Carb Questions

[metallicaman0258]

I have a 1987 GF stock 318 Lean Burn Carter 2bbl. I was told at purchase that the carb had been cleaned and rebuilt and had less than 100 miles on it and it just "needed tuned"

Cold starts are crank for 3 seconds, 2 pumps, fire and hold 1500 (est rpm) for about 30 seconds before vehicle will idle on its own (at about 800 or so est).

Lean Burn carbs, in my experience, 2 pumps and then the automatic choke/idle does its thing and automatically calms down after 2 minutes or so depending on temperature. Mine does not. It also stumbles on take off (cold or hot) unless you roll very gently into the throttle until you feel the power come in then you can go all out. Also, unless the vehicle is up to almost operating temp, it will not drive on its own without "two footing" it then I still have the take off and stop issues even when fully warmed up.

Any suggestions oh wise knowers of the Carbasaurus?

 

[metallicaman0258]

It feels like to me the float level is too low and it wants to lean out. I'm thinking also the base idle mixture is off a touch. I know how to adjust idle mixture with the screws at the base or the carb but how does one tune these things?

 

[Darth-Car]

It needs the choke adjusted. You are not getting any choke assist at start up, which is causing your issues. You should not need to mess with the mixture screws. Usually they have plugs over them to keep you from tampering with their adjustment.

 

[Master M]

It feels like to me the float level is too low and it wants to lean out. I'm thinking also the base idle mixture is off a touch. I know how to adjust idle mixture with the screws at the base or the carb but how does one tune these things?

I'm with Darth-Car in making sure you have the choke working properly first. How confident are you the carb was rebuilt by someone competent ? Someone saying they just rebuilt the carb and now it needs to be tuned, could make you think they shouldn't be rebuilding a carb if they can't adjust it. FWIW I would rebuild the carb ( or have it rebuilt ) just to make sure it is done properly. You say it also stumbles when hot which shouldn't be the choke, if it is not closing when cold. Could be more than 1 thing going on.

 

[Jack Meoff]

I also agree.
Sounds like your carb is out of whack.
When it's cold pull the air cleaner lid off. Pump the gas and you should see the choke plate snap closed. Then it'll gradually start to open as the car warms up. Carburetors are funny little beasts. If it was "rebuilt" by a guy who doesn't know what he's doing you've got instant issues. You'd be amazed at how many people don't know how to correctly.

 

[metallicaman0258]

...If it was "rebuilt" by a guy who doesn't know what he's doing you've got instant issues. You'd be amazed at how many people don't know how to correctly.

Considering this guy was my age I wouldn't doubt it.

How does one adjust the choke on this carb? it doesnt have the round electric choke on the side like my old Motocraft 2150. This Carter has a wire going into the intake where a rod comes up and attaches to the linkage. There is a stepped cam on the other side of the carb that I have played with and have had minimal success.

Also toyed with the idea of going to a Holly XP series 2bbl to retain the LB and get a more modern (and infinitely adjustable) carb. Or would I just be better off getting an aluminum intake and 4bbl? Then again if I did that I would need to go to a conventional spark such as a 6AL or Mopar orange box and double pickup distributor right? I'm beginning to rant, one thing at a time. I'm going to shop rebuild places...

 

[metallicaman0258]

It needs the choke adjusted. You are not getting any choke assist at start up, which is causing your issues. You should not need to mess with the mixture screws. Usually they have plugs over them to keep you from tampering with their adjustment.

The plugs were removed by the PO. I used the supplied special tool to adjust the base mixture to 1.5 turns out from seat just to have a "good enough to figure out the rest" setting.

 

[metallicaman0258]

Also, could this be timing related too? I had these problems before I installed the new distributor but it seems worse now than it was. It is also considerably colder so the winter may have something to do with it too.

 

[Jack Meoff]

On my stock Fifth I do the timing by feel. Warm it up. Get it idling and dial in the sweet spot. Keep in mind though that if the carb isn't right that's a moot point.

 

[Mr C]

How's the rest of your ignition? My 5th Ave displayed similar bogging. I did a tune up (cap, rotor, plugs, wires) and the stumble is gone. Never touched the carb. I offer this as a possible solution.

 

[Jack Meoff]

How's the rest of your ignition? My 5th Ave displayed similar bogging. I did a tune up (cap, rotor, plugs, wires) and the stumble is gone. Never touched the carb. I offer this as a possible solution.

I was going to ask if you've done a full tune up like Mr C just described? If not that's your first order of business. I had the same results with my Fifth after a full tune up. Never touched my carb either.

 

[Monkeyed]

check your vacuum lines while you're at it. Also, just because he said it had been "cleaned" that could just mean he sprayed carb cleaner all over the outside of it and got all the dirt off when he rebuilt it which does 0 for varnish on jets.

 

[metallicaman0258]

Its been busy around here lately. Sorry I haven't been on much

On my stock Fifth I do the timing by feel. Warm it up. Get it idling and dial in the sweet spot. Keep in mind though that if the carb isn't right that's a moot point.

Just did the timing on Thursday set at 8 BTDC with a light

How's the rest of your ignition? My 5th Ave displayed similar bogging. I did a tune up (cap, rotor, plugs, wires) and the stumble is gone. Never touched the carb. I offer this as a possible solution.

When I had the LB computer debacle in November (thanks again Cap'n) I did a full tune up and new distributor.

check your vacuum lines while you're at it. Also, just because he said it had been "cleaned" that could just mean he sprayed carb cleaner all over the outside of it and got all the dirt off when he rebuilt it which does 0 for varnish on jets.

Changed all vacuum lines (still present after the smog pump was removed by PO) and the PO said he disassembled and rebuilt the carb. The validity of that statement has gone unchecked. Supposedly his dad is a good mechanic and has rebuilt dozens of these things but we all know how that is.

 

[metallicaman0258]

i need to find a good carb rebuilder guy

 

[Grandmas84]

Rebuilding a carb is easier than you think. The rebuild kit cost like 20$ and comes with directions.

 

[Grandmas84]

Or if you wanna spend a little more. I have an entire lean burn setup i removed from my perfectly running 84 fifth ave. 50$ if you pay shipping.

 

[metallicaman0258]

Or if you wanna spend a little more. I have an entire lean burn setup i removed from my perfectly running 84 fifth ave. 50$ if you pay shipping.

Because of the relative expense of the computer alone I may do that. My extra $$ has been taken down by an elite task force determined to keep me in a running vehicle. If you still have it in a month or so I will buy it form you but by no means hold it for me.

 

[Grandmas84]

Because of the relative expense of the computer alone I may do that. My extra $$ has been taken down by an elite task force determined to keep me in a running vehicle. If you still have it in a month or so I will buy it form you but by no means hold it for me.

Ive been trying to sell it for awhile. Im sure ill still have it. Hit me up if you want it.

 

[metallicaman0258]

Right on. I appreciate that.