quadrajet (Mercruiser 305): F-26

[oldboat1]

I want to check operation of the secondary throttle plate on my quadrajet carb. With the engine off, I plan to hold the air doors open to look down on the throttle plates — think the throttle should be in WOT position, and the transmission in gear.

Does that sound like a way to check? It’s my understanding that the secondary plate is mechanically connected to the primary plate, and they open together when the throttle is advanced. As the engine will be cold, the choke linkage will have to be tweaked in order to open the air doors (and obviously no mass air flow with the engine off).

If the secondaries aren’t fully opening, I’m going to check the remote cable connection to see if it needs to be relocated to fully pull the plate open — likely check operation of the carb linkage, and then reattach the remote cable at the appropriate spot.

Would welcome ideas….

[prowlersfish]

Your on the right track but no need to put it in gear .

[oldboat1]

Thanks, Prowlerfish. Noted.

[P-Dogg]

Plenty of youtube vids on these carbs. Make sure plates are perpendicular to top of carb at WOT. And good luck!

[oldboat1]

Yeah, love 'em/hate 'em. I think I'm finding that the throttle plate isn't perpendicular at WOT, so is presumable not opening sufficiently. I haven't pulled off the remote cable yet to check the carb linkages (which don't seem real straightforward between the primaries and secondaries.) It's possible that the jets are plugged as well -- tried some carb spray after lifting the metering rods by way of the air doors, but no change. Good excuse to go out and run it this afternoon, but would like to hear and feel the secondaries kick in.