Still pinging
- Thread starter rooster57
- Start date
Screaming Metal
Active Member
Hey Rooster........hows the Bucket running? Have you made any progress??????
rooster57
Member
Sorry ive been out of pocket and some rain here has made a test drive impossible. I did degree the cam and my balancer pointer was correct. I set the timing to 6 before and drained out the ethenol and put prem gas from a local mom and pop place here in town , and am waiting on the weather to clear. I ordered a jet kit from a local speed shop. what size jets should i use for a stock 305??? My headder pipes have almost no soot in them still very clean. Is this a sighn of being to lean. The plugs were very clean(only 200 miles on it .
Screaming Metal
Active Member
On a stock motor you want a grayish brown color on your electrode insulators.........whatever jets you got in your carb.....go 2 steps up in size. There will be #'s stamped on the jets from the side the screwdriver slots are on.......you might have as small as 68's and go up to as big as 74's......just depends on what the carb was origionally setup to run.............
Wild Mango
Member
Rooster, the most important part of the ignition timing is how much total you have.
36 degrees is a conservative advance for a proper stoich. fuel mix.(see my little blurb on HEI timing in here).Assuming the weights and posts are in good condition;
Take the flyweight springs out and set 36 degrees. Put the springs back in and see what the idle timing is (all with the advance signal blocked off) should be somewheres about 12 deg, if its any more the springs are pooftered and the advance is starting too early, replace the springs with ones that let the advance start at say 1200 and all in by 3000rpm latest.
If it still rattles after that it ain't the ignition timing.
36 degrees is a conservative advance for a proper stoich. fuel mix.(see my little blurb on HEI timing in here).Assuming the weights and posts are in good condition;
Take the flyweight springs out and set 36 degrees. Put the springs back in and see what the idle timing is (all with the advance signal blocked off) should be somewheres about 12 deg, if its any more the springs are pooftered and the advance is starting too early, replace the springs with ones that let the advance start at say 1200 and all in by 3000rpm latest.
If it still rattles after that it ain't the ignition timing.
Screaming Metal
Active Member
I'd rather run too rich than too lean anyday, economics aside.....thats the wrenchturner in me talkin'. Yes....you should have some soot in the pipes....if not.....well....its too lean.
The 600's are pretty good carbs as long as your ranging from really mild farly warm. For any kinda performance, Holleys or the Barry Gants are good..........
The 600's are pretty good carbs as long as your ranging from really mild farly warm. For any kinda performance, Holleys or the Barry Gants are good..........
I read this thread a while back and almost sure I read the solution, IF the vacuum advance is hooked to manifold vacuum. The pinging does not occur under acceleration, but when you let off the gas. This is when manifold vacuum is highest and will put in max vacuum advance, which seems to be too much. If this is the case, move the vacuum line to a ported vacuum ( increases with carb opening) and your
advance increase with engine speed. If you have a ping then, it will be adjustable with the correct vac adv or springs in the mech adv. ( after base timing is optimized).
good luck,
railroad.
advance increase with engine speed. If you have a ping then, it will be adjustable with the correct vac adv or springs in the mech adv. ( after base timing is optimized).
good luck,
railroad.
rooster57
Member
OK guys my new timing light came in and tonight i found that with the vac line connected to the vac advance at 3000 rpm i had a total of 44 deg of advance. With it disconnected and pluged i had 25 deg advance at 3000 rpm and 8 deg adv at idle 750 rpm. Drove it and no pinging. So thanks guys i may still replace the distributor with a MSD street fire with adj VA. Thanks Railroad for the suggestion you were right there where the problem was . And screeeeemin sheetmetal thanks for hangin in there with a novice, you guys are golden.
Screaming Metal
Active Member
rooster57 said:
Hey....thats what we're here for!!!!!! Happy Haulin!!!!!!!!!!!!!!!!!!!!!!!!!!!
Wild Mango
Member
Not quite done yet, Rooster.
Plug the vacuum advance line into the ported vacuum.There's your problem area.
With 25 deg advance she wouldn't pull a toddler off the pot. Try 36deg. Most HEI's have around 24 deg in the centifugal, so if you start with 12 you should end up with 36. It should be all in by 3000rpm so sounds like you need to put some lighter springs in it.
20deg sounds about right for the vacuum advance, but she must be pulling a good vacuum at 3000rpm or if you got an adjustable vacuum can she might be too light on the adjust.
Then go out, burn some rubber, and then go home and have a decent drink. You deserve it.
Plug the vacuum advance line into the ported vacuum.There's your problem area.
With 25 deg advance she wouldn't pull a toddler off the pot. Try 36deg. Most HEI's have around 24 deg in the centifugal, so if you start with 12 you should end up with 36. It should be all in by 3000rpm so sounds like you need to put some lighter springs in it.
20deg sounds about right for the vacuum advance, but she must be pulling a good vacuum at 3000rpm or if you got an adjustable vacuum can she might be too light on the adjust.
Then go out, burn some rubber, and then go home and have a decent drink. You deserve it.
Ted Brown
Member
Roost, the only real good way to set timimg is to drive it, at 30-35 MPH press down on the gas and it should ping maybe a couple of times before it down shifts, then no pinging should happen, The vac advance is for fuel mileage, as it only works with max vacuum, at cruising speeds, ported from the intake manifold, not the carb, only Fords pull from there... Thats how I have been taught... Works great for me... Happy crusin.
one finger john
Active Member
I'm going to chime in here and say that if I remember correctly, there are two vacuum ports. One port will have very little suction at idle. That is the port that draws its signal from ABOVE the throttle plates. With the plates in the idle position there is little or no vacuum to open the vacuum advance. The other port is below the throttle plates and has a strong vacuum signal at idle because it draws directly from the manifold. I believe it could be used for a vacuum gage. With the vacuum advance hooked to that port you will get the full vacuum at idle that drops off when the throttle plates are opened. As the vacuum drops off the vacuum advance will also close and there will be less davance in the ignition system.
Makes for a bass ackwards sort of advance set up.
So if what I have just described is true, then hook the vacuum advance to the weakest sucking port on the carb at idle. You should be able to run the full 36 degrees at 2500 rpms with no pinging. Your motor has approx. 8.5 compression. Are you running the original dist?
Where ever your cruise rpms are, when you have reached a steady load, the added advance (44 degrees is not unusual) will improve the efficiency of the engine at a steady cruise rpm. It will mpg better and be smoother. Also don't be afraid of 200 degree temps at a steady cruise, The engine does mpg better at that temp. Just make sure your fan thermostat is working properly and the fan comes on at the proper temp.
A trip to a shop with a distributer machine can be the best investment you'll ever make. In my opinion, your engine has all the spark it needs, its just getting everything timed out properly.
You don't need a MSD type of ignition.....yet.
Now you can start to play with the jetting.
If any one disagrees or would like to add, please feel free. I could be wrong.
John
Makes for a bass ackwards sort of advance set up.
So if what I have just described is true, then hook the vacuum advance to the weakest sucking port on the carb at idle. You should be able to run the full 36 degrees at 2500 rpms with no pinging. Your motor has approx. 8.5 compression. Are you running the original dist?
Where ever your cruise rpms are, when you have reached a steady load, the added advance (44 degrees is not unusual) will improve the efficiency of the engine at a steady cruise rpm. It will mpg better and be smoother. Also don't be afraid of 200 degree temps at a steady cruise, The engine does mpg better at that temp. Just make sure your fan thermostat is working properly and the fan comes on at the proper temp.
A trip to a shop with a distributer machine can be the best investment you'll ever make. In my opinion, your engine has all the spark it needs, its just getting everything timed out properly.
You don't need a MSD type of ignition.....yet.
Now you can start to play with the jetting.
If any one disagrees or would like to add, please feel free. I could be wrong.
John
Wild Mango
Member
Right on, One Finger.
Ported vacuum doesn't produce any signal until the throttle is cracked open.
In a light bucket that advance is good for several more miles per gallon, and a clean running engine because all the fuel gets burnt instead of the tarry part ("heavy ends") gooping up the chambers.
Lets all have a decent drink!!!
Ported vacuum doesn't produce any signal until the throttle is cracked open.
In a light bucket that advance is good for several more miles per gallon, and a clean running engine because all the fuel gets burnt instead of the tarry part ("heavy ends") gooping up the chambers.
Lets all have a decent drink!!!
Screaming Metal
Active Member
Ted Brown said:Roost, the only real good way to set timimg is to drive it, at 30-35 MPH press down on the gas and it should ping maybe a couple of times before it down shifts, then no pinging should happen, The vac advance is for fuel mileage, as it only works with max vacuum, at cruising speeds, ported from the intake manifold, not the carb, only Fords pull from there... Thats how I have been taught... Works great for me... Happy crusin.
Hey TED......YOU DA MAN!!!!!!!!!!!!!!!!!!!!!
rooster57
Member
My distributor was connected to the low vac port. When i looked at the timing with the VA connected at idle . It was showing no differance connected or disconnected. but when i ran the motor at 2500 and disconnected the VA it droped from 44 to about 25-28 . What am i doing wrong then guys??? Its a aftermarket new distributor off Ebay. The VA is NOT adjustable. Do i need new springs and weights??? Adj vac pot???
This is an article I found a long time ago that was written by a former GM engineer. His words, not mine, but I thought it was interesting. I will apologize in advance if it is too long.
Jeff
As many of you are aware, timing and vacuum advance is one of my favorite subjects, as I was involved in the development of some of those systems in my GM days and I understand it. Many people don't, as there has been very little written about it anywhere that makes sense, and as a result, a lot of folks are under the misunderstanding that vacuum advance somehow compromises performance. Nothing could be further from the truth. I finally sat down the other day and wrote up a primer on the subject, with the objective of helping more folks to understand vacuum advance and how it works together with initial timing and centrifugal advance to optimize all-around operation and performance. I have this as a Word document if anyone wants it sent to them - I've cut-and-pasted it here; it's long, but hopefully it's also informative.
TIMING AND VACUUM ADVANCE 101
The most important concept to understand is that lean mixtures, such as at idle and steady highway cruise, take longer to burn than rich mixtures; idle in particular, as idle mixture is affected by exhaust gas dilution. This requires that lean mixtures have "the fire lit" earlier in the compression cycle (spark timing advanced), allowing more burn time so that peak cylinder pressure is reached just after TDC for peak efficiency and reduced exhaust gas temperature (wasted combustion energy). Rich mixtures, on the other hand, burn faster than lean mixtures, so they need to have "the fire lit" later in the compression cycle (spark timing retarded slightly) so maximum cylinder pressure is still achieved at the same point after TDC as with the lean mixture, for maximum efficiency.
The centrifugal advance system in a distributor advances spark timing purely as a function of engine rpm (irrespective of engine load or operating conditions), with the amount of advance and the rate at which it comes in determined by the weights and springs on top of the autocam mechanism. The amount of advance added by the distributor, combined with initial static timing, is "total timing" (i.e., the 34-36 degrees at high rpm that most SBC's like). Vacuum advance has absolutely nothing to do with total timing or performance, as when the throttle is opened, manifold vacuum drops essentially to zero, and the vacuum advance drops out entirely; it has no part in the "total timing" equation.
At idle, the engine needs additional spark advance in order to fire that lean, diluted mixture earlier in order to develop maximum cylinder pressure at the proper point, so the vacuum advance can (connected to manifold vacuum, not "ported" vacuum - more on that aberration later) is activated by the high manifold vacuum, and adds about 15 degrees of spark advance, on top of the initial static timing setting (i.e., if your static timing is at 10 degrees, at idle it's actually around 25 degrees with the vacuum advance connected). The same thing occurs at steady-state highway cruise; the mixture is lean, takes longer to burn, the load on the engine is low, the manifold vacuum is high, so the vacuum advance is again deployed, and if you had a timing light set up so you could see the balancer as you were going down the highway, you'd see about 50 degrees advance (10 degrees initial, 20-25 degrees from the centrifugal advance, and 15 degrees from the vacuum advance) at steady-state cruise (it only takes about 40 horsepower to cruise at 50mph).
When you accelerate, the mixture is instantly enriched (by the accelerator pump, power valve, etc.), burns faster, doesn't need the additional spark advance, and when the throttle plates open, manifold vacuum drops, and the vacuum advance can returns to zero, retarding the spark timing back to what is provided by the initial static timing plus the centrifugal advance provided by the distributor at that engine rpm; the vacuum advance doesn't come back into play until you back off the gas and manifold vacuum increases again as you return to steady-state cruise, when the mixture again becomes lean.
The key difference is that centrifugal advance (in the distributor autocam via weights and springs) is purely rpm-sensitive; nothing changes it except changes in rpm. Vacuum advance, on the other hand, responds to engine load and rapidly-changing operating conditions, providing the correct degree of spark advance at any point in time based on engine load, to deal with both lean and rich mixture conditions. By today's terms, this was a relatively crude mechanical system, but it did a good job of optimizing engine efficiency, throttle response, fuel economy, and idle cooling, with absolutely ZERO effect on wide-open throttle performance, as vacuum advance is inoperative under wide-open throttle conditions. In modern cars with computerized engine controllers, all those sensors and the controller change both mixture and spark timing 50 to 100 times per second, and we don't even HAVE a distributor any more - it's all electronic.
Now, to the widely-misunderstood manifold-vs.-ported vacuum aberration. After 30-40 years of controlling vacuum advance with full manifold vacuum, along came emissions requirements, years before catalytic converter technology had been developed, and all manner of crude band-aid systems were developed to try and reduce hydrocarbons and oxides of nitrogen in the exhaust stream. One of these band-aids was "ported spark", which moved the vacuum pickup orifice in the carburetor venturi from below the throttle plate (where it was exposed to full manifold vacuum at idle) to above the throttle plate, where it saw no manifold vacuum at all at idle. This meant the vacuum advance was inoperative at idle (retarding spark timing from its optimum value), and these applications also had VERY low initial static timing (usually 4 degrees or less, and some actually were set at 2 degrees AFTER TDC). This was done in order to increase exhaust gas temperature (due to "lighting the fire late") to improve the effectiveness of the "afterburning" of hydrocarbons by the air injected into the exhaust manifolds by the A.I.R. system; as a result, these engines ran like crap, and an enormous amount of wasted heat energy was transferred through the exhaust port walls into the coolant, causing them to run hot at idle - cylinder pressure fell off, engine temperatures went up, combustion efficiency went down the drain, and fuel economy went down with it.
If you look at the centrifugal advance calibrations for these "ported spark, late-timed" engines, you'll see that instead of having 20 degrees of advance, they had up to 34 degrees of advance in the distributor, in order to get back to the 34-36 degrees "total timing" at high rpm wide-open throttle to get some of the performance back. The vacuum advance still worked at steady-state highway cruise (lean mixture = low emissions), but it was inoperative at idle, which caused all manner of problems - "ported vacuum" was strictly an early, pre-converter crude emissions strategy, and nothing more.
What about the Harry high-school non-vacuum advance polished billet "whizbang" distributors you see in the Summit and Jeg's catalogs? They're JUNK on a street-driven car, but some people keep buying them because they're "race car" parts, so they must be "good for my car" - they're NOT. "Race cars" run at wide-open throttle, rich mixture, full load, and high rpm all the time, so they don't need a system (vacuum advance) to deal with the full range of driving conditions encountered in street operation. Anyone driving a street-driven car without manifold-connected vacuum advance is sacrificing idle cooling, throttle response, engine efficiency, and fuel economy, probably because they don't understand what vacuum advance is, how it works, and what it's for - there are lots of long-time experienced "mechanics" who don't understand the principles and operation of vacuum advance either, so they're not alone.
Vacuum advance calibrations are different between stock engines and modified engines, especially if you have a lot of cam and have relatively low manifold vacuum at idle. Most stock vacuum advance cans arent fully-deployed until they see about 15 Hg. Manifold vacuum, so those cans dont work very well on a modified engine; with less than 15 Hg. at a rough idle, the stock can will dither in and out in response to the rapidly-changing manifold vacuum, constantly varying the amount of vacuum advance, which creates an unstable idle. Modified engines with more cam that generate less than 15 Hg. of vacuum at idle need a vacuum advance can thats fully-deployed at least 1, preferably 2 of vacuum less than idle vacuum level so idle advance is solid and stable; the Echlin #VC-1810 advance can (about $10 at NAPA) provides the same amount of advance as the stock can (15 degrees), but is fully-deployed at only 8 of vacuum, so there is no variation in idle timing even with a stout cam.
For peak engine performance, driveability, idle cooling and efficiency in a street-driven car, you need vacuum advance, connected to full manifold vacuum. Absolutely. Positively. Don't ask Summit or Jeg's about it they dont understand it, they're on commission, and they want to sell "race car" parts.
Jeff
As many of you are aware, timing and vacuum advance is one of my favorite subjects, as I was involved in the development of some of those systems in my GM days and I understand it. Many people don't, as there has been very little written about it anywhere that makes sense, and as a result, a lot of folks are under the misunderstanding that vacuum advance somehow compromises performance. Nothing could be further from the truth. I finally sat down the other day and wrote up a primer on the subject, with the objective of helping more folks to understand vacuum advance and how it works together with initial timing and centrifugal advance to optimize all-around operation and performance. I have this as a Word document if anyone wants it sent to them - I've cut-and-pasted it here; it's long, but hopefully it's also informative.
TIMING AND VACUUM ADVANCE 101
The most important concept to understand is that lean mixtures, such as at idle and steady highway cruise, take longer to burn than rich mixtures; idle in particular, as idle mixture is affected by exhaust gas dilution. This requires that lean mixtures have "the fire lit" earlier in the compression cycle (spark timing advanced), allowing more burn time so that peak cylinder pressure is reached just after TDC for peak efficiency and reduced exhaust gas temperature (wasted combustion energy). Rich mixtures, on the other hand, burn faster than lean mixtures, so they need to have "the fire lit" later in the compression cycle (spark timing retarded slightly) so maximum cylinder pressure is still achieved at the same point after TDC as with the lean mixture, for maximum efficiency.
The centrifugal advance system in a distributor advances spark timing purely as a function of engine rpm (irrespective of engine load or operating conditions), with the amount of advance and the rate at which it comes in determined by the weights and springs on top of the autocam mechanism. The amount of advance added by the distributor, combined with initial static timing, is "total timing" (i.e., the 34-36 degrees at high rpm that most SBC's like). Vacuum advance has absolutely nothing to do with total timing or performance, as when the throttle is opened, manifold vacuum drops essentially to zero, and the vacuum advance drops out entirely; it has no part in the "total timing" equation.
At idle, the engine needs additional spark advance in order to fire that lean, diluted mixture earlier in order to develop maximum cylinder pressure at the proper point, so the vacuum advance can (connected to manifold vacuum, not "ported" vacuum - more on that aberration later) is activated by the high manifold vacuum, and adds about 15 degrees of spark advance, on top of the initial static timing setting (i.e., if your static timing is at 10 degrees, at idle it's actually around 25 degrees with the vacuum advance connected). The same thing occurs at steady-state highway cruise; the mixture is lean, takes longer to burn, the load on the engine is low, the manifold vacuum is high, so the vacuum advance is again deployed, and if you had a timing light set up so you could see the balancer as you were going down the highway, you'd see about 50 degrees advance (10 degrees initial, 20-25 degrees from the centrifugal advance, and 15 degrees from the vacuum advance) at steady-state cruise (it only takes about 40 horsepower to cruise at 50mph).
When you accelerate, the mixture is instantly enriched (by the accelerator pump, power valve, etc.), burns faster, doesn't need the additional spark advance, and when the throttle plates open, manifold vacuum drops, and the vacuum advance can returns to zero, retarding the spark timing back to what is provided by the initial static timing plus the centrifugal advance provided by the distributor at that engine rpm; the vacuum advance doesn't come back into play until you back off the gas and manifold vacuum increases again as you return to steady-state cruise, when the mixture again becomes lean.
The key difference is that centrifugal advance (in the distributor autocam via weights and springs) is purely rpm-sensitive; nothing changes it except changes in rpm. Vacuum advance, on the other hand, responds to engine load and rapidly-changing operating conditions, providing the correct degree of spark advance at any point in time based on engine load, to deal with both lean and rich mixture conditions. By today's terms, this was a relatively crude mechanical system, but it did a good job of optimizing engine efficiency, throttle response, fuel economy, and idle cooling, with absolutely ZERO effect on wide-open throttle performance, as vacuum advance is inoperative under wide-open throttle conditions. In modern cars with computerized engine controllers, all those sensors and the controller change both mixture and spark timing 50 to 100 times per second, and we don't even HAVE a distributor any more - it's all electronic.
Now, to the widely-misunderstood manifold-vs.-ported vacuum aberration. After 30-40 years of controlling vacuum advance with full manifold vacuum, along came emissions requirements, years before catalytic converter technology had been developed, and all manner of crude band-aid systems were developed to try and reduce hydrocarbons and oxides of nitrogen in the exhaust stream. One of these band-aids was "ported spark", which moved the vacuum pickup orifice in the carburetor venturi from below the throttle plate (where it was exposed to full manifold vacuum at idle) to above the throttle plate, where it saw no manifold vacuum at all at idle. This meant the vacuum advance was inoperative at idle (retarding spark timing from its optimum value), and these applications also had VERY low initial static timing (usually 4 degrees or less, and some actually were set at 2 degrees AFTER TDC). This was done in order to increase exhaust gas temperature (due to "lighting the fire late") to improve the effectiveness of the "afterburning" of hydrocarbons by the air injected into the exhaust manifolds by the A.I.R. system; as a result, these engines ran like crap, and an enormous amount of wasted heat energy was transferred through the exhaust port walls into the coolant, causing them to run hot at idle - cylinder pressure fell off, engine temperatures went up, combustion efficiency went down the drain, and fuel economy went down with it.
If you look at the centrifugal advance calibrations for these "ported spark, late-timed" engines, you'll see that instead of having 20 degrees of advance, they had up to 34 degrees of advance in the distributor, in order to get back to the 34-36 degrees "total timing" at high rpm wide-open throttle to get some of the performance back. The vacuum advance still worked at steady-state highway cruise (lean mixture = low emissions), but it was inoperative at idle, which caused all manner of problems - "ported vacuum" was strictly an early, pre-converter crude emissions strategy, and nothing more.
What about the Harry high-school non-vacuum advance polished billet "whizbang" distributors you see in the Summit and Jeg's catalogs? They're JUNK on a street-driven car, but some people keep buying them because they're "race car" parts, so they must be "good for my car" - they're NOT. "Race cars" run at wide-open throttle, rich mixture, full load, and high rpm all the time, so they don't need a system (vacuum advance) to deal with the full range of driving conditions encountered in street operation. Anyone driving a street-driven car without manifold-connected vacuum advance is sacrificing idle cooling, throttle response, engine efficiency, and fuel economy, probably because they don't understand what vacuum advance is, how it works, and what it's for - there are lots of long-time experienced "mechanics" who don't understand the principles and operation of vacuum advance either, so they're not alone.
Vacuum advance calibrations are different between stock engines and modified engines, especially if you have a lot of cam and have relatively low manifold vacuum at idle. Most stock vacuum advance cans arent fully-deployed until they see about 15 Hg. Manifold vacuum, so those cans dont work very well on a modified engine; with less than 15 Hg. at a rough idle, the stock can will dither in and out in response to the rapidly-changing manifold vacuum, constantly varying the amount of vacuum advance, which creates an unstable idle. Modified engines with more cam that generate less than 15 Hg. of vacuum at idle need a vacuum advance can thats fully-deployed at least 1, preferably 2 of vacuum less than idle vacuum level so idle advance is solid and stable; the Echlin #VC-1810 advance can (about $10 at NAPA) provides the same amount of advance as the stock can (15 degrees), but is fully-deployed at only 8 of vacuum, so there is no variation in idle timing even with a stout cam.
For peak engine performance, driveability, idle cooling and efficiency in a street-driven car, you need vacuum advance, connected to full manifold vacuum. Absolutely. Positively. Don't ask Summit or Jeg's about it they dont understand it, they're on commission, and they want to sell "race car" parts.
one finger john
Active Member
Alright, we're getting there.
We know that the distributer is plugged into the proper vacuum port. Remember that.
We know that the vacuum advance is working properly by the way the timing retards at 3000 rpms when the vacuum is disconnected. It drops from 44 degrees to 25 degrees.
We know that with the vacuum advance disconnected the timing retards to 25-28 degrees total at 3000 rpms. This is on the mechanical advance system of springs and weights.
Now disconnect the vacuum advance and plug the vacuum port. The car will run fine without it.
We need to find out how many TOTAL degrees of advance there are in the distributer. Should be 24 degrees. Set the ignition timing at 0 degrees and then check the timing at 3000 rpms. Advance should be be all in at that point and it should be 24 degrees.
Now go back, with the vacuum advance still disconnected, and set the ignition timing at 12 degrees befor top dead center. Adjust idle to approx. 700-800 rpms. Recheck timing and adjust to 12 degrees before top dead center @ 700-800 rpms.
Recheck TOTAL ignition at 3000 rpms and it should be 36 degrees.
Reconnect vacuum advance and at 3000 rpms the total timing should be 44-46 degrees. With the timing reset to the proper total timing, there should be 10 degrees more vacuum advance timing added. If more, say 50 or more, then an adjustable vacuum advance canister will need to be installed to get the proper extra 10 degrees of vacuum advance
(46 degrees total under vacuum).
Drive the car with the vacuum both disconnected and connected to determan if the car is now pinging under any conditions. (With the vacuum disconnected, don't forget to plug the port)
Again I would recommend that if all this running up of the engine makes you unconfortable, take the distributer out and take it to a shop that has a distributer machine and spend the money to have it done properly. Be safe, I would put the rear up on sturdy jack stands and make sure it was in park.
Also, is the dampener on the car a degreed dampner? Or do you have one of those pieces of tape with the degrees on it. Has the dampener broken the rubber and can move (changing the timing marks and giving different readings)
Lastly, is this a used distributer or a new distributer? Is It HEI or regular electronic? Is it a points distributer? Is it a known American product or from off shore (say Quam, Peru, or China, even India)?
If it is an American or Australian product you should be able to call a hotline and get suggestions to diagnose and repair the problem.
Let us know how it goes, John
We know that the distributer is plugged into the proper vacuum port. Remember that.
We know that the vacuum advance is working properly by the way the timing retards at 3000 rpms when the vacuum is disconnected. It drops from 44 degrees to 25 degrees.
We know that with the vacuum advance disconnected the timing retards to 25-28 degrees total at 3000 rpms. This is on the mechanical advance system of springs and weights.
Now disconnect the vacuum advance and plug the vacuum port. The car will run fine without it.
We need to find out how many TOTAL degrees of advance there are in the distributer. Should be 24 degrees. Set the ignition timing at 0 degrees and then check the timing at 3000 rpms. Advance should be be all in at that point and it should be 24 degrees.
Now go back, with the vacuum advance still disconnected, and set the ignition timing at 12 degrees befor top dead center. Adjust idle to approx. 700-800 rpms. Recheck timing and adjust to 12 degrees before top dead center @ 700-800 rpms.
Recheck TOTAL ignition at 3000 rpms and it should be 36 degrees.
Reconnect vacuum advance and at 3000 rpms the total timing should be 44-46 degrees. With the timing reset to the proper total timing, there should be 10 degrees more vacuum advance timing added. If more, say 50 or more, then an adjustable vacuum advance canister will need to be installed to get the proper extra 10 degrees of vacuum advance
(46 degrees total under vacuum).
Drive the car with the vacuum both disconnected and connected to determan if the car is now pinging under any conditions. (With the vacuum disconnected, don't forget to plug the port)
Again I would recommend that if all this running up of the engine makes you unconfortable, take the distributer out and take it to a shop that has a distributer machine and spend the money to have it done properly. Be safe, I would put the rear up on sturdy jack stands and make sure it was in park.
Also, is the dampener on the car a degreed dampner? Or do you have one of those pieces of tape with the degrees on it. Has the dampener broken the rubber and can move (changing the timing marks and giving different readings)
Lastly, is this a used distributer or a new distributer? Is It HEI or regular electronic? Is it a points distributer? Is it a known American product or from off shore (say Quam, Peru, or China, even India)?
If it is an American or Australian product you should be able to call a hotline and get suggestions to diagnose and repair the problem.
Let us know how it goes, John
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