Sooty Camaro

[Shortiecar]

Ok. So, this is going to be a bit of a long paragraph. I am the son of the owner of 9L512227. Our beloved Camaro recently had a motor built and installed in it as the car's 3rd motor so we know. The car has been a beast. The motor has exactly 110.6 miles on it from brand new from GM (Part# 12691673) but it is running very rich. Fast idle doesn't work, it blows black gas smoke going down the road, and has downturned exhaust pipes blowing toward the ground which shows another problem, which is that in warm or cold weather, or warm or cold engine temps, the darn thing blows sooty gas across the ground and all the time. The scenario most recent is that we got it back from our mechanic the other day, and Dad decided to surprise me by driving it home. When he pulled in after driving it 6 miles, it was blowing blue smoke. He enthusiastically jumps out, and goes "It's back he said to drive it" and responded with "Why is it burning oil? SHUT IT OFF!" He goes "It is perfect it drove fine I don't care if it blows up". So I explained to him that we may glaze the cylinders and destroy the block/pistons with this mess and he is stubborn about it.

I understand how carburetors work. Yes, it seems as if it is very rich. Our mechanic took it off and put it in smaller jets. The plot twist is that it is an FST, which I want to switch to an Edelbrock for fuel economy and street performance/easy tunability.

Also, why does the engine smoke oil (blue) smoke on deceleration and when parking only, and only when warm? It does not smoke oil smoke when cold leading me to think that clearances have changed with the piston rings already because it's been hard to start with it being rich recently (I seriously hope not because I don't want to see the car torn down for the 3rd time in 3 years). If anyone can help, please do, your knowledge is appreciated.

[Ohioscott]

 i had an issue with  carb float sticking adding almost a quart of fuel to the oil. She'd smoke alright black to blue to white and back again

[FRANKTHECRANK]

If it has been running so rich to actually blow black smoke, and leave a trail on the road from your down turned exhaust pipes, there's a good chance your oil in the pan is full of fuel, therefore thinning it out immensely, which can consequently be letting it get past your rings and be burned up in your cylinders. That would cause the oil smoke. Hopefully you haven't "fuel washed" the engine completely, and ruined the cylinders because of improper lubrication due to the gas/oil mix.

Fuel wash

There is a condition that contributes to many failures of rebuilt or re-rung engines generally referred to as “fuel wash”. It is caused by engine flooding at initial startup or in early operation of a newly rebuilt engine. This phenomenon can cause very serious damage to the cylinder bores, pistons, and piston rings.

There is a condition, that contributes to many engine failures, generally referred to as, “fuel wash”.
Consequently, the only thing protecting your cylinder walls and bearings from fuel wash is; the thin layer of oil on them.
When you douse the inside of the engine with raw fuel, you wash-off that protective layer of oil.

[Shortiecar]

No gas in oil surprisingly. And it doesn't trail down the road, just when parked for like a minute. Though, if it did, I would call the motor toasted

[Mike S]

Is the power valve in the carb matched for the engines idle vacuum?
My initial thought is the power valve is opening during idle and/or too soon while driving.

Mike

[Leon in Mn.]

That's the first thing I was thinking.  Power valve sticking open.  They do make power valve springs to match the manifold vacuum.  The weaker the vacuum, the weaker the spring needed.  If blowing blue smoke especially during deceleration, then valve seals (intake) and or worn guides could be the problem too, but you said it was a new engine. Was engine broke in properly?  Some take longer than others.  Just my 2 cents......

[Shortiecar]

Is the power valve in the carb matched for the engine idle vacuum?
My initial thought is the power valve is opening during idle and/or too soon while driving.

Mike

The Carb is an FST RT-X 41650XB, with smaller than stock main jets, installed literally a week ago (stock was 69prime/63second). the power valve in the primary/secondary is 6.5/76 and the engine vacuum is an average of 20. The jets changed nothing. The engine was broken in initially for 30 minutes at 2000 rpm. The engine has never seen anything over 3000 rpm, and again, has 110 miles on it. Has idled for like 15 minutes at a time  max but only once and no more, my ignorance. Dieseled once, in 80-degree weather after 3 hours of driving which was the time I realized it may be rich. I am questioning the reliability of that carb because I cannot find any tuning info/positive reviews of it. The engine vacuum is 20

[Tinkerr]

Was the motor broken in with the current Carb? Didn't notice it smoking during break in? What size motor, specs.? It's pulling some great vacuum numbers. I'd check the simple things first... float levels, choke fully open, timing. At 20" of vacuum power valve should 10., but that won't make it smoke unless you get bigger than 10 or it's blown.

[Shortiecar]

Was the motor broken in with the current Carb? Didn't notice it smoking during break in? What size motor, specs.? It's pulling some great vacuum numbers. I'd check the simple things first... float levels, choke fully open, timing. At 20" of vacuum power valve should 10., but that won't make it smoke unless you get bigger than 10 or it's blown.

The float level is good, the FST has sight glass on the metering blocks so I can see that. I didn't break it in but I have the video from the guy literally 5 minutes after he broke it in. He said it ran perfectly and had no smoke. When he drove us around in it it did a bit on start but not much. When we brought it home it coaled the ground. On that 3-hour drive me and my dad had it lost ground at a pep boys. while going home it coal rolled for 1/4 a mile and at a red light but we were about a mile from home. Then it promptly dieseled when it cut off.

All the specs

GM 12691673 Block (L31 Vortec 350) with stock hypereutectic bottom end (Brand new not rebuilt, cast 11/7/21)

Comp Cams XE262HR Cam

Edelbrock E-TEC-200 Heads, ported, polished, new springs, seats, valves

Comp Roller Tip Rockers (1.6. Scorpion rollers would not fit under valve cover)

Edelbrock intake (not sure what exactly will check tomorrow)

Headman headers

runs 180 degrees Fahrenheit has never seen 190 degs.

[David K]

This carb shows as a manual choke. Assuming it’s fully open when driving?

https://www.summitracing.com/parts/fut-41650xb-1Q

What is the timing set to?
What coil are you using?
Distributor?
Spark plugs?

[Shortiecar]

This carb shows as a manual choke. Assuming it’s fully open when driving?

https://www.summitracing.com/parts/fut-41650xb-1Q

What is the timing set to?
What coil are you using?
Distributor?
Spark plugs?

They have shared part numbers which is stupid but mine has an electric choke

The timing is around 35 I think

Coil is an MSD Blaster and Distributor

Dont know plugs off of my head

[David K]

Looking for timing at base idle speed.
Have you verified the choke plate fully opens and stays open when it’s warm?

[Shortiecar]

Looking for timing at base idle speed.
Have you verified the choke plate fully opens and stays open when it’s warm?

No, but I don't want to run it because I was previously aware that I could fuel-wash the cylinders. What I have checked is the resistance to the plate with my finger. It is pretty soft and easy to actuate. But I will check asap. Will also get a timing reading