carb way too rich

[charlie's 68-6]

i have a 68 mustang coupe with a 200 stock internals, patriot headers 2.25 pipes all the way with an h and mufflershop turbo's.carb is a carter mfg.for motorcraft one barrel. i made an adapter to turn the carb so the throttle tips in to the intake instead of across it. after the engine warms up it starts to miss and load up.if i back the mixture screw out about three turns the idle goes up to about 11or 12 hundred rpm.way too fast.but the engine smoothes out.with the mixture screw set at one and a half to two turns out idle is about 8 to 900 rpm. but rough and very rich. timing is 14 degrees static with the advance backed out to bring it all in sooner. carb is a new rebuilt from national carburetors their catalog says it is for a 200 or 250.i can't afford to buy another carb right now. how can i make this one work better? thanks for any and all hints and help.
charlie
charlie's 68-6

 

[CZLN6]

Howdy Charlie:

What distributor/ignition are you using? Have you checked for vacuum leaks? Have you verified that your timing mark is accurate? Did this carb ever work right? What did you use before this "rebuilt"? What was on the engine the last time it ran right?

Sorry for all the questions, but as with all engine problems, the devil is in the details..

Adios, David

 

[jamyers]

offhand, the idle mixture screw should usually lean the mixture as its screwed in, and richen it as it's backed out.

 

[JackFish]

Check the float level.

 

[63RancheroGuy]

How can you check to see if your timing mark is accurate?

 

[69.5Mav]

63RancheroGuy

Checking the timing mark, there are a number of ways to do it, some have a preferred way, but they all come down to bringing the number one piston up to top dead center and checking the alignment of the timing marks.

Some stores sell a top dead center checker that screws into the spark plug hole. Others use a srew driver or piece of rope to check, some look in the cylider to see the piston. You can use a bore scope to do it.

What ever way you chose use cation to not damage the cylinder or piston.

 

[63RancheroGuy]

So...my naivetee will show, but you've got a 50% chance of being at the top of the exhaust stroke versus the compression stroke. So you may have to crank it another full 180 degrees to get it to the right spot. What's the easiest way to go about cranking it to the right spot? I've got a manual tranny, should I put it in 1st or 4th and push it (my brain is not figuring out which would be best)? Park it on a hill and let roll backwards slowly in gear while somebody watches the #1 cylinder? I don't know...

Thanks for the help.

Adam

 

[ludwig]

Take all the plugs out and remove the fan belt so that the crankshaft turns easier. I use a ratchet wrench with socket on the bolt securing the damper/balancer. Some guys don't like that, saying it will shear off the head of the bolt. I never had any problem with that but maybe you can turn it by hand.

Anyway, from the driver side of the car, stick your right finger into the first plug hole so that it seals the hole. Turn the crank clockwise with the ratchet in your left hand until you feel pressure building around your finger. That is the compression stroke. Next, back the crank off a bit and insert a screwdriver into the hole. You can use a screwdriver or a thin dowel rod or a piece of stiff wire. Some guys do a bit of black magic with a rope. I never understood how that works. Anyway, turn the crank clockwise again until the rod or whatever starts to rise and then stop when it stops rising. That is TDC.

Look down at the indicator next to the balancer and see if the TDC mark lines up with the slot/notch/line on the outside of the damper/balancer (same thing). If it does not, mark a new one with light colored paint. I used a white dry marker.

There is your official TDC on the compression stroke. Put all the stuff back on and fire it up. Now you can adjust the advance accurately with your light.

 

[JackFish]

The easiest way is to buy a remote start switch and use that to bump the engine over.

 

[ludwig]

Also good. I've never hit my numbers that way. Power to ya.

 

[69.5Mav]

50% chance of being at the top of the exhaust stroke versus the compression stroke

It dose not matter for checking the timing marks. The marks will line up twice per cam rotation. As long as they line up when the piston is at top dead center it's okay.

However when installing the distributor it matters a great deal.

one and a half to two turns out idle is about 8 to 900 rpm. but rough and very rich

Any Progress?