Get your real service manual for your car and also get the another manual for your souped up engine too so you can get everything to work together nicely.
To stop those ick, you have to go all out cleaning rest of fuel system. 🙁 I used fuel injection filter from a truck with nipples for the rubber hose clamps on my caravan. Stopped the black dust getting into my carb.
Please, ever, do NOT drive with choke on all the time! This washes out the engine and ruins the oil rapidly, and rapid wear. Choke is only for helping with engine warm up stage so fix that so it is now automatic. I did that too and made my caravan so fun to drive and easy start when cold. Tap the accelerator pedal then Just a bump on the starter key fires up.
Spluttering on acceleration is your accelerator fuel pump system not working right. Should squirt stream of fuel into throats every time you turn the throttle shaft, every time. Blame on air being so easy to compress and expand with vacuum.
Every time the throttle opens from anywhere to there, the intake manifold below the throttle plate has volume of air under some vacuum then air rushes in sudden and carb is slow to respond. Every time that throttle opens, carb cannot keep up with sudden lean condition, hence the need for accelerator fuel pump to fill in that opening transition or else the engine dies on lean out.
Make sure the timing is correct and done correctly according to manual. Not your toilet paper hayes. 😀
If you are not able to drive at cruise means ignition timing is wrong, look at your computer's manifold vacuum rather well to make sure everything is connected correctly and no leaks. If your car uses mechanical distributor with vacuum advance, make sure this works by opening the throttle slowly, the advance diaphragm on distributor should pull in, then release as throttle opens more. When you are at cruise, the vacuum advance should be full. This is most leanest condition for best MPG or 100km/L requires advanced timing. There is only one port in correct location on the throttle throat where throttle blade partially open edge lines up to this tiny round port leads directly to the nipple that connects directly only to the ignition advance diaphragam. Only! Service manual will help with you on this.
Do NOT forget the EGR valve! Replace this too. Also another couple leaks to check can mess up with fuel air mixture too. That also come in play at cruise too and helps with emissions that lean fuel air mixture cruise presents.
On my caravan, had computer controlled ignition only based on 4 pulses per turn from distributor's hall effect and used manifold vacuum reading direct to the computer's transductor sensor, sounds crude but very very good system and darned simple and reliable.
Service manual will always say this way in same steps like my service manual did for any cars with carb and mechanical distributor:
1. Adjust and setup the carb's functions on bench: Choke adjustment, float height, etc. Important!
2. Diagnose your ignition advance vacuum circuit are all correct, you must keep emissions systems in place! (I only dumped partial part of the emissions stuff due to carb not correct one), Including correct PCV! Not from NAPA, get it from your dealer! I had trouble with this before and had to go this way. This is a controlled leak on purpose and computer or carb, etc expects this and really depends on.
3. Once done. Warm up the engine and adjust fuel/air mixture screw for strongest manifold vacuum and then dial in idle rpm when hot. Also ignition timing interacts so recheck this.
Oh, don't forget to make sure your brake booster holds vacuum as this is HUGE leak if it loses it's vacuum integrity even brake applied.
What I dumped was air pump, throttle opening solenoid or vacuum operated circuit this leans out the carb by keeping throttle open on deceleration as computer was partially confused by the weber.
If you have different design for deceleration system that still works, put it back on diagnose and repair, this prevents transitory rich condition on deceleration and emissions tests checks for this too. Engine is an air pump, when engine is still spinning at high rpm and throttle closes is much higher vacuum than idle vacuum will pull more fuel in.
Cheers,
Great Northern aka Canada.
