degreeing a slant camshaft with no cam card

[1930]

Maybe a silly question that I will regret asking but looking at my wheel, blue shows intake valve opening at 6 degrees BTDC, ( lets call this A ) it also shows Intake valve closing at 42 Degrees ABDC ( lets call this C ) as per the FSM shows.

The engine is turning clockwise rotation, A and C are part of the same lobe. This would mean that it has to travel less distance if passing thru area B than it would have to travel if moving thru D.

I cant seem to grasp how it passes thru D to make up that 6+180+42

The way I am looking at it there are only 132 degrees between A and C cause the engine is turning clockwise.

Its been a long day but what am I missing?

Intake valve ramps up and A starts to take place, at some point it reaches intake lobe centerline B and then drops down the other side to C.

Intake valve opens and closes......

I have a feeling I must be looking at something all wrong but until I can muddle through these obvious simplistic questions I cannot proceed into the harder to grasp areas.

 

[1930]

I just had someone send me a P.M that stated ......................Just saw your post on the A Bodies forum. In post number 11 of the degreeing a Slant camshaft, your red line designating 6° BTC is on the wrong side of TDC. When you rotate the crankshaft in the normal clockwise direction, everything on the 1 o'clock side of the TDC mark is BTC or BTDC, and everything on the 11 o'clock side of TDC is ATC or ATDC...................

He is the other guy that has been helping me over on this site http://www.hotrodinlines.com/forum/ubbthreads.php?ubb=showflat&Number=5046&gonew=1#UNREAD Another good web-site

Clearly in this video [ame="https://www.youtube.com/watch?v=gqerHlVIqS4"]Camshafts (Part 2) - Characteristics of a performance camshaft - YouTube[/ame] 2.23 seconds into it they guy portrays the degree wheel as I have marked it above as far as where BTDC AFTC ect are located

So much confusion on my part

 

[krazykuda]

Your wheel is marked wrong.

The first quadrant (top left) is labeled both "A" and "B", It should be "A"

The second quadrant (bottom left) is labelled "C" and should be "B".

The third quadrant (bottom right) doesn't have a letter assigned. It should be "C".

The fourth quadrant (top right) is labelled correctly at "D".


Now your Before and after tdc and bdc are backwards.

BTDC should be quadrant "D" or the top right.

ATDC should be quadrant "A" on the top left.

BBDC should be quadrant "B" on the bottom left

ABDC should be quadrant "C" on the bottom right.

 

[1930]

Your wheel is marked wrong.

The first quadrant (top left) is labeled both "A" and "B", It should be "A"

The second quadrant (bottom left) is labelled "C" and should be "B".

The third quadrant (bottom right) doesn't have a letter assigned. It should be "C".

The fourth quadrant (top right) is labelled correctly at "D".


Now your Before and after tdc and bdc are backwards.

BTDC should be quadrant "D" or the top right.

ATDC should be quadrant "A" on the top left.

BBDC should be quadrant "B" on the bottom left

ABDC should be quadrant "C" on the bottom right.

Yes I made the ABCD marks as part of a question that I had within the same posts.

Back to the drawing board on the wheel. Let me start over and come back with some fresh questions

 

[1930]

This should be correct,

Blue indicates intake valve opening @ 6 degrees BTDC
Blue indicates intake valve closing @ 42 degrees ABDC
Red indicates exhaust valve opening @ 36 degrees BBDC
Red indicates exhaust valve closing @ 12 degrees ATDC

 

[krazykuda]

This should be correct,

Blue indicates intake valve opening @ 6 degrees BTDC
Blue indicates intake valve closing @ 42 degrees ABDC
Red indicates exhaust valve opening @ 36 degrees BBDC
Red indicates exhaust valve closing @ 12 degrees ATDC

Yes, you have it! :thumleft:

Congratulations... :cheers:

 

[nothingbutdarts]

All I have to say is KRAZYKUDA is the MAN!!!!! Thank You!!!!!

 

[1930]

Yes, you have it! :thumleft:

Congratulations... :cheers:

Its still not over ( I believe this is still just the beginning ) but thanks. Still will have questions but at this point trying to absorb more things.

 

[krazykuda]

All I have to say is KRAZYKUDA is the MAN!!!!! Thank You!!!!!

Thanks guys. I love math and engines....

 

[krazykuda]

Its still not over ( I believe this is still just the beginning ) but thanks. Still will have questions but at this point trying to absorb more things.

No problem.


Look at it over and over, and eventually it will set in.


Whenever you are ready for another round of questions, just let me know.

 

[1930]

No problem.


Look at it over and over, and eventually it will set in.


Whenever you are ready for another round of questions, just let me know.

Hi Karl, what exactly is the measuring standard of a camshaft, I am trying to put it in educated sounding words but am having a tough time although I think now I have a pretty good idea.

As far as I can say at this point every cam manufacturer at one time had their own measuring standards and this simply meant a baseline of where they took all their measurements from.

Evidently from what I have read most cam manufacturers got together and united on the .050 standard at some point but this may still not hold true for all stock cams for all engines.

In my case I am sure/believe it was .006 but I am still confused why things are just not measured from the lobes lowest point?

 

[krazykuda]

Hi Karl, what exactly is the measuring standard of a camshaft, I am trying to put it in educated sounding words but am having a tough time although I think now I have a pretty good idea.

As far as I can say at this point every cam manufacturer at one time had their own measuring standards and this simply meant a baseline of where they took all their measurements from.

Evidently from what I have read most cam manufacturers got together and united on the .050 standard at some point but this may still not hold true for all stock cams for all engines.

In my case I am sure/believe it was .006 but I am still confused why things are just not measured from the lobes lowest point?

Funny that you ask this question.


There is no official "standard". The most common one being the .050" ratings. But not every manufacturer uses .050" either.... :banghead:


As for the "advertised" duration numbers, they are all over the map so to speak. Some companies measure just as it starts to lift off of it's seat, some at .001", some at .002" and a few a little more. that is why it's hard to know how to judge the "advertised duration" numbers. If they aren't measured using the same procedure, then it's useless to try to compare the numbers.

I myself compare both the advertised duration and .050" duration numbers to get an idea of the "ramp speed" of the company. This is the rate at which the valve is lifted off of its seat and how fast it closes on it's seat. The faster that you lift the valve, the sooner you get into the lifts where the air can flow efficiently through the head. However, the faster you set the valve back down on it's seat, the more it's going to wear/beat up your seats and you will need valve jobs sooner/more often. Also if it moves the valves too fast, they can "float", where the inertia keeps the valve opening after it passes the ramp of the cam. This can cause the valves to hit the pistons and will destroy an engine. Stiffer valve springs also can keep this from happening, but the stiffer springs will cause your cam lobe to wear faster.


When I degree my cams, I put the dial indicator on the valve retainer, not the cam lobe. I feel that this is more like the engine sees, and with the rocker arm ratio. I also don't have to convert the rocker arm ratio to figure out what lift at the lobe is equal to .050" at the valve. Basically, I like to see what is happening at the valve, because that is what determines how the engine acts more closely.

I try to catch as soon as I see the dial indicator start to move and also at .001" lift on the valve. Then .002', .005", .050", .100", 150", .200", .250, .300, .350, .400, .450, MAX Lift, [then repeat for the same lifts on the way back down].


So the only way to accurately compare one cam to another is for you to pick how you are going to degree YOUR cam and then degree each one yourself. Mark each one, so you know which is which with at least a wire and tag. Then by measuring the cams with the same method each time, then you will be able to compare which one is bigger etc. I use all of those lifts so I can get an accurate "map" of how the valve is moving. Only you can control the procedure to make sure that they are measured the same way so you can compare the numbers. And then you can see how fast the ramps are from one cam to another. This is where you will find the difference between the different cam grinders and grinds.

 

[67Dart273]

Hi Karl, what exactly is the measuring standard of a camshaft,

The measuring standard is whatever the guy who ground it "says" it is. These days, "many?" "most" cam grinders go by similar standards, but not necessarily. I've forgotten "what all" I think the old factory Mopar grinds were rated at just a few thou of lifter movement, where many others were going by .050"

The thing is, you should be able to take the published figures, whether they are .050, just a few thou, or 10 feet, and figure "the middle" of that to get the centerline.

But a far more accurate way is to measure it yourself. Get it in the block with your wheel, and measure an equal amount of lift on "either side" of center, then split the difference to get centerline.

(Come down from max indicated an equal amount of lift on each side of max. Note the degree readings, and "in the middle" is your centerline)

In other words, to set a centerline, you don't need to KNOW anything about the cam, you can measure it.

Now, that does not mean that whatever centerline you've "picked" is either "the right one" for the cam, or for your particular use, as in more top end, or more bottom end.

 

[krazykuda]

The measuring standard is whatever the guy who ground it "says" it is. These days, "many?" "most" cam grinders go by similar standards, but not necessarily. I've forgotten "what all" I think the old factory Mopar grinds were rated at just a few thou of lifter movement, where many others were going by .050"

Typically for MP cams, multiply the advertised duration number by .85 to get the duration at .050"

 

[1930]

At this point I am fooling with stock engines with as far as I know stock cams.

I have two un-touched ( as far as I know ) slants, I pulled a second one out tonight and set it up in my workshop on the engine stand.

My plan is to degree both engines and compare the readings I will be getting between the two.

I am convinced at this point that the standard for measurement on these engine is as mentioned @ .006 lift and am hoping to confirm that with the second engine this weekend.

Alot of what you guys have said above is starting to make sense too me but there is also alot that I still do not understand so I will keep working at it and ask questions.

I read alot about the degreeing process and some like the centerline method and some like the @.050 method.

This has me confused a bit.

If I know the standard in which my cam was measured ( @ .006 ) and I can measure intake opening and closing points using this standard than what other measurements and I trying to accomplish and why?

I hope this does not make me sound lazy or as a slouch. I would like to take any opportunity I can to learn anything I can but I am un-clear of what else I am trying to accomplish I guess.

Isnt the timing of the valves opening and closing all we need to know? What else is there and why are they important?

If we know the standard of measurement ( Like I think I do ) than what else is there to accomplish?

Why do I want to know my intakes and exhaust valve centerline as an example?

Yes I plan to up-grade to a more suitable cam eventually for my truck so Im going to guess that all these other measurements that I still need to learn how to make will help me to better understand what might be a better cam to choose.

This has got to be an answer to my own question I suppose.

Thanks

 

[krazykuda]

Alot of what you guys have said above is starting to make sense too me but there is also alot that I still do not understand so I will keep working at it and ask questions.


This has me confused a bit.
Thanks

Don't worry. It takes a while to absorb it all.


I've been doing this for years/decades....

 

[1930]

Attached

 

[1930]

Guys, I hate to admit it cause the answer is prob. right here in something you have written already but I am just still not seeing it.


I have been pondering on these things all week and have made alot of headway in my understanding of all of this but I am still stuck.

I am getting the factory set-ups/factory cam motors licked I believe cause I am figuring out their original standard of measurement.

Here is my question below,

My question is.........


Just to condense it down in simple steps to degree a camshaft step



1- find TDC


2- rotate engine clockwise ( always ) till .050 of lift is showing off the intake lifter, record what the degree wheel reading is at that point.



3- continue rotating the engine until peak lift is shown, come down the other ( closing ) side and record the number seen at .050 again.


4- Compare the numbers seen to those on the cam card,



As you know I have no cam card.



I have attached the camshaft numbers that I have avail to me from my FSM


How are these numbers going to help me if I do not know the standard in which the cam was originally measured............Do I need to find the standard of measurement for each and every cam that I degree with no cam card?

If the cam was not originally measured @ .050 than how is this procedure going to help me?



In the case of the two parts engines I am fooling around with that have stock/original Chrysler cams I have concluded that the standard of measurement for them was 006.


I have been successful ( to a degree, no pun intended ) in measuring these engines.



As far as the newly re-built engine ( with aftermarket stock cam ) I have no clue at all what cam is in that engine, I do not know what the standard was for that camshaft so I am stuck.



This has me very confused. I plan on hittin this hard this weekend so any help in dummied down terms would be much appreciated. Thanks

 

[krazykuda]

You're getting there.


Yes, for a "basic" check for your cam, you can put it in and check the numbers @ .050".


The reason that you check the cam at .050" on the "upstroke", and then at .050" on the "downstroke". Since the cam lobes are ASSUMED to be symmetrical, these numbers can be used to find the lobe center. The lobe center is just the middle between .050" up and .050" down. Measuring the up and down enables you to be able to use those measurements to find the centerline of the lobe.

I would also check at .001". So for a quick check, I would check .001" up, .050" up, .050" down, and .001" down. Then at max lift, record the measurement at the dial indicator. With this information, then we can figure out the cam specs.


Don't worry about trying to figure out how the different companies measured their camshafts. If you measure them the same way every time, then you can compare them yourself. You set the standard for measuring, as you are doing the measuring. As long as you measure all of the cams the same, then you can compare the info. If you measure them differently each time, then the info won't be able to be compared to the others. You have to measure the same each time with the same method/procedure.

Once you find the valve open and close points, then you can calculate the lobe centers for intake and exhaust valves. then with that info, you can calculate the lobe centers (how far apart the lobe centers are).

 

[1930]

You're getting there.


Yes, for a "basic" check for your cam, you can put it in and check the numbers @ .050".


The reason that you check the cam at .050" on the "upstroke", and then at .050" on the "downstroke". Since the cam lobes are ASSUMED to be symmetrical, these numbers can be used to find the lobe center. The lobe center is just the middle between .050" up and .050" down. Measuring the up and down enables you to be able to use those measurements to find the centerline of the lobe.

I would also check at .001". So for a quick check, I would check .001" up, .050" up, .050" down, and .001" down. Then at max lift, record the measurement at the dial indicator. With this information, then we can figure out the cam specs.


Don't worry about trying to figure out how the different companies measured their camshafts. If you measure them the same way every time, then you can compare them yourself. You set the standard for measuring, as you are doing the measuring. As long as you measure all of the cams the same, then you can compare the info. If you measure them differently each time, then the info won't be able to be compared to the others. You have to measure the same each time with the same method/procedure.

Once you find the valve open and close points, then you can calculate the lobe centers for intake and exhaust valves. then with that info, you can calculate the lobe centers (how far apart the lobe centers are).

I still need to re-read this and absorb it better but I am already late to get on my way to work.

I was just logging on to add............Yes at this point thanks to everyone I can map out the cam to the degree but what has me confused is that unless I know the standards in which the cam was originally measured I still do not understand how mapping out the cam is going to tell me if the cam is opening and closing the valves at the correct time........

Can you explain this too me Karl?

Just briefly looking over the post you just made I do not see the answer there so I am still confused.

Thanks again Karl

 

[krazykuda]

I still need to re-read this and absorb it better but I am already late to get on my way to work.

I was just logging on to add............Yes at this point thanks to everyone I can map out the cam to the degree but what has me confused is that unless I know the standards in which the cam was originally measured I still do not understand how mapping out the cam is going to tell me if the cam is opening and closing the valves at the correct time........

Can you explain this too me Karl?

Just briefly looking over the post you just made I do not see the answer there so I am still confused.

Thanks again Karl

Mapping out the cam does tell you when the valves are opening and closing. Mapping the cam is more accurate than going by the "cam card". the cam card is what the cam is supposed to be.... Just numbers on paper.

Mapping the cam tells us EXACTLY what the cam is doing and when. We can write the cam card with the information that you get from degreeing/mapping the cam.

If you give me the intake and exhaust valve open/close points, I can tell you what the cam is and what the cam card will read for that cam. I can calculate lobe centers, lobe centerline, and overlap from that information.


Or another way to say it. Cam cards are "theoretical", mapping the cam is "real world". Cam cards tell you what it SHOULD be, mapping the cam tells you WHAT IT IS....

 

[krazykuda]

Go to work. We can talk this out later....

 

[1930]

Mapping out the cam does tell you when the valves are opening and closing. Mapping the cam is more accurate than going by the "cam card". the cam card is what the cam is supposed to be.... Just numbers on paper.

Mapping the cam tells us EXACTLY what the cam is doing and when. We can write the cam card with the information that you get from degreeing/mapping the cam.

If you give me the intake and exhaust valve open/close points, I can tell you what the cam is and what the cam card will read for that cam. I can calculate lobe centers, lobe centerline, and overlap from that information.


Or another way to say it. Cam cards are "theoretical", mapping the cam is "real world". Cam cards tell you what it SHOULD be, mapping the cam tells you WHAT IT IS....

This does makes perfect sense to me, my only question though still is how am I too know that the points in which things are happening are at the correct/optimal timing in regards to the crankshaft position................




I will be mapping out two different engines this weekend, both somehow ended up being 1983 vintage, both are of unknown wear/mileage/usage and I am assuming both have had the tar beat out of them for a very long time but I am assuming I should be able to get similar readings from both engines as far as valve timing.

I have two degree wheels so I will be able to jump back and forth between them pretty easily.

Eventually, ( prob. not this weekend cause I still do not have enough info collected ) I plan to degree the cam that is in my newly re-built engine. I have no idea what sort of cam is in that nor know what standard was used to measure that. I can only assume it is stock with stock specs much like the FSM manual indicates.

So I go back to my original confusion as stated above.

EDIT: Id like of course for you to show me how I can do these things you mention........If you give me the intake and exhaust valve open/close points, I can tell you what the cam is and what the cam card will read for that cam. I can calculate lobe centers, lobe centerline, and overlap from that information. ...........

 

[krazykuda]

This does makes perfect sense to me, my only question though still is how am I too know that the points in which things are happening are at the correct/optimal timing in regards to the crankshaft position................

The purpose here is to degree the cam and see what it is.


You can always "degree" the cam in later (bump it forward or back 2° or 4°). Bumping the cam forward (advancing) will give you more grunt off the line, bumping it back (retarding) gives a stronger top end (higher rpm).

For a street slant 6, I think installing it "straight up" (no advance/retard) will be the best...


The purpose to take the information on the cam is to see how it ramps up and down. that's why I degree every .050" lift, so I can compare the rate that the valve lifts and lowers from one cam to the next.

 

[krazykuda]

EDIT: Id like of course for you to show me how I can do these things you mention........If you give me the intake and exhaust valve open/close points, I can tell you what the cam is and what the cam card will read for that cam. I can calculate lobe centers, lobe centerline, and overlap from that information. ...........

Yes, I can walk you through the calculations.


You find intake open/close and exhaust open/close at .001" and .050" lifts and we can figure it out when you are ready.