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"But how do it know?"
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Discussion Starter · #1 ·
Hi All,


I need to find the specs on a camshaft for turning purposes. I am trying to do this without removing the camshaft.


I did a search on this forum, along with a few other forums, and found that determining the specs requires a degree wheel and a dial indicator.


I understand that the automotive world is full of "you get what you pay for" parts, and that tools are no exception. With that said, I don't want to over spend nor unintentionally go for overkill. I would like to get a recommendation from fellow members on a good quality degree wheel kit.


I have done a search on Summit Racing and got a list of 19 degree wheels and kits. The one I am considering the moment is the Lunati Cam Degree Wheels Kits (80001). The kit seems complete, the company has a good rep and price is between the cheap and the expensive ones.


Any thoughts? Thanks in advance :D




EDIT: The articles I am using as reference for this procedure are:

"cam spec help wanted ......"


"How To Determine Cam Specifications of an Unknown Cam"
 

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This looks like a reasonable kit...
http://www.summitracing.com/parts/LUN-80001/?rtype=10
It includes a strap to find top dead center on a short block piston. I have no idea of the quality of the dial indicator, but being marketed by Lunati, you would think it would be ok.

You will need a flat, stable surface for the dial indicator stem to indicate off of, so find a lathe and turn down a piece of cold rolled steel rod, 1 inch in diameter. Make it 8 inches long and turn one end down to a Chevy tappet diameter (0.842") and the other end to another make of tappet, maybe a Ford at (0.875"). Finish off the ends nice and square. This heavy tool will ride on the cam lobe and follow it perfectly if you turn the block on an engine stand so that the tool is straight up and down. Use the magnetic stand function on the block deck to hold the dial indicator. Make sure the indicator is square with the tool by standing and eyeballing the stem of the indicator from both the side and the front of the motor. The indicator stem and the tool should be parallel.
 

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"But how do it know?"
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Discussion Starter · #3 ·
Hi Mr. Techinspector1,

techinspector1 said:
This looks like a reasonable kit...
http://www.summitracing.com/parts/LUN-80001/?rtype=10
It includes a strap to find top dead center on a short block piston. I have no idea of the quality of the dial indicator, but being marketed by Lunati, you would think it would be ok.
That's my thinking as well. Lunati is a popular company with a good rep, so I'm leaning towards that particular kit. The one thing that did concern me was the precision of the dial indicator, since I've never used or bought one before, but Im comfortable enough with Lunati's rep to give it a shot.




techinspector1 said:
You will need a flat, stable surface for the dial indicator stem to indicate off of, so find a lathe and turn down a piece of cold rolled steel rod, 1 inch in diameter. Make it 8 inches long and turn one end down to a Chevy tappet diameter (0.842") and the other end to another make of tappet, maybe a Ford at (0.875"). Finish off the ends nice and square. This heavy tool will ride on the cam lobe and follow it perfectly if you turn the block on an engine stand so that the tool is straight up and down. Use the magnetic stand function on the block deck to hold the dial indicator. Make sure the indicator is square with the tool by standing and eyeballing the stem of the indicator from both the side and the front of the motor. The indicator stem and the tool should be parallel.
Didn't realize I was going to need this custom-made tool, and I wouldn't be able to use it since the motor is in the car. Going by the steps I found on the thread from LS1tech, I think I might be able to get away with not having one.


It did take me some to mentally visualize how this tool would work (as you can probably tell by my posts, my knowledge in cars is quite limited), and I gotta say that sounds quite helpful. I'm surprised such a thing isn't sold on the market. But then again, how many people regularly measure cam specs with the cam still inside the engine and in the car?




Did a little more searching online today and found another helpful article and calculators:
Degreeing a Cam

Calculators



Thanks for the help! :thumbup:
 

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Thats a nice wheel. The dial indicator is the cheapest thing out there. If you think you will continue to need a dial indicator in the future, I would get one a little nicer, like from a machine shop supply company, or my favorite source, pawn shops.

You wont need the piston stop if you are not removing the head. You will need a stop that screws into the spark plug hole.
 

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lmsport said:
Thats a nice wheel. The dial indicator is the cheapest thing out there. If you think you will continue to need a dial indicator in the future, I would get one a little nicer, like from a machine shop supply company, or my favorite source, pawn shops.

You wont need the piston stop if you are not removing the head. You will need a stop that screws into the spark plug hole.
For quality dial indicators, look at Starrett, Brown & Sharp or Mitutoyo. If you purchase any of these quality tools, keep them in the box in a cool, dry place and they'll last you the rest of your life. On a dial indicator, you'll want resolution of 1/1000 and revolutions of 100/1000.
Crane makes a piston stop with a hole drilled down through the center. This will let compression pressure out as you bring the piston up to top dead center on the compression stroke.
 

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Cheap cam measuring/degreeing rig

Hey Man, I put my kit together years ago with piece parts cheap. I love tools, would love to own all high dollar stuff.
I put together a kit, don't have pics of it all but heres the TDC finder for heads on engine;
Cheap degree wheel about 6 bucks
Homemade piston stop(heads on) free
Store bought TDC finder(heads off)discount sale 10 bucks(easily homemade)
Tent sale cheap dial indicator w/magnetic base 20 bucks
Long 1/4" bolt and piece of stiff tie wire free
Pair of store bought check springs 6 bucks
Two cheap store bought solid lifters 8 bucks

50 bucks, its degreed a bunch of cams and I keep it all together in the drawer with my other precision tools as a kit.

Whatever you decide, get a big degree wheel, bigger is more accurate because its easier to read when you get into half degrees. Mines only about an 8". When I catch one dirt cheap I'm going bigger or get better cheaters. Been saying that for years now, still ain't done it. :thumbup:
 

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I didn't read each link so this may be a repeat of info.

If the lift is to be measured using hydraulic lifters, you might try to "bleed down" the lifter so the lifter piston is at the bottom of its travel. That way there will be no error caused by the lifter bleeding down during the actual measurement process.

This can usually be done by adjusting the rocker arm 'too tight' until the spring pressure has evacuated the oil from the lifter. It can take some time for a lifter to bleed all the way down, I'd suggest setting it tight then come back after a while and check the progress. Backing off the adjustment won't allow the lifter to refill w/oil, so it's OK to loosen the rocker if you want as long as the engine isn't run or the oil pump primed to refill the lifter. Once it is empty of oil the lifter piston will compress easily.
 

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"But how do it know?"
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Discussion Starter · #8 ·
lmsport said:
Thats a nice wheel. The dial indicator is the cheapest thing out there. If you think you will continue to need a dial indicator in the future, I would get one a little nicer, like from a machine shop supply company, or my favorite source, pawn shops.

You wont need the piston stop if you are not removing the head. You will need a stop that screws into the spark plug hole.
techinspector1 said:
For quality dial indicators, look at Starrett, Brown & Sharp or Mitutoyo. If you purchase any of these quality tools, keep them in the box in a cool, dry place and they'll last you the rest of your life. On a dial indicator, you'll want resolution of 1/1000 and revolutions of 100/1000.
Crane makes a piston stop with a hole drilled down through the center. This will let compression pressure out as you bring the piston up to top dead center on the compression stroke.
I did look into the brands for the dial indicators which Mr. Techinspector recommended. They are quite pricey, costing more than the Lunati kit itself, but I'm sure worth every penny for guaranteed accuracy every time. So I'm
going to get the better tools the first time.




Hey Nolan,
OLNOLAN said:
Hey Man, I put my kit together years ago with piece parts cheap. I love tools, would love to own all high dollar stuff.
I put together a kit, don't have pics of it all but heres the TDC finder for heads on engine;
Cheap degree wheel about 6 bucks
Homemade piston stop(heads on) free
Store bought TDC finder(heads off)discount sale 10 bucks(easily homemade)
Tent sale cheap dial indicator w/magnetic base 20 bucks
Long 1/4" bolt and piece of stiff tie wire free
Pair of store bought check springs 6 bucks
Two cheap store bought solid lifters 8 bucks

50 bucks, its degreed a bunch of cams and I keep it all together in the drawer with my other precision tools as a kit.

Whatever you decide, get a big degree wheel, bigger is more accurate because its easier to read when you get into half degrees. Mines only about an 8". When I catch one dirt cheap I'm going bigger or get better cheaters. Been saying that for years now, still ain't done it. :thumbup:
Thats a heck of a set up you got there for $50. How do you like the cheapo dial indicator?




Hey Cobalt,
cobalt327 said:
I didn't read each link so this may be a repeat of info.

If the lift is to be measured using hydraulic lifters, you might try to "bleed down" the lifter so the lifter piston is at the bottom of its travel. That way there will be no error caused by the lifter bleeding down during the actual measurement process.

This can usually be done by adjusting the rocker arm 'too tight' until the spring pressure has evacuated the oil from the lifter. It can take some time for a lifter to bleed all the way down, I'd suggest setting it tight then come back after a while and check the progress. Backing off the adjustment won't allow the lifter to refill w/oil, so it's OK to loosen the rocker if you want as long as the engine isn't run or the oil pump primed to refill the lifter. Once it is empty of oil the lifter piston will compress easily.
Actually, this information wasn't mentioned in the articles I linked so thank you for posting this. All other helpful tips and tricks welcome.




Thanks guys! :thumbup:
 

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Good enough for me.

"Thats a heck of a set up you got there for $50. How do you like the cheapo dial indicator?"

Its accurate enough for most any use. On a dial indictor, plus or minus .001" is good enough IMHO. When I use it or put it away, I treat it with the care and maintenance that a precision tool deserves. If you drop a dial indicator, calipers, micrometers, etc. on the floor its gonna be messed up regardless of whether it cost twenty or two hundred. So far the only precision tool I've dropped was a vernier dial caliper and it was immediately junk.

When I get time I may get a photo of my rudimentary precision tools. They were all bought through cheap outlets or flea markets. My set of mics, 1" to 6" I bought from J.C. Whitney years ago. I had a friend who is a machinist, check my mics and standards against his Starretts and he found them repeatably accurate into the fractions of a thousandth. The only cheap precision tools I have that were pretty disappointing is my telescope snap gauges, they have a junky action to them and are hard to use and hard to get a good lock down on. Someday I might buy a set of inside mics and a nice dial bore gauge for cylinders. I usually just trust the shop thats gonna bore it.
 

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Discussion Starter · #10 ·
OLNOLAN said:
"Thats a heck of a set up you got there for $50. How do you like the cheapo dial indicator?"

Its accurate enough for most any use. On a dial indictor, plus or minus .001" is good enough IMHO. When I use it or put it away, I treat it with the care and maintenance that a precision tool deserves. If you drop a dial indicator, calipers, micrometers, etc. on the floor its gonna be messed up regardless of whether it cost twenty or two hundred. So far the only precision tool I've dropped was a vernier dial caliper and it was immediately junk.
Well, that's all the warning I need to be extra careful with these tools. Lesson learned.




OLNOLAN said:
When I get time I may get a photo of my rudimentary precision tools. They were all bought through cheap outlets or flea markets. My set of mics, 1" to 6" I bought from J.C. Whitney years ago. I had a friend who is a machinist, check my mics and standards against his Starretts and he found them repeatably accurate into the fractions of a thousandth. The only cheap precision tools I have that were pretty disappointing is my telescope snap gauges, they have a junky action to them and are hard to use and hard to get a good lock down on. Someday I might buy a set of inside mics and a nice dial bore gauge for cylinders. I usually just trust the shop thats gonna bore it.
Yes, pictures would be great! I'm a visual learner. :D I myself would let the shop do the measuring but at the same time, it is something I want to learn how to do.




Btw, here's a rookie question: You mentioned the term "mic" and I've seen it several times on this site. Is that short for micrometers?
 

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Yep

Yep, thats correct. I was speaking of C-mics in the set. But they could be inside mics or other forms of micrometers. May buy a valve spring height mic some day, they are real easy to use versus the alternatives.

While I can't vouch for them, this company appears to sell and manufacture some middle of the road engine building tools;
http://www.powerhouseproducts.com/ph/
 

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Discussion Starter · #12 ·
I just checked 'em out and their prices are definitely in between the cheapos and the expensive stuff. I'm gonna have to take some time and see what the reviews are alike also. Thanks for the link. :thumbup:
 

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cam degreeing kit

Hey Hawk, I had forgotten about this but remembered to get you a photo last night. This is what I put together dirt cheap years ago; Oh, My cheap dial indicator is about 20 yrs. old, haven't used it in about a year. Well, when I took it out for the photo it was stuck, so I thumbed the plunger a couple of times and damed if it didn't fall to pieces internally. Guess I got my moneys worth out of it. The spark plug piston stop is homemade as well as the degree pointer. It gets the job done, but a bigger degree wheel is easier to see. Nolan
 

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Forgive me if i sound dicky, but what kind of tuning are you doing that would require knowing the opening and closing of the valves?
I can understand, in some rare situations, that needing to know the lobe centers or intake angle may be needed. Like maybe if you are putting forced air or nitrous or EFI on an existing engine.

Are you looking to find the LIFT of the cam? I suspect you are, and in that case you dont need a degree wheel, just a dial indicator mounted ideally off the rocker stud, with the plunger on the pushrod.
As long as the pushrod doesnt roll around in the guideplate/head (it shouldnt) you will get extremly close to the lift of the cam.
After you find the lobe lift, X by your rocker ratio and you get the valve lift.
Nobody, and i mean NOBODY bleeds out lifters before degreeing a cam. A dial indicator has like a half ounce spring in it, if thats overpowering the spring AND bypass in the lifter, you have major problems!!

Keep in mind that if you decide to degree it, you should have ALL the rockers OFF the engine (keeping balls with the rocker they came out of if stamped) all the sparkplugs out, ideally the converter unbolted and use the longest possible ratchet or bar for a smooth pull.
This is because with all the drag the engine becomes very difficult to roll over smoothly and jerks the dial indicator and timing chain, causing the reading to be off 5 deg or more, which is ALOT when you are talking about looking for .001 @18btdc. Which could be 24, or 15 degrees depending on how tight your chain is and how much deflection in the chain you have caused with how you may be turning the engine over.

As a matter of fact, unless you know your timing chain is brand new and tight, doing any of this but measuring the lift is really quite pointless.

AND on top of that, i dont think anyone has informed this fellow how fast and fun it is to find true top dead center, while leaning over a rad saddle. lol
 

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Judging by the first post, the reason is to come up w/the same info that would be on a cam card- which isn't available since the cam is unknown. Another reason for wanting the intake closing point is to calculate the DCR. Another reason would be to set the intake centerline, or to adjust the phasing to compensate for tolerance stacking and/or wear, etc.

As far as bleeding the lifter down, a better option is to make or use a solid lifter w/the same seat height as the hydraulic lifters that are being used. But to say the lifter won't bleed down under the pressure of a valve spring would be a mistake. If he wanted to he could install checking springs to avoid bleeding down the lifters from the spring pressure.

I don't know of anyone who mounts the dial indicator to the rocker stud in order to measure the lobe lift.
 

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Yes Cobalt, I understand what he was after, I said I don't know what kind of tuning he is doing that would require THAT much info of a installed camshaft, and that he doesn't want to tear anything apart.

*I* understand everything, don't worry about that.

The L/C is fixed and intake angle depends on how sloppy the chain is, so a rookie doing this most likely won't even be close to accurate

And as I said, perhaps if he is "tuning" it to efi or forced air knowing the L/C might be good, but with a carb (I assume) the tuning isn't dependant on any cam related geometry, only the manifold vacuum CREATED by the L/C (and overlap), which isn't "tunable"

Maybe knowing the compression ratio, and setting up an advance curve not to come on too hard in the midrange and rattling everything apart would be what he's looking for?

And I suppose I should have been more PC and said that bottoming the lifters on purpose may damage the spring or bypass, so don't do that.

So if the original poster would like to elaborate on what he would like to accomplish here, someone could help him out?
 

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...bottoming the lifters on purpose may damage the spring or bypass, so don't do that...
A Chevy hydraulic lifter piston/spring/check ball cup will not contact the bottom of the lifter body when the piston is fully depressed. The way the lifter body ID is machined prevents the spring or cup being what stops the travel of the piston. Therefore there will be no damage done. After all, it's not like the engine will be run that way- it's being turned over by hand.
 

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Discussion Starter · #18 ·
Hi All,


Sorry for the late reply. I never got a notification on the recent posts and haven't been able to log on for very long the past few days. Thank you Nolan for the reminder. :D




OLNOLAN said:
Hey Hawk, I had forgotten about this but remembered to get you a photo last night. This is what I put together dirt cheap years ago; Oh, My cheap dial indicator is about 20 yrs. old, haven't used it in about a year. Well, when I took it out for the photo it was stuck, so I thumbed the plunger a couple of times and damed if it didn't fall to pieces internally. Guess I got my moneys worth out of it. The spark plug piston stop is homemade as well as the degree pointer. It gets the job done, but a bigger degree wheel is easier to see. Nolan
Hey Nolan,

I very much appreciate you taking the time to take the picture for me. :thumbup: And for sacrificing the dial indicator for this. :( :pain: I figure I can steal your ideas on making the spark plug piston stop and the degree pointer. Can't say I've ever fabbed up a tool, aside from a bent paper clip, so this might be something to look forward to.

Thank you again Nolan! I owe ya :thumbup:




Hey mouse77 and cobalt,


First off, I want to thank both of you for the various tips and pointers that I was not previously aware of. Sometimes I ask questions in a general sense so that the responses are useful for anyone who reads the thread, and it doesn't become too specific, and as a result, lengthy. That may not have been a wise decision in this case, and I apologize for any confusion.


Here is my scenario. I have a '95 Impala SS with a 383 LT1 under the hood. A couple years ago this month, I blew out the transmission and it has been on jack stands ever since. I have been split between buying a solid rebuilt transmission the first time, or rebuilding it myself. So far, it has been a chase for time and money.


How the whole degreeing of the cam fits into this situation is this: the engine is a 383 and the cam specs are unknown. The shop that built this car for the previous owner is the one that sold it to me (he had sold it to the shop after it got rear-ended and he got the money from the insurance for it). The engine has roughly 25k miles on it.


According to the shop owner, who claims he did the work on the car, the previous owner had supposedly sent off the computer from this car to be reprogrammed on several occasions. He also mentioned that the cam was a custom grind and he did not have the specs available.


Not knowing the cam specs, the transmission suddenly blowing out, computer being reprogrammed several times, and a few other issues have made me quite nervous about just putting in another transmission and calling it a day. My plan is to get the computer reprogrammed again just once, but to do it right by making sure I have all necessary specs (as accurate as possible) before-hand.


On a related note, due to a couple of life-changing situations in the recent months, I am not sure if I will be holding on to the car much longer. I've had it up for sale for two years but no buyers have come forward, which is to be expected in this economy. Parting it out remains a difficult but possible option.


With that said, I am still open to any tips, suggestions and guidance on this task. I don't mind learning for the sake of learning, and I may still tackle this project. If you feel I am in over my head with this, going about it in the wrong way or simply going for overkill, please say so. I am a rookie in all respects.


Thanks again for the continued help! :thumbup:
 

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All the more reason to need to know the specs/what the cam is going to be like- you want to match the torque converter stall RPM to the power band of the camshaft.

If I had a choice of just two things that I could know about a cam, it would be the duration at 0.050" lift and the intake closing point. Lift would be way low on a list by priority.
 

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Ok, well there you go.
The Duration would be very important in that situation.

The Lobe centerline/overlap is static and cant be adjusted, but should be known anyways.

Heres something i thought of earlier but didnt know that you had the transmission out at that point. Would it be worth it to pull the cam plug out and see if there is a manufacterer name or part number?? That would be sweet and save a ton of time and frustration.
 
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