Choke adjustments and Cheap Chinese carburetor WARNING

[LARIAT 85]

What part of SC? WE have crews working down there this month at severalplaces, Ladson, Marion, Lexington, N Charleston last month, Beaufort last month.

I'm all the way up I-77 at the VA line, but not far off I 74 where it splits and goes South separately. Mt Airy

Mt Airy? As in "Mayberry?" Say hello to Andy for me.

I am in Florence, SC.

Before I got started on this again recently, the truck would be warm (gauge and heat) but the choke would not come down to hot idle. So that's been my thing. Getting the choke system working from scratch.

It could be something as simple as a faulty choke cap. You can try the chinese choke cap and see if you get the same results. But I still think you need an electric assist choke cap to make the choke work more accurately.

 

 

[rcarlisle]

What part of SC? WE have crews working down there this month at severalplaces, Ladson, Marion, Lexington, N Charleston last month, Beaufort last month.

I'm all the way up I-77 at the VA line, but not far off I 74 where it splits and goes South separately. Mt Airy

Mt Airy? As in "Mayberry?" Say hello to Andy for me.

I am in Florence, SC.

Before I got started on this again recently, the truck would be warm (gauge and heat) but the choke would not come down to hot idle. So that's been my thing. Getting the choke system working from scratch.

It could be something as simple as a faulty choke cap. You can try the chinese choke cap and see if you get the same results. But I still think you need an electric assist choke cap to make the choke work more accurately.

 

Yes as in "mayberry" - ugh. Goober says HEY

The sales person I support is in Summerton - apparetnly when they go to "town", they go to Florence. We did a Gulf station in Marion last week. Had to go to the Sherwin Williams in Florence for paint. HAve done other stores in the past in Florence as well. If there was ever a Kangaroo store, you've seen my work. All in the past as they are owned by Circle K now.

The cap on the Autolite is the one that was on it when I bought it. I'm using the Autolite again since losing the screw. I put a hair dryer to the spring in the cap and it moves quickly when heat applied. I did consider putting the Chinese one wire cap on the Autolite, but would really not like to have to do that wire deal to the Alternator - no easy way to get my fat hiney down to the alternator. Pretty sure it was me turning the screw in teh white plastic thing in the wrong direction. Hope to get that adjusted this evening.

Can't find a screw that will thread back into the throttle shaft of the Chinese unit.

[rcarlisle]

First - shame on you for buying a chinese carburetor.

Second - you are supposed to set the high idle speed to 1600 RPM when the engine is HOT, like I said in one of your earlier posts. You do not want your engine to shoot up to 1600 RPM when it's started in the cold.

Third - if it is really cold, your choke should *not* come completely off - if at all - when you hit the gas too soon. As the engine builds up some heat and the choke spring relaxes a little, hitting the gas should bring it down to the next step of the carburetor, which should drop the idle speed down to about 1000 RPM. When your engine is at full operating temperature, your choke plate should be completely vertical with tension holding it open and your engine should be idling at curb idle speed.

Fourth - Provided it is set up correctly, a thermostatic choke will always work better than an all-electric choke.

Ford used supplementary heat to help the thermostatic choke open up completely and faster, and to stay open when the choke isn't really needed. In the 1960s, a heater hose was routed against the choke cap. In the 1970s and 1980s, an electric assist choke cap was used. You are using neither, and that is probably why your choke isn't opening up all the way. The only way to get it your choke plate completely vertical without the heater hose or electric assist choke cap in place is to make the choke really lean (very little tension), but then that means the choke isn't going to stay on long enough.

Replace your choke cap with an electric assist choke cap and hook that to the alternator and I bet your problem will go away.

Here is one I found for you:

https://www.ebay.com/itm/371957582173?epid=174779043&hash=item569a66495d:g:7YIAAOSwY3BZIb3i

https://forum.garysgaragemahal.com/file/n112643/Electric_Assist.gif

Ok, yesterday, I checked the vac pulloff. Document on here for a 1980 said right around 1/8" measured at front of choke plate. Did that. THen set the choke arm to the first step off high idle. Checked and adjusted the choke arm adjuster. Drove to get gas (~4 miles). Seemed to be stumbly right out of driveway, but got better by the stop sign 1/4 mile away. I had to tighten up the pulloff to get 1/8" and there is play in the plate. It ran better first thing a little more open (the old setting by eye). I may open that vac pull off a little more. 1/8" at front is not much opening of the choke plate.

At the gas station, I had to adjust on the choke arm adjuster to get the plate to drop to fully open.

I also put the choke arm on high idle and the rpm is at 1600 hot.

I'm not sure what the hot idle should be for a manual trans. 600 sounds good, but is that too low for proper lubrication? The sticker on core support is for an auto trans. It says 875 in Neutral? I need to take a pic of that for reference when away from truck.

This evening's cold start will be with no checks or adjustments. Just a cold start and see if it works properly.

[Gary Lewis]

First - shame on you for buying a chinese carburetor.

Second - you are supposed to set the high idle speed to 1600 RPM when the engine is HOT, like I said in one of your earlier posts. You do not want your engine to shoot up to 1600 RPM when it's started in the cold.

Third - if it is really cold, your choke should *not* come completely off - if at all - when you hit the gas too soon. As the engine builds up some heat and the choke spring relaxes a little, hitting the gas should bring it down to the next step of the carburetor, which should drop the idle speed down to about 1000 RPM. When your engine is at full operating temperature, your choke plate should be completely vertical with tension holding it open and your engine should be idling at curb idle speed.

Fourth - Provided it is set up correctly, a thermostatic choke will always work better than an all-electric choke.

Ford used supplementary heat to help the thermostatic choke open up completely and faster, and to stay open when the choke isn't really needed. In the 1960s, a heater hose was routed against the choke cap. In the 1970s and 1980s, an electric assist choke cap was used. You are using neither, and that is probably why your choke isn't opening up all the way. The only way to get it your choke plate completely vertical without the heater hose or electric assist choke cap in place is to make the choke really lean (very little tension), but then that means the choke isn't going to stay on long enough.

Replace your choke cap with an electric assist choke cap and hook that to the alternator and I bet your problem will go away.

Here is one I found for you:

https://www.ebay.com/itm/371957582173?epid=174779043&hash=item569a66495d:g:7YIAAOSwY3BZIb3i

https://forum.garysgaragemahal.com/file/n112643/Electric_Assist.gif

Ok, yesterday, I checked the vac pulloff. Document on here for a 1980 said right around 1/8" measured at front of choke plate. Did that. THen set the choke arm to the first step off high idle. Checked and adjusted the choke arm adjuster. Drove to get gas (~4 miles). Seemed to be stumbly right out of driveway, but got better by the stop sign 1/4 mile away. I had to tighten up the pulloff to get 1/8" and there is play in the plate. It ran better first thing a little more open (the old setting by eye). I may open that vac pull off a little more. 1/8" at front is not much opening of the choke plate.

At the gas station, I had to adjust on the choke arm adjuster to get the plate to drop to fully open.

I also put the choke arm on high idle and the rpm is at 1600 hot.

I'm not sure what the hot idle should be for a manual trans. 600 sounds good, but is that too low for proper lubrication? The sticker on core support is for an auto trans. It says 875 in Neutral? I need to take a pic of that for reference when away from truck.

This evening's cold start will be with no checks or adjustments. Just a cold start and see if it works properly.

I think 550 - 600 RPM hot is a good idle speed. There's nothing magical about it, and there should be plenty of oil flowing at any speed for good lubrication After all, the engine is just ticking over and not pulling a load.

On the choke pull off measurement, or any of the other adjustments, my thinking is that the factory specs are a good starting point. But I usually adjust things a bit more after setting up a carb to the factory specs, and then when I rebuild the carb I don't change anything. Each carb and each application are slightly different and once you get it "right" then there's no need to change it back.

[rcarlisle]

I think 550 - 600 RPM hot is a good idle speed. There's nothing magical about it, and there should be plenty of oil flowing at any speed for good lubrication After all, the engine is just ticking over and not pulling a load.

On the choke pull off measurement, or any of the other adjustments, my thinking is that the factory specs are a good starting point. But I usually adjust things a bit more after setting up a carb to the factory specs, and then when I rebuild the carb I don't change anything. Each carb and each application are slightly different and once you get it "right" then there's no need to change it back.

Thanks. I agree that on a 40 year old truck, factory settings are a starting point. I tried the smaller opening, but it was working well before the adjustment and I think I'll go back. But I am trying everything to make it best possible. And getting closer and closer.

As for idle speed, I ask because.... Harley guys want that slow slow slow idle. And that kinda works on a harley. But the other cruiser brands want that slow idle, but the oiling system doesn't work under like 600 or something. Just didn't want to hurt the engine with too low Idle speed. But any hot idle under 1200 is making me happier these days.

I *think* the previous tuners of this engine had the fuel just opened up on hot idle til it would start and run with no choke. LOTS of idle screw fuel. So now we're getting it refined. Come warmer weather, going to remove plugs and probably replace or at least clean them really well if they look ok. Engine doesn't have that many miles since install, so they may be okay, but all the carb adjustments may have them feeling a bit rich?

This year won't be so much replace and fix up so much as getting what I have refined and working properly and better.

[LARIAT 85]

First - shame on you for buying a chinese carburetor.

Second - you are supposed to set the high idle speed to 1600 RPM when the engine is HOT, like I said in one of your earlier posts. You do not want your engine to shoot up to 1600 RPM when it's started in the cold.

Third - if it is really cold, your choke should *not* come completely off - if at all - when you hit the gas too soon. As the engine builds up some heat and the choke spring relaxes a little, hitting the gas should bring it down to the next step of the carburetor, which should drop the idle speed down to about 1000 RPM. When your engine is at full operating temperature, your choke plate should be completely vertical with tension holding it open and your engine should be idling at curb idle speed.

Fourth - Provided it is set up correctly, a thermostatic choke will always work better than an all-electric choke.

Ford used supplementary heat to help the thermostatic choke open up completely and faster, and to stay open when the choke isn't really needed. In the 1960s, a heater hose was routed against the choke cap. In the 1970s and 1980s, an electric assist choke cap was used. You are using neither, and that is probably why your choke isn't opening up all the way. The only way to get it your choke plate completely vertical without the heater hose or electric assist choke cap in place is to make the choke really lean (very little tension), but then that means the choke isn't going to stay on long enough.

Replace your choke cap with an electric assist choke cap and hook that to the alternator and I bet your problem will go away.

Here is one I found for you:

https://www.ebay.com/itm/371957582173?epid=174779043&hash=item569a66495d:g:7YIAAOSwY3BZIb3i

https://forum.garysgaragemahal.com/file/n112643/Electric_Assist.gif

Ok, yesterday, I checked the vac pulloff. Document on here for a 1980 said right around 1/8" measured at front of choke plate. Did that. THen set the choke arm to the first step off high idle. Checked and adjusted the choke arm adjuster. Drove to get gas (~4 miles). Seemed to be stumbly right out of driveway, but got better by the stop sign 1/4 mile away. I had to tighten up the pulloff to get 1/8" and there is play in the plate. It ran better first thing a little more open (the old setting by eye). I may open that vac pull off a little more. 1/8" at front is not much opening of the choke plate.

At the gas station, I had to adjust on the choke arm adjuster to get the plate to drop to fully open.

I also put the choke arm on high idle and the rpm is at 1600 hot.

I'm not sure what the hot idle should be for a manual trans. 600 sounds good, but is that too low for proper lubrication? The sticker on core support is for an auto trans. It says 875 in Neutral? I need to take a pic of that for reference when away from truck.

This evening's cold start will be with no checks or adjustments. Just a cold start and see if it works properly.

I am not sure I understand what you mean by the 1/8" measurement on the choke plate. Is that the gap when you first set the choke? If so, that may be your problem. On my Autolite 4100, my choke plate snaps completely shut (less tension when temperatures are warm, more tension when temperatures are cold) when I first set the choke/prime the carburetor for the first cold start. Then when the engine fires up, the choke plate immediately cracks open about 1/8" and gradually opens up from there until the choke comes completely off.

For example:

I drove my truck last week when it got down to the 30s. It was the first drive of the day, and I had driven it the day before. I get in, and step on the gas pedal once to set the choke and get a shot of gas down the intake. Because of the cold weather, I can actually hear my choke plate snap shut. It has a bit of tension holding it tightly closed against the air horn. The throttle is now set on the highest step of the fast idle cam. I key the engine, and it quickly fires up and starts [fast] idling at about 1250 RPM. The choke plate cracks open about 1/8" as soon as the engine fires up.

Since it is so cold outside, the spring in the choke cap is tightly wound up. So if I were to stab the gas pedal before enough heat has been generated from the engine, the fast idle cam would not drop down and the idle speed would not reduce. But that's not a problem. If I wanted to drive away right then, the load of the automatic transmission would drop the [fast] engine idle speed down to about 1000 RPM, which is enough to keep it running smoothly.

But since I care so much for Lucille and I wasn't in any particular hurry, I let the engine idle for about 30 seconds - just like I do with my fuel injected vehicles when it's that cold. As the engine begins to build up some heat, the RPMs will slowly start increasing. When it gets up to about 1600 RPM (hot fast idle setting), I give the throttle a quick but gentle stab. By this point, the spring in the choke cap has relaxed enough to drop the fast idle cam down to the second step. In turn, this drops the [fast] engine idle speed down to 1000 RPM. But that's not a problem. If I wanted to drive away right then, the load of the automatic transmission would drop the [fast] engine idle speed down to about 750 RPM, which is enough to keep it running smoothly.

This is a good time to drive away and let the automatic choke open up the rest of the way gradually. Again, your engine will get up to full operating temperature faster in 2 miles of [conservative] driving than it would if you let it sit and idle for 15 minutes. And that is actually better for your engine than letting it sit there and idle.

If I choose to sit there a bit longer, the engine speed will begin to rise again. When it gets up to about 1600 RPM (hot fast idle setting), I give the the throttle a quick but gentle stab again. By this point, the spring in the choke cap has relaxed even more to drop the fast idle cam completely off the throttle. In turn, this drops the engine idle speed down to 750 RPM, which is my curb idle speed in PARK. If I wanted to drive away right then, the load of the automatic transmission would drop the engine idle speed down to about 500 RPM, which is enough to keep it running smoothly.

Capiche?

 

[rcarlisle]

I am not sure I understand what you mean by the 1/8" measurement on the choke plate. Is that the gap when you first set the choke? If so, that may be your problem. On my Autolite 4100, my choke plate snaps completely shut (less tension when temperatures are warm, more tension when temperatures are cold) when I first set the choke/prime the carburetor for the first cold start. Then when the engine fires up, the choke plate immediately cracks open about 1/8" and gradually opens up from there until the choke comes completely off.

For example:

I drove my truck last week when it got down to the 30s. It was the first drive of the day, and I had driven it the day before. I get in, and step on the gas pedal once to set the choke and get a shot of gas down the intake. Because of the cold weather, I can actually hear my choke plate snap shut. It has a bit of tension holding it tightly closed against the air horn. The throttle is now set on the highest step of the fast idle cam. I key the engine, and it quickly fires up and starts [fast] idling at about 1250 RPM. The choke plate cracks open about 1/8" as soon as the engine fires up.

Since it is so cold outside, the spring in the choke cap is tightly wound up. So if I were to stab the gas pedal before enough heat has been generated from the engine, the fast idle cam would not drop down and the idle speed would not reduce. But that's not a problem. If I wanted to drive away right then, the load of the automatic transmission would drop the [fast] engine idle speed down to about 1000 RPM, which is enough to keep it running smoothly.

But since I care so much for Lucille and I wasn't in any particular hurry, I let the engine idle for about 30 seconds - just like I do with my fuel injected vehicles when it's that cold. As the engine begins to build up some heat, the RPMs will slowly start increasing. When it gets up to about 1600 RPM (hot fast idle setting), I give the throttle a quick but gentle stab. By this point, the spring in the choke cap has relaxed enough to drop the fast idle cam down to the second step. In turn, this drops the [fast] engine idle speed down to 1000 RPM. But that's not a problem. If I wanted to drive away right then, the load of the automatic transmission would drop the [fast] engine idle speed down to about 750 RPM, which is enough to keep it running smoothly.

This is a good time to drive away and let the automatic choke open up the rest of the way gradually. Again, your engine will get up to full operating temperature faster in 2 miles of [conservative] driving than it would if you let it sit and idle for 15 minutes. And that is actually better for your engine than letting it sit there and idle.

If I choose to sit there a bit longer, the engine speed will begin to rise again. When it gets up to about 1600 RPM (hot fast idle setting), I give the the throttle a quick but gentle stab again. By this point, the spring in the choke cap has relaxed even more to drop the fast idle cam completely off the throttle. In turn, this drops the engine idle speed down to 750 RPM, which is my curb idle speed in PARK. If I wanted to drive away right then, the load of the automatic transmission would drop the engine idle speed down to about 500 RPM, which is enough to keep it running smoothly.

Capiche?

You got it perfectly. That is what I would like to get tom if I can get it all adjusted correctly.

The 1/8" measurement is exactly what you said. We're on the same page.

[rcarlisle]

I am not sure I understand what you mean by the 1/8" measurement on the choke plate. Is that the gap when you first set the choke? If so, that may be your problem. On my Autolite 4100, my choke plate snaps completely shut (less tension when temperatures are warm, more tension when temperatures are cold) when I first set the choke/prime the carburetor for the first cold start. Then when the engine fires up, the choke plate immediately cracks open about 1/8" and gradually opens up from there until the choke comes completely off.

For example:

I drove my truck last week when it got down to the 30s. It was the first drive of the day, and I had driven it the day before. I get in, and step on the gas pedal once to set the choke and get a shot of gas down the intake. Because of the cold weather, I can actually hear my choke plate snap shut. It has a bit of tension holding it tightly closed against the air horn. The throttle is now set on the highest step of the fast idle cam. I key the engine, and it quickly fires up and starts [fast] idling at about 1250 RPM. The choke plate cracks open about 1/8" as soon as the engine fires up.

Since it is so cold outside, the spring in the choke cap is tightly wound up. So if I were to stab the gas pedal before enough heat has been generated from the engine, the fast idle cam would not drop down and the idle speed would not reduce. But that's not a problem. If I wanted to drive away right then, the load of the automatic transmission would drop the [fast] engine idle speed down to about 1000 RPM, which is enough to keep it running smoothly.

But since I care so much for Lucille and I wasn't in any particular hurry, I let the engine idle for about 30 seconds - just like I do with my fuel injected vehicles when it's that cold. As the engine begins to build up some heat, the RPMs will slowly start increasing. When it gets up to about 1600 RPM (hot fast idle setting), I give the throttle a quick but gentle stab. By this point, the spring in the choke cap has relaxed enough to drop the fast idle cam down to the second step. In turn, this drops the [fast] engine idle speed down to 1000 RPM. But that's not a problem. If I wanted to drive away right then, the load of the automatic transmission would drop the [fast] engine idle speed down to about 750 RPM, which is enough to keep it running smoothly.

This is a good time to drive away and let the automatic choke open up the rest of the way gradually. Again, your engine will get up to full operating temperature faster in 2 miles of [conservative] driving than it would if you let it sit and idle for 15 minutes. And that is actually better for your engine than letting it sit there and idle.

If I choose to sit there a bit longer, the engine speed will begin to rise again. When it gets up to about 1600 RPM (hot fast idle setting), I give the the throttle a quick but gentle stab again. By this point, the spring in the choke cap has relaxed even more to drop the fast idle cam completely off the throttle. In turn, this drops the engine idle speed down to 750 RPM, which is my curb idle speed in PARK. If I wanted to drive away right then, the load of the automatic transmission would drop the engine idle speed down to about 500 RPM, which is enough to keep it running smoothly.

Capiche?

Ok, Lariat, Help me out here. Or anyone.

Drive truck last night - no adjustments whatever. Choke did all it was supposed to do EXCEPT that last step to hot idle. The choke plates were still partially closed and the high idle was on the last step of high idle cam. I went to check it, touched the linkage on choke side lightly, and it dropped to hot idle and choke vertical. So I need just a touch more heat in there?

Do you guys think I could put that metal plate in front of the choke housing? To reduce cool air from front of engine. The choke housing might read hot enough to let it open fully. I'm also considering trying to get the hot air tube in contact with the exhaust manifold to put more heat into the tube going to carb. If I can bend it over to be in contact, might be able to run a hose clamp around it all.

I don't want to loosen the choke cap any more at this time of year. Not sure if there is anything else short of electric assist choke or full electric. And I need less than 12v switched for an electric assist cap, right? Not full 12v?

I feel like I'm dangerously close to having it working right.

 

[Gary Lewis]

Ok, Lariat, Help me out here. Or anyone.

Drive truck last night - no adjustments whatever. Choke did all it was supposed to do EXCEPT that last step to hot idle. The choke plates were still partially closed and the high idle was on the last step of high idle cam. I went to check it, touched the linkage on choke side lightly, and it dropped to hot idle and choke vertical. So I need just a touch more heat in there?

Do you guys think I could put that metal plate in front of the choke housing? To reduce cool air from front of engine. The choke housing might read hot enough to let it open fully. I'm also considering trying to get the hot air tube in contact with the exhaust manifold to put more heat into the tube going to carb. If I can bend it over to be in contact, might be able to run a hose clamp around it all.

I don't want to loosen the choke cap any more at this time of year. Not sure if there is anything else short of electric assist choke or full electric. And I need less than 12v switched for an electric assist cap, right? Not full 12v?

I feel like I'm dangerously close to having it working right.

My first thought was to back off the choke cap one notch. I think that will open it up fully and drop the fast idle. And if it doesn't you can put it back where it was.

As for the electric assist, it does use the 7v off the alternator. And the 1981 factory shop manual says:

The hot air choke with the electric assist choke cap functions as follows: as the engine warms up, manifold heat transmitted by hot air to the choke housing relaxes the bimetal permitting the choke to open. The electric assist has a ceramic heating pill. At temperatures above 12 degrees C (54 degrees F) to 23 degrees C (74 degrees F), the temperature sensing switch closes and current is supplied to the heater causing the bimetal to pull the choke plate open at an increased rate. The electric assist choke cap is powered from the stator tap of the alternator.

[rcarlisle]

My first thought was to back off the choke cap one notch. I think that will open it up fully and drop the fast idle. And if it doesn't you can put it back where it was.

As for the electric assist, it does use the 7v off the alternator. And the 1981 factory shop manual says:

The hot air choke with the electric assist choke cap functions as follows: as the engine warms up, manifold heat transmitted by hot air to the choke housing relaxes the bimetal permitting the choke to open. The electric assist has a ceramic heating pill. At temperatures above 12 degrees C (54 degrees F) to 23 degrees C (74 degrees F), the temperature sensing switch closes and current is supplied to the heater causing the bimetal to pull the choke plate open at an increased rate. The electric assist choke cap is powered from the stator tap of the alternator.

I tried it, Gary. And it worked! Took a little longer than I thought, but that may be me. But it worked.

Unfortunately, it's raining and on my test drive at turn around point, truck started missing badly. I pulled under a leaky carpet at a church, found nothing amiss. Figured I'd limp home. It cleared up and ran fine by the time I got home.

So I'll be waiting till it stops raining before I try it again. And my heat seems to be sick in defrost position. Dang it. Frustrating.

But your tip seems to have worked for the moment. Thanks