Exhaust Spewage

[MrFurious]

So who can tell me what's causing this jet black crap to spew out of my exhaust? I get a little bit when I first start up the engine when cold, then as it warms up it is replaced with the usual moisture evacuation caused by condensation as the exhaust heats up. Once warmed up though it starts spewing this black crap out again. Needless to say, I'm continually getting reamed over this as the lower rear quarter on my better half's car keeps getting a fresh goat of exhaust spew.

My best guess is that it's worn valve seals letting some oil down into the cylinders, but I imagine it could be worn rings causing the same thing. Planned to have the heads reconditioned this winter, but if new rings are needed I'll put the heads off for a bit and do a full rebuild.

[FuzzFace2]

How bout carb running rich or choke not pulling off all the way?
If it's sooty black I say carb.
My .02
Dave ----

[Goose]

Yea that would be my guess as well.. the sooty black crap mixes with the condensates and presto sticky black goo..I am guessing you may be running a bit rich. (the first little blast on a cold start is normal and will pretty much always be there.)

[MrFurious]

Highly possible it's the carb as I'm still tweeking the jetting and metering rods trying to get it just right. Engine runs good and smooth with no bogging anywhere to indicate being overly rich, but you can smell it in the exhaust. Will be ordering a HEI dizzy in a week or two as the ignition is all stock at present and probably pretty weak given it's age, so hopefully that extra fire will help things out a bit and make the carb tuning easier.

[AMX69PHATTY]

Could try pulling the coil wire off of the distrbutoer cap, putting near metal, crank engine, and check for blue white hot sparks that snap. If the spark is kinda orange-ish then coil is weak. Mine was difficult to start, had orange-ish spark, changed coil, and it started very easily. Also had some of the black exhaust discharge. Wondered if it was just the condensate in the pipes washing out some of the carbon. Could just be the car marking it's territory.

[ironman_gq]

if you can smell that its rich try leaning out the idle circuit. i had a carb that wouldn't respond to idle circuit tuning. turned out that the idle air bleeds were partially plugged and was causing erratic idle problems.

[AMX69PHATTY]

I agree, dirty air bleeds will cause rich problems and poor atomization. Another possibility, if it's an Edelbrock / Carter carb, engine vacuum plays a BIG role in leaning the mixture. The Rods are pulled down into the Main jets by aluminum "pistons" in bores to lean the mixture. These pistons must be clean and free in the bores and are backed up by counterbalnce springs. These springs come in different strengths and can be changed to adjust the leaning point and range based on engine vacuum, especially at idle. The rods, pistons, springs, take the place of power valves on Holleys. Have ya checked your manifold vacuum at idle and messed around with changing out these power enrichment springs ? Engine condition, Spark Timing, Cam, and other factors can reduce vacuum and cause it to go rich or the Rods/Pistons to "bounce" open and closed. Holleys usually use a 6.5" vacuum Power Valve, but in hot rod motors I've often seen cold engine start vaccums around 8.0" or less and have changed out the power valves to 5.5" to prevent them from "leaking" or "bouncing" open and makin' the motors go phat.
If a Holley has a blown power valve you can usually screw the idle mixture screws all the way in cutting off all idle fuel and the motor'll still run cause it's gettin' gas through the blown power valve diaphram.

[Holeshot]

I certainly hope your oil is NOT black!!!!

Here's a way to tell if it's rich or lean. Pull a vacuum line off & see if it revs up or down, if it revs up it's rich, if it revs down it's lean.

If you have a large cam, you can drill small air bleeds in the primary butterlies to let more air in, if all else fails.

Sorry for all you guys running Edelbrock (Carter) carbs, but that design is from the 1950s & had run it's course way back when, Carter could sell no more of them. Edelbrock started reproducing them after Carter went belly-up with their obsolete products!!!

I'll take a Holley anyday over one of those old POSs.

You couldn't get me to use one by giving me $100 & a brand new one!!!