Soot from tailpipes

J

JJHstang

5 Year Member

Sep 12, 2018

222

14

18

Fort Worth, TX

Apr 17, 2021

#1

• Apr 17, 2021

• #1

I have read some Q and A on this subject but asking again based on my situation.
When I start my 71 Mach 1 with 351 Windsor (yes small block Windsor not Cleveland) with Summit 4bbl carb. I notice some black soot on my concrete, pic attached.
It stops after warmed up. As most know from previous posts I am by far not a mechanic.
I did get power back to my electric choke with some great help from a forum user and think I have it adjusted correctly. Closes when cold and gradually opens as it warms up. Idle drops with a little flick of the gas peddle.
Any thoughts and suggestions?

 

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7991LXnSHO

wanna catch the space herp

10 Year Member

Sep 1, 2010

7,387

2,745

194

Kearney, NE

Apr 17, 2021

#2

• Apr 17, 2021

• #2

Your choke may be adjusted a bit too tight or it could be getting too much fuel when parked. Or it could be a standard carb start up.
Besides some soot, is there any other signs of flooding when parked?

 

HemiRick

I'd be looking at jacking under the house

Jun 28, 2020

723

272

73

Memphis TN

Apr 17, 2021

#3

• Apr 17, 2021

• #3

Its normal. Water condenses in the cold exhaust pipe, it washes the soot outta the pipes.....the pipes ideally should not be that sooty, but if the car is just short tripped and not let to warm up this is nothing to be concerned with. It the car is only driven for reasonably long distances the pipes should be cleaner, and its rich.

 

Reactions: stormsedge

J

JJHstang

5 Year Member

Sep 12, 2018

222

14

18

Fort Worth, TX

Apr 17, 2021

#4

• Apr 17, 2021

• #4

Thank you.
I will check the choke again and look up adjusting to run leaner.
I do need to take it out for a good drive.

 

7991LXnSHO

wanna catch the space herp

10 Year Member

Sep 1, 2010

7,387

2,745

194

Kearney, NE

Apr 17, 2021

#5

• Apr 17, 2021

• #5

If you adjust it just tight enough to start and run without stumbling when cold, that’s tight enough.
And if the weather is nice, of course you need to take it for a good drive.

 

J

JJHstang

5 Year Member

Sep 12, 2018

222

14

18

Fort Worth, TX

Apr 20, 2021

#6

• Apr 20, 2021

• #6

I checked the choke, temperature in garage around 65.
Started the car and watched the choke plate. After about a minute it started opening and around 4 minutes was fully opened.
Does that sound about right?

 

7991LXnSHO

wanna catch the space herp

10 Year Member

Sep 1, 2010

7,387

2,745

194

Kearney, NE

Apr 20, 2021

#7

• Apr 20, 2021

• #7

That sounds ok if it runs fine. The Holley high idle cam usually has steps that only let the choke open when the throttle is opened, so I’ve never timed it. But that seems like about what I do with a manual choke, maybe a bit slower at 65 deg.

 

Last edited: Apr 20, 2021

J

JJHstang

5 Year Member

Sep 12, 2018

222

14

18

Fort Worth, TX

Apr 21, 2021

#8

• Apr 21, 2021

• #8

Thank you, going to take it for a drive today maybe clean out some of the condensation. Temp will be in the lie 50s.

 

stormsedge

5 Year Member

Jun 17, 2018

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Here

Apr 21, 2021

#9

• Apr 21, 2021

• #9

I had one years ago that would soot a bit like yours every now and then. After a good highway drive, the pipes were white to light brown...always thought that a good indicator of proper mix with a carb.