Timing. How you can accurately check your ignition timing and cam timing.

[ace.cafe]

Big subject this morning.
I got an email from a member who requested that I post some information on this subject.


Okay, here we go.

First, you need some tools.
A graduated degree wheel(timing disc) that can fit on the crank on the primary side. Large diameter size is good, so that it's easy to read.
A dial-indicator with a clamp mount and a gooseneck or strut for positioning is needed.
A spark-plug adapter for the dial indicator would be a nice thing too.

So what do we do first?
Well first, we drain the primary chaincase, and remove the  cover.
Then we take a look at our crankshaft stub that comes thru the alternator.  If we have enough threads sticking out there, then we can just put the degree wheel right on, and put a correctly threaded nut on to hold it in place. If we don't have enough threads, then we can remove the alternator nut, and use that to hold the degree wheel in place.
Don't tighten it up yet, because we haven't indexed it yet..

Then, we can take out the spark plug to find top-dead-center(TDC).
After removing the spark plug, rotate the engine until the piston is coming to the top on the compression stroke.
How do you know you're on the compression stroke?
Both valves are fully closed near TDC on the compression stroke. Just like when you are adjusting your valves.
You can use your dial indicator to find exact TDC, with your spark plug adapter for the dial indicator. Or you can use your TDC finding tool from CMW. Or whatever you want, but find TDC exactly. TDC is when the piston has come all the way up, and hasn't started to go down. In reality, there is a short "dwell time" at the top of the stroke around TDC, which may not be easily seen. So you take your dial indicator or measuring tool, and find the "halfway point" between where you can determine that it is moving either up or down. This will settle your location at TDC.
Leave it right there, and don't move the engine at all after that.

Then, we can index the degree wheel.
Rotate the degree wheel until the 0/360 mark is at the top.
Then tighten the nut gently, but firmly enough to hold the degree wheel from being moved when we later turn the engine by hand.
MAKE CERTAIN that when you tighten it, you don't move the engine. It may be good to go back and re-check your TDC position after you tighten the nut.

Ok, now you must make a pointer.
This can be a wire or a pointy piece of metal, or whatever you can affix to the primary case or any non-moving bolt near the top of the degree wheel.. Bend the pointer tip so that it points directly and perfectly at the 0/360 mark.
This is your timing indicator pointer. Make sure it is tight enough to not move around.

Now you have the engine at TDC, the degree wheel affixed to the crank, and the pointer pointing at the TDC mark on the degree wheel.
Double-check that your piston is at perfect TDC, and that the pointer is pointing exactly at the 0/360 mark on the degree wheel.
You are now indexed, and ready to start measuring timing.

To check ignition timing, you can rotate the crank backwards(opposite of the direction during running), back down into the compression stroke area, until you note that the distributor cam lobe is not opening the points yet. Then begin to rotate the engine in the direction that it runs, until the points just begin to open. If you have a 12v timing test light, you can use it for determining this. When the points just begin to open, you can then look at what degree the pointer is pointing at. This is your static ignition timing point, at start-up/cranking. If you've previously timed at 0.8mm BTDC, you can now see how many engine degrees BTDC that is.
If you want to know what your points "dwell" is, you can note the degrees when the points just open, and then again as the points just barely close, and that number of degrees is your "ignition points dwell angle".
Easy, right?
Yep!

Okay, now let's say we now want to find our cam timing, using the degree wheel and dial indicator.
Well, we'll have to get the tank off, and remove the rocker covers for this.
So, while you're doing that, I'll go get a cup of coffee.

Ready?
Okay, now use the clamp mount of your dial indicator to clamp it onto the head or rocker block or something solid that isn't going to move. If you have a magnetic clamp, you can put it on the steel rocker block, but be careful that it doesn't get bumped by the moving rocker arm.

Let's do the intake valve first.
Make sure you are at TDC on the compression stroke, just like before.
Slack-off the pushrod adjuster nut, and back it off some, so that you can use a .012" automotive-style feeler gauge to slide in between the rocker arm tip and the lash cap or the valve tip, depending on what valves you have in the head. Then lock-up your pushrod adjuster to set that .012" lash, so it doesn't move. A nice sliding fit for the feeler gauge. Not too tight, and not loose. We're measuring the distance between the rocker tip and the valve.
We're going to check the timing at .012" lash, just like the book specs call for.

Okay, got that done?
Good.

Now, put the tip of the dial indicator on the valve retainer. That's the metal top piece that holds the valve spring. It's nice and big and has some flat areas on it, so you can easily find a place to set the tip of the dial indicator. make sure the tip is actually touching the valve spring retainer, and you can ensure this by getting a slight registering of movement on the dial-indicator dial. Push the dial indicator down onto the valve spring retainer until you are registering about .330" on the dial. Clamp it in that position, so that we can read the entire lift range of movement on that valve. Then rotate the dial of the dial indicator to register zero(0), right there, and leave it.


Now you can rotate the engine in the direction that it runs, slowly by hand.
Since we are on the intake valve, we won't see any movement until we get past the power stroke and almost all the way around near the top of the exhaust stroke. When we get near 40 degrees BTDC on the exhaust stroke, we'll start to see the intake valve register some negative direction movement on  the dial indicator. When the dial indicator just starts to show some movement, then the valve is beginning to open, and you have your intake valve opening timing degree, showing on your degree wheel. That's your intake valve opening timing.

Now, as you continue to rotate the engine you'll notice that the dial indicator is showing more movement in the negative direction. This is because we set the dial indicator in a position to read full closed as our benchmark, and as the valve begns to open, it is moving away from the dial indicator tip. Since we compressed the dial indicator tip to .330" at the setup, the tip will follow the valve down as it goes thru the lift cycle, and will read negative(backwards) on the dial. You can watch your entire lift cycle this way, and record exactly what valve lift you have at any given engine degree on the degree wheel. It's informative to see your cam profile in action.
What's your reading of engine degrees at the maximum lift? What is your maximum lift?

Okay, then continue to rotate the engine until you start getting near the area around 60 degrees ABDC, and you'll begin to see the dial indicator needle approaching zero again. You're getting near closing time for the intake valve.
When the dial indicator needle hits zero, then your intake valve is closed.
Look at the degree wheel, and that shows you your intake valve closing timing.

Get the picture?
Good.

Now, repeat the entire procedure for the exhaust valve. That will give you your timing for your exhaust valve then.

When you are done, you can compare what your actual valve timing is in your engine, against what the spec sheet says, and see how close your particular cam set matches what the published specs are.
Good info to have.

Then you have to remove all the test gear, re-set the pushrods to 0 lash, button it up, put the tank back on, and primary back together properly and refill, and you are ready to ride again.

If you are contemplating doing the cam re-phasing, you need to do this to check what your starting cam timing is, to see if you are a candidate for re-phasing.
You can ask me if your timing is able to be re-phased, after you measure it, and give me the numbers.

This is a look into how your engine operates. It gives you valuable information, particularly if you are contemplating modifications to the cam timing.

Now we have it in black and white here, so that anybody who's wanting to do some of this stuff, can refer to it.

I'm going to re-read it, and check to see if I forgot anything.
If you notice anything that doesn't make sense when you are trying it, or think I wrote something wrong, please bring it to my attention.
I'm just doing this off the top of my head.
I'm not perfect.
I can make mistakes.
Use your own head when you  do this stuff.

[Chuck D]

Ace, that was brilliant , as usual. Believe me , I'm NO mechanic and I could follow along without stopping to re-read any part of it. Your tech articles are the first things I look at when I log on. Keep'em coming and thanks.   Chuck.

[ace.cafe]

Ace, that was brilliant , as usual. Believe me , I'm NO mechanic and I could follow along without stopping to re-read any part of it. Your tech articles are the first things I look at when I log on. Keep'em coming and thanks.   Chuck.

Thanks Chuck!
I really had the coffee pot cooking this morning..
Today was a two pot day!

[deejay]

Ace you should be charging for this stuff.

[baird4444]

ace- somebody is going to ask, so hear it is.
          - Mike

[ace.cafe]

ace- somebody is going to ask, so hear it is.
          - Mike

Cool!
Thanks Mike!

That's what a timing disc looks like.

People may even be able to print that on their printer and glue it to a thin piece of sheet metal.
But, the  commercially-made discs aren't too expensive really, and they are worth having in your tool box
.

[davrobgee]

Message for Ace
I have checked the cam timing on my 612cc 2008 Classic with standard cams and the results seem so far out that maybe i am doing something wrong!

Inlet:- open 28 BTDC & close 42 ATDC
Exhaust:- open 58 BTDC & close 10 ATDC

Lift on inlet was 0.287" & on exhaust 0.260"

0.012" gap between rocker & valve top and ran 3 cycles with same result within 1-2 degrees.

Any ideas? Regards, David Gee.

[ace.cafe]

Message for Ace
I have checked the cam timing on my 612cc 2008 Classic with standard cams and the results seem so far out that maybe i am doing something wrong!

Inlet:- open 28 BTDC & close 42 ATDC
Exhaust:- open 58 BTDC & close 10 ATDC

Lift on inlet was 0.287" & on exhaust 0.260"

0.012" gap between rocker & valve top and ran 3 cycles with same result within 1-2 degrees.

Any ideas? Regards, David Gee.

I'm assuming a typo, and that you really meant that the inlet closed at 42 After BOTTOM Dead Center(ABDC), and that the Exhaust opened 58 Before BOTTOM Dead Center(BBDC). Yes?

Okay David, the next thing that I would do is take off your timing cover and remove  the cams to check them. Just remove one at a time, and don't  rotate the engine while you are doing it, so that you can put it right back in the same way it was before, when you replace it. Use the alignment marks, so you don't get it in the wrong way.

You want to measure the cams with a dial-caliper.
First measure the "base circle" diameter, by using the calipers to measure across the round part of the cam, where there is no lobe. I believe that this measurement is one inch. Then measure the cam from the bottom of the base circle to the top of the lobe with the calipers.
Subtract the base circle diameter from that measurement, and you have the lift
If you get anything less than .312" for lift, then your cams are worn down.

If your cams measure okay, then you have to look at the valve train parts and the rockers, and see where the play is.

I suspect you may have worn cams.

If your cams measure okay, and there's no loose play anywhere in the valve train, then you need to re-check your measurement procedure to see where it may have gone wrong.
The use of our .012" lash for timing measurement, will result in our full valve lift measurement being .012" less than the cams actually have for lift. So, in this case we would have expected you to get .300" lift on your dial indicator for both valves, when you did your measurement at the valves. Since you got considerably less than that on both cams, AND your timing is short on both cams, it seems to indicate worn cams.

If the cams are worn that far down, you'll see it on the cam lobes immediately upon inspection.

Let me know what you find.

[davrobgee]

Hi Ace,have replaced cams! Timing is:- Inlet open 34 close 60 and Exhaust is open 60 and close 19. Lift is ok at 0.298/.299". I would imagine that these are suitable for your timing mod ? Regards, David Gee.

[ace.cafe]

Hi Ace,have replaced cams! Timing is:- Inlet open 34 close 60 and Exhaust is open 60 and close 19. Lift is ok at 0.298/.299". I would imagine that these are suitable for your timing mod ? Regards, David Gee.

Hi David,
That sounds much more like it!
Glad you got it taken care of, but sorry it cost you the money to buy cams.

Yes, those cams can be re-phased.
The duration on both intake and exhaust is a tad short, but we can work with it, because I just had a successful go with a 350 that had similar issues, and he's ecstatic with his results.

Now remember, for this to be successful, you must have the high compression piston in your engine.

First, line the cams up on the dots, for a starting position.
Then Retard ONLY your intake cam by one tooth.(One tooth counter-clockwise)
Then use the 3-way adjustable timing pinion installed on your crankshaft, to advance both cams by 4.5 degrees, which is one keyway notch on the adjustable pinion, clockwise.
Then check your work by measuring the timing after re-phasing, to be sure that it comes out with the figures that I show below.

With this timing adjustment, your timing after the re-phasing would be
Intake opens 20.5*BTDC
Intake closes 73.5*ABDC
Exhaust opens 64.5*BBDC
Exhaust closes 14.5*ATDC
Overlap period of 35 degrees
Intake cam duration @ .012" lash is 274 degrees
Intake Lobe Center Angle is 116.5*ATDC as installed
Exhaust cam duration @ .012" lash is 259 degrees
Exhaust Lobe Center Angle is 115*BTDC as installed
Lobe Separation Angle is  115.75* as installed

This is a good overall street setup, with good low-range and mid-range torque, with a nice wide torque band, and a boost in performance up in the higher rpms too.
Very streetable, with good power and a bit of rpm extension, compared to the stock set-up.
The stock cam set-up is too duration-limited for good breathing with the 612, so we're getting about 13.5 degrees more "effective duration" on the intake, by shifting that cam retarded. And we're banking on not losing anything significant from the reduced overlap, because of the inability of the Bullet to really capitalize well on overlap. The advancing of both cams after retarding the intake cam helps to get a better "blow-down" of the exhaust, for less gas dilution left in the cylinder, and also makes for a better cylinder "trap"  with less losses during overlap.
I think this should work out well, and I'd love to hear what you think of the performance change, after you ride it with the re-phased cams!
This is my first go at a re-phase with a 612. Should be interesting to hear the results.

[Chuck D]

Did someone say "more"?