Lean primaries after rebuild

[68 Goat]

I recently took the opportunity refresh the 7028262 on my '68 Pontiac 400 with one of Cliff's HP kits. I previously went through it about 6 years ago and built it to the #1 recipe in Cliff's book. I'm running a Crower 60916 cam with a 13" Continental stall.

The two things I changed this time around were installing the well plug kit with Marine Tex and a new set of idle tubes from the HP kit. I used the same rods and jets (73/42B).

I've got a pronounced lean spot right off the throttle I'm trying to tune out. The AFR will spike to 16-17 until the carb catches up then it seems to settle back down to high 14s/low 15s. The car is sluggish until the AFR settles down, but it doesn't sputter or knock. Prior to the rebuild I'd consistently see a 14.6-14.7 cruise AFR.

I've screwed the main air bleed adjustment screw in all the way, so it should be as rich as it can get. I'm confused why it seems to be lean now since the jet/rod combo seemed to work really well before the rebuild.

[Cliff Ruggles]

Check the float level, may be lower than it was prior to the rebuild.

Also make sure the power piston is moving freely, and the hanger arms didn't get bent, common problem I see here after rebuilding.....Cliff

[68 Goat]

Thanks for your reply.

Float level is at 1/4". I could raise it to 3/16 and see if makes any difference. Power piston appears to be moving freely (polished it before install) and the hanger arms look good.

Any possibility I bungled something when I installed the primary well plugs? Just wondering if there's any way I could have hindered the fuel flow through the primary jets.

[68 Goat]

I tore down the carb last night and found some excess MarineTex that was pushed up by the well plugs under the primary jets. It wasn't blocking the fuel passage but must have been hindering the flow quite a bit. I used a tiny Dremel bit to clear out as much as I could. Cleaned and reassembled everything and it looks like I'm back in business. Cruise AFR is still a tad more lean than I'd like, but the flat spot upon acceleration is completely gone and the carb appears to be somewhat back to normal.

Just a tip for anyone installing well plugs - go light on the MarineTex 

[Cliff Ruggles]

Good advise.  I put the epoxy on the threads of the set screws, not on the threads in the carb body.  This keeps any from getting pushed ahead and ending up under the plugs.  I've had a few carbs sent in here with a LOT of epoxy under the plugs, which as we have seen here, is not a good thing.....Cliff