Camshaft degree

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72ScampTramp

72ScampTramp

Scamp Tramp
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Ok been watching some videos on how to degree a camshaft. Says timing figures taken at .050. If im understanding this right after i find true TDC, when the #1 intake is open to .050 my degree wheel should be at 15.5 degrees BTDC is this correct?
 

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Yes, that is true.......BUT........ that is .050" lift at the lifter, NOT THE VALVE and I only use that as sort of a double check. It is better to continue on until the lifter, in your case, is at .320" lift, note the degrees at that point, then continue on until the lifter has gone all the way over the nose of the cam and come back down to .320" lift, note the degrees, add the two degrees together and divide by two and that will give you the intake centerline. According to the cam ticket it should be 106 degrees, or 4 degrees advance, 110 lobe separation minus 106 centerline = 4 degrees advance.

The .320" is an arbitrary lift. You could use .280", .300", anything you chose as long as you use the same lift on each side of maximum lift.
 
Right was going to do it with the heads off. That gives me a more accurate reading correct? If so then that means at the lifter i should stay at .050 right?
 
I just figured out how to degree a cam when I put in a solid in my stroker. It is a lot easier than the instructions make it out to be. Job one when putting in a new cam is checking the numbers they put on the cam to see that they shipped you the right one! Mine was supposed to be (Lunati) 60434 but I swear the marks said 60134. That number is the same grind as mine buy on a Chebby cam. It was a Mopar configuration so I went ahead with install and would check lift / duration with the measurements. The first thing you need to do is orient the degree wheel on the crank and find true TDC and position the degree wheel pointer at true zero. The set I used only had a wire that you bend but I had a magnetic base thingy that had a pointer which worked real well.

Then start with setting the cam up "straight up". Depending on the timing set you have you can adjust the cam vs the crank with different notches on the cam or crank gear, and/or offset keyways. I returned one gear/chain set because I didn't like the way the crank gear was so loose and therefore not really able to find a place to settle in at and bought a Pro Gear set which was better. Your crank gear should be tight against the crank during all this but DON'T put on the balancer yo keep it there yet because you will probably need to reposition the gear set. You position the dial indicator by locating it on the post and clamps that come with the timing set - try the best you can to make the indicator parallel to the lifter but it is difficult to get it perfect. Not that big a deal really. Zero the dial indicator at the base circle of the cam (I zero at 0.100 travel on the indicator). Now rotate the crank clockwise. Then get some masking tape and when the lifter goes 0.050 off the base circle, when the crank is rotated clockwise when viewed from the front of the engine - and BTW always rotate in that direction when making measurements because the slop in the chain is taken out - put the tape on the wheel where the pointer is and make a mark on the tape showing where the pointer tip is. In your case the mark should be close to 15 degrees BTDC. Now keep rotating the crank clockwise until the indicator is maxed out on the cam lobe. Note the total lift reading - yours should be 0.546 / 1.5 = 0.364". Keep rotating clockwise until the dial indicator is now back at 0.050 and put another piece of tape on the wheel and mark it where the pointer is. Yours should be around 48* ABDC. Now you can check the duration by adding 15* + 180* + 48* = 243*. The centerline of the lobe lift is the duration as measured / 2 added to the opening. For your cam that is -15* + (243/2) = 106*.

If the opening and closing are earlier (advanced) or later (retarded) that gives you an idea how much you need to change the index between the crank and the cam using the slots and/or keyway. I suggest keeping the cam gear, crank gear, and chain in the same tooth orientation when removing and re-installing them so that variable is removed.

If you want to put that cam in at say 108* centerline then you need the start of the lift (at 0.050) to start 2* later which would be 13.5* BTDC. The closing at 0.050 would also be 2* later which would be 49.5* ABDC. So you would do whatever your timing set does to make the change and measure it again.

On my set-up on a cam with 0.400 lobes measured by subtracting the base circle from the lobe height, and also by taking the lift and dividing by the rocker ratio, I had 0.399 total lift measured by the dial indicator and 1 degree less total duration (close point minus opening point at 0.050). This was because of the non-optimal geometry of the dial indicator on the lifter. Like I said, not that big a deal but do the best you can when setting up the indicator on the lifter.

On my engine I used the timing chain tensioner. When I was degreeing the cam I just took off the bannana part of the tensioner so it was easier to get the timing set on and off. I put that on after I was done and the cam bolt was locktited in place.

I repeated the cam measurement after I had put the timing cover on and had installed the dampener just to be sure things were still in the right place. BTW, do not use the dampener bolt to install the dampener. There is a tool which screws all the way into the crank and then uses a washer and nut to pull on the dampener. Otherwise if you try to use the bolt you will have few threads in the crank when you start to tighten things up and possibly screw up the crank threads. Since the dampener is tight on the crank, heat it in boiling water to expand it. I dried the ID of the dampener off before I slipped it on the crank and had a little oil on the crank nose OD to displace moisture. Make sure the dampener is ALL THE WAY ON because that is what holds the cam chain gear tightly in place. Once the dampener is put on that is a good time to repeat the true TDC exercise and check the marks on the dampener/timing cover.

They make it a lot harder than it is in the instructions. What made the light come on for me was to draw a horizontal line with 0* TDC, 180* BDC, 360* TDC marked on it and the cam lobe drawn in starting with 15* BTDC and ending with 47* ABDC, and the center of the lobe at 106* ATDC. Then I adjusted the opening and closing numbers on that diagram to suit the centerline I wanted (108* in my example for your cam).

Like I said, easy really. I borrowed the timing set from a friend but already had the mag base unit and pointer. Never really had a good use for it until now and it worked so well with the timing set I returned it to the guy so the two sets would be together. Now that I have the valve train all set-up and done I need to go get that set and measure the actual lift I am getting. It will be less than the cam card due to geometry and deflection and solid lifter clearance. I should get 0.640 but suspect it is probably 0.025 less or so.

Oh, one more thing. MRL wanted the cam I used set at 108* centerline and the card said to use 104*. I started the process with the timing set at "straight up" and was actually 4* retarded after the measurements were done. This with a new, quality timing set and a new straight up key. It is worth the time to check the degree of your cam!
 
If you mean use .050" lift at the lifter, for checking the opening and closing events, then yes.
 
Wow all I can say to you fellas is THANKS. Thanks Airwoofer for put that in noob terms. Makes it easy to understand. I need to read that a few times to soak it all in. Much appreciated. I have a magnetic base and indicter and can use it. What i dont have is a degree set. Does anyone rent these out?
 
Ok I have a question looking at this video. It seems to follow what you guys have already said. But I have a question. How and where do you set the piston stop? Is this just a random depth to set the stop?


[ame="http://www.youtube.com/watch?v=-VwsbEg7Z4I"]Camshaft Degreeing the Easy Way.MP4 - YouTube[/ame]
 
i guess i question if that number is just random depth. It could be .100 in the hole how to they call that TDC. Sorry having trouble grasping that idea.
 
Please watch the video AGAIN. You are NOT "calling some random depth TDC."

You are using the random depth to ADUST (either the degree wheel or pointer) so that it is actually DISPLAYING TDC

Just like the video...............................

1---You set up the wheel and pointer

2---You install a piston stop at a "random depth."

3---Rotate engine the normal rotation until the piston stops on the device. NOTE the degree wheel reading, whatever that might be

4---Rotate engine in the OPPOSITE direction, (CCW) until it AGAIN stops at the device, and again note the degree wheel reading.

5---True TDC is HALF WAY between the two readings, so you must adjust the pointer/ degree wheel HALF the difference.

(In the video example, the degree wheel had a DIFFERENCE of 1 degree between the two readings. . That means the pointer/ wheel was 1/2 degree wrong.)
 
print this out....and glue it to some posterboard. Free.....
CrankDegreeWheel.png


http://avs.spot-mate.com/images/tech/CrankDegreeWheel.png
 
72ScampTramp said:
so if the reading is say 25 before and 25 after true TDC is 0 is that correct?
Click to expand...

Yes. Forget your degree wheel and imagine your stock balancer, all put together with the timing cover. If you check the factory marks, you use the same basic method, only you can use a stop in the piston hole.

Imagine the piston is coming up at stops "at some point." As the piston comes up, the balancer is approaching TDC but cannot "get there" because it's stopped. You make a mark on the balancer UNDER the TDC mark (pointer)

Now if you rotate the engine the opposite direction, the piston will stop, coming up, TO THE SAME POINT, because (I hope) you have not changed the stop. Now, the timing marks are approaching TDC FROM THE OPPOSITE engine direction.

You now make a SECOND mark under the TDC pointer onto the balancer wheel. What do you have?

THREE marks on the wheel, the first temp, the original TDC mark, and the second temp mark.

True TDC will be HALF WAY between the two temp marks you have made, and if the original mark is still correct, that is where it will be.
 
67Dart273 said:
Yes. Forget your degree wheel and imagine your stock balancer, all put together with the timing cover. If you check the factory marks, you use the same basic method, only you can use a stop in the piston hole.

Imagine the piston is coming up at stops "at some point." As the piston comes up, the balancer is approaching TDC but cannot "get there" because it's stopped. You make a mark on the balancer UNDER the TDC mark (pointer)

Now if you rotate the engine the opposite direction, the piston will stop, coming up, TO THE SAME POINT, because (I hope) you have not changed the stop. Now, the timing marks are approaching TDC FROM THE OPPOSITE engine direction.

You now make a SECOND mark under the TDC pointer onto the balancer wheel. What do you have?

THREE marks on the wheel, the first temp, the original TDC mark, and the second temp mark.

True TDC will be HALF WAY between the two temp marks you have made, and if the original mark is still correct, that is where it will be.
Click to expand...

You have a way with words, great explanation.
 
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