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59 cdv runs rich

Started by Paul, November 20, 2021, 06:58:30 PM

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Paul

Hello! My 390 seems to be running rich. The exhaust is strong. I've adjusted the idle air screws correctly. The engine idle is smooth. Am I missing and adjustment somewhere that could lean out the mixture—or do old cars just smell this way? Thank you.
59 Caddy, Seminole Red with Dover White top

Joe Jensen

I would check your spark plugs and see if they are dark with soot to confirm you are running rich.  Aside from the mixture screws you could have a situation where the choke is not full opening when warm.  You might just try backing off your choike adjustment.

You could have issues within the carburetor itself which you couldn't discover without rebuilding it.

Good luck!
Joe

Omarine

The carter 2 bbl on my 52 cdv was running rich a few months ago and it wouldn't lean out even with screws all the way in.

Turned out float was so high, it was letting fuel spill into the venturi while idling. Corrected the float and that solved the issue....

Cheers
Oscar
1949 Harley Davidson FL
1952 Cadillac Coupe de Ville
1961 Chevy Impala 2 dr hardtop

Paul

Appreciate the thoughts on this. The carb is new. It's an edelbrock similar to the carter version. Works well. I will experiment with leaning the choke.
59 Caddy, Seminole Red with Dover White top

35-709

New carb --- could very well the jets need to be a little smaller.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

bctexas

Hi Paul,

My '65 CDV came to me with an Edelbrock 1406.  The 429 ran pretty well overall, but at cruise it had a subtle twitch.  I picked up a tuning kit from Edelbrock, and switched the metering rods to 1 step richer.  Cleared it right up - the car now runs great.  The metering rods and jets can be changed with the carb on the car in just a few minutes.  Edelbrock also has clear instructions as to which parts cause the mixture to change in which direction and how much.  With a bit of fiddling I suspect you can make it run well, assuming a healthy engine and ignition.

Happy Motoring!
1965 CDV
1970 SDV