Big CJ fuel issue..

[brandymb]

Hello all, I have a problem with my '75 CJ5 . It has been running very rich for some time. It is a CJ5 with a AMC 304 , just rebuilt. RV cam, Edebrock 1406 carb, HEI distributor. Timing is about 10 degrees, carb was right out of the box. Starts up fine in the morning, but after it sits a while, it turns over a long time then starts with black exhaust smoke like it's been flooded. Gets 10mpg if Im lucky. I experimented with everything I can think of to no avail. It ran similarly with the Carter AFB carb that was on it prior, which was why I installed the 1406. I lowered the floats thinking it may be flooding due to that. The fuel pump is the original stock pump. If anyone has any ideas, I'd sure like to hear them. Thanks much..
Mark

 

[Old Dog]

what size (cfm) carb do you have? (both old and new)
It's confusing when you say it runs rich with both the old and new carb.
Does it run rich all the time or only at idle

 

[brandymb]

Both carbs were 600's. Seems to run rich all the time as it uses a LOT of gas, and the exhaust tips are black inside and so is under the choke on the carb. As I said, the engine now is new, has about 120 miles on it. Did this before and after rebuild. Also, the engine doesn't run smoothly. Almost seems like its running on 7 instead of 8, but Ive puled the plugs and wires one at a time and there is a big diff when one plug wire is off..

 

[Old Dog]

600 cfm is mighty big for a AMC 304 , should be more like 400-470 cfm. You might try some smaller primary jets and see what happens.
I would check the fuel pressure
make sure the air/fuel mix. screws are right
check the float
after that smaller jets or smaller carb.
All this asuming you have strong spark.

 

[73CJ]

Might want to play with the timing. 10deg might be OK for stock, but with a cam maybe more?