Carb float info
Thread Starter
Instructor
Joined: Sep 2005
Posts: 241
Likes: 0
From: St Louis Missouri
Carb float info
So after a long overhaul, I started the engine. I’ve rebuilt everything form the pistons to the carb, and here is the problem. I set the float level on my Q-Jet 4MV out of my 75 as the rebuild kit, and all the instructions showed. I found that as the engine ran, black water came out of the pipes, and fuel started to flow out of the top of the carb. I found that there is a plastic piece that holds the pivot point of the float a little higher then the base. Also this plastic piece stops the float from going too high which in turn stops the valve from sealing. I found that I had to set the float height with the bowl full and the plastic that holds it in place. I hope this helps someone that is rebuilding a carb. If you find this information wrong, let me know.
Tech Contributor
Joined: Aug 1999
Posts: 14,356
Likes: 6,332
From: At my Bar drinking and wrenching in Lafayette Colorado
On a '75, you should be able to set the float level dry to .420" and be good to go. The plastic peice does not retain or support the float in any way - it's just a bowl filler. The float hinge pin should be seated firmly in the bowl casting groove, and the spring action of the pin should hit the airhorn so that the airhorn firmly seats the float pin when installed. If the float hit the filler, the float level was not set to .420", or the hinge pin was not spread enough to allow it to hit the airhorn. Pre-'75 Q-Jets should be set to .375".
Thread Starter
Instructor
Joined: Sep 2005
Posts: 241
Likes: 0
From: St Louis Missouri
Thanks for the info. I didn’t know that the float hinge pin was supposed to be adjusted. I’ll take the top off and spread it a little. I should have already thought of that. Thanks.
