Heavy Black Exhaust

mike42

mike42

Well-known member
Morning ....

Car runs great after the new carb, but heavy black exhaust. Do I need to adjust the needle valves ?

Thx.....Mike
 
Aussie……1940 V8 standard brand new 2 barrel from Dennis Carpenter. I believe the paperwork said jets were 53

Thx……Mike
 
It doesn't sound right to me that it should be making heavy black smoke. I would be calling Carpenter to see what they suggest.
 
Kind of strange that it runs great, but has heavy black smoke ? Those two things don't go together. Maybe take off the top and verify the float level is correct, and that the float isn't taking on fuel. Especially if a plastic float.

Sal
 
Guys ……

Only black smoke on start up. It leaves a huge mark on the driveway. After running no problems.

Thx
 
Gee, I thought 51 jets were standard issue not 53. My Holley 4 barrel uses 51's.
Can you try some #51's as 53 sounds a bit large and will be too rich. What size jets did the original 40 Ford carb use?
 
Fordy ......original '40 carb I believe had 49.....I'll try some 51's as I have a set of those too.

Thx
 
Mike: I even ran 49's on my Holley with no problems. Just check the plugs to see the color with each change you make. My fuel pressure is about 4 psi. You have be very persistent in making your 40 run the way you desire. Well done.
 

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mike42 said:
Guys ……Only black smoke on start up. It leaves a huge mark on the driveway. After running no problems.Thx
Click to expand...

OK, that's new info not disclosed before. If only on start up, I would guess it has nothing to do with the jets.

Maybe your new carb just needs less choke, less pumping the throttle on start up?
 
Guys ……

Before I pull the new carb apart I have to find those extra smaller jets. Had it out for a run yesterday and it really runs great except at start up where black soot comes out. I’ll try less choke today when I start it up.

Have a great 4th of July !

Thx……Mike
 
The soot is not being created at startup because after a good run it would be gone. I tend to believe that there is a too rich issue causing carbon build up. It could be jets or even just mixture adjustment. What spark plugs are you running? Are you just low engine speed driving the car?
Is the engine warming up, are you running thermostats? Without them the engine warms up slower in cold weather. Michigan in July, not an issue.
Park on the street or off the driveway or even when your driving and rev the engine to blow the build-up out just before you shut it down and see what happens the next day when you start it up.
I like to believe that anew carb from a reputable dealer would not be the issue. Do you have an old carb you can try for a couple of days and see what happens?
A lot of questions I know but that's how this old guy processes "what if's". Run through al the possibilities before you start buying parts. We all have shelves full of those never used fix-it parts...
Keep us posted. Chap
 
Finally got around to checking out jet size in new carb. They are 50's so I expect that is standard size. I hated like hell taking that new carb apart, but everything went okay.

Thx....Mike
 
i had the black soot up on start up also. I went to 1 step hotter plug and have not noticed it anymore. I was running Autolite 216 and swapped to a NGK B-4L (i believe is a hotter plug) and much less noticeable soot on start up.
 
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