We started with the ignition system, and somehow transitioned to the fuel system. So let me add that on my Motorcraft 4350 a manual choke conversion works a lot better than the auto choke ever did, especially starting.

 

Sorry for the delay responding. Here is a photo of the Edelbrock carb that came on the truck. Once it is warm the engine fires right up and right away. When it's cold, the starting sequence is a series of starts and stops until it decides to keep running. The funny thing is that the choke works perfectly, as you can see the choke plates closed off; they open as the engine warms up. I've circled the fast idle screw in yellow, as I understand this carb, which is accessible only by opening the linkage fully (i.e. the screw does not sit on top like the FoMoCo models I've adjusted in the past. So far I've cranked the screw down one turn at a time, when I think about it, and the fast idle has yet to present itself; maybe it's just a couple more full turns away(?).

 

Is the fast idle cam and linkage moving freely with the choke? It's on a slot I think and has to be able to move freely of the choke, to a degree. If it's all working right and you have no vacuum leaks, no reason it should ever die after starting.

 

A manual choke works good if you know how to use it correctly.

A Ford thermostatic "hot air" automatic choke works even better if it is set correctly.

Fully electric automatic chokes do *not* work as well.


Before you start your cold engine up the next time, take the air cleaner lid off so that you can observe the carburetor choke plate. Push the gas pedal all the way to the floor one time, and the choke plate should close completely. DO NOT PUMP THE GAS! As long as it was driven within 1 - 2 days, the engine should start right up.

Once the engine fires, the choke plate should immediately crack open about 1/8" of an inch. If it does that, the choke is working as it should and you need to adjust the fast idle speed so that it idles at about 1500 RPM. Without touching the gas, let the truck idle for a few seconds, and the RPMs should automatically start to creep up. Once it gets to about 1500 RPM, tap the gas pedal and the fast idle cam should drop down to the next step. It should now idle at about 1000 RPM. This is a more reasonable RPM for you to put the truck in gear and drive away. As the engine warms up more, the choke plate opens up more and the fast idle cam will automatically drop completely off. Then the curb idle speed will take over.


Capiche?

 

Have you check ignition timing? I had a hard time starting in the cold awhile back. It would start but only keep running if I held the gas a bit, then once warmed up I could let off. I thought it was a carb issue and no matter how much I adjusted the fast idle, nothing happened.
Then when I checked the ignition timing I found it was 10-15 retarded. I set it to 14 BTDC and now I have no issues. Coldest I've seen since then is 5F and it started right up.

 

I never found a manual choke conversion I liked better than a properly tuned automatic choke. The kits are generally janky junk and the first time someone doesn't hold the pedal down when pulling it, the notch on the fast idle cam jams it and it all moves the cable adjustment. At least take the fast idle cam and weld it up to a ramp instead of notches.

 

Again, sorry to be slow responding. Yes, this started as an ignition question who's motivation was starting / potentially carburetor based. Lariat, yes your comments match my experience; I really think the issue is that I don't have a fast-idle function as the carb is set up (again, it was a CA truck). The truck starts up right away when cold but then immediately dies. LB79, I haven't checked the timing. I'm sure it has an aftermarket cam and am unsure how having one will affect the timing - but something easy to do and I know how. I'll also check the linkage attached to the FI screw; I just need to make the time.

 

For what it's worth, there are other high-energy/spark distributors for the FE's. I'm running a procomp kit on my dad's 62 Galaxie w/ a mildly built 390. It still runs off 1 hot wire, though I've got it running through a CDI box. Here's a really old pic, when was in middle of mockup of parts... but it clears even a full size K&N airfilter.

 

This past month, off and on, I've been adjusting my fast idle screw and I've set it around 1,100 RPM to warm the engine. BUT, it's still "cold-blooded" in that it takes a half-dozen starts that don't stay started. So I assume the next step if I want to try and improve the condition, is to check my timing (but the engine arrived in my hands rebuilt and I assume from the power that there is some kind of cam installed) just to see where it's set. I've had a plug out before and they are burning clean. The cap and rotor seem fine and I'll check everything again this week. Would be nice to have an engine that started when cold easier, but the problem goes away when she's warmed up - so I'm just chasing perfection with a 40 year old truck with lots of not-year-correct parts and upgrades.

 

That is too low. That may be why your engine is "cold-blooded."

1,100 RPM is what you should get on the *second* step of the fast idle cam. Ford and every single aftermarket carburetor I have ever seen specifies a fast idle speed of at least 1500 RPM. Even my 1998 Jeep Wrangler with EFI will initially cold start at 1500 RPM for a few seconds. Set it there and see if that helps.

 

On my manual choke/throttle conversion, I disabled the original fast idle function. The manual choke allows for the fuel-air ratio the engine needs while the manual throttle allows for the fast idle the engine needs.

 

Thanks Lariat. The engine doesn't stay started long enough for the fast idle to even bring the engine up to any RPM. When I say it starts and stops, it's almost immediate the first time. Each time it starts, it stays running a millisecond longer (figuratively) until it starts and runs. Normally I feather the gas pedal just a scoch to keep it alive until I feel the fast idle will sustain. I've owned enough carbureted vehicles, including a CJ-7 that had three different carbs on it over the 16 years, and this is not what I'm used to but currently tolerating. Starts just fine once warm and I noticed that the more days I wait to drive it, the worse it acts. There is fuel in the clear filter just outside the carb, so I know there's gas and spark; I've not done a compression test, but the truck has GREAT power and didn't use a drop of oil over the first full year's oil change. What I haven't done yet: 1) determine that the spark plug is the proper temperature; 2) ensure the timing is correct (no overheating or pinging though...); 3) ???

 

Set the fast idle speed to 1500 RPM. That is where is it supposed to be to work correctly. The engine needs to run faster to burn the richer mixture provided by the choke. The fast idle cam and speed screw allows the engine to do this while the choke is on. Here is how you set it:

Get your engine up to full operating temperature, and then shut it off. Remove the air cleaner. With the engine OFF, take one hand and open the throttle a little, and with your other hand pull the fast idle cam down until the highest step (or "V" mark on Ford carburetors) is lined up with the fast idle screw. While holding it there, release the throttle. This will hold the fast idle cam in position and tricks the carburetor into fast idle mode. Then, start the engine again - but do not touch the gas! (Doing so will drop the fast idle cam back down and you will have to start over.) Now you simply turn the fast idle screw to the specified fast idle RPM. It is usually 1500 RPM. After the fast idle RPM is set, give the engine a little gas to bring it back down to normal curb idle speed. Curb idle should be set to about 600 RPM.


Does the choke plate snap shut when you press the gas on a cold engine? If it doesn't, you need to adjust the choke cap. The choke cap sets the tension on the choke plate and determines how long the choke stays on. Here is how you set it:

When the engine is cold, loosen the screws on the choke cap. Then, turn the choke cap counter-clockwise (to the left) until the choke plate just makes contact and fully closes against the air horn. You want just a little bit of tension here - but not too much. Make a note of the orientation of the choke cap by the little tick marks on the top of the cap compared to the marks on the choke housing. Usually, you will end up close to the index position on the choke cap or 1-2 marks in either direction. Tighten the screws on the choke cap.

Clockwise from this position (turning the choke cap to the right) is a leaner setting, which means the tension on the choke plate will be looser and the choke will open up sooner. Counter-clockwise (turning the choke cap to the left) is a richer setting, which means the tension on the choke plate will be tighter and choke will stay on longer.


That means you have a problem with the choke circuit. See above.

Even if you see fuel in the filter, a carburetor will still lose pressure after a few days. If your truck is driven daily, 1 pump should be all it takes. If it sits a few days, you have to prime the carburetor first: If it is 3 - 4 days, try 3 pumps before you start the engine. If it is a week, try 5 pumps before you start your engine. This is the procedure I follow with my own truck and it starts up on the first try every time.


How much vacuum is your truck producing?

 

You must do this.
It might not be the only problem (and might even be set perfectly already) but you gots to know.

This is a HUGE point in this discussion. What else has been done to the engine?
A bigger cam effects literally everything, from what timing your engine likes to how the carburetor needs to be jetted. To how the choke has to be adjusted too.

Is there any additional linkage or adjusting screw over on the other side, adjacent to the choke coil? I haven't fiddled with one in a long time, so can't remember how the Carters and Edelbrocks are set up

Back to the hard starting issue, what exhaust do you have on there now? With the cam change, is it headers and dual exhaust? Your problem could be as simple as the engine running too lean. Free breathing exhaust can have a major (or minor) effect on how things play together.
But you really have to play with the timing if you can. You may have to fight the distributor to twist it in the block like many of us do, but since it sounds like the engine has been worked on at some point, maybe you'll get lucky and the distributor won't be stuck in the block after all.
Making sure you have a good spark at the plugs is critical, but at least with the factory ignition you're off to a good start. Did you verify that you have a Duraspark with it's associated module in use? Yes, you should have had one from the factory, but I've seen PO's change them out to old points distributors because that's what they were comfortable with. Hard starting is a hallmark of an out of adjustment points type ignition, so it never hurts to check under the cap.
And proper advancing is critical as well.

So as you see there are still many things you have to check out to get to the bottom of this. What about a tune up? When was the last time the plugs and wires were changed? I think you said the plugs look good, so that's good. But it would not be the first time that a good looking plug was causing a misfire especially with a weakened ignition from an old tired coil, or failing pickup or points or condenser.

Good luck.

Paul

 

Pertronic has a nice product