[alex1965]

Hey guys, I'm new to the whole engine tuning thing. I've got a 289 with an Autolite 4100 and Pertronix II ignition. I've got some questions about my engine's idle, vacuum, and timing. I'm virtually certain that something's off, but I'm not sure what. It's kindof like a "I don't know what I don't know" situation. Here's my scenario:

1. About 10hg of vacuum when setting timing (distributor-to-carb line disconnected and plugged at dizzy end)
1a. This goes up to around 15-16hg when I reconnect the line to the distributor. Is this normal/acceptable? The vacuum reader I have indicates that this is typical of "Late ignition timing." The needle is constant and doesn't jump around, so I don't think I have an intake leak anywhere.
1b. My cam is a mild street cam. Nothing crazy. I can find specs if needed.
2. I currently have set the timing to about 9* BTDC.
2a. I have no clue how to tune an engine to find optimal timing. I've heard about increasing timing until you hear pinging and then backing off. I have no idea what to listen for or how to do so. Help?
2b. What's an acceptable range for the timing? I'm not exactly stock with my Pertonix ignition and slightly modified engine.
3. Carburetor has not been adjusted very much. Both of the mixture screws are 1.5 turns out.
3a. Engine idles at around 800 when setting timing with vacuum disconnected (not exactly sure, rally-pac says about 1,000 but external tach says 750. Don't know which to trust). When I reconnect the vacuum line, the RPM jumps to around 1,200. Is this normal? Why is this? How do I get this engine to idle at the proper RPM when everything is connected?
3b. I also have no idea what I'm doing with the fast idle adjustment. I've heard that you should adjust it cold, but the shop manual says to do it hot. I don't really understand the instructions on the fiddling with the fast idle screw on the cam shoulder either. Can somebody help explain how fast idle works/how to adjust it?
3c. Also, how does this tie in with the idle adjustment screw at the accelerator linkage? How do these relate to the timing and which should I adjust first?

I'm not trying to tune this engine to perfection; I just want to get it driving well enough to take it to somebody who really knows what they're doing. What I'm really after is finding an order in which to adjust things so that they don't affect the other factors after I've messed with them and throw me into a loop or a goose chase. Does anybody have an idea of what to do first, next and last? Any general tuning advice to get this 289 running adequately enough to drive to a tuning shop?

I know this is a lot of questions. I would appreciate any bit of advice you could offer! This is my first project car, let alone car that I've owned from this era, and I'm very new to this generation of vehicle. Thanks in advance everybody!

Alex

 

[alex1965]

Should also mention that carb has been rebuilt by Mustang Barn

 

[64-1/2 first.... 66 now]

Take this anyway you want, but you ask a lot of questions that could be answered by sticking your head in and seeing how things work and a little trial and error. There were a lot of 17yr old kids back in the day that figured things out before internet.

 

[66coupe289]

The pinging you reference is not at idle, but under load.

Your distributer should be connected to ported vacuum like this:

Take vacuum measurements off a manifold vacuum source, NOT this ported vacuum. Make sure you do not have any open vacuum ports when doing the test. Disconnect distributer and plug off ported vacuum when checking timing.

 

[alex1965]

Take this anyway you want, but you ask a lot of questions that could be answered by sticking your head in and seeing how things work and a little trial and error. There were a lot of 17yr old kids back in the day that figured things out before internet.

You're absolutely right. I've spent a fair amount of time messing around in the engine bay adjusting the 4100 and messing with the timing, but I have no way of knowing what is best or the way things should behave. I have no previous experience with these cars, and therefore no reference point to compare to. That is why I am asking this wonderful community, which has always been a great help to me. Usually...

 

[alex1965]

The pinging you reference is not at idle, but under load.

Your distributer should be connected to ported vacuum like this:

Take vacuum measurements off a manifold vacuum source, NOT this ported vacuum. Make sure you do not have any open vacuum ports when doing the test. Disconnect distributer and plug off ported vacuum when checking timing.

I am taking my vacuum measurements off the PCV port on the carburetor spacer. Sorry if I somehow gave the impression I was using the carburetor vacuum port... let me know the source of confusion and I'll fix it. Thanks for the response!

Cheers, Alex

 

[64-1/2 first.... 66 now]

You're absolutely right. I've spent a fair amount of time messing around in the engine bay adjusting the 4100 and messing with the timing, but I have no way of knowing what is best or the way things should behave. I have no previous experience with these cars, and therefore no reference point to compare to. That is why I am asking this wonderful community, which has always been a great help to me. Usually...

Trial and error, one person's optimum settings aren't necessarily another's. It's not instant gratification, but the Mustang Shop Manual will answer most questions. Usually...

 

[alex1965]

Trial and error, one person's optimum settings aren't necessarily another's. It's not instant gratification, but the Mustang Shop Manual will answer most questions. Usually...

Again, you are right. Optimum settings are not universal, nor is there a single ideal one. But also again, you miss my point: I did not make this thread to compare my "optimum settings" to others'. I'm here to learn from people who've done this before, because I haven't. For you to assume that I haven't consulted the shop manual or even tinkered with my engine before asking a couple specific questions about things I can't figure out is annoying and in no way helpful to my situation.

I know beggars can't be choosers when it comes to asking a question online, but is wanting responses that are relevant too much to ask? This community has been an invaluable resource to me in the past and I feel comfortable asking for help from the experienced individuals that I have the pleasure of sharing this hobby with. Please don't take up more space in this discussion, because I'll only be scrolling past your comments to find ones that are actually useful to me.

Cheers! Alex

 

[Woodchuck]

Hey guys, I'm new to the whole engine tuning thing. I've got a 289 with an Autolite 4100 and Pertronix II ignition. I've got some questions about my engine's idle, vacuum, and timing. I'm virtually certain that something's off, but I'm not sure what. It's kindof like a "I don't know what I don't know" situation. Here's my scenario:

1. About 10hg of vacuum when setting timing (distributor-to-carb line disconnected and plugged at dizzy end)

Check you cam specs. With a stock camshaft, acceptable vacuum for a 289 was 18-21"hg. A reading of 10"hg seems abnormally low. Check for vacuum leaks (first), ignition timing (second) and carburetor idle mixture adjustment (third)

1a. This goes up to around 15-16hg when I reconnect the line to the distributor. Is this normal/acceptable? The vacuum reader I have indicates that this is typical of "Late ignition timing." The needle is constant and doesn't jump around, so I don't think I have an intake leak anywhere.

It would be normal if your vacuum source is manifold vacuum and would be a solid indicator that your static (initial) timing is late and should be advanced. It is not uncommon for timing, at idle, with the vacuum advance connected to manifold vacuum to be in the neighborhood of 30*BTDC.

It would be ABnormal if your vacuum source is the vacuum port at the lower front right side of the 4100 and an indication that the primary throttle plates are open too far, exposing the vacuum port which is located ABOVE the throttle plates.

1b. My cam is a mild street cam. Nothing crazy. I can find specs if needed.

Would probably be a good idea.

2. I currently have set the timing to about 9* BTDC.

With today's fuel I'd start at 12-15*BTDC.

2a. I have no clue how to tune an engine to find optimal timing. I've heard about increasing timing until you hear pinging and then backing off. I have no idea what to listen for or how to do so. Help?

The first thing you want to do is accurately set your curb idle speed so that the mechanical advance is not kicking in. On a stock 289-4V with an automatic transmission, curb idle is 575 rpm in DRIVE. On a manual transmission, curb idle is 610 rpm. Your "mild" camshaft may require a bit higher idle, but try to keep it under 800 rpm.

2b. What's an acceptable range for the timing? I'm not exactly stock with my Pertonix ignition and slightly modified engine.

For the most part, ignition timing is irrespective of the type of ignition, whether it be breaker points, solid-state, etc. If the "slightly modified" aspect of your engine is the "mild street cam" and maybe a set of headers and dual exhaust, with stock cylinder heads, I would shoot for a total advance (disconnect the vacuum advance to set) of around 36-38* by the time the engine reaches 3,500 rpm. You adjust this using different tension advance springs in the distributor as well as limiting the travel of the advance weights using "limiter caps". A good idea is to send your distributor out to someone who "recurves" them, like Dan Nolan at The Mustang Barn.

3. Carburetor has not been adjusted very much. Both of the mixture screws are 1.5 turns out.

Connect your vacuum gauge to a manifold vacuum source. Starting at 1.5 turns out, adjust each mixture screw, ALTERNATELY, in 1/4 turn increments, until you obtain the highest vacuum reading. While doing this, keep re-adjusting your curb idle, as needed.

3a. Engine idles at around 800 when setting timing with vacuum disconnected (not exactly sure, rally-pac says about 1,000 but external tach says 750. Don't know which to trust). When I reconnect the vacuum line, the RPM jumps to around 1,200. Is this normal? Why is this? How do I get this engine to idle at the proper RPM when everything is connected?

Turn the curb idle screw, on the drivers side of the carburetor clockwise to increase and counter-clockwise to decrease curb idle. If you are using manifold vacuum for your vacuum advance set the curb idle with it connected. If you are using "ported vacuum" (or the 4100's vacuum port) it shouldn't make a difference (unless the throttle plates are open too far as mentioned above and then, if they are, it's indicative of another underlying issue that is causing them to be adjusted too far open to enable the car to idle).

3b. I also have no idea what I'm doing with the fast idle adjustment. I've heard that you should adjust it cold, but the shop manual says to do it hot. I don't really understand the instructions on the fiddling with the fast idle screw on the cam shoulder either. Can somebody help explain how fast idle works/how to adjust it?

Fast idle adjustment is on the passenger side of the carburetor. The choke mechanism moves a "fast idle cam" which has steps that the stop screw sits on. When the choke is first set, the fast idle cam turns to its farthest extent and the stop screw keeps the throttle plates open a bit further than normal, increasing the idle. As the choke opens the cam moves to a lower step and then, when the choke is fully open the cam moves to a place where there is no step and the fast idle is "off". You can set the fast idle on a warm engine by doing this, with the engine off.
1. Remove the air cleaner lid.
2. Hold the throttle open 1/2 way.
3. Manually (with your finger) close the choke plate and hold it.
4. Release the throttle.
5. Release the choke plate.
6. Start the engine. Adjust the fast idle speed to around 1,600 rpm. "Blip" the throttle and it should immediately come off fast idle.

3c. Also, how does this tie in with the idle adjustment screw at the accelerator linkage? How do these relate to the timing and which should I adjust first?

Always make your ignition adjustments (dwell/timing) first and carburetor adjustments (mixture/speed) last. However, when adjusting ignition timing always make sure your idle speed is slow enough that the mechanical advance is not activated and your vacuum advance line is disconnected and plugged.

I'm not trying to tune this engine to perfection; I just want to get it driving well enough to take it to somebody who really knows what they're doing. What I'm really after is finding an order in which to adjust things so that they don't affect the other factors after I've messed with them and throw me into a loop or a goose chase. Does anybody have an idea of what to do first, next and last? Any general tuning advice to get this 289 running adequately enough to drive to a tuning shop?

I know this is a lot of questions. I would appreciate any bit of advice you could offer! This is my first project car, let alone car that I've owned from this era, and I'm very new to this generation of vehicle. Thanks in advance everybody!

Alex

HTH

 

[alex1965]

HTH

Bart, thanks for taking the time to write out this response. If gold could be converted to a text state, I assume it would take the form of your posts. Thank you so much! I will no doubt be referencing this post when I'm in the garage next, especially your fast idle process description. It's much clearer to me now.

Cheers, Alex

 

[64-1/2 first.... 66 now]

Again, you are right. Optimum settings are not universal, nor is there a single ideal one. But also again, you miss my point: I did not make this thread to compare my "optimum settings" to others'. I'm here to learn from people who've done this before, because I haven't. For you to assume that I haven't consulted the shop manual or even tinkered with my engine before asking a couple specific questions about things I can't figure out is ignorant and annoying.

I know beggars can't be choosers when it comes to asking a question online, but is wanting responses that are relevant too much to ask? This community has been an invaluable resource to me in the past and I feel comfortable asking for help from the experienced individuals that I have the pleasure of sharing this hobby with. Please don't take up more space in this discussion, because I'll only be scrolling past your comments to find ones that are actually helpful to me.

Cheers! Alex

Scroll away.... cover your eyes.... stomp your feet, if you don't hear want you want to hear. You seem to miss my point, "A Mind is a Terrible Thing to Waste''.

 

[alex1965]

Scroll away.... cover your eyes.... stomp your feet, if you don't hear want you want to hear. You seem to miss my point, "A Mind is a Terrible Thing to Waste''.

I have no qualms about ignoring information that is in no way helpful to me. The "wasting one's mind" expression would fall better into the category of engaging in online banter with somebody who clearly has no intent to help than it would asking a question to further one's knowledge. The sad thing is, you've probably forgotten more than I'll ever know about these classic cars, and it's all locked away behind an affinity for sarcasm and pessimism. I'm doing my best to learn when I make these posts, so why not take your own advice and scroll or cover your eyes if it's not what you want to see?

 

[64-1/2 first.... 66 now]

I have no qualms about ignoring information that is in no way helpful to me. The "wasting one's mind" expression would fall better into the category of engaging in online banter with somebody who clearly has no intent to help than it would asking a question to further one's knowledge. The sad thing is, you've probably forgotten more than I'll ever know about these classic cars, and it's all locked away behind an affinity for sarcasm and pessimism. I'm doing my best to learn when I make these posts, so why not take your own advice and scroll or cover your eyes if it's not what you want to see?

La, La, La, La, La........ Not listening, not listening.

 

[Mustang4SF]

La, La, La, La, La........ Not listening, not listening.

I don’t get your point. A newbie has some questions and is asking the community for help. This is why people are joining the forum. To ask questions or help others with their answers. You are not willing or capable to answer them. That is fine so just ignore this topic and let great people like @Woodchuck help him. Alex will learn and share the learnings with others in the future to keep the knowledge alive.


Sent from my iPhone using Tapatalk

 

[64-1/2 first.... 66 now]

I don’t get your point. A newbie has some questions and is asking the community for help. This is why people are joining the forum. To ask questions or help others with their answers. You are not willing or capable to answer them. That is fine so just ignore this topic and let great people like @Woodchuck help him. Alex will learn and share the learnings with others in the future to keep the knowledge alive.


Sent from my iPhone using Tapatalk

No point there, just a jovial retort to the op's previous diatribe about scrolling past my posts. My points were made earlier in that getting your hands dirty and using your noggin along with the shop manual will resolve the bulk of his queries. Schooling has taught us how to formulate solutions, why not apply it?
When in high school my newly purchased 64-1/2 suddenly wouldn't idle, my first thought was let's pop the top on this Autolite 4100 and see what's going on. When I saw a float had sunk, I dug in the box of spare carbs in the back seat that came with the car and found one. I didn't have to ask anyone if the plastic float would work as a replacement for the metal one, one look told me yes.
When the lower clutch rod kept falling out of the release lever, I looked at it, determined it was too short and went to shop class and hammered out a longer one.
I'm all for sharing information and have done so in many threads including the op's past and present topics. The tone of the op's many posts would indicated a trend of more computer time than hands on time.
Just because you can't glean the answer from a statement, doesn't mean it's not there. There's truth to the saying "You can't help someone if they're not willing to help themselves".
Hey, don't sweat it, not everyone gets my "dry wit".

 

[alex1965]

No point there, just a jovial retort to the op's previous diatribe about scrolling past my posts. My points were made earlier in that getting your hands dirty and using your noggin along with the shop manual will resolve the bulk of his queries. Schooling has taught us how to formulate solutions, why not apply it?
When in high school my newly purchased 64-1/2 suddenly wouldn't idle, my first thought was let's pop the top on this Autolite 4100 and see what's going on. When I saw a float had sunk, I dug in the box of spare carbs in the back seat that came with the car and found one. I didn't have to ask anyone if the plastic float would work as a replacement for the metal one, one look told me yes.
When the lower clutch rod kept falling out of the release lever, I looked at it, determined it was too short and went to shop class and hammered out a longer one.
I'm all for sharing information and have done so in many threads including the op's past and present topics. The tone of the op's many posts would indicated a trend of more computer time than hands on time.
Just because you can't glean the answer from a statement, doesn't mean it's not there. There's truth to the saying "You can't help someone if they're not willing to help themselves".
Hey, don't sweat it, not everyone gets my "dry wit".

There's a difference between identifying a sunken float in your carb or a clutch rod that's too short and getting a relatively complex machine like an engine running smoothly. If it was easy, anybody could just eyeball it and use their detective skills to get it running well. How many books about getting a clutch rod to perform to the best of its ability have you bought? How many people can you name whose job it is to tune lower clutch rods? There's a world of difference between identifying and fixing a simple part like a clutch rod and making an entire engine run harmoniously. I didn't make any posts for the various problems I've solved like your float or lever stories, but you judge me for asking advice on a topic I'm unfamiliar with and haven't been able to figure out despite a fair amount research and hands-on time. I have no shame in asking this fantastic community for advice and help. In fact, many members have actually encouraged this behavior so I can avoid making the mistakes they did. This kind of attitude is why I love this forum and the culture it sustains. You, on the other hand, are a stain on this otherwise amazing community.

Dry wit, deadpan humor, whatever you want to call it-- has nothing to do with how you're acting. If half the effort you put into being patronizing and snobby was put toward sharing your experience, I could be twice as knowledgeable about carburetors and engines as I was this morning. As a college student trying to expand my knowledge base by working on one of these cool old cars, I have much to learn. You're the first person that I've encountered on this site that has taught me literally nothing. I've learned more from 3 word responses and a single hyperlink than I have reading the half dozen posts you've so kindly provided in this thread. I'm 19 years old. You've surely owned these cars longer than I've been alive, and as I said earlier, it's a damn shame you've chosen to put all this energy into acting this way when the opportunity for positive headway presented itself. At this stage in my journey, the bar to raise my comprehension of these old cars is very low, and you've still managed to fall short multiple times. It's almost impressive.

Also, the assumptions you make about people you don't know personally are classless and unwarranted. There's no way you could possibly know anything about how much time I spend in front of a computer compared to how much time I spend working on my car. If I had to guess, you're probably the guy people try to avoid at parties.

You talk down to the younger generation for not using their noggin enough, but I know all of them could figure out how to upload a profile picture with more than a grand total of 32 pixels. It's even easier than replacing the float in your carburetor... While I do feel strongly that being able to tune a carb is a far more valuable skill than knowing how to upload a photo to the internet, I merely wish to emphasize the importance of perspective. I'm appalled that somebody your age would act this way toward somebody from my generation who's trying not only to learn about something from your era, but keep it alive. All of the gentlemen I've talked to, both in-person and online, have been eager to share what they know. You are a rare exception. You insult my abilities and provide me with useless commentary, and then chalk it up to a quirky personality trait or "jovial retort". You're not witty or droll; you're just a Type-D personality with immature tendencies. You've done nothing but annoy and slow down the progression of myself, and from a quick search of your profile, others too. Read the room: nobody else in this thread shares your point of view. The vast majority of users here-- as in, everybody except for you-- have been endlessly helpful and kind to me, and given the nature of the internet, it's somewhat of a miracle it took this long for me to encounter somebody who acts like you do. I give respect to those I feel deserve it but either way, I wish you all the best, friend. You're going to need it with your disposition.

To the rest of you, from whom I have learned much, thank you. This website-- more importantly, its users-- has single-handedly helped me restore a '65 coupe from the ground up. I have no doubt that I'll have more questions, but I'll also be able to provide more answers as my experience grows

Keep the dirty side down!
Alex

 

[Rufus68]

You should watch all the carburetor videos on ThunderHead289's Youtube channel. In addition to basics, it points out the importance of fuel pressure and throttle cable adjustment when trying to sort out a carburetor. After watching everything there, I think you'll be ready to set that carb and your timing both to the starting point for a tune. The first thing you set in your carb is your throttle cable adjustment to insure your throttle blades are positioned correctly at the transfer slots. If the throttle blades are open a little too much, you've already moved the carb out of the idle circuit.

My advice, watch all the videos then go out to the garage and start fresh.

 

[Knapper]

As usual, Bart has you covered. However, it might be helpful to get a picture of your top end with the vacuum gauge attached and distributor plugged. I saw someone doing this and they actually had the vacuum advance on the distributor plugged with the hose left open.

 

[Caper50]

La, La, La, La, La........ Not listening, not listening.

Barnett, is that you?

 

[64-1/2 first.... 66 now]

There's a difference between identifying a sunken float in your carb or a clutch rod that's too short and getting a relatively complex machine like an engine running smoothly.

Really... that's what you took from my post? That's just a 17yr old's occurrences from the first month of owning his first car. Again, you seem to choose to miss the point.
Let us reflect,

3b. I also have no idea what I'm doing with the fast idle adjustment. I've heard that you should adjust it cold, but the shop manual says to do it hot. I don't really understand the instructions on the fiddling with the fast idle screw on the cam shoulder either. Can somebody help explain how fast idle works/how to adjust it?

a few minutes of hands on time actually manipulating the choke flap in relationship to the throttle linkage and it becomes abundantly clear how it works, the fast idle cam isn't exactly a complex machine.
Give two children each a book of dots. The children ask "what do I do with this"? You tell them "you connect the dots to make a picture. One parent takes a child's hand in theirs and proceeds to guide the pen dot to dot, page by page until the book is finished. This child then asks that parent to help them upload the pictures to the internet only using 32 pixels each. The other parent hands the second child a pencil and tells them the first page says cat, connect the dots until it looks like one. Some time later, after much trial and error and a worn out eraser, the child has a completed book. This child then grabs a maze book and knocks it out in an hour.
Tell me, with parent did the teaching?
All I've done in this thread is present an alternate progression to problem solving, something you don't seem open to. You on the other hand have chosen to lash out with only can be described as a lack of maturity. Who has truly taken the low road?
Obviously I've hurt your feelings, I honestly believe the best bit of advice you'll get on this forum is that on the internet you can't have thin skin.

Barnett, is that you?

No, but I think I'd like him.