Sneezy/backfire at idle doesn't like to idle

[pcrussell50]

carbs sat for a couple of years with old gas. prior to that, i'd go several months at a time sometimes without draining them for years. slowly the idle quality got worse and worse.

i'm going to guess that i should pull them and clean/rebuild? before i do, i just want to be sure that the backfiring and unsteady idle is probably due to some clogged passages in the carbs?

I've got no problem doing this, i just want to make sure i'm not wasting my time.

-peter

[pappa pete]

Check bleedlines if it has them, if they leaking it'll sneeze and backfire

[pcrussell50]

it doesn't have bleed lines like the newer ones do. it's a '75. well, there is one fitting exiting the block right at the bottom, facing forward. i was never sure what that one was for.

-peter

[EMDSAPMGR]

The port at the bottom front of the intake manifold is for the airbox drain. As any fuel/oil leaks from the carbs (maybe after tilting upward overnight) the fuel collects at the bottom of the airbox. When started, the bottom cyl of the engine will suck the excess fuel/oil into the engine for combustion. When this occurs at startup, the engine may smoke somewhat more for the first few minutes till all the fuel/oil is consumed. The famous "lean sneeze" is a carb issue for sure-not an ignition problem.

[pcrussell50]

^^^This.

Thanks as always for sharing your v4 crossflow expertise. Over my 8 years as a boater, I've rebuilt a dozen of these carbs, and I got most of the way through these until those damned @#$_&-+ core plugs. I've always been able to get them out by drilling a small hole and starting a drywall screw into it, then yanking it out with the plug. But these suckers were hammered in but GOOD! I think I'm going to do what I HATE doing and take them to a pro to get these suckers out. (Kevin at RandR, recommend by STV_Keith).

In the mean time, I finally got around to installing the Chris Carson fiberglass reeds and block stuffers I got 7 years ago from him. All that part went really well. Looking forward to it, big time.

-Peter