degreeing a slant camshaft with no cam card

[1930]

Thanks Karl, just one more time to clarify where my confusion is.

I have been shown how to arrive at the standard of measurement for the stock cams in my slant engines.

I am able to confirm ( somewhat... I am still working on things ) that @.006 of intake cam lift my degree wheel reads 6 degrees BTDC just as my FSM says it should.

Since this is happening I am under the impression that the cam is in proper phase with the crankshaft.....in other words things ( or thing at this point ) is happening when it should.

I am lost without this standard of measurement. I do not get how I can say that the valve is opening at the correct time AKA when it should cause I do not have this standard of measurement for my newly re-built engines cam.

I know there is something ( at least one thing ) that you know that I dont know in all of this so I will just take my measurents as you have asked me to do and get this information to you.

You can then show me what I am missing.

Ill spend 12 hrs doing something that you might do in 30 minutes but Ill have it at some point over the weekend.

Thanks for your time.

 

[krazykuda]

I like to take measurements just as I see it lifting off .000 on the dial indicator, then .001" and .050", then every .050" after that until I get to max lift, then on the .050" intervals on the way down.


A sloppy timing chain is your enemy. Only turn the engine in one direction to reduce the error from the slop in the timing chain. It's best to use a new chain if possible. Just keep turning in one direction only.


It still takes me some time, but you have to take your time to do it right.

This is not easy to figure out. I've been doing this for years. It took me a while to figure it out also. It will eventually sink in if you keep trying. Hang in there.

 

[1930]

Just curious if hitting a cylinder with a honing tool while engine is still assy is a no-no.

I did not put away/store this engine right and after just a few months of inside dry storage there is a bit of surface rust on the cylinder walls. Nothing to heavy, just rubbing the rust with my fingers removes most of it.

Id like to clean this one up and put it away properly next time but with the rust removed before doing so.

I thought that even with the newly re-built engine that that is in my truck that it might be a good idea just to score the walls with a honing tool before putting the head back on.

 

[krazykuda]

No, I would not recommend trying to hone it with the pistons in it.


If you want to knock the rust off the cylinder walls, get a 3" or 4" wire wheel on a drill to clean the cylinders. Then if you are going to store it, coat the cylinder walls with STP or Motor Honey.

 

[1930]

No, I would not recommend trying to hone it with the pistons in it.


If you want to knock the rust off the cylinder walls, get a 3" or 4" wire wheel on a drill to clean the cylinders. Then if you are going to store it, coat the cylinder walls with STP or Motor Honey.

I ended up using kero and a scotchbrite. Worked pretty good.

This engine has some tight spots when spinning it. I notice that as well with the spare engine that is sitting in my parts truck but this one may be tighter. Hard to say for sure since this one is up on a stand and so its not nearly as stable as the engine still bolted in the chassis.

Hard to get a real smooth revolution of it. Prob. going to serve what I want to do with it for now though.

 

[1930]

I know this is not what you are asking me to get but I am working on collecting that info. I got a late start this afternoon on all of this.

I hope you can help me to understand some things. I want to tackle one problem at a time and I need to get closure to this one first if thats OK with you.

A fellow on this site http://www.hotrodinlines.com/forum/ubbthreads.php?ubb=showflat&Number=5046#Post5046 was helping me along with all of this cam phasing stuff. He helped me to see alot of things I would not have seen without his help. I do not know what happened though, maybe he has been sidetracked and just does not have the time at this point for any more questions.

Anyway he directed me to try and find the standard of measurement for my camshaft, he suggested that I raise the cam to a .006,020, 050 lift and see if the degree wheel at all coincided with my 6 degree BTDC cam reference found in my FSM.

See which of these possible 3 was closest to my intake opening figure from my FSM of .006 BTDC.

I did this, as it turned out raising the intake lobe .006 gave my degree wheel a reading of exactly 6 degrees BTDC.

This was in his words the measuring standard used when they cut my cam.

I have now tested this on two different engines and sure enough both engines read 6 degrees on the degree wheel when the lifter is raised .006.

He told me that ............Well it seems you were finally able to solve the measuring standard mystery. It appears as you have shown that the @.006" lift is the standard they used. You should be able to also check the closing events of both the intake and exhaust with the lobe at .006" lift when it opens and then .006" before it is totally closed.....................

Ok so what he has told me is that when the lifter goes up over the top, back down the other side and at just .006 before it closes again I should see 42 degrees ABDC ( closes 42 ABDC per FSM ) on my degree wheel.

This is not the case. Both engines read the same. At .006 thousands lift my degree wheel reads 54 degrees ABDC. Should only read 42.

At 42 degrees the dial indicator reads 13ish/14ish thou.

A difference of .006/7 ish

This has me confused. Why am I finding this on two engines.

It is nice BTW to see similar #s between the two engines.

Thanks Karl

 

[1930]

I think it interesting that this cam I am measuring now shows .251 lift and the engine in my parts truck shows .248 lift. Is cam wear what I am seeing?

I got as far as @ 001 degree wheel reads 19 degrees BTDC
@ 050 lift degree wheel reads 17 ATDC.

Not much I know but at least its a start.

 

[krazykuda]

I think it interesting that this cam I am measuring now shows .251 lift and the engine in my parts truck shows .248 lift. Is cam wear what I am seeing?

I got as far as @ 001 degree wheel reads 24 degrees BTDC
@ 050 lift degree wheel reads 17 ATDC.

Not much I know but at least its a start.

The difference in your two cams is only .003", that could be production tolerances and some wear.


And yes. You're off to a good start.

 

[1930]

Hello Karl, this is about 5 hours work but I am pretty sure I could cut that time in half now.

They have been checked and re-checked and checked one more time.

The spare engine has tight spots, hard to get the wheel spinning smoothly cause of these tight spots.

The parts truck engine is much smoother.

Most difficult point to measure ( and hope for accuracy ) is the .001.

I am prob. not working with ideal equipment and so there is a small margin for error but again this is very close.

How do I know that the timing is not advanced or retarded a tooth or ten.

How do I know that these opening and closing points are happening at the correct time for this engine?

Thanks

 

[1930]

Try this

 

[1930]

One thing that helped was to make sure the pointer was just pointing at the digits on the wheel instead of being longer and passing thru the digits.

Another thing that helped was to use the stop tool as a bridge to mount the dial indicator.

 

[krazykuda]

Try this

I'm working on it as I can. Putting it into a spread sheet. Trying to figure out how to make it easier to explain/understand without getting too confusing... :banghead:

 

[1930]

I'm working on it as I can. Putting it into a spread sheet. Trying to figure out how to make it easier to explain/understand without getting too confusing... :banghead:

Thanks very much, I did not think that you had forgotten about me. I am not in a rush but only wanted to make sure you had not given up on me. Yes the easiest the better. I am thickheaded.

I am still trying to figure things/ what I can out myself, trying to collect what info I can from some other people as well.

I called Erson cams tech guy, he is nice to talk with but he may or may not have the time/interest to help me to understand, only time will tell, still awaiting some reply that I am assuming I will get.

The tech guy at Comp cams was as rude/useless, would not give my questions a second thought.

I mention these things cause I want you to understand I am not just idly sitting by waiting for you to do something for me.

I am trying to help myself.

Someone recently told me that as you had mentioned the centerline method would work to tell me if my #1 intake valve was opening at the correct point.

Unfortunately although I have read much on the centerline method I cannot quite connect the dots on the procedure to make it work for me and give me the info I am after.

Hoping you can walk me thru all of this.
Thanks again

 

[67Dart273]

You may be overthinking this vastly. All in the world that the centerline of a lobe "IS", is, it's the true peak of the center of the lobe, the point at which the lifter is teetering at the peak, has just come "up" and is getting "ready" to go back down

YOU CAN NOT measure it at that point, for the same reason that you cannot measure TDC actually "at" TDC.......in the case of the piston, the action of the crank coming "up and "over" center makes the piston slow way down, actually stop (of course) for a split instant and head "back down" ATC

So whether a piston and measuring TDC, or a cam lobe and measuring centerline, you SPLIT the measurement so that it's equal on both sides of the peak.

It does not REALLY matter what this IS so long as you are consistent, and so long as you give it "enough" movement to maintain accuracy, without using so much movement that you actually introduce errors.

All in the world that you are doing...........

Measure maximum lift by watching the indicator, and NOT what that is.

Back up the engine, WAY before "the event" so as to approach again with "slop" taken up in the chain, and bring the lifter up to .050" BEFORE your max reading.

NOTE the reading on the degree wheel.

Now go "up and over" the lobe top, and down the other side, and AGAIN set your indicator to the SAME lift minus .050, so and again note your degree wheel.

Now you have two degree readings "some distance apart." These degree readings are now the point at which the lifter was .050 below max lift

ALL YOU ARE DOING here is picking two arbitrary lift points.......050" below max lift..........and using the idea that IF IF IF the lobe is symmetrical, then the centerline (max lift) is exactly halfway (rotationally) between whatever crank degrees indicated those to settings.

so with your two crank rotational degree settings, all you need to do is figure halfway in between those readings.

 

[1930]

You may be overthinking this vastly. All in the world that the centerline of a lobe "IS", is, it's the true peak of the center of the lobe, the point at which the lifter is teetering at the peak, has just come "up" and is getting "ready" to go back down

YOU CAN NOT measure it at that point, for the same reason that you cannot measure TDC actually "at" TDC.......in the case of the piston, the action of the crank coming "up and "over" center makes the piston slow way down, actually stop (of course) for a split instant and head "back down" ATC

So whether a piston and measuring TDC, or a cam lobe and measuring centerline, you SPLIT the measurement so that it's equal on both sides of the peak.

It does not REALLY matter what this IS so long as you are consistent, and so long as you give it "enough" movement to maintain accuracy, without using so much movement that you actually introduce errors.

All in the world that you are doing...........

Measure maximum lift by watching the indicator, and NOT what that is.

Back up the engine, WAY before "the event" so as to approach again with "slop" taken up in the chain, and bring the lifter up to .050" BEFORE your max reading.

NOTE the reading on the degree wheel.

Now go "up and over" the lobe top, and down the other side, and AGAIN set your indicator to the SAME lift minus .050, so and again note your degree wheel.

Now you have two degree readings "some distance apart." These degree readings are now the point at which the lifter was .050 below max lift

ALL YOU ARE DOING here is picking two arbitrary lift points.......050" below max lift..........and using the idea that IF IF IF the lobe is symmetrical, then the centerline (max lift) is exactly halfway (rotationally) between whatever crank degrees indicated those to settings.

so with your two crank rotational degree settings, all you need to do is figure halfway in between those readings.

I have been informed that the lobes are asymmetrical

I will re-read your post, thanks

 

[1930]

You may be overthinking this vastly. All in the world that the centerline of a lobe "IS", is, it's the true peak of the center of the lobe, the point at which the lifter is teetering at the peak, has just come "up" and is getting "ready" to go back down

YOU CAN NOT measure it at that point, for the same reason that you cannot measure TDC actually "at" TDC.......in the case of the piston, the action of the crank coming "up and "over" center makes the piston slow way down, actually stop (of course) for a split instant and head "back down" ATC

So whether a piston and measuring TDC, or a cam lobe and measuring centerline, you SPLIT the measurement so that it's equal on both sides of the peak.

It does not REALLY matter what this IS so long as you are consistent, and so long as you give it "enough" movement to maintain accuracy, without using so much movement that you actually introduce errors.

All in the world that you are doing...........

Measure maximum lift by watching the indicator, and NOT what that is.

Back up the engine, WAY before "the event" so as to approach again with "slop" taken up in the chain, and bring the lifter up to .050" BEFORE your max reading.

NOTE the reading on the degree wheel.

Now go "up and over" the lobe top, and down the other side, and AGAIN set your indicator to the SAME lift minus .050, so and again note your degree wheel.

Now you have two degree readings "some distance apart." These degree readings are now the point at which the lifter was .050 below max lift

ALL YOU ARE DOING here is picking two arbitrary lift points.......050" below max lift..........and using the idea that IF IF IF the lobe is symmetrical, then the centerline (max lift) is exactly halfway (rotationally) between whatever crank degrees indicated those to settings.

so with your two crank rotational degree settings, all you need to do is figure halfway in between those readings.

I do completely understand this.... I have understood this for some time now. I have no issue whatsoever with the comprehension of this.

My question is .........how will I use that info to tell if the #1 intake valve is opening at the precise time ( in degrees or to be more specific @ 6 degrees intake opening timing as per my FSM ) that it is supposed to open.

Please tell me this.

 

[1930]

This is perfectly clear, again I have understood this for a while now.............All in the world that you are doing...........

Measure maximum lift by watching the indicator, and NOT what that is.

Back up the engine, WAY before "the event" so as to approach again with "slop" taken up in the chain, and bring the lifter up to .050" BEFORE your max reading.

NOTE the reading on the degree wheel.

Now go "up and over" the lobe top, and down the other side, and AGAIN set your indicator to the SAME lift minus .050, so and again note your degree wheel.

Now you have two degree readings "some distance apart." These degree readings are now the point at which the lifter was .050 below max lift

ALL YOU ARE DOING here is picking two arbitrary lift points.......050" below max lift..........and using the idea that IF IF IF the lobe is symmetrical, then the centerline (max lift) is exactly halfway (rotationally) between whatever crank degrees indicated those to settings.

so with your two crank rotational degree settings, all you need to do is figure halfway in between those readings................


But again what I am not understanding is how to use this degree number ( the halfway point ) to verify that my #1 cylinder intake valve is opening at 6 degrees BTDC and that my # 1 intake valve is closing at 42 degress ABDC and that my #1 exhaust valve is opening at 36 degrees BBDC and my # 1 exhaust valve is closing at 12 degrees ATDC.

This is where I am and have been stuck.

I just want to verify that my cams are installed correctly, that they are neither advanced nor retarded. That they are installed straight up as they should be.

 

[67Dart273]

But again what I am not understanding is how to use this degree number ( the halfway point ) to verify that my #1 cylinder intake valve is opening at 6 degrees BTDC and that my # 1 intake valve is closing at 42 degress ABDC and that my #1 exhaust valve is opening at 36 degrees BBDC and my # 1 exhaust valve is closing at 12 degrees ATDC.

This is where I am and have been stuck.

I just want to verify that my cams are installed correctly, that they are neither advanced nor retarded. That they are installed straight up as they should be.

You can NOT if you do not know how the original cam was measured. About all you can do is to get the cam in an engine, or on V blocks, and piddle with it until you get things to match "what you know" about it.

In other words map out the cam at several thousands lift

at .050 lift.

At computed points above both at tappet lift and at rocker arm lift, unless the chart specifies what they originally are.

But again, you are overthinking.

There's only so close you can come. If you don't know "what you are starting with" then there's no way you can expect to hit the target.

And, think about this...........there are many cams that are ground / sold to be installed at a recommended timing, only to find that for many of us, this point might be better MOVED one way or the other. So in the end, unless you are prepared to spend a lot of time tearing the engine "back down" and doing comparative dyno runs, you'll never know for sure.

This very thing happened to a member here near me. He had a small block "purple" grind and it turns out that not only was the original cam drive off some, but that installing the cam "as advertised" resulted in a pig at lower RPM. After talking to the guys on here, we advanced it several degrees to a marked improvement.

BUT this was based on a somewhat known cam, with people's past experience. And even then, without exhaustive R & D time on a dyno, "we" might have left several HP "on the table."

 

[krazykuda]

Back up the engine, WAY before "the event" so as to approach again with "slop" taken up in the chain, and bring the lifter up to .050" BEFORE your max reading.
.

I would just keep rotating in the same direction. Backing up can induce more error in measurement.

 

[krazykuda]

So far, I got the intake lobes calculated, and I need to figure out the best way to calculate the exhaust lobe centerline.


So far the cams look close.

 

[1930]

You can NOT if you do not know how the original cam was measured. About all you can do is to get the cam in an engine, or on V blocks, and piddle with it until you get things to match "what you know" about it.

In other words map out the cam at several thousands lift

at .050 lift.

At computed points above both at tappet lift and at rocker arm lift, unless the chart specifies what they originally are.

But again, you are overthinking.

There's only so close you can come. If you don't know "what you are starting with" then there's no way you can expect to hit the target.

And, think about this...........there are many cams that are ground / sold to be installed at a recommended timing, only to find that for many of us, this point might be better MOVED one way or the other. So in the end, unless you are prepared to spend a lot of time tearing the engine "back down" and doing comparative dyno runs, you'll never know for sure.

This very thing happened to a member here near me. He had a small block "purple" grind and it turns out that not only was the original cam drive off some, but that installing the cam "as advertised" resulted in a pig at lower RPM. After talking to the guys on here, we advanced it several degrees to a marked improvement.

BUT this was based on a somewhat known cam, with people's past experience. And even then, without exhaustive R & D time on a dyno, "we" might have left several HP "on the table."

All these months and just now I am starting to get the opinions that it cant be done accurately. At least now I understand the whys

Just one more question though.

I had asked ( and have been asking similar question over on slant.org ) for several months and one of the members over there who is very knowledgeable/technical told me this................................................1930,, here is an idea for you

leave the stock cam in the engine, remove enough off the engine so you can properly attach a degree wheel and measuring devices.

then degree the cam and determine where the FSM cam specs are arived from...

start a thread on your process, document with photos,, that would get you the hands on experience that you need.

I did not understand how to do this, could not comprehend the route I should take to start this process, when I asked for clarification via PM/E-mail I was basically told that I was a nuisance and I should stop attempting to waste everyones time.

I did however still in earnest attempt this, I found that the intake and the exhaust valves opened up at the correct time according to the degree wheel at the .006 reading on my dial indicator.

I thought I had found the magical number, both measuring instruments lined up perfectly. I was and am still confused however in that both closing points were a tad off, in other words @.006 on the dial the wheel was a pretty good amount off from the FSM specified closing figure.

So any suggestions on a different approach that maybe this slant.org member may have wanted me to take?

I would still like to find that magical number if I have not already done so.

Thanks

 

[1930]

I would just keep rotating in the same direction. Backing up can induce more error in measurement.

This is what I do, if I miss my point I just go back around again

 

[krazykuda]

This is what I do, if I miss my point I just go back around again

Exactly. I feel that it's more accurate this way if you don't reverse direction. Any slop in the timing chain can affect your readings.

you did pretty good. Only one data point that I feel is a little off, but not to bad. I'm still working on calculating the exhaust lobe centerline. Will post up when I get it figured out.

 

[krazykuda]

I thought I had found the magical number, both measuring instruments lined up perfectly. I was and am still confused however in that both closing points were a tad off, in other words @.006 on the dial the wheel was a pretty good amount off from the FSM specified closing figure.

So any suggestions on a different approach that maybe this slant.org member may have wanted me to take?

I would still like to find that magical number if I have not already done so.

Thanks

So far, I'm finding that the readings above .200" lift and below .050" lift have more variation with the centerline than the ones from .050" - .200" lift. Those are pretty close to +/- 1° when I calculated the lobe center.

Both cams seem to have the same profile for intake and exhaust valves.

I feel that the variation on the top and bottom of the lift are because the valve is slowing down and there is more "room for error" in catching the marks as they stay in the same place longer, and can have a few degrees where it reads the same (if you follow what I mean here).

You did a good job taking the data. It looks good so far, I just have to filter it out a little more.

 

[1930]

So far, I'm finding that the readings above .200" lift and below .050" lift have more variation with the centerline than the ones from .050" - .200" lift. Those are pretty close to +/- 1° when I calculated the lobe center.

Both cams seem to have the same profile for intake and exhaust valves.

I feel that the variation on the top and bottom of the lift are because the valve is slowing down and there is more "room for error" in catching the marks as they stay in the same place longer, and can have a few degrees where it reads the same (if you follow what I mean here).

You did a good job taking the data. It looks good so far, I just have to filter it out a little more.

The readings below .050 are the toughest especially with the engine set-up on the stand, as mentioned it does not turn smoothly in some spots. From what I can make of it the bearings must wear more at certain positions and the bearings in this engine must be really worn in certain positions.

Also ( like you said ) it seems to me that because things really slow down when things get low it makes it tough to get things really accurate.

I want to learn more about what can be done with centerline figures. I have done a search on-line but am not finding much of anything.

It seems to me from what I have read here that a cams centerline cam tell me a few different things.

Any suggestions on where I can read something that will clue me in on the uses for this measurement?

Trying key words like what are the uses for a camshaft centerline are not proving helpful.

I guess also I am confused in regards to overlap at the camshaft centerline.

Since the camshaft is asymmetrical ( assuming from what I have read that this means the ramps on each side are not the same shape ) than how measuring down both sides and assuming that the center of these two points is the center is going to work??

If the intake side is broader/longer than the exhaust than @.050 on the intake side will not be the same distance down the side of the cam if my thinking is correct??

And one last question......Lets say the cam were symmetrical, and I were to find the center point on the degree wheel for this event ( AKA intake centerline ) how would this coincide with any of my opening/closing points on the few specs I do have?

I will have to re-read prior posts, maybe that answer is there and I overlooked it cause it confused me at the time.