Check My Cam Degreeing

-
SpeedThrills

SpeedThrills

FABO Gold Member
FABO Gold Member
Joined
Jun 3, 2008
Messages
2,584
Reaction score
1,454
Location
Very South Jersey
As I've mentioned in other posts about the 360 I'm re-assembling, it's been a long time since I've done this, and even back when, I didn't do it a lot.

The engine came w/a hyd cam w/ purple paint on it and the lift checks at .508". I'm going to assume (uh,oh) that it's a 292-508 MP cam.

Searching on FABO, I am finding that there were 108 and a 112 versions. I just checked mine (twice) and I'm getting 98*. I used the method in the pictures, taken from Larry Shepard's book. Even if it's a 108, isn't that pretty far off? Am I missing something? It wouldn't be the first time...
IMG_2601.JPG
IMG_2602.JPG
 
I would first double check your dial indicator to your lifter (or pushrod) alignment. I just did my camshaft degreeing with heads off and basing it off the lifter. It was troubling to get alignment with the items I had (big clunky magnetic stand for the indicator ). I kept getting at least 9-10 degrees off and I knew that wasn't right. Setting it up with great detail to being parallel with the lifter helped me get the right numbers and the centerline was dead on for me. You may experience a few degrees retarded or advanced. Good luck!
 
That method is used to measure installed centerline of the intake lobe (ICL). I am guessing that the 108 and 112 numbers you refer to are LSA (lobe separation angle) numbers. Those are are 2 different things. So are you looking for ICL, or LSA? Sounds like LSA, which is a different measurement.

As a side comment, if your ICL is at 98*, then that is quite heavily advanced for either cam version. To verify ICL, I'd repeat the measurements at .050" lift from 0 lifter lift (just because that is more standardly done) and compare. Make sure you are measuring at the lifter body, not the pushrod or lifter cup; the possibility of the hydraulic lifter being 'soft' when there is is no oil pressure is a good source of error.
 
When degreeing a cam, I prefer to use the .050" lift numbers as if you try to use the 'advertised' numbers or .001", .002" etc it can be inaccurate as when the lifter begins to lift, it is moving slower and it may be at the same lift for a few degrees...

I take measurements at .001", .010", .050", .100", .150", .200", .250", .300", .350", .400" and then try to get a number at max lift, but that also is difficult as the cam is slowing down and changing directions and you may have max lift for a few degrees - sometimes 4° - 10° before it starts to move down... I record the 'range' of degrees when it reaches max lift and then compare the calculated center line for that lobe to that number using the lift ranges from: 050", .100", .150", .200", .250", .300", .350"... I also compare the calculated center line from each of those lifts to see if they come out the same to tell how accurate my numbers are....
 
I never do what the Chrysler book says. I don't like touching the dial indicator that much and there no reason to do that.

If you know what the lobe lift is, just subtract .050 from that and check the degree wheel at that lift on both sides of the nose.

Let's say you have a lobe lift of .350. I'm assuming you have found absolute TDC and have the degree wheel correctly set to zero at TDC.

Roll the crank over until the lifter is on the base circle and zero the indicator. Keep turning the crank until the lifter reaches .300 lift (.350 lobe lift minus .050 is .300) and read the degree wheel. Keep turning the crank until you go past max lift and down the closing side until the indicator reads .300 lift again. Read the degree wheel.

Now you can do the math. You will have found the exact intake centerline. Which isn't always at max lobe lift. Which is why the Chrysler method of zeroing the indicator at max lift is a crap shoot at best.
 
Dodge72 said:
I would first double check your dial indicator to your lifter (or pushrod) alignment.
Click to expand...
Doing it w heads off. I have it parallel, as you mentioned, it's a bit tricky.

nm9stheham said:
That method is used to measure installed centerline of the intake lobe (ICL). I am guessing that the 108 and 112 numbers you refer to are LSA (lobe separation angle) numbers. Those are are 2 different things. So are you looking for ICL, or LSA? Sounds like LSA, which is a different measurement.

Make sure you are measuring at the lifter body, not the pushrod or lifter cup; the possibility of the hydraulic lifter being 'soft' when there is is no oil pressure is a good source of error.
Click to expand...
Yes, I'm looking for ICL, to install it.
I am measuring at the lifter body.

krazykuda said:
When degreeing a cam, I prefer to use the .050" lift numbers as if you try to use the 'advertised' numbers or .001", .002" etc it can be inaccurate as when the lifter begins to lift, it is moving slower and it may be at the same lift for a few degrees...

I take measurements at .001", .010", .050", .100", .150", .200", .250", .300", .350", .400" and then try to get a number at max lift, but that also is difficult as the cam is slowing down and changing directions and you may have max lift for a few degrees - sometimes 4° - 10° before it starts to move down... I record the 'range' of degrees when it reaches max lift and then compare the calculated center line for that lobe to that number using the lift ranges from: 050", .100", .150", .200", .250", .300", .350"... I also compare the calculated center line from each of those lifts to see if they come out the same to tell how accurate my numbers are....
Click to expand...
I understand the .001 vs. .050. I like your thoroughness.

yellow rose said:
I never do what the Chrysler book says. I don't like touching the dial indicator that much and there no reason to do that.

If you know what the lobe lift is, just subtract .050 from that and check the degree wheel at that lift on both sides of the nose.

Let's say you have a lobe lift of .350. I'm assuming you have found absolute TDC and have the degree wheel correctly set to zero at TDC.

Roll the crank over until the lifter is on the base circle and zero the indicator. Keep turning the crank until the lifter reaches .300 lift (.350 lobe lift minus .050 is .300) and read the degree wheel. Keep turning the crank until you go past max lift and down the closing side until the indicator reads .300 lift again. Read the degree wheel.

Now you can do the math. You will have found the exact intake centerline. Which isn't always at max lobe lift. Which is why the Chrysler method of zeroing the indicator at max lift is a crap shoot at best.
Click to expand...
I checked TDC (heads off) by putting a flat washer on the piston and bringing it up against a stop CW, reading the wheel and reversing, doing the same thing CCW. Split the difference. Hope that makes sense in writing!
Your method does sound much better than Chryslers.

I had a good friend and race partner years ago who did all of this stuff. (He was killed in a car accident by a young girl who bent over to pick up a spilled soda, and she came across and hit him.) I thought I was paying closer attention, but actually doing it is more involved than you think. I did learn rear gear set up from him. I have about 30 runs w slicks on a set of gears I did. Still works!

I have tool and die work in my past, so it's a matter of learning procedure, I'm pretty good with close measuring.

Thanks everyone, I hope to work on this today.
 
You're confusing lobe separation with intake center line. Lobe separation is how far apart the intake and exhaust lobe peaks are in degrees. That's where the 108 and 112 come into play. You have either one or the other. That measurement is ground in and cannot be changed....without regrinding the camshaft.

Intake center line refers to "where" the camshaft installs in the engine and is generally 4 degrees advanced FROM the LSA. So, if you have a 108 LSA camshaft, you would install it at 104 intake center line. I would probably go on down to around 100, because that 508/292 on the 108 is a cylinder pressure robbin sumbitch unless you have a pretty high static compression ratio. But it can be made to run well if advanced properly.
 
krazykuda said:
When degreeing a cam, I prefer to use the .050" lift numbers as if you try to use the 'advertised' numbers or .001", .002" etc it can be inaccurate as when the lifter begins to lift, it is moving slower and it may be at the same lift for a few degrees...

I take measurements at .001", .010", .050", .100", .150", .200", .250", .300", .350", .400" and then try to get a number at max lift, but that also is difficult as the cam is slowing down and changing directions and you may have max lift for a few degrees - sometimes 4° - 10° before it starts to move down... I record the 'range' of degrees when it reaches max lift and then compare the calculated center line for that lobe to that number using the lift ranges from: 050", .100", .150", .200", .250", .300", .350"... I also compare the calculated center line from each of those lifts to see if they come out the same to tell how accurate my numbers are....
Click to expand...
You should make a video of your process
Great topic
 
512Stroker said:
You should make a video of your process
Great topic
Click to expand...

I'm doing a series of how to's on building a small block... I plan to do a chapter on degreeing a cam, but my son went away to college and won't be able to come back until a long break from college... I'm building an engine with him for his Valiant....

I have to wait for him to come back for a visit to degree his cam with him...
 
Last edited:
SpeedThrills said:
As I've mentioned in other posts about the 360 I'm re-assembling, it's been a long time since I've done this, and even back when, I didn't do it a lot.

The engine came w/a hyd cam w/ purple paint on it and the lift checks at .508". I'm going to assume (uh,oh) that it's a 292-508 MP cam.

Searching on FABO, I am finding that there were 108 and a 112 versions. I just checked mine (twice) and I'm getting 98*. I used the method in the pictures, taken from Larry Shepard's book. Even if it's a 108, isn't that pretty far off? Am I missing something? It wouldn't be the first time...View attachment 1715382382View attachment 1715382383
Click to expand...
Purple shafts are well known to be 8-10 degrees advance when dot to dot about 80% ime.
 
RustyRatRod said:
You're confusing lobe separation with intake center line. Lobe separation is how far apart the intake and exhaust lobe peaks are in degrees. That's where the 108 and 112 come into play. You have either one or the other. That measurement is ground in and cannot be changed....without regrinding the camshaft.

Intake center line refers to "where" the camshaft installs in the engine and is generally 4 degrees advanced FROM the LSA. So, if you have a 108 LSA camshaft, you would install it at 104 intake center line. I would probably go on down to around 100, because that 508/292 on the 108 is a cylinder pressure robbin sumbitch unless you have a pretty high static compression ratio. But it can be made to run well if advanced properly.
Click to expand...
Gotcha. I'm looking to install it, so I need that number.

I have 11.82:1 static compression ratio (in cylinder 1, other cyl cc's vary from 63.2 to 66.3). I entered my values in Wallace's calculator.

Bore 4.030
Stroke 3.58
MP P4120094 HG .035 (mics .038 new)
Deck -.013
Comb Chamber cc 65.4
Dome -.013 (per KB website)
Gasket Bore Dia. (Scaled) 4.125

I'm thinking I don't need to advance the cam more than what it should be installed at.
What is that number?

I rechecked TDC and ICL today. For ICL, I checked it 3 times and got between 113.5 and 114.5 using YR's method. My TDC indicator probably got bumped yesterday.
I moved the crank gear to the 4 advanced position, hoping to get around 110. I don't know why, but I'm thinking I'm shooting for 108, maybe I'm wrong.
I checked again 3 times. I got between 102 and 102.5. How did it move so far? I had it straight up the first time.

More help needed!
 
Last edited:
SpeedThrills said:
Gotcha. I'm looking to install it, so I need that number.

I have 11.82:1 static compression ratio (in cylinder 1, other cyl cc's vary from 63.2 to 66.3). I entered my values in Wallace's calculator.

Bore 4.030
Stroke 3.58
MP P4120094 HG .035 (mics .038 new)
Deck -.013
Comb Chamber cc 65.4
Dome -.013 (per KB website)
Gasket Bore Dia. (Scaled) 4.125

I'm thinking I don't need to advance the cam more than what it should be installed at.
What is that number?

I rechecked TDC and ICL today. For ICL, I checked it 3 times and got between 113.5 and 114.5 using YR's method. My TDC indicator probably got bumped yesterday.
I moved the crank gear to the 4 advanced position, hoping to get around 110. I don't know why, but I'm thinking I'm shooting for 108, maybe I'm wrong.
I checked again 3 times. I got between 102 and 102.5. How did it move so far? I had it straight up the first time.

More help needed!
Click to expand...
Always check with the direction the motor turns while running, chain slack will fk with you otherwise.
If it's the 108....do 102 if you want tire frying early in the range..or 106 if you want it later.
Imo 4+ degrees is noticable, 2...is barely noticable and not worth it.
 
Last edited:
MOPAROFFICIAL said:
Always check with the direction the motor turns while running, chain slack with fk with you otherwise.
If it's the 108....do 102 if you want tire frying early in the range..or 106 if you want it later.
Imo 4+ degrees is noticable, 2...is barely noticable and not worth it.
Click to expand...
I checked everything in CW (from front) rotation. Chain is very tight. Slack is barely, if at all, noticeable.
 
SpeedThrills said:
I rechecked TDC and ICL today. For ICL, I checked it 3 times and got between 113.5 and 114.5 using YR's method. My TDC indicator probably got bumped yesterday.
I moved the crank gear to the 4 advanced position, hoping to get around 110. I don't know why, but I'm thinking I'm shooting for 108, maybe I'm wrong.
I checked again 3 times. I got between 102 and 102.5. How did it move so far? I had it straight up the first time.
Click to expand...
How do you figure 114 is straight up.............. is that a 114LSA cam? Do you know that for sure?
At your Scr, your pressure is gonna be approaching 175 psi or more; can you run that with iron heads?
 
Last edited:
Hell, if the static is really that high, I would just install it straight up at 108.
 
Last edited:
OP, what model of KB piston do you have? Something is missing from your static CR computation. Is this an LA block?

Any way that you had the crank sprocket at the -4 position, and moving it to the +4 position changed the timing by 8-10 degrees. Something like this might be going on. Sometimes the little stamped geometric shapes that designate the timing keyways are hard to read.
 
AJ/FormS said:
How do you figure 114 is straight up.............. is that a 114LSA cam? Do you know that for sure?
At your Scr, your pressure is gonna be approaching 175 psi or more; can you run that with iron heads?
Click to expand...
I left out some details. I first installed it dot to dot. (If I saw the marks correctly. I'll check.) That's where I saw the 114.

RustyRatRod said:
Hell, of the static is really that high, I would just install it straight up at 108.
Click to expand...
Is that where a MP 292-508 cam should be?
The truck that it was in was street driven before the previous owner wrecked it. I used 92 in it while I was fiddling with it before I pulled it and parted out the (totaled) truck. No pinging.

nm9stheham said:
OP, what model of KB piston do you have? Something is missing from your static CR computation. Is this an LA block?

Any way that you had the crank sprocket at the -4 position, and moving it to the +4 position changed the timing by 8-10 degrees. Something like this might be going on. Sometimes the little stamped geometric shapes that designate the timing keyways are hard to read.
Click to expand...
Sorry, KB190. LA block. The KB website says they're 11 plus to 1, depending on chamber cc. Seems correct.
Pretty sure I had it at "0". It was in the center of the three keyways. I'm thinking I advanced it 4*. I'll check tomorrow or Saturday.
I need to recheck everything. I checked several times, as I mentioned. I'll look closer to see if something's not right.
 
OK on the pistons. I come up with 11.1 Static CR. I suspect the valve pocket volume is not being put into the Wallace calculator, and that is why your numbers are high. Roughing in some cam numbers from the MP cam, it looks like around 8.2-8.4 DCR at an ICL of 108.

Are these milled open chamber heads? If so, then it sounds like the heads have been milled about .040" and so the head cambers will be about .070" deep + or -. With the head gasket a .035" compressed, and the piston dome up about .065" above deck, it would be about .040" dome to head clearance. Is that the setup?

BTW, on measuring the angles for equal lift on opening and closing ramps of the intake lobe, you want to be on the steepest possible points of the ramps for the best accuracy. At the steep points, the lift versus degrees of rotation is the highest and gives the best accuracy in the way we tend to measure things. Being .050" down from the lift peak may not be the steepest part of the ramp and so accuracy may suffer.
 
AJ/FormS said:
How do you figure 114 is straight up.............. is that a 114LSA cam? Do you know that for sure?
At your Scr, your pressure is gonna be approaching 175 psi or more; can you run that with iron heads?
Click to expand...
I did compression check before I took it apart. They were all between 145# and 155#.

nm9stheham said:
OP, what model of KB piston do you have? Something is missing from your static CR computation. Is this an LA block?

Any way that you had the crank sprocket at the -4 position, and moving it to the +4 position changed the timing by 8-10 degrees. Something like this might be going on. Sometimes the little stamped geometric shapes that designate the timing keyways are hard to read.
Click to expand...
I just looked back at post #12. I typoed the dome volume. According to KB's site, it should be -1.2, not the -.013 that I typed. I still get the 11.82. The .035 gasket thickness is a guess. New they're .038.
I have no idea if they were milled. They are 915's.

Wyrmrider said:
wade through this one
it will tell you what not to do
then how to do it
Degree an installed/unknown camshaft
Click to expand...
Didn't finish it yet. Some of it made my eyes glaze over! Good stuff though, thanks.

In addition to checking TDC as in post #6, today I used an indicator on the top of the piston. Same results.

I rechecked everything again today, using YR's method and Chrysler's. I still got 113 w/ it advanced. I returned it to "0", and I got 108 twice. I'm good with 108. I'm pretty sure the tip of my indicator was dragging on the side of the lifter bore. I'm not sure what happened when, but that's why I'm checking over and over. Each time makes me more comfortable with the procedure. I think I broke in the rings already!!!
I have indicator extensions on the way. I don't think they'll show any difference though, but I'll try them. Mainly to prove that 108 figure more.

The lobe has .338 to .339 lift. Multiplied by 1.5 gives me .507 and .5085, respectively.
 
Last edited:
SpeedThrills said:
I just looked back at post #12. I typoed the dome volume. According to KB's site, it should be -1.2, not the -.013 that I typed. I still get the 11.82. The .035 gasket thickness is a guess. New they're .038.
I have no idea if they were milled. They are 915's.
Click to expand...
I found the confusing part of that Wallace Calculator..... pistons nominally below deck (like you should have with a standard deck) require you put in a + number for deck height.....in other words, put in .013 for Deck Height, not -.013. Yeah, I know, that does not make sense, but it's how that calculator works..... below deck, put in a + deck height ; above deck, put in a - deck height. Change that and you will get the correct number of around 11.1.

As for your heads....you NEED to see what is what there because that dome on the piston is .080" high than the 'deck height' of the piston (which is the piston's outer edge), so the piston dome will indeed stick well above a standard LA deck... by about .065". With that head gasket, the dome will protrude around .030" above the head gasket and into the open chamber of the head.

For your 64-ish chamber volume to be correct for a 915 head, it has to have been milled down something like .040" + or -. That will make the open part of the head about .070" deep, + or -. That open area depth will work OK with the dome sticking up as far as it will. But, if the head has been milled more than .040" or the deck is short for some reason, and the piston domes stick up too far, then you risk piston to head contact.

Hope that all makes sense. Just trying to make sure you are not getting in trouble on piston-to-head clearance. Time to know that for sure; you can adjust the head gasket thickness to make small corrections. If things are assembled with the heads torque down.... dunno how to advise you.

FWIW, with an 11.1 Static CR and your cam installed at a 114 ICL, the numbers for cranking compression come out to around 153 psi.... right at what you measured, within the tolerances of everything considered.... gauges, calculators, etc....) So that confirms that your Static CR has to be close to 11.1.
 
SpeedThrills said:
I rechecked everything again today, using YR's method and Chrysler's. I still got 113 w/ it advanced. I returned it to "0", and I got 108 twice.
Click to expand...
113 is retarded, not advanced. Something sounds off with the markings on the crank sprocket keyways, or the reading of the markings. As a check, if you move the crank sprocket to a more advanced position, and line up the crank at exactly the same angle (like at TDC), you will see that any marks and the teeth on the cam sprocket have moved to a slightly more CW position than before.

Just to be sure.... you are measuring an INTAKE lifter, correct? If you advance the cam the ICL will decrease. The ECL (exhaust centerline) will increase.
 
I rechecked everything again today, using YR's method and Chrysler's. I still got 113 w/ it advanced. I returned it to "0", and I got 108 twice."

please clarify
usually 113 ATDC for the ICL center line is retarded compared to 108


I see that nm has just posted on this- carry on
 
Lemme see if I can clarify...

Definitely number 1 intake. I am certainly capable of using an exhaust by mistake. lol

The first readings I got (1st post), were about 98*. The crank gear was installed on the "0". Also, the crank gear was installed on "0" when I disassembled it. (To check what was inside an unknown-to-me engine.)

I moved the crank gear to the "A"dvanced position hoping to retard it to somewhere close to 108*.
That's when I started getting the 113* readings.
I stopped and rechecked everything and reset my indicator.

Moved the crank gear back to "0". Now I have gotten 108* twice, and I'm going to check it a couple more times.

Of course, that's the reading I should've gotten the first time. Maybe my TDC wasn't right, and I think my indicator may have been dragging on the side of the lifter bore.

The head gasket that was on it when I got it was .051 compressed. I'm using the MP P4120094, which is .038 new.

I'll check PV. It had a minimum of .180 I and E with the .051 gasket (at "0", of course).
I measured the open area on 1 cylinder. It is .070. I'll clay that with the thinner gasket and see what it is between piston and head.
Yes, a good time to check! I even have a set of the thicker gaskets in case.
 
You must log in or register to reply here.
-

Back
Top