Vacuum and Timing question from a newbie

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Heardatbeat

Well-known member
Joined
Nov 22, 2016
Messages
162
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4
Location
Washington
My Car
1971 Mach 1
Hi again. If anyone remembers my last thread it was about the horrible ticking and engine vibrations. Well it turns out some of the bolts on the rocker arms are not the original to spec ones so I bought a set and torqued them down appropriately. While also inspecting the engine I realized that one of the exhaust manifold bolts is also missing. And to top it off the two bolts that hold the transmission mount were completely loose. Needless to say I will never take my car to such an incompetent mechanic again... Anyways. So now I am getting ready to put the engine back together and I am not sure about timing or if I even need to do it. To recap from the other thread, I replaced the harmonic balancer, added a Pertronix Ignitor II with the correct coil, I switched my dual diaphragm vacuum advance to a single. So how do I determine the timing and how do I adjust it so? I know I need to find TDC but I am not clear on what I need to do once I find it.

 
The post that Don is referring to has pretty much all you'll need to set up the timing, with some excellent information. It is daunting at first, but once you start understanding what and why, it's actually quite fun playing with it. I would just remind you to make sure the distributor base area is clean before you move or remove the dizzy. You don't want any dirt getting in. Also mark its current position as a start point.

From my experience, mega as it is, you made a good start with the Pertronix II, but did you dismantle, clean and re-lube the baseplate? It needs to be free moving to get the best out of the P II. Another tip I can offer is to install socket head (hex) flat head screws. Done correctly, this will stop any unwanted movement of the baseplate.

Can you briefly remind us of your engine and trans and carb.

To rehash briefly what I did on my 71 351 C 4V manual trans, I dismantled the dizzy completely, added some weld to the right side of the L15 slot (looking down on it) and recut it to equal an L10 (.410") or 20* on the crank. L15 =30* and so on. Then I put in a Mr Gasket spring on the light side and readjusted the heavy spring with a bit more tension. I then set my initial to 14* giving 34* total mechanical advance as a start point. With my brand new shiny adjustable timing light, I set it to these numbers @ 3000 rpm. I think I can get a bit more out of it with a bit more tweaking of springs. At this time, I set the adjustable vac. can to only about 3-4* of vacuum advance for a total of 37-38*. It seems to run well on this without pinging.

Hope you find the "sweet spot"! Also, glad you are finding the "other" issues and getting them sorted.

Geoff.

 
Last edited by a moderator:
The post that Don is referring to has pretty much all you'll need to set up the timing, with some excellent information. It is daunting at first, but once you start understanding what and why, it's actually quite fun playing with it. I would just remind you to make sure the distributor base area is clean before you move or remove the dizzy. You don't want any dirt getting in. Also mark its current position as a start point.

From my experience, mega as it is, you made a good start with the Pertronix II, but did you dismantle, clean and re-lube the baseplate? It needs to be free moving to get the best out of the P II. Another tip I can offer is to install socket head (hex) flat head screws. Done correctly, this will stop any unwanted movement of the baseplate.

Can you briefly remind us of your engine and trans and carb.

To rehash briefly what I did on my 71 351 C 4V manual trans, I dismantled the dizzy completely, added some weld to the right side of the L15 slot (looking down on it) and recut it to equal an L10 (.410") or 20* on the crank. L15 =30* and so on. Then I put in a Mr Gasket spring on the light side and readjusted the heavy spring with a bit more tension. I then set my initial to 14* giving 34* total mechanical advance as a start point. With my brand new shiny adjustable timing light, I set it to these numbers @ 3000 rpm. I think I can get a bit more out of it with a bit more tweaking of springs. At this time, I set the adjustable vac. can to only about 3-4* of vacuum advance for a total of 37-38*. It seems to run well on this without pinging.

Hope you find the "sweet spot"! Also, glad you are finding the "other" issues and getting them sorted.

Geoff.
Certainly. It is a 351C 4V M code. 4 speed. From the little research I have done one the carb it is a Holley 600 CFM. I did not relube the dizzy plate but I can. I am going to put the engine back together today. Hopefully I will have fixed the ticking and vibration issues I had.

 
The post that Don is referring to has pretty much all you'll need to set up the timing, with some excellent information. It is daunting at first, but once you start understanding what and why, it's actually quite fun playing with it. I would just remind you to make sure the distributor base area is clean before you move or remove the dizzy. You don't want any dirt getting in. Also mark its current position as a start point.

From my experience, mega as it is, you made a good start with the Pertronix II, but did you dismantle, clean and re-lube the baseplate? It needs to be free moving to get the best out of the P II. Another tip I can offer is to install socket head (hex) flat head screws. Done correctly, this will stop any unwanted movement of the baseplate.

Can you briefly remind us of your engine and trans and carb.

To rehash briefly what I did on my 71 351 C 4V manual trans, I dismantled the dizzy completely, added some weld to the right side of the L15 slot (looking down on it) and recut it to equal an L10 (.410") or 20* on the crank. L15 =30* and so on. Then I put in a Mr Gasket spring on the light side and readjusted the heavy spring with a bit more tension. I then set my initial to 14* giving 34* total mechanical advance as a start point. With my brand new shiny adjustable timing light, I set it to these numbers @ 3000 rpm. I think I can get a bit more out of it with a bit more tweaking of springs. At this time, I set the adjustable vac. can to only about 3-4* of vacuum advance for a total of 37-38*. It seems to run well on this without pinging.

Hope you find the "sweet spot"! Also, glad you are finding the "other" issues and getting them sorted.

Geoff.
Certainly. It is a 351C 4V M code. 4 speed. From the little research I have done one the carb it is a Holley 600 CFM. I did not relube the dizzy plate but I can. I am going to put the engine back together today. Hopefully I will have fixed the ticking and vibration issues I had.
 Ok, so you have the same engine as mine. My numbers seem to be working quite well, but as I said, I'm still going to 'play' with it some more later, got other issues to sort first.

Once you get all the vibration wows behind you, you might want to paly with carbs, just as a suggestion. If you do have a 600 Holley, you might want to go up to at least a 670 or 750. I have a 670 Street Avenger that runs well, but needed a bit of work to get the idle air ratio better. My tuner guy drilled a 3/32" hole in each primary throttle plate to get the ratio right. It was idling way too rich. If I was buying a new carb and I might yet, it would be a Quick Fuel 750.

On the dizzy, I use ported vacuum off the carb as it doesn't need advance at idle.

Let us know when you have it running and vibration free

Good luck with it,

Geoff.

 
The post that Don is referring to has pretty much all you'll need to set up the timing, with some excellent information. It is daunting at first, but once you start understanding what and why, it's actually quite fun playing with it. I would just remind you to make sure the distributor base area is clean before you move or remove the dizzy. You don't want any dirt getting in. Also mark its current position as a start point.

From my experience, mega as it is, you made a good start with the Pertronix II, but did you dismantle, clean and re-lube the baseplate? It needs to be free moving to get the best out of the P II. Another tip I can offer is to install socket head (hex) flat head screws. Done correctly, this will stop any unwanted movement of the baseplate.

Can you briefly remind us of your engine and trans and carb.

To rehash briefly what I did on my 71 351 C 4V manual trans, I dismantled the dizzy completely, added some weld to the right side of the L15 slot (looking down on it) and recut it to equal an L10 (.410") or 20* on the crank. L15 =30* and so on. Then I put in a Mr Gasket spring on the light side and readjusted the heavy spring with a bit more tension. I then set my initial to 14* giving 34* total mechanical advance as a start point. With my brand new shiny adjustable timing light, I set it to these numbers @ 3000 rpm. I think I can get a bit more out of it with a bit more tweaking of springs. At this time, I set the adjustable vac. can to only about 3-4* of vacuum advance for a total of 37-38*. It seems to run well on this without pinging.

Hope you find the "sweet spot"! Also, glad you are finding the "other" issues and getting them sorted.

Geoff.
Certainly. It is a 351C 4V M code. 4 speed. From the little research I have done one the carb it is a Holley 600 CFM. I did not relube the dizzy plate but I can. I am going to put the engine back together today. Hopefully I will have fixed the ticking and vibration issues I had.
 Ok, so you have the same engine as mine. My numbers seem to be working quite well, but as I said, I'm still going to 'play' with it some more later, got other issues to sort first.

Once you get all the vibration wows behind you, you might want to paly with carbs, just as a suggestion. If you do have a 600 Holley, you might want to go up to at least a 670 or 750. I have a 670 Street Avenger that runs well, but needed a bit of work to get the idle air ratio better. My tuner guy drilled a 3/32" hole in each primary throttle plate to get the ratio right. It was idling way too rich. If I was buying a new carb and I might yet, it would be a Quick Fuel 750.

On the dizzy, I use ported vacuum off the carb as it doesn't need advance at idle.

Let us know when you have it running and vibration free

Good luck with it,

Geoff.
I do intend to get a better carb. Around 700-750 CFM. To say I had a rough day would be appropriate. I finally put the car all back together. Put some Risoline in the crank case and put some 92 octane in the tank and Seafoam in the carb  after a few tries it finally started up pretty nicely. Let all the Seafoam burn off then turned it off. After about 45 minutes I started it again and it turned over just fine. So I decided it was time to take it for a spin see if my work paid off you know. It was going good until I got a little down the road. It started like... Stuttering I guess would be the way to put it. Jerking back and forth. And the all of the sudden the car died. I was able to park it but now I was downtown with a dead car. I tried cranking it and it sounded very weak. So I walked a couple miles back home and grabbed my other car and picked up a new battery. I put I on and it turned over and was back on the road. I went to the gas station and after I was done the car started acting up again the shifter would shake violently and It started jerking back and forth and then it died once again. I tried cranking it but this time I could not get it to idle. It would crank and just die. Even with the accelerator all the way to the floor the RPM's would not go above 1500. And then after a while it would not even turn on anymore it just cranks and cranks but never turns on. 

Any ideas?

 
The first thing I would check is for spark. It could be the coil breaking down when it warms up.

I would also check the alternator output, both voltage and amperage.

 
The first thing I would check is for spark. It could be the coil breaking down when it warms up.

I would also check the alternator output, both voltage and amperage.
Thanks for the reply. I am fairly new at this. What tools do I need to do these tests? It has a new coil a Flamethrower II epoxy filled from Pertronix.

 
The first thing I would check is for spark. It could be the coil breaking down when it warms up.

I would also check the alternator output, both voltage and amperage.
Thanks for the reply. I am fairly new at this. What tools do I need to do these tests? It has a new coil a Flamethrower II epoxy filled from Pertronix.
New coil does not always mean good. When I did the pertronix conversion it took until the third coil until I got a good one.

 
The first thing I would check is for spark. It could be the coil breaking down when it warms up.

I would also check the alternator output, both voltage and amperage.
Thanks for the reply. I am fairly new at this. What tools do I need to do these tests? It has a new coil a Flamethrower II epoxy filled from Pertronix.
New coil does not always mean good. When I did the pertronix conversion it took until the third coil until I got a good one.
Ah! Well that is not good. How can I rule out the coil?

 
Like Don said. Check voltage and amperage out of the alt. Also make sure you are getting a full 12v to the coil. If all those check out, then check for spark. Good strong clean spark. If you are not getting that then check the plug wires with any ohm meter for resistance. If they don't ohm out they are bad. If they are good your coil likely isn't. Hope this helps.

 
You can get an inexpensive spark tester from Harbor Freight that connects between the spark plug cable and spark plug.

To check the voltage on the alternator you'll need a volt-ohm meter. You can also check the resistance on both the primary and secondary sides of the coil with it.

Checking the amperage takes more expensive test equipment, I would just start with checking the voltage.

Make sure the coil is connected tightly so it gets a good ground.

You can also take the alternator to parts stores, like AutoZone, and they'll test it free.

Another possibility is the fuel system, weak fuel pump, plugged filter, or gas tank that isn't vented.

 
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You can get an inexpensive spark tester from Harbor Freight that connects between the spark plug cable and spark plug.

To check the voltage on the alternator you'll need a volt-ohm meter. You can also check the resistance on both the primary and secondary sides of the coil with it.

Checking the amperage takes more expensive test equipment, I would just start with checking the voltage.

Make sure the coil is connected tightly so it gets a good ground.

You can also take the alternator to parts stores, like AutoZone, and they'll test it free.

Another possibility is the fuel system, weak fuel pump, plugged filter, or gas tank that isn't vented.
Well it looks like I got my work cut out for me. Unfortunately I will not be able to check any of it until Thursday. I will buy whatever tools I do not have in the mean time.

 
You can get an inexpensive spark tester from Harbor Freight that connects between the spark plug cable and spark plug.

To check the voltage on the alternator you'll need a volt-ohm meter. You can also check the resistance on both the primary and secondary sides of the coil with it.

Checking the amperage takes more expensive test equipment, I would just start with checking the voltage.

Make sure the coil is connected tightly so it gets a good ground.

You can also take the alternator to parts stores, like AutoZone, and they'll test it free.

Another possibility is the fuel system, weak fuel pump, plugged filter, or gas tank that isn't vented.
Well it looks like I got my work cut out for me. Unfortunately I will not be able to check any of it until Thursday. I will buy whatever tools I do not have in the mean time.
Good call. I didn't even think about taking the alternator in and having it tested. Much easier.

 
I do intend to get a better carb. Around 700-750 CFM. To say I had a rough day would be appropriate. I finally put the car all back together. Put some Risoline in the crank case and put some 92 octane in the tank and Seafoam in the carb  after a few tries it finally started up pretty nicely. Let all the Seafoam burn off then turned it off. After about 45 minutes I started it again and it turned over just fine. So I decided it was time to take it for a spin see if my work paid off you know. It was going good until I got a little down the road. It started like... Stuttering I guess would be the way to put it. Jerking back and forth. And the all of the sudden the car died. I was able to park it but now I was downtown with a dead car. I tried cranking it and it sounded very weak. So I walked a couple miles back home and grabbed my other car and picked up a new battery. I put I on and it turned over and was back on the road. I went to the gas station and after I was done the car started acting up again the shifter would shake violently and It started jerking back and forth and then it died once again. I tried cranking it but this time I could not get it to idle. It would crank and just die. Even with the accelerator all the way to the floor the RPM's would not go above 1500. And then after a while it would not even turn on anymore it just cranks and cranks but never turns on. 

Any ideas?
 Wow!! If it were a horse, I'd shoot it!!

I too would be stumped as to what was going on with it. Obvious checks are in order as others have mentioned. I guess I got lucky when I put in a Flamethrower II coil as it is not a problem. If it is a bad coil, contact Pertronix and they should replace it if it is newish.

Hope you find the cause soon, I feel your frustration.

 
Is the Pertronix Ignitor II internal or external resistence? If it is internal, did you reqire around the primary resistor wire?

Also, is you distibutor clamped down tight? Try moving it by hand (while the car is off).

 
Is the Pertronix Ignitor II internal or external resistence?  If it is internal, did you reqire around the primary resistor wire?

Also, is you distibutor clamped down tight?   Try moving it by hand (while the car is off).
 The Pertronix II MUST have a full 12 V  non resisted connection. They have a relay that makes it a simple connection, but of course I didn't know about that until AFTER I'd cut the dreaded pink resistor wire and bypassed it on my car.

Good point on a loose dizzy.

 
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