Man, it smells - Just the nature of the beast?

[c1500sbc]

I have a fairly stout, street 383. Running a Holley street avenger 770. I appreciate y'alls help with the choke. It's working now, but man it smokes quite a bit on cold starts. I'll have to pay attention to the color next cold start but i'm thinking its fuel. That subsides once the truck warms up and the choke opens. I'm running true duals, long tube headers with no cats. This thing smells! Like, kill you in the garage in 2 minute smells. According to the AFR gauge its about 14:1 at idle. Even leaning it out a little doesn't seem to help.

Two questions, how normal is the smoking on initial start? Is the smell just the nature of the beast? I know the cat delete doesnt help but I didn't think it would be this bad!

[BillK]

Without being there its hard to say but a lot of younger guys have never had to experience how the cars of the 60's and 70's ran as far as emissions go. It was pretty normal for cars to run pretty rich and stink the place up, especially when cold.

I would try loosening the choke up so it is not closed as much at cold start. To be honest with you most Holley carbs I have had in the last 50 years would run rich enough at idle that you really did not need the choke at all.

Also, make sure you have enough ignition timing in it.

Just thinking out loud

[c1500sbc]

Without being there its hard to say but a lot of younger guys have never had to experience how the cars of the 60's and 70's ran as far as emissions go. It was pretty normal for cars to run pretty rich and stink the place up, especially when cold.

I would try loosening the choke up so it is not closed as much at cold start. To be honest with you most Holley carbs I have had in the last 50 years would run rich enough at idle that you really did not need the choke at all.

Also, make sure you have enough ignition timing in it.

Just thinking out loud

It may just be the nature of the beast. I may switch to a Holley EFI set up at some point. I thought about doing that when I purchased the Avenger but I like tweaking on carbs. Plus, who knows how much it would really help. Choke is set fairly open when cold. It opens fully within a couple minutes. Initial ignition timing is set at 22 degrees if I remember right. It may just be "the nature of the beast."

[dannobee]

One thing that factory carbs had was a choke pull-off (aka Choke Break) that would crack open the choke once the engine started and vacuum was applied to the diaphragm. This had the effect of leaning out the carb once the engine started and a closed choke was no longer required. See if one can be retrofitted to that carb.

[F-BIRD'88]

Don't run the truck in the garage.
Carbon monoxide is getting into your house..
A cold engine/warm up run vacuum advance control device will help burn unburned slow burn fuel during warm up
OUTSIDE.. It would apply full max vacuum advance at idle, during warm up.
Revert back to normal (ported) vacuum advance curve after warm up running.

Blocked or restricted manifold plenum exhaust heat.
Stock engines had a valve on the passenger side exhaust manifold that closed when cold to force hot exhaust thru the crossover passage under the intake plenum to heat the plenum faster. (Exhaust crosover). Heat aids fuel vapourization especially on cold engines.
Liquid fuel will not burn..
When fuel vapourizes it MUST ABSORB HEAT. If when the available heat is used up, fuel vapourization STOPs.
This the need for adding heat under the carb from a external source to replace consumed heat.

Liquid fuel wears your rings ,cylinders quick.

When the engine is cold it is actually running lean not rich but part burned and unburned fuel is passing out the exhaust also.

[F-BIRD'88]

It is better to drive the truck at moderate throttle to warm it up faster than idling. You waste fuel and increase engine wear. Run it for a minimum time 1-3 minutes, (fast) idling, then go DRIVE IT to warm the engine.

[F-BIRD'88]

Any TBI style EFI system will also want a exhaust heated plenum. All that OEM emissions control Cold start heat control stuff that hotrodders want to remove has valid real purpose on a street car/truck.

[tblentrprz]

No smoke is not normal on cold start. How long does it smoke? See if the choke is opening correctly. How long til choke opens fully. Verify it is not dripping fuel after shutdown. It could dripping and loading the intake and cylinders until next start.

[77cruiser]

If it's idling 14-1 when it's warmed up that makes it stinky too. Adjust to best idle highest vacuum.

[F-BIRD'88]

If it's idling 14-1 when it's warmed up that makes it stinky too. Adjust to best idle highest vacuum.

Yes, ignor the AFR guage at idle.. Adjust for best idle.

The (real) afr will be a bit richer than 14.7:1 at idle
12.5 to 13.5 usually. This is normal.. warmed up..
Not all cylinders run the same, at idle so....


When cold the guage means nothing.

[F-BIRD'88]

There should be no ex smoke other than water vapour.
A minor brief puff of blue that stops right away on startup is ok. This is oil in the valveguides being sucked in.
Alil valveguide lube is good on iron valve guides.

Cold start fast idle should be in the 1500-2000 rpm range at first... As said the choke has to open up a bit on start.

If it stays shut the sdjustment is wrong.
A non heated manifold plenum is going to mess you up over time.

[Schurkey]

One thing that factory carbs had was a choke pull-off (aka Choke Break) that would crack open the choke once the engine started and vacuum was applied to the diaphragm. This had the effect of leaning out the carb once the engine started and a closed choke was no longer required. See if one can be retrofitted to that carb.

It's got a pulloff piston inside the choke housing. Some carbs supply vacuum to the pulloff piston with a vacuum hose, (Holley calls this "external vacuum") some supply vacuum via drilled passages sealed with a cork "O-ring" that easily falls out-of-place when the choke housing is assembled to the carb body (internal vacuum).

2009 Choke Article 306 small.jpg

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2009 Choke Article 120 small.jpg

I've never seen an aftermarket Holley carb that had the pulloff piston adjusted properly from the factory. The procedure isn't in most of the Holley literature. The adjustment screw is covered in caulking. It's two steps away from a National Security Secret. Most folks don't know it exists.

The problem as described in the first post is most-likely caused--or made worse--by a misadjusted pulloff piston (not a misadjusted choke coil.)