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Discussion Starter #1
I need help timing my cam when I go to install it. It is the Crane Powermax 2020 (specs below). The cam card is written based on a 1.6 roller rocker, but I am using the Harland Sharp 1.7rr. Should I go by the cam card and use their numbers for timing in the cam or is there a better place to set the cam or should I just keep the timing the same as it was stock? If this is confusing to you, please let me know and I will try and explain it better. A list of mods are below in my signature.

> Part Number: 704115 Grind Number: POWERMAX 2020
>
> Valve Setting: Intake .000 Exhaust .000 HOT
>
> Lift: Intake @Cam 271 @Valve 434 All Lifts are based
> on zero lash and theoretical rocker arm ratios.
> Exhaust @ Cam 286 @Valve 458
> Rocker Arm Ratio 1.60
>
> Cam Timing: TAPPET @.004
> Lift: Opens Closes ADV Duration
> Intake 16.0 BTDC 54.0 ABDC 250 °
> Exhaust 65.0 BBDC 15.0 ATDC 260 °
>
> Spring Requirements: Triple Dual Outer Inner
> Part Number ---
> Loads Closed --- LBS @ --- or ---
> Open --- LBS @ ---
> Recommended RPM range with matching components
> Minimum RPM ----
> Maximum RPM ----
> Valve Float 6500
>
> Cam Timing: TAPPET @.050
> Lift: Opens Closes Max Lift Duration
> Intake (10.0) ATDC 24.0 ABDC 107 194 °
> Exhaust 39.0 BBDC (15.0) BTDC 117 204 °
 
G

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What exactly do you mean when you say "cam timing"?
I'm assuming this is a 4.7 engine? If yu really mean cam timing then just follow the manufactures instructions from a manual...

What your probably looking for is info on degreeing the cams???
I don't know alot about the 4.7 but mostly you're just going to confrim the information on the degree card that came with your cams.
That being said if you have adjustable cam sprockets (pulleys) you can change the intake and exhaust cam center lines from the manufactures specs (107/117 @ 0.50) to whatever you want.
WARNING....you can bend valves doing this...so be careful.....
 

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Discussion Starter #3
This is a 5.9L out of a Ram that I am building. I know the specs and degrees that the cam card said, but that was based on using a 1.6 ratio roller rocker. I am using a 1.7rr which opens the valve a little more. I am wondering if I should change the degrees of the cam or still go by what the cam card said.
 
G

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Sorry, I should have noticed that you posted in the 5.9 thread..
It's just that most people don't degree in single cam engines, but they should.....

You should always "degree in" a new cam if for no other reason than to assure that it was cut correctly. If you check the timing and it's not what the manufactures says it supposed to be you'll have to use offset pins to correct it. You should be abe to get very close to the numbers on the cam card. Depending on what you're using the engine for, whether you looking for more RPM or more torque, you can play with the timing a little bit. But be careful....

The ratio of the rockers will not matter when degreeing the cam.
You'll notice that the information card reads TAPPET @.004 or TAPPET @.050. That statement tells you the reading is taken at the tappet, not at the valve. Make sure you take your readings at the top of the push rod or directly off of the tappet, not off of the valve retainer.
The ratio of the rocker arm only increases the lift of the valve and, when degreeing the cam. will not matter.

You'll notice on your cam card the rockers are only mentioned in the "Lift" section. That because they're telling you what the lift will be using a RR of 1.6. The only thing you have to be aware of is the piston to valve clearance. The 1.7 rockers are going to position the valves closer to the piston at max lift and depending on the cams higher lift, where you degree in the cam and where you set your pistons in the bores you could crunch thing up if you're not careful. If you're using aftermarket pistons make sure you know what the manufacture recommended piston to valve clearance is before you degree in the cam and then make sure you check the clearance by mocking up the engine and using modeling clay. If you're using stock Mopar pistons you can get clearance information from most manuals..
Do you have the information you need to do the math calulations for the cam? If not let me know and I'll send it along...
 

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Discussion Starter #5
I think what I am going to do is experiment before final assembly. 10* ATDC seems a bit much to me, it isn't that aggressive of a cam. I think I am going to use modeling clay and see if I can get it a bit closer to TDC. Of course I could be way off on my perception of 10 degrees so any information would still be appreciated. I just wonder if the 1.7rr will be too much lift.

Thanks in advance!!!!
 
G

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When degreeing the cam don't think of the 10 deg. ATDC as a stand alone number. All it means is the Intake cam is at 10 deg ATDC when you take a reading @.050 after the cam starts to open. In other words this is just when the cam is beginning to open.
The 10 deg and 24 deg are added together and one half of a full cam rotation is added (180) to the sum of the first two numbers. The total is divided by 2 to come up with the cam center line.
In the case of your cam the intake checked at .050 would work out like this: 10 plus 24 equals 34 plus 180 equals 214. Divide 214 by 2 and this gives you an intake cam center line of 107 and the MAX intake duration is 194 deg. of cam rotation.

On the exhaust side of the cam (if the cam is installed as the manufacture suggest, 39 deg & 15 deg) the center line is 117 with a MAX duration of 204.
You'll notice that the maximun duration of the intake is 194 degrees and the maximun duration of the exhaust is 204 degrees.
We all know there are only a total 360 degrees rotation in the cam so that tells you that you'll have 38 degrees of overlap (when both the intake and exhause cams are open at the same time.
If I were you I'd talk to the shop who did your head work. Tell them what cam you're using and what you'll be using the engine for. Changing the cam center line will effect the performance of the cam so make sure you talk to the cam manufacture after you take to the head builder.
You might find out that the specification the cam manufacture gave you are just right for your application in which case all you'll have to do is check and make sure the cam was cut correctly.
Good Luck.
 
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