Hope this makes it a little more clear
CK5
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Timing Marks
- Thread starter RootBreaker
- Start date
Hope this makes it a little more clear
^^^ yes that makes sense...
so i just went out..
fired the truck up... set the timing light to 12°.... then set timing to 30° and cranked the throttle up to 3000rpms...
adjusted.. very little to get it to 0°.....
then turned the idle screw down.. adjusted the air fuel screws some... and viola.. she is running what seem good to me..
go to shut the truck off.. and it does the running on as if the timing is too high... dunno.....
so i just went out..
fired the truck up... set the timing light to 12°.... then set timing to 30° and cranked the throttle up to 3000rpms...
adjusted.. very little to get it to 0°.....
then turned the idle screw down.. adjusted the air fuel screws some... and viola.. she is running what seem good to me..
go to shut the truck off.. and it does the running on as if the timing is too high... dunno.....
Have you checked where the engine really is yet? I mean by dropping the oil pan or sticking something down the spark plug hole. When you know where #1 TDC really is then you know whether or not to believe the timing marks. Maybe you did this and I forgot I read it.
we did this when we put the new distributor in... but im thinking of doing this again too...
im so frustrated.. i almost pulled over tonight and walked away.. adjusted it up and thought it was good.. but couldnt give more than 1/2 throttle... tried a few adjustments and just got tired of it...
so my uncle is into race cars.. hopefully he will help me.. waiting for a callback..
however.. im going to pay a shop to work on the truck if not.. so with that..
ryoken... wanna make a few extra bucks? i know you know what your doing. or if anyone else out there is able to...
i got CASH!!!!!
you are catching me at a bad time bud... spring commisioning season is rough, but I could manage some time for ya if it wasn't for the Nogo..... it's barely roadworthy these days and I really don't trust it much further than my marina down the street... just trying to eeeek her thru till the CC gets here..
we CAN walk you thru this... you should verify TDC.... most sure fire way without being positive on the tab will be this...
first pull the coil wire out of the truck... pull all the plugs out... than set up a big ratchet on the crank bolt... you can either put your finger over the #1 plug hole and feel for compression, or might I suggest pulling the valve cover on that side to watch the valves, bit less of a 3 fisted monkee fock that way..
anyway, once you feel some compression start, or the intake valve has closed, take a small diameter piece of wire, like a folded out paper clip, put a bit of a bend in the end.. than stick that in the plug hole, going downward till you feel the piston. rotate the motor over, you will feel the wire coming up..
if your timing mark is correct it will come up to 0 the next time around. but double check/verify this with the wire, rotate till the wire is up top of the cylinder bore, check the mark...
once at known TDC, verify the dizzy by pulling the cap and marking where the rotor is pointing on the intake with a sharpie... reinstall cap and verify the mark is at the #1 tower... adjust accordingly, or relace as necessary..
if your certain that is all correct, we'll move on to the next diagnostic..
we CAN walk you thru this... you should verify TDC.... most sure fire way without being positive on the tab will be this...
first pull the coil wire out of the truck... pull all the plugs out... than set up a big ratchet on the crank bolt... you can either put your finger over the #1 plug hole and feel for compression, or might I suggest pulling the valve cover on that side to watch the valves, bit less of a 3 fisted monkee fock that way..
anyway, once you feel some compression start, or the intake valve has closed, take a small diameter piece of wire, like a folded out paper clip, put a bit of a bend in the end.. than stick that in the plug hole, going downward till you feel the piston. rotate the motor over, you will feel the wire coming up..
if your timing mark is correct it will come up to 0 the next time around. but double check/verify this with the wire, rotate till the wire is up top of the cylinder bore, check the mark...
once at known TDC, verify the dizzy by pulling the cap and marking where the rotor is pointing on the intake with a sharpie... reinstall cap and verify the mark is at the #1 tower... adjust accordingly, or relace as necessary..
if your certain that is all correct, we'll move on to the next diagnostic..
CGT80
1/2 ton status
I just dropped a new engine in my K5. On the engine stand, with manifolds, I could see the piston and exhaust valve through the spark plug hole with a flash light. I don't know if it can be done in a truck. You could always use a cell phone to take a picture of video of it, or use it as a view finder.
When I turned my engine by hand I felt pressure twice for each revolution. Once for the exhaust stroke, and once for compression. The pulse from the exhaust stroke was weaker because the exhaust valve was open-I could also see the valve drop down just before the piston came to the top. My timing mark also lined up-this is 180 out.
The next stroke of the piston produced more pressure and I could not see the exhaust valve when the piston approached the top. I rotated the engine until the piston was all the way up-TDC. This set my harmonic balancer mark to the zero mark on the timing scale.
My 406sbc runs best at 12 degrees BTDC or advanced-it has the comp cams 270h magnum-224/224 @ 50. I think the scale on my pickup goes to 16 degrees of advance, so don't rely on counting teeth unless you are sure of the value of each one.
The idle will effect the timing. You may have to adjust the idle and then the timing a few times. Both of my trucks idle at 550 rpm while stopped in gear (auto trans). I think I set my timing at about 650 while in park, without the vacuum advance connected.
Total timing can get quite complex. I am still not done setting mine up for the 406. If your msd distributor hasn't been messed with, and it has a mechanical advance, it should be set pretty slow just as my msd was. To get your truck running, just check the total timing as Ryoken suggested.
I am working on fine tuning the vac advance signal strength and amount, and am using an advance stop as well, and I am trying to get the mechanical rate and total correct. This is all on a 10:1 engine with a mid sized cam that sits in a 6500 pound truck and tows a 9k pound trailer. I wish I had a digital timing light with a tach built into it to help me get things set right. I need to give my truck another shot-setting the timing that is. My dad has the single dial timing light. It works, but I have to have someone watch my tach as I try to check the timing.
Maybe you could put marks on both parts of the balancer and maybe even the crank pulley, so that you can see if they slip in the future.
One last thing. I run an adjustable timing controller in my cab, from MSD. When I first installed it, I didn't take the ignition module out of my dizzy. End up, I saw the ground wire on my module and thought it was a 5 wire, it really is a 4 wire and has to be removed when using the controller. I had two modules fighting each other. Make sure that if your using an MSD box that everything is hooked up properly. I am running the 8365 pro billet HEI. It is the equivalent of the factory HEI with the coil in the cap. Yours may be different and the setup could be different than my truck.
Good luck.
When I turned my engine by hand I felt pressure twice for each revolution. Once for the exhaust stroke, and once for compression. The pulse from the exhaust stroke was weaker because the exhaust valve was open-I could also see the valve drop down just before the piston came to the top. My timing mark also lined up-this is 180 out.
The next stroke of the piston produced more pressure and I could not see the exhaust valve when the piston approached the top. I rotated the engine until the piston was all the way up-TDC. This set my harmonic balancer mark to the zero mark on the timing scale.
My 406sbc runs best at 12 degrees BTDC or advanced-it has the comp cams 270h magnum-224/224 @ 50. I think the scale on my pickup goes to 16 degrees of advance, so don't rely on counting teeth unless you are sure of the value of each one.
The idle will effect the timing. You may have to adjust the idle and then the timing a few times. Both of my trucks idle at 550 rpm while stopped in gear (auto trans). I think I set my timing at about 650 while in park, without the vacuum advance connected.
Total timing can get quite complex. I am still not done setting mine up for the 406. If your msd distributor hasn't been messed with, and it has a mechanical advance, it should be set pretty slow just as my msd was. To get your truck running, just check the total timing as Ryoken suggested.
I am working on fine tuning the vac advance signal strength and amount, and am using an advance stop as well, and I am trying to get the mechanical rate and total correct. This is all on a 10:1 engine with a mid sized cam that sits in a 6500 pound truck and tows a 9k pound trailer. I wish I had a digital timing light with a tach built into it to help me get things set right. I need to give my truck another shot-setting the timing that is. My dad has the single dial timing light. It works, but I have to have someone watch my tach as I try to check the timing.
Maybe you could put marks on both parts of the balancer and maybe even the crank pulley, so that you can see if they slip in the future.
One last thing. I run an adjustable timing controller in my cab, from MSD. When I first installed it, I didn't take the ignition module out of my dizzy. End up, I saw the ground wire on my module and thought it was a 5 wire, it really is a 4 wire and has to be removed when using the controller. I had two modules fighting each other. Make sure that if your using an MSD box that everything is hooked up properly. I am running the 8365 pro billet HEI. It is the equivalent of the factory HEI with the coil in the cap. Yours may be different and the setup could be different than my truck.
Good luck.
yeah no time to work on it this weekend...
when i put the dizzy in we took the hei out.. to replace with the msd 6al plug in.. i also have a timing advance unit...
here is the parts list on msd in my truck..
MSD Wires - 8.8
MSD Distributor 8362
MSD advanced curve kit 8428
MSD 6AL 6425 - serviced by MSD
MSD Adjustable timing control 8680
MSD Adjustable REV pill 8671
ok so i went out... turned motor over till the line on the balancer was in the V (0).... just for a starting point..
i put a long zip tie through the #1 plug... had my son push on it.. while I turned the motor clockwise... he said the zip tie went in.. did not go up or anything.... i then backed it out and zip tie came out some.. till it plateaued... at that point... im at TDC... we looked at the timing mark on the balancer and V and it is lined up... so good there..
i then took the distro cap off.. and it is pointing at #1 so that is good too..
so what now?...
i have to take my 12yr old to soccer practice.. but figured that I would come home.. start the truck and let it warm up... then... use the new timing light set to 12 degrees then adjust the idle screw till 30 degrees zeroes out...
sound right?
im thinking it is something with this carb... i know it..
i usually just work the throttle by hand while using the timing light in the other hand... you can see exactly how much total timing ya have fine adjusting the lights advance till the pointer is at zero.. like i said, sbc are usually a minimum of 28, but not uncommon to run 32 -34... most GM curves are all in by 3 g's...
watch your appendages...
watch your appendages...
Think my new timing light is bad... Cant get it to give any strobe or rpm.... It will give a flash on occasion but not constantly
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CGT80
1/2 ton status
If you set the timing light dial to 12 degrees and adjust your dizzy to 0 degrees when the light in on wire number 1, you will have your 12 initial. My truck calls for 8 initial for CA emissions. I run my 406 at 12 though. With your vacuum advance not hooked up and the line capped, your idle should be around 650rpm in park. My smog sticker says a curb idle of 550rpm. My truck idles at 550-600 at an idle, in gear, at a stop light. After you adjust the idle, recheck the timing. One will affect the other.
To get total timing. Leave the vacuum can unhooked and bring the engine up to speed with the light on the timing mark. When the mark stops moving, adjust the dial on the light so that the mark is at 0 degrees on your timing cover. If your timing light dial says 30 degrees then that is what your total is. 30 total - 12 initial = 18 mechanical advance.
This part does not make sense: adjust the idle screw till 30 degrees zeroes out...
thanks for the explanation...
my new timing light took a crap as i mentioned.. it wont light anymore.. it will flicker once or twice.. the rpm just reads 0000.. so going to have to take it back...
now side note...
I found out my neighbor had my old timing light so will be able to get the initial timing of 12 set.. hopefully tonight..
on my way home im going to pickup a qjet carb from craigslist... guy said it is fresh and clean.. just took off of car 2 weeks ago.. he took it off cuz it wasnt enough for 500hp....
so will pick that up and put it on.. then start the truck and try what you say for initial 12 (with old gun so no set to 12 on gun).. then idle down to 650rpm...
will get my new gun swapped out tomorrow hopefully.. then can try and set the max timing..
now when you didnt understand what i was saying...
i was mainly saying what you said but you worded it better.. since i got this timing light i figured you should be able to ajust the idle screw to 3000 rpm's instead of just using the throttle and holding the gun.. that makes it difficult to also hit the buttons on the timing light..
so as Ryoken mentioned.. 3000 rpms roughly.. so i was mentioning to use the idle screw... then when done.. idle back down to 600-700rpms..
now side note... you are saying to do all of this with the mechanical advance disconnected and plugged...
sorry im so bad at this timing as you can see from this long thread.. but if the can is supposed to give 18 degrees of timing... if it is plugged and not connected.. how is it going to read 19+12 for 30???
more to come..
and thanks all for being patient.. im really horrible with this part...
side note.. my uncle said i should be turning 18lbs vacuum...
does that sound right? i think when i was setting my air fuel screws with a vacuum gauge.. it read 14.... he is saying that means i may have an issue with my motor.. ..
CGT80
1/2 ton status
Now I get what you meant by the idle for 3000 rpm. You are dealing with three different controls for your timing. The initial you understand-it is just a matter of turning the whole distributor. The vacuum advance is the "can"-when it has a vacuum signal (part throttle and sometimes at an idle) it pulls on an arm to turn the inside of the dizzy, similar to you turning it by hand.
The mechanical advance also turns the inside of the dizzy, but it is controlled by a set of weights and springs. The weights move more as the engine is spun faster. It is also called centrifugal advance. The centrifugal force moves the weights. The springs control how soon it moves. There is also a bushing on some to control how many degrees it can move.
The mechanical advance is always tied directly to the engine rpm. Every time the engine hits 2k rpm it will have a certain amount of advance. Every time it hits 3krpm it will have a certain amount. It doesn't matter how well the engine runs, or how hard or easy you are working the engine. Vacuum signal doesn't matter. Only rpm.
Your initial timing is only controlled by turning the distributor body and tightening the hold down clamp. It never changes if you don't change it.
You start with 12 degrees of initial set by you. That should never change from where you put it, if everything is in working order. At an idle you will have 12 degrees.
As soon as you start to spin the distributor faster, by revving the engine, the mechanical/centrifugal advance will twist the inner part of the dizzy to 13 degrees, then 14, 15, etc. as it is spun faster. If your mechanical advance is set to add 20 degrees, you will start at 0 added at an idle (12 initial+0 mechanical=12 total), when the engine rpm gets up around 3k rpm the mechanical will advance the distributor by 20 degrees. You already have 12 initial, so add 20 to that. You get 32 degrees total initial and mechanical.
With the vacuum can disconnected, you only have two variables. initial and mechanical.
Once the vacuum can is connected it too will add timing to the dizzy. The more vacuum signal you have, the more timing it adds. At wide open throttle you should have 0 inches of vacuum if the carb and exhaust are big enough for the engine.
(my 406 sbc still pulls 5 inches of vacuum at 5500 rpm with a 600 cfm carb. The engine is still trying to suck more air than the carb will allow.) 0 pull on the vacuum advance means 0 degrees added.
If you are cruising down the freeway at very light throttle, you will have decent vacuum. You might see something like 18 degrees of vacuum advance plus 20 degrees of mechanical advance (if your rpm is up there) and your initial of 12 degrees.
18+20+12=50 degrees
Your engine at light throttle will not be likely to ping and is not working hard. 50 degrees of advance will help to better burn all the fuel your using.
If you mash the throttle, to wide open, you will put a load on the engine and cause it to work very hard. Your engine would ping with 50 degrees of advance. Luckily when you mash the throttle, your vacuum level in the engine drops to near 0. That mean 0 degrees of vacuum advance. You end up with 20 mechanical (because you are still spinning near 3krpm or better) and the 12 initial (because it never changes) and you have only 32 degrees of advance while the truck is floored. This keeps the pinging down or eliminated.
Since the vacuum advance changes often, you leave it out of the equation when setting up your distributor. When you want to get all crazy, like I have, you start to adjust how much advance the can will give and at what vacuum levels it will do it. That is a whole other story, that I haven't even finished dealing with.
I am no pro with all of this, but I have been through what you are doing. I still have to go back and double check what my mechanical advance is doing. You can control at least two variables on the mechanical advance and two on the vacuum advance, plus you can choose whether you want vacuum advance at an idle. This can be a bit of work. As you can see, I'm just a little ahead of you in the same game.
Well I hope this gives you some help.
Oh yes, in regards to your vacuum level at an idle: The bigger the cam you run in an engine, usually, the less vacuum you will have. My POS cheap rebuilt 350 used to have about 18" of vacuum. It had a hamburger cam in it. You know, what hamburger is right? ground round (steak)
The cam probably way less than a 200 duration for intake and exhaust. It probably didn't have much bump on the bump stick. The sound of the idle was completely smooth and boring, and the performance was just as bad. A bigger cam (higher duration) would give you less vacuum. My 406 is a 224/224. In that size engine with the head and intake work it has, there is definitely a noticeable idle, but it is not lopey or real choppy. Without some of the head work or if it was installed in a smaller engine, it would seem bigger and give a rough idle. It's been a while, but I don't think I had more than 15 or 16 inches of vacuum at an idle. My carb is pretty well adjusted as well. I think most people adjust a carb to obtain the highest amount of vacuum. The advice you got doesn't seem to be bad.
Your mechanical advance may max out somewhere other than 3000 rpm. A stock distributor could max out at a higher rpm. Your throttle screw idea may or may not work well. I can control the throttle at the carb and watch the timing light at the same time. I will run the engine up and check the mark. If it is off, I adjust the knob on the light a little, and run the speed up again. Eventually you will get the mark to line up at zero so you can read the total advance from the dial on the light. You will also see the mark come up toward zero on your engine timing chain cover as you rev the engine. When you rev it more, but the mark fails to continue to move, you have found the "all in" point. If it's all in by 3k, your amount of advance will be the same from 3k to red line. If it is all in by 2k, you will end up with too much advance too soon. I had this problem on mine. The adjustments I made to the mechanical advance didn't match what MSD's chart said I should have.
Damn that is one long post
The mechanical advance also turns the inside of the dizzy, but it is controlled by a set of weights and springs. The weights move more as the engine is spun faster. It is also called centrifugal advance. The centrifugal force moves the weights. The springs control how soon it moves. There is also a bushing on some to control how many degrees it can move.
The mechanical advance is always tied directly to the engine rpm. Every time the engine hits 2k rpm it will have a certain amount of advance. Every time it hits 3krpm it will have a certain amount. It doesn't matter how well the engine runs, or how hard or easy you are working the engine. Vacuum signal doesn't matter. Only rpm.
Your initial timing is only controlled by turning the distributor body and tightening the hold down clamp. It never changes if you don't change it.
You start with 12 degrees of initial set by you. That should never change from where you put it, if everything is in working order. At an idle you will have 12 degrees.
As soon as you start to spin the distributor faster, by revving the engine, the mechanical/centrifugal advance will twist the inner part of the dizzy to 13 degrees, then 14, 15, etc. as it is spun faster. If your mechanical advance is set to add 20 degrees, you will start at 0 added at an idle (12 initial+0 mechanical=12 total), when the engine rpm gets up around 3k rpm the mechanical will advance the distributor by 20 degrees. You already have 12 initial, so add 20 to that. You get 32 degrees total initial and mechanical.
With the vacuum can disconnected, you only have two variables. initial and mechanical.
Once the vacuum can is connected it too will add timing to the dizzy. The more vacuum signal you have, the more timing it adds. At wide open throttle you should have 0 inches of vacuum if the carb and exhaust are big enough for the engine.
(my 406 sbc still pulls 5 inches of vacuum at 5500 rpm with a 600 cfm carb. The engine is still trying to suck more air than the carb will allow.) 0 pull on the vacuum advance means 0 degrees added.
If you are cruising down the freeway at very light throttle, you will have decent vacuum. You might see something like 18 degrees of vacuum advance plus 20 degrees of mechanical advance (if your rpm is up there) and your initial of 12 degrees.
18+20+12=50 degrees
Your engine at light throttle will not be likely to ping and is not working hard. 50 degrees of advance will help to better burn all the fuel your using.
If you mash the throttle, to wide open, you will put a load on the engine and cause it to work very hard. Your engine would ping with 50 degrees of advance. Luckily when you mash the throttle, your vacuum level in the engine drops to near 0. That mean 0 degrees of vacuum advance. You end up with 20 mechanical (because you are still spinning near 3krpm or better) and the 12 initial (because it never changes) and you have only 32 degrees of advance while the truck is floored. This keeps the pinging down or eliminated.
Since the vacuum advance changes often, you leave it out of the equation when setting up your distributor. When you want to get all crazy, like I have, you start to adjust how much advance the can will give and at what vacuum levels it will do it. That is a whole other story, that I haven't even finished dealing with.
I am no pro with all of this, but I have been through what you are doing. I still have to go back and double check what my mechanical advance is doing. You can control at least two variables on the mechanical advance and two on the vacuum advance, plus you can choose whether you want vacuum advance at an idle. This can be a bit of work. As you can see, I'm just a little ahead of you in the same game.
Well I hope this gives you some help.
Oh yes, in regards to your vacuum level at an idle: The bigger the cam you run in an engine, usually, the less vacuum you will have. My POS cheap rebuilt 350 used to have about 18" of vacuum. It had a hamburger cam in it. You know, what hamburger is right? ground round (steak)
The cam probably way less than a 200 duration for intake and exhaust. It probably didn't have much bump on the bump stick. The sound of the idle was completely smooth and boring, and the performance was just as bad. A bigger cam (higher duration) would give you less vacuum. My 406 is a 224/224. In that size engine with the head and intake work it has, there is definitely a noticeable idle, but it is not lopey or real choppy. Without some of the head work or if it was installed in a smaller engine, it would seem bigger and give a rough idle. It's been a while, but I don't think I had more than 15 or 16 inches of vacuum at an idle. My carb is pretty well adjusted as well. I think most people adjust a carb to obtain the highest amount of vacuum. The advice you got doesn't seem to be bad.Your mechanical advance may max out somewhere other than 3000 rpm. A stock distributor could max out at a higher rpm. Your throttle screw idea may or may not work well. I can control the throttle at the carb and watch the timing light at the same time. I will run the engine up and check the mark. If it is off, I adjust the knob on the light a little, and run the speed up again. Eventually you will get the mark to line up at zero so you can read the total advance from the dial on the light. You will also see the mark come up toward zero on your engine timing chain cover as you rev the engine. When you rev it more, but the mark fails to continue to move, you have found the "all in" point. If it's all in by 3k, your amount of advance will be the same from 3k to red line. If it is all in by 2k, you will end up with too much advance too soon. I had this problem on mine. The adjustments I made to the mechanical advance didn't match what MSD's chart said I should have.
Damn that is one long post
Last edited:
ok... my qjet carb is now on.. she is running better..
fired up the truck.. set timing to 12 degrees... set idle...
now i have a question..
if i turn the truck off and it shutters.. (doesnt want to shut off) timing is still too advanced right?
hit the gas a few times and it backfired through the carb though.. does that mean too advanced or too low of timing?
i thought the pop meant too low.. but when i went to turn it off.. it shuttered a little bit.. not much.. so i turned the dizzy down a tad like a militad and now it will shut off on its own...
fired up the truck.. set timing to 12 degrees... set idle...
now i have a question..
if i turn the truck off and it shutters.. (doesnt want to shut off) timing is still too advanced right?
hit the gas a few times and it backfired through the carb though.. does that mean too advanced or too low of timing?
i thought the pop meant too low.. but when i went to turn it off.. it shuttered a little bit.. not much.. so i turned the dizzy down a tad like a militad and now it will shut off on its own...
CGT80
1/2 ton status
I think you are correct about the engine dieseling or running on. Mine will do it once in a while. I think I also found that reducing the timing helped. Also make sure the idle is low enough. If the initial timing advance is too high, it will also be hard to start.
I can't run any more than 12 degrees on my engine. I tried it, but the powermaster high torque mini starter just wasn't up to the task. For all I know, it could be hard on the engine anyway. I was told that due to the work on the heads, the compression, and the cam being advanced, that the cylinder pressure would be high on my engine and that it will require a decent effort from the starter to spin it over.
Have you driven your truck? Did you try to check the total timing at 3k rpm?
I can't run any more than 12 degrees on my engine. I tried it, but the powermaster high torque mini starter just wasn't up to the task. For all I know, it could be hard on the engine anyway. I was told that due to the work on the heads, the compression, and the cam being advanced, that the cylinder pressure would be high on my engine and that it will require a decent effort from the starter to spin it over.
Have you driven your truck? Did you try to check the total timing at 3k rpm?
