So I just got everything hooked up with my new (used) motor. 136k on it. It fired without an exhaust on it, and now it seems as if it doesn't like my exhaust. NO cats. NO emissions equipment. It will start with a pump of gas, and it will settle into a solid 1000rpm idle almost instantly, and then within 3-5 seconds it shuts off. If I try to give it any gas when it's running it dies instantly. I have spark. I have fuel. I have compression.

Primary Jets are shooting gas into the carb. Fuel level is halfway up the sight glasses. I have everything that should allow for combustion, and it will run, but just at idle. What gives?

-Jim

 

vacuum leak?

 

Nope. When it was idling I sprayed carb cleaner around the carb-block interface and all intake manifold block off plates and I didn't notice any difference in idle.

 

are you getting enough fuel to the carb? plugged fuel filter maybe? does the carb need rebuilt?

 

If bowl levels are still right after it stalls, it's probably not fuel delivery related, though it could still be a carb issue (like leaking accel pump circuit, fast idle setting, stuck-closed bowl vent etc.) Or it could be ignition rather than carb, like a leading ignitor that is thermalling out under load.

How much of the engine was replaced? Just the keg, or are you using an intake, carb, ignition electricals that came with it? More details of the surgery, please.

 

My first thought is that damned safety "feature" that will allow the pump to run while cranking, but will not keep it running unless it senses that you have spark on the trailing ignition system.

I suppose an easy way to check this is to see if the float bowls are empty after it stalls.

And hurry up! We've got racing next weekend!



.

 

Float bowls are still 1/2 full after the engine stalls.

I am using the dizzy and igniters that were in the engine when I bought it.

I am using the intake and carb from my old blown motor (ran just fine on the old motor). The accelerator pump is leaking, but it did that on the old motor too. I am planning on doing a carb rebuild, but only after I get the engine running and some initial break-in (so to speak...loosen up the seals and whatnot) miles on it.

I am using the cap and rotor from my old blown motor (good condition).

Spraying carb cleaner down the carb when the motor is running causes the engine speed to increase, but only if I'm on the throttle.

I do have tach signal, so my trailing igniter works, however I am not sure that I'm getting trailing spark.

I'll try putting on the igniters from my old dizzy and see if that helps.

 

I am starting a 2 week road trip for my internship on Sunday driving all over hell and gone in my Impala, so I won't be able to put on my new spindle and race next weekend. I will be in the GR area on the 11th and 12th, so after I'm done with my work for the day I'll probably come out and watch you guys race.

-Jim

 

Get out there early enough and you're welcome to race mine.

 

We'll see. What time do the races start?

 

So it turned out that the car was seriously out of time. We fixed the timing issue, and now I am trying to figure out why my choke won't work. I have the cable routed correctly, however when I pull on the choke, it doesn't actuate the choke. Pictures of carb coming soon.

It will run (and run well) if we manually hold the choke.

 

If it runs only under choke after reaching temperature, then it's mixed too lean.

When you say "actuate,' do you mean the butterfly doesn't move at all when you pull the ****, or that it won't stay pulled out unless you hold it?

Choke linkage is pretty simple; cable to one link to butterfly. Can't see too well in the attached pic, but it looks correct based on the parts you have installed.

 

I haven't gotten it warmed up to check it. The car ran fine with these exact carb settings (it's the same carb and intake) on my old engine.

The butterfly doesn't move at all when I pull on the choke **** in the car.

If you look at the picture with the red box in it (MS Paint FTW), focus on the interface between the "L" shaped piece in the middle of the box and the part it's touching. When I pull the choke, the "L" shaped piece pulls away from the interface, however the part it's touching is the part that is attached to the choke shaft. The "L" shaped piece, and thus the carb cable, doesn't actuate (turn) the choke shaft.

 

Another issue: I went through the idle tuning writeup on sterling's website, and now my engine won't stay running at all. I fire it up with the Idle Fuel screw @ 2.5 turns from stopped, and the idle air screw 2 turns from stopped (stopped = bottomed out) and start it. It'll run with the choke, but when I let off the choke, it immediately dies. If I try and give it ANY throttle, it chokes off and dies.

When it would idle, I checked with carb cleaner for vacuum leaks. Sprayed the hell out of everywhere around the intake manifold and carb base, and didn't get any change in engine speed, so I have a system that is devoid of vacuum leaks.

-Jim

What are your Nikki idle air and idle fuel mixture screws set at?

 

for the choke: the part that has the coil spring in it needs to be put back on the carb, otherwise u'll need to wire/weld the area in the red box.

 

That's what I thought. I zip-tied it for the moment. I'll install that part when I get home from my 2 week work road trip.

 

Yes, OK, now I can see - your thermo unit is missing. Without the thermostat spring to hold the butterfly lever against the arm, the choke won't close. Rxtasy FTW.

 

Any ideas on this post?

 

Well, until you can run it long enough to get it up to operating temperature, your idle settings really can't get refined. When the carb's on choke, it's not using just the idle circuit to control the mix.

If you cant put the thermo unit back on, try wiring the choke butterfly to the choke arm, so you can keep the car choked long enough to get it warm. Then you can sort the base idle out.

There's a sequence of circuits the carb uses as you advance the throttle off of idle - - idle, then transition, then mains, and the accel pump plays into covering that transition if the throttle opens rapidly.

But IMHE troubleshooting any of that on-car requires getting the engine up to operational temp.

When you had the carb off, did you meddle with your throttle initial opening at all? & are the secondaries tight closed at idle?

 

I had a vacuum leak on the hose off the back of the lower intake mani. i don't know exactly what it is off hand b/c at the time mine was plugged from removing my emissions long ago. The bottom of the hose that sits right above the header was cracked but the carb cleaner spray did not show a single sign of motor speed change. The only way I found the cracked hose was to take it off and visually inspect it via advice from the board here after checking a bunch of other things it could of been to no avail. Bottom line is I no longer trust the carb cleaner spray to tell me if theres a vacuum leak 100%. I used an entire can too.

 

That's the imfamous "mystery leak;" on SA's it's the brake booster hose that goes in that fashion.

My understanding is that on FB's that the hose that works the shutter valve that tends to burn, crack, and leak.

 

I did not change any of the settings when the carb was off of the car. That's why it was so strange when I put it on, that it would idle for ~5 seconds w/o any throttle, then shut off.

I did screw down both the idle fuel and idle speed screws and set them to Sterling's recommendations.

I have gotten the engine warm (now that I've zip-tied the choke actuator), and that hasn't helped keep it running.

I eliminated Anti-Afterburn Valve #2, so that hose is gone.

 

Jim, start by simply increasing the idle speed until you can get it to idle. Once you reach that point, then start tuning the idle mixture (just get it to where it runs smoothest). If that results in an increase in engine speed, then reduce the idle speed accordingle, then move back to the mixture screw again incase that has changed. keep repeating until you feel it is tuned finely enough.

Then check the timing.

P.S. Races usually start around 11am

 

So I've had the last 1.5 weeks to contemplate whats been going on with my engine. I put the plugs out of my old engine into my new engine. It flooded out once while I was trying to get it to start, and the plugs are quite black and carboned up. I'm going to pick up a new set of plugs and see if they help the issues.

 

Usually if it will start, but not stay running, then it isn't your ignition system. Starting the car is the hardest thing it has to do, sort of. But then again, new plugs certainly can't hurt.

You need to live closer...