**Help: problems with carburetor, I think.


May 11, 2005
Sorry for the long post

Ive had a smoke and rough Idle problem since Ive installed a new Carter 625
Carburetor. I was running a tunnel ram with 2 holley 450s and the engine ran great and Idled great.
I would have some hard warm starts with this setup. Im running a 302
with a 4 spd by the way. I switched the tunnel ram out after I took the
engine out to clean up and paint and do some transmission work. When I
reinstalled the engine with the Stealth manifold and Carter 625 I got the rough Idle and white smoke that burned the eyes and It just didn't run great. I thought maybe I didn't get the intake manifold sealed up right so I tried
that same problem. Thought maybe a head gasket so I took the heads
off and resealed the manifold with the same problems. I did a compression
check and the cylinders averaged 165 to 170 per cylinder. I also did a
leakdown test with around 15% leakdown on each cylinder. All the
Spark plugs had alot of black soot carbon on them and thats why Im thinking
the carburetor is running rich. I dont really care for the Carter anyway because it has a manual choke. I was thinking of going with a Holley Avenger 570 or 670 cfm with the Electric choke. The Engine is built up and has a bigger than stock cam. I bought the car this way so Im not sure of the cam size. The engine does seem to have good power except with the
Idle and the smoke. The car sat awhile before I installed the carb also so
There could of be some crap in the fuel tank that maybe got in carb. Since
then Ive replaced the tank with a new one.

Thanks for Any help given
Im at a loss as what my next step is
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302 coupe

Founding Member
Mar 2, 2000
Macon, Ga.
White smoke that burns your eyes? interesting, normally white smoke would mean a coolant leak into the cylinder/s, or maybe a faulty transmission modulator. Its sounds like you've ruled out the possibility of a coolant leak.


May 11, 2005
It doesn't smell sweet. Its smell like bad
to me more like fuel. It doesn't smell like
oil. It does leave some splatered black
specks of black on the ground also. Thats why I was leaning towards carburetor or to much fuel pressure.


10 Year Member
Jul 9, 2003
Lubbock Tx
I have been running a carter carb for years, but I have never experienced the problem you are having. The only things I can think of with a new carb causing you problems would be fuel pressure, float settings or choke setting. The Jets those carbs come with are pretty mild, but fairly close to what I figured out my 302 needed for max power. I just stepped up the secondary jets to the next higher size on my 302.