing quadrajet well plugs
Thread Starter
Heel & Toe
Joined: Jul 2024
Posts: 23
Likes: 6
testing quadrajet well plugs
Going to be rebuilding my Q-jet shortly. I have Cliff's book and the parts directly from him (Thank you, Cliff!)
As suggested in the book, I want to text the well plugs (even though they're supposed to be leak-free on 99.9% of late model Q-jets).
Original carb on 1975 L48 has been reworked at least once because there is epoxy/JB Weld on the plugs that I can see. I will be pressure testing the plugs with soapy water and air, but I can't, for the life of me, find a photo or diagram showing which holes to blow the air thru. I'm a machinist by trade, and know my way around cars fairly well, but some of the jargon is foreign to me.
Can someone post a simple picture or two with arrows pointing out the spots to blast the air? I've searched YouTube and every forum I can find to look for something that shows it. All they show is how to epoxy the plugs, not how to test them.
(I'm asking here because if someone can reply with a pic, maybe it will help someone else, too.)
Thanks in advance!!!
As suggested in the book, I want to text the well plugs (even though they're supposed to be leak-free on 99.9% of late model Q-jets).
Original carb on 1975 L48 has been reworked at least once because there is epoxy/JB Weld on the plugs that I can see. I will be pressure testing the plugs with soapy water and air, but I can't, for the life of me, find a photo or diagram showing which holes to blow the air thru. I'm a machinist by trade, and know my way around cars fairly well, but some of the jargon is foreign to me.
Can someone post a simple picture or two with arrows pointing out the spots to blast the air? I've searched YouTube and every forum I can find to look for something that shows it. All they show is how to epoxy the plugs, not how to test them.
(I'm asking here because if someone can reply with a pic, maybe it will help someone else, too.)
Thanks in advance!!!
Last edited by Heirloom75Coupe; Mar 23, 2026 at 03:24 PM. Reason: added more info
Tech Contributor
Joined: Aug 1999
Posts: 14,377
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From: At my Bar drinking and wrenching in Lafayette Colorado
You don't need any air blast. Just disassemble the carb down to the bare float bowl. Set the bowl up on 3 tall sockets on your work bench and then fill the float bowl with fuel or lacquer thinner up to the level of the inlet seat. If any of the plugs are leaking, they will immediately start dripping from the bottom of the bowl. If there are no drips after 5 minutes, you are leak free.
...and you can't fix leaky plugs by smearing them with epoxy - that's completely useless and ineffective...
...and you can't fix leaky plugs by smearing them with epoxy - that's completely useless and ineffective...
Thread Starter
Heel & Toe
Joined: Jul 2024
Posts: 23
Likes: 6
You don't need any air blast. Just disassemble the carb down to the bare float bowl. Set the bowl up on 3 tall sockets on your work bench and then fill the float bowl with fuel or lacquer thinner up to the level of the inlet seat. If any of the plugs are leaking, they will immediately start dripping from the bottom of the bowl. If there are no drips after 5 minutes, you are leak free.
...and you can't fix leaky plugs by smearing them with epoxy - that's completely useless and ineffective...
...and you can't fix leaky plugs by smearing them with epoxy - that's completely useless and ineffective...
I didn't goop them, but someone else did. I don't know if they were leaking at some past time or if someone was trying to be proactive. Either way, I don't want to mess with them if they are not leaking. I did not have any starting issues, just want to make sure since I have it apart now.
I'll fill the bowl now and, hopefully no leaks 🤞
