What is technically running "cool"
#46
04-11-2010, 12:21 PM
Well, before you run it any more, hook up the vacuum advance hose. Leaving the port on the carb unused and uncapped is making a significant vacuum leak, and is contributing to the run on when you shut off the engine. Get a timing light and do a proper timing (disconnecting the vacuum advance and plugging the carb vacuum port while you do it. If you have a helper, they can simply put their finger over the port to plug it off, otherwise disconnect the hose at the dizzy and stick a snug fitting plug like a piece of rod or an awl in the end.).
The continued temp increase, the run on says to me the engine timing is likely too far advanced. First go to a hobby or craft store and pick up two light colored paint pens, yellow and white are good choices, clean off the timing marks on the damper with solvent, then draw over the 0 line and the specified advance line with the two colors of paint so they will be easily seen and able to be told apart when you shine the timing light on them. loosen the distributor hold down clamp just enough that the dizzy can be turned easily. Let the engine warm up until the thermostat opens (so the choke is open and the throttle cam is on low idle), disconnect and plug the vacuum advance, set the idle speed, set the timing. recheck and readjust the idle speed, recheck the timing. Tighten the dizzy hold down clamp. Hook up the vacuum advance and check that the timing increases when you advance the throttle and returns (it probably will not return completely to the setting mark with the advance hooked up, that's OK.) when you release it. You'll see that the vacuum advance starts to increase almost immediately above idle, not just at high speed.
I suspect that will end your overheating issues.
Julie we were posting at the same time. I forgot about adjusting the mixture screw (single barrel carb, one screw) It's been a long time since I've messed with carbs that were adjustable.
. Hooking a vacuum gauge to the advance port on the carb is effectively acting as a plug if it fits snugly.
The continued temp increase, the run on says to me the engine timing is likely too far advanced. First go to a hobby or craft store and pick up two light colored paint pens, yellow and white are good choices, clean off the timing marks on the damper with solvent, then draw over the 0 line and the specified advance line with the two colors of paint so they will be easily seen and able to be told apart when you shine the timing light on them. loosen the distributor hold down clamp just enough that the dizzy can be turned easily. Let the engine warm up until the thermostat opens (so the choke is open and the throttle cam is on low idle), disconnect and plug the vacuum advance, set the idle speed, set the timing. recheck and readjust the idle speed, recheck the timing. Tighten the dizzy hold down clamp. Hook up the vacuum advance and check that the timing increases when you advance the throttle and returns (it probably will not return completely to the setting mark with the advance hooked up, that's OK.) when you release it. You'll see that the vacuum advance starts to increase almost immediately above idle, not just at high speed.
I suspect that will end your overheating issues.
Julie we were posting at the same time. I forgot about adjusting the mixture screw (single barrel carb, one screw) It's been a long time since I've messed with carbs that were adjustable.
. Hooking a vacuum gauge to the advance port on the carb is effectively acting as a plug if it fits snugly.
#47
04-11-2010, 12:26 PM
Post Fiend
#48
04-11-2010, 12:33 PM
Posting Guru
Join Date: Jul 2006
Location: Westminster,Md
Posts: 1,276
Likes: 0
Received 0 Likes
on
0 Posts
#50
04-11-2010, 02:55 PM
I'm assuming you reconnect it when you've done an initial timing with a timing light^^^.
Julie--Holy crap.....never saw that coming.... Well, I have a timing light and even the original vacuum tube, hahaha, so hooking it up and/or plugging the carb for initial timing should be hard.
I don't have a vacuum gauge...is that really necessary? I didn't read about one of those being used to time the motor in the shop manual.
AX--OK, I see what needs to happen.(Julie covered a lot) About marking the timing marks, I used a black permanent marker to mark what would be the 4ºBTDC mark(what it's supposed to be at). What is the significance of marking 0º, if I may ask? Just for reference?
This stuff that needs to be done I am ready to do and have most of the stuff and knowledge(shop manual). So I should be getting to it within the next day or two.
P.S.--So could all of this crap I didn't do have something to do with the fact that when my dad and I were playing around with the "idle mixture screw" it wasn't doing anything to the idle or running quality? The engine was at idle, and my dad said that when gently bottoming out the screw, it should run terribly, or even kill it--but it wasn't changing a thing. ??? Whatever, we'll see.
Thank you very much.
Julie--Holy crap.....never saw that coming.... Well, I have a timing light and even the original vacuum tube, hahaha, so hooking it up and/or plugging the carb for initial timing should be hard.
I don't have a vacuum gauge...is that really necessary? I didn't read about one of those being used to time the motor in the shop manual.
AX--OK, I see what needs to happen.(Julie covered a lot) About marking the timing marks, I used a black permanent marker to mark what would be the 4ºBTDC mark(what it's supposed to be at). What is the significance of marking 0º, if I may ask? Just for reference?
This stuff that needs to be done I am ready to do and have most of the stuff and knowledge(shop manual). So I should be getting to it within the next day or two.
P.S.--So could all of this crap I didn't do have something to do with the fact that when my dad and I were playing around with the "idle mixture screw" it wasn't doing anything to the idle or running quality? The engine was at idle, and my dad said that when gently bottoming out the screw, it should run terribly, or even kill it--but it wasn't changing a thing. ??? Whatever, we'll see.
Thank you very much.
#51
04-11-2010, 03:25 PM
I covered reconnection in my post.
a vacuum gauge is a good thing to have, but you can adjust it close by ear or tach reading. A rule of thumb we always used when adjusting a new engine or replacement carb was to gently close the screw (actually officially called the idle bleed screw) all the way in, then back it out 2.5 turns. Almost every engine will start and run at that setting. Adjusting that screw without the vacuum line connected will have little to no affect. That screw sets a controlled vacuum "leak" when the throttle plate is closed, whereas having the line disconnected is allowing a much larger uncontrolled leak.
Once you have the timing set correctly and everything hooked up slowly adjust the mixture screw in and out until you reach the highest steady rpm. Back the screw out 1/4 turn from that point and you're close enough. You'll likely have to adjust the idle speed once again.
I like to highlite the timing marks with light colored marks because they show up quite well in the timing light strobe even in bright daylight (we used a white or yellow crayon at the service station to temporarily mark customer's cars). By marking both marks in different colors there was no doubt which was the right one and it also aided in assuring the advance was working and in the proper direction and amount. It wasn't that unusual to find a vacuum advance that was disconnected inside the dizzy or had a ruptured diaphram most dizzys have a mechanical advance as well as the vacuum advance (and sometimes only a mechanical advance) watching the timing marks while increasing the throttle and kinking off the vacuum hose by folding it off or clamping with a smooth jawed pair of vise grips to determine if each advance was working properly.
a vacuum gauge is a good thing to have, but you can adjust it close by ear or tach reading. A rule of thumb we always used when adjusting a new engine or replacement carb was to gently close the screw (actually officially called the idle bleed screw) all the way in, then back it out 2.5 turns. Almost every engine will start and run at that setting. Adjusting that screw without the vacuum line connected will have little to no affect. That screw sets a controlled vacuum "leak" when the throttle plate is closed, whereas having the line disconnected is allowing a much larger uncontrolled leak.
Once you have the timing set correctly and everything hooked up slowly adjust the mixture screw in and out until you reach the highest steady rpm. Back the screw out 1/4 turn from that point and you're close enough. You'll likely have to adjust the idle speed once again.
I like to highlite the timing marks with light colored marks because they show up quite well in the timing light strobe even in bright daylight (we used a white or yellow crayon at the service station to temporarily mark customer's cars). By marking both marks in different colors there was no doubt which was the right one and it also aided in assuring the advance was working and in the proper direction and amount. It wasn't that unusual to find a vacuum advance that was disconnected inside the dizzy or had a ruptured diaphram most dizzys have a mechanical advance as well as the vacuum advance (and sometimes only a mechanical advance) watching the timing marks while increasing the throttle and kinking off the vacuum hose by folding it off or clamping with a smooth jawed pair of vise grips to determine if each advance was working properly.
#52
04-11-2010, 10:50 PM
Post Fiend
Oye Vey! Those are really important points. N0 wonder you are having problems 
Your timing and idle mixture have got to be WAY off. First, the vacuum advance is a gradual advance and works increasingly as you increase rpm. so you can't set the timing with it hooked up.
Next, with that vacuum line left open, you have a substantial vacuum leak - bad news. That will also change all your idle, mixture and timing settings.
You need to take a step back and take care of this stuff before you run the motor again - these things will have a SIGNIFICANT impact on how the engine runs, the timing, and the operating temperature.
And if it diesels on shut off, that is preignition. That will break your engine - not good. That's the heat and your vacuum leak- 91 octain will help some, but you have to put the motor in proper running order before you run it again.
Forget about any of the other insignificant rumors you have heard about gas, etc, and do this to the letter:
First, put the 91 octain gas in the truck - just do it.
Second, place a vacuum hose on the carb/manufold vacuum inlet for your distributor vacuum advance, leave it disconnected from the vacuum advance AND PLUG IT.
Third, hook up the timing light, vacuum gauge, and tachometer, and start the truck. Chances are the idle rpm will shoot up high with the vacuum leak plugged.
Fourth, reset the idle rpm to the proper setting, then set the timing to the proper setting, then set the idle mixture to the highest vacuum reading you can get.
Fifth, reset the idle rpm if necessary to 500 rpm. Check the timing again for the proper setting and adjust it as necessary. Continue to check and reset timing and idle rpm until both are correct at the same time. Then, shut the engine off.
Let it sit for about 5 minutes to distribute heat and start it up again and recheck the idle rpm, timing and idle mixture. Reconnect the vacuum advance hose to the distributor. Run it for 20 minutes at 2000 rpm spraying the radiator as necessary with water and using the box fans. Allow it to go up to 230 degrees before you feel the need to shut it off.
I'll bet it shuts off with no problem now, and will run cooler.
DO NOTrun it at idle after the 20 minute break-in. There's insufficient air flow through the radiator and insufficient coolant circulation that will cause it to overheat at this point - shut it off.
Then, it should be fine and cam broken in. Don't run it again until you are ready to drive it except for a possible battery charge once a week for 2-3 minutes.
One last thing, if it still diesels on shut down (and it shouldn't now) DO NOT use unprotected hands to choke it off. If it backfires you could loose fingers or significantly burn you hands. Use a folded up wet towel and hold it on with the hand. It shouldn't, and if it does there's another problem
AX? Any corrections or additions?
Your timing and idle mixture have got to be WAY off. First, the vacuum advance is a gradual advance and works increasingly as you increase rpm. so you can't set the timing with it hooked up.
Next, with that vacuum line left open, you have a substantial vacuum leak - bad news. That will also change all your idle, mixture and timing settings.
You need to take a step back and take care of this stuff before you run the motor again - these things will have a SIGNIFICANT impact on how the engine runs, the timing, and the operating temperature.
And if it diesels on shut off, that is preignition. That will break your engine - not good. That's the heat and your vacuum leak- 91 octain will help some, but you have to put the motor in proper running order before you run it again.
Forget about any of the other insignificant rumors you have heard about gas, etc, and do this to the letter:
First, put the 91 octain gas in the truck - just do it.
Second, place a vacuum hose on the carb/manufold vacuum inlet for your distributor vacuum advance, leave it disconnected from the vacuum advance AND PLUG IT.
Third, hook up the timing light, vacuum gauge, and tachometer, and start the truck. Chances are the idle rpm will shoot up high with the vacuum leak plugged.
Fourth, reset the idle rpm to the proper setting, then set the timing to the proper setting, then set the idle mixture to the highest vacuum reading you can get.
Fifth, reset the idle rpm if necessary to 500 rpm. Check the timing again for the proper setting and adjust it as necessary. Continue to check and reset timing and idle rpm until both are correct at the same time. Then, shut the engine off.
Let it sit for about 5 minutes to distribute heat and start it up again and recheck the idle rpm, timing and idle mixture. Reconnect the vacuum advance hose to the distributor. Run it for 20 minutes at 2000 rpm spraying the radiator as necessary with water and using the box fans. Allow it to go up to 230 degrees before you feel the need to shut it off.
I'll bet it shuts off with no problem now, and will run cooler.
DO NOTrun it at idle after the 20 minute break-in. There's insufficient air flow through the radiator and insufficient coolant circulation that will cause it to overheat at this point - shut it off.
Then, it should be fine and cam broken in. Don't run it again until you are ready to drive it except for a possible battery charge once a week for 2-3 minutes.
One last thing, if it still diesels on shut down (and it shouldn't now) DO NOT use unprotected hands to choke it off. If it backfires you could loose fingers or significantly burn you hands. Use a folded up wet towel and hold it on with the hand. It shouldn't, and if it does there's another problem
AX? Any corrections or additions?
I'm assuming you reconnect it when you've done an initial timing with a timing light^^^.
Covered that and so did AX...See above in Red. I know it was a long post - Sorry.
Julie--Holy crap.....never saw that coming.... Well, I have a timing light and even the original vacuum tube, hahaha, so hooking it up and/or plugging the carb for initial timing should be hard.
I don't have a vacuum gauge...is that really necessary? I didn't read about one of those being used to time the motor in the shop manual.
You would use the vacuum gauge to set the idle mixture to the correct setting. It effects rpm and mixture (which controls heat as well).
AX--OK, I see what needs to happen.(Julie covered a lot) About marking the timing marks, I used a black permanent marker to mark what would be the 4ºBTDC mark(what it's supposed to be at). What is the significance of marking 0º, if I may ask? Just for reference?
This stuff that needs to be done I am ready to do and have most of the stuff and knowledge(shop manual). So I should be getting to it within the next day or two.
P.S.--So could all of this crap I didn't do have something to do with the fact that when my dad and I were playing around with the "idle mixture screw" it wasn't doing anything to the idle or running quality? The engine was at idle, and my dad said that when gently bottoming out the screw, it should run terribly, or even kill it--but it wasn't changing a thing. ??? It should if everything else is set right - but...... Whatever, we'll see.
Thank you very much.
Covered that and so did AX...See above in Red. I know it was a long post - Sorry.
Julie--Holy crap.....never saw that coming.... Well, I have a timing light and even the original vacuum tube, hahaha, so hooking it up and/or plugging the carb for initial timing should be hard.
I don't have a vacuum gauge...is that really necessary? I didn't read about one of those being used to time the motor in the shop manual.
You would use the vacuum gauge to set the idle mixture to the correct setting. It effects rpm and mixture (which controls heat as well).
AX--OK, I see what needs to happen.(Julie covered a lot) About marking the timing marks, I used a black permanent marker to mark what would be the 4ºBTDC mark(what it's supposed to be at). What is the significance of marking 0º, if I may ask? Just for reference?
This stuff that needs to be done I am ready to do and have most of the stuff and knowledge(shop manual). So I should be getting to it within the next day or two.
P.S.--So could all of this crap I didn't do have something to do with the fact that when my dad and I were playing around with the "idle mixture screw" it wasn't doing anything to the idle or running quality? The engine was at idle, and my dad said that when gently bottoming out the screw, it should run terribly, or even kill it--but it wasn't changing a thing. ??? It should if everything else is set right - but...... Whatever, we'll see.
Thank you very much.
The other "Idle RPM Set Screw" is on your carburetors throttle linkage. It is a mechanical set screw that physically opens the carburetor throttle plate more to increase the idle rpm.
There is a second one of these on the cam that is activated by your choke. That is the Fast Idle Set Screw and mecahnically sets the fast idle rpm when your choke is engaged, and can be set later. Make sure for all of this the engine is warmed up and the choke is OFF.
For this exercize, it should be sufficient to close the Idle Mixture Screw completely then back it out 2 and 1/4 to 2 1/2 turns - close enough - then leave it alone.
During timing, the idle rpm is adjusted with the Set Screw on the linkage. In short it does exactly the same thing as if you were to twist the throttle with your hand to rev up the engine.
One more little tidbit: This is all really fascinating and pretty (light show) when you are timing. WATCH OUT FOR THE FAN AT ALL TIMES!
#54
04-12-2010, 12:33 PM
#55
04-12-2010, 12:39 PM
Post Fiend
#56
04-16-2010, 07:52 PM
Good news.
So today, we started it up. I didn't time it any further, but I did hook up the vacuum advance line. We used 91 octane this time.
Amazing.
It ran a million times better. Response was much better. Ran smoother.
It doesn't diesel after shutoff.
Best part? The truck stayed cool. No water sprayer. No auxiliary fan.
On it's own, whether at 2000 rpm, or at 1400(idle), it got to just above 180º, and NEVER went past it. I wanted to cry.
I am beyond happy right now. We finished up the cam break in. We took it to 2k rpm and left it there for about 14 minutes(even though It really only needed about 7-8). It gained in temp much faster than last time, but like I said, it sat happily at ~180º the whole time.
I tried using a timing light that claimed could be seen in broad daylight, but it wasn't bright enough, so we are going to finish that up on sunday evening/night.
It is time for it's first oil change, also be doing that on sunday.
--------------------------------------
Issues: It misses. For some reason, when we let off the pedal completely, it misses just a bit. Not a lot, just a little. But after it reaches ~1600+ rpm, it completely stops and runs like a top. My dad claims something in the ignition, but everything is brand new and set to spec.....
It's idle. I understand these trucks have some kind of "fast idle".....but this thing idles at 1400 rpm, warm or not. Before I hooked up the vacuum advance, I had seen this truck idle at 450-500 before, so I know it can! But the next time(still with no vacuum advance), it idled at 800. Now with the VA hooked up, it wouldn't go lower than 1200 after adjusting the screw a bit. But that miss is making it sound like it'd never make it to 450.
Idle/air screw still has no response. seated the screw gently and nothing. I thought hooking up the VA would change that. Nothing. We set it back 1 1/2 turns anyway(as it says in shop manual), and left it there.
What a day. Issues or not, man I feel............
So today, we started it up. I didn't time it any further, but I did hook up the vacuum advance line. We used 91 octane this time.
Amazing.
It ran a million times better. Response was much better. Ran smoother.
It doesn't diesel after shutoff.
Best part? The truck stayed cool. No water sprayer. No auxiliary fan.
On it's own, whether at 2000 rpm, or at 1400(idle), it got to just above 180º, and NEVER went past it. I wanted to cry.
I am beyond happy right now. We finished up the cam break in. We took it to 2k rpm and left it there for about 14 minutes(even though It really only needed about 7-8). It gained in temp much faster than last time, but like I said, it sat happily at ~180º the whole time.
I tried using a timing light that claimed could be seen in broad daylight, but it wasn't bright enough, so we are going to finish that up on sunday evening/night.
It is time for it's first oil change, also be doing that on sunday.
--------------------------------------
Issues: It misses. For some reason, when we let off the pedal completely, it misses just a bit. Not a lot, just a little. But after it reaches ~1600+ rpm, it completely stops and runs like a top. My dad claims something in the ignition, but everything is brand new and set to spec.....
It's idle. I understand these trucks have some kind of "fast idle".....but this thing idles at 1400 rpm, warm or not. Before I hooked up the vacuum advance, I had seen this truck idle at 450-500 before, so I know it can! But the next time(still with no vacuum advance), it idled at 800. Now with the VA hooked up, it wouldn't go lower than 1200 after adjusting the screw a bit. But that miss is making it sound like it'd never make it to 450.
Idle/air screw still has no response. seated the screw gently and nothing. I thought hooking up the VA would change that. Nothing. We set it back 1 1/2 turns anyway(as it says in shop manual), and left it there.
What a day.
Issues or not, man I feel............
#57
04-16-2010, 09:31 PM
Post Fiend
Well that's super good news!
Remember I told you that when you plugged that vacuum leak it would increase the idle rpm? Just reset it by backing off the mechanical idle screw by the throttle linkage. It looks like the vacuum leak was causing all kinds of problems - timing, mixture - lots of stuff.
When you time it correctly, the low rpm performance will improve and the missing should stop. Timing wil change the idle rpm too.
The fast idle is over on the choke side and should be disengaged if the choke is off. It's a mechanical screw just like the regular idle - other side of the carb though.
Just leave the idle mixture where it is until you time it. All three of those things: idle rpm, idle mixture and timing all change when you adjust one of the others. It has to be timed right and be at idle rpm (500) for that to work.
I'm excited for you - great job!
Remember I told you that when you plugged that vacuum leak it would increase the idle rpm? Just reset it by backing off the mechanical idle screw by the throttle linkage. It looks like the vacuum leak was causing all kinds of problems - timing, mixture - lots of stuff.
When you time it correctly, the low rpm performance will improve and the missing should stop. Timing wil change the idle rpm too.
The fast idle is over on the choke side and should be disengaged if the choke is off. It's a mechanical screw just like the regular idle - other side of the carb though.
Just leave the idle mixture where it is until you time it. All three of those things: idle rpm, idle mixture and timing all change when you adjust one of the others. It has to be timed right and be at idle rpm (500) for that to work.
I'm excited for you - great job!
#58
04-16-2010, 11:39 PM
#59
04-17-2010, 04:15 PM
Hmmmmm, the funny thing is, that we can get the choke almost completely vertical. The **** only has maybe an 1/8th of an inch left to go and it'll run perfectly.
But as soon as you open it just that little bit more, BAM! It shuts off. It's done this since the first time we ran it. And continues to do it will all of the changes that have been made.
Is the choke plate not supposed to be completely vertical?
But as soon as you open it just that little bit more, BAM! It shuts off. It's done this since the first time we ran it. And continues to do it will all of the changes that have been made.
Is the choke plate not supposed to be completely vertical?
#60
04-17-2010, 11:55 PM
Post Fiend
Hmmmmm, the funny thing is, that we can get the choke almost completely vertical. The **** only has maybe an 1/8th of an inch left to go and it'll run perfectly.
But as soon as you open it just that little bit more, BAM! It shuts off. It's done this since the first time we ran it. And continues to do it will all of the changes that have been made.
Is the choke plate not supposed to be completely vertical?
But as soon as you open it just that little bit more, BAM! It shuts off. It's done this since the first time we ran it. And continues to do it will all of the changes that have been made.
Is the choke plate not supposed to be completely vertical?
Well, ok so when you open it up all the way it shuts off like the idle mixture screw is not adjusted correctly. Basically you are doing things to compensate for tune up items that are way out of adjustment. That choke plate is compensating for idle mixture being too lean (screwed in too far) just as it should do.
Warm the truck up, remove the vacuum tube from the distributor vacuum advance and plug it.
Adjust the idle down to 450-500rpm.
Time the truck and continue to adjust he idle rpm and timing until the idle and timing are correct. Then adjust the idle mixture screw using a vacuum gauge - timing set correctly, and idle rpm set correctly. Then fine adjust the timing and Idle rpm again until all are set correctly at the same time!
Ti