Rough Idle 340

[gregsgs@yahoo.com]

Just got a 70 cuda 340 it wasnt run very long over the last 5 years. I had the carb rebuilt and plugs wires cap new gas tank and all lines. It still idles very bad a little better at 1500-1800 and even misses at times. If i lower the idle a little it will stole but it will restart. On the highway it runs good but it all ways smells of fuel. The vacum is showing around 1450 - 1500. Does any one know were number 1 plug is on the cap. iam thinking maybe its off by one tooth. I checked the firing order and its right I see some oil around the distributor on the block if that means any thing. Any help would be GREATLY appreciated.

 

[C O D Y]

What's the timing set at?

 

[moparleo]

I am going to assume that everything up top is stock. A cast iron factory 4 barrel manifold and Carter carberator, no spacers, or adapters. To check for a vacuum leak quickly, start the engine without the aircleaner installed. While it idles, with your hands, slowly cover the top of the airhorn, if the idle improves and is smoother, you have an intake leak somewhere. It is very hard to be one tooth off on the initial timing as the Mopar ignition system does not have the cam drive teeth on the distributor, only a straight, like a standard screw driver blade on the bottom. So unless the distributor and oil pump drive have been removed, the timing is either right or 180 off. Number one can actually be any where you put it as long as the rotor points to the tower on the cap that alignes with tdc on the crank. As far as oil near the distributor, the oil pressure sending unit is mounted on the same pad that the distributor is mounted to. May need a new sending unit or maybe just the manifold seal to the block and heads. You should degrease the area first and then when your car can idle , you can watch for the leak. Make sure to use high quality igniton parts. It came with Champion spark plugs. Check and set the gap with a proper wire gauge. Do not tap the electrode to close up the gap. It should be bent in to shape. The plugs use a washer, so make sure the old washer comes out and is not sticking to the head. 35 lbs torque. Use dielectric grease in the plugwire boots, makes removal easier in the future and seals against moisture. The rotor is the most important item to replace and I didn't see that in your description. Unless the carberator was flow tested when rebuilt you will have to adjust the air/fuel your self. If you use a vacuum gauge you must have the idle problem taken care of first. When adjusting your carb with a vacuum gauge you must make sure you use the proper vacuum source. You adjust to the highest, steady reading on your gauge, as close to 20lbs as possible. Let us know what happens.

 

[Chryco Psycho]

wow typed out a long response & it took to long & would not let me post it !!
It is all about tuning , you are not off by one tooth if it is running , the #1 wire can go anywhere on the cap as long as the wire is in the terminal the rotor is pointed to with the engine @ TDC firing stroke .
I would check the reluctor gap in the dist , it should be .008 , then check float level & idle mixture settings , you could have bad spark plug wires or plugs

 

[gregsgs@yahoo.com]

Thank you both I will get someone to check the timeing for me. The rotor is new and so are the plugs but i will recheck them for gap. The oil by the dist seems to be coming from were the dist goes into the block, is there a ring in there. I will try the thing with my hands over the carb and let you know. I dont know were or how to check the reluctor gap if you can tell me i will try that. Again thanks for the help.

 

[moparleo]

There is an o-ring near the top of the distributor housing that may be cracked/or missing. Since it a 1970 model, it should still have the point type of ignition unless it was upgraded to electronic. So if it is point type, it will require new points and condensor. Again, use quality parts, no generics. If it is still the standard type it would be much better to upgrade to electronic now. A factory conversion kit which will include a new distributor, cap, rotor, orange ecm box, and wiring harness adapter runs around $200.00 depending on where you buy it.

 

[gregsgs@yahoo.com]

The car has a electronic dist. I washed the engine down and cleaned around it and there is still oil coming around the dist were it meets the block. I tryed the hands over the carb air horn and the idle went down so I think thats a good sign. When the car idles you can see gas going into the carb like a lot of it. I took the plugs out and the gaps were good but they were all wet with fuel.

 

[moparleo]

If you can see fuel running into the carb when idling you might have the floats too high and need to reset them. What setup are you running, the stock carb and manifold ? Sounds like the oil leak is the distributor o-ring. Mark where the distributor position with an awl or something similar and loosen the hold down bolt and lift the didtributor up and check the rubber o-ring. If it is cracked, broke or missing you will need to replace it.

 

[Chryco Psycho]

Could be leaking under the rear of the intake also

 

[gregsgs@yahoo.com]

Leo the setup is all stock it has a AVC card with a standard manifold. The rebuilder is checking the carb to day, may be some durt may have gotten in. Tha car was using E84 gas all its life and he said that may have damaged the body of the carb and if so it can't be fixed. He said to put a new Edelbrock card 600 with electric choke and keep the original stock carb for resale. The retail price he said would be 400-500
with no core return. I changed the oil ring and that was it. let me know what you think of the carb idea.

 

[moparleo]

I am assuming that you meant Carter AVS carb. I use the Edelbrock Thunder Series AVS. I have used the Holleys and while they will put out more HP. I found them not to be user friendley if you don't like to fool with the carb all the time. The Edelbrock is very simple to adjust and will hold a tune longer. It is really preference, some have to have a Holley and some don't. The electric choke 650 cfm model is # 1806 . Ifd you have an a/t , you will need part# 1481 throttle adapter. I also use the fuel line adapter #8126 . An inline fuel filter is also available.
The basic carb runs about $350.- $400. Shop around
No matter what carb you use I cannot stress enough to use at least one, good fuel filter. Most carb problems trace back to debris in the fuel passages.

 

[Chryco Psycho]

I would choose a Proform 650 CFM over an Eddy Carb , at least usee a Thunder series AVS type Eddy if you have to use that type of carb