Cam timing question

[StockMan]

I purchased a new MP `Resto`magnum cam and I`m trying to degree it (Stock 68-440).  The card states that the intake should begin to open at 19degrees BTDC.  With the timing set I had originally I found that it was opening at 26d BTDC, this was with the marks aligned.  I found that moving the chain on the sprocket would not get me to the 19 so I purchased an adjustable Cloyes set.

I installed the new set using the `Retarded`marks (supposed to be 2degrees retarded at the cam) and still found that the intake value was opening early at 25d.
I moved the cam back by jumping a tooth on the cam gear and now I read the 19 degrees, which is where I want to be (based on the card).

Heres how I`m setup...
- Dial indicator on the no1 intake lifter.
- Found TDC using piston stop (no heads on the motor).
- Set pointer to 0 on the wheel.
- Turn the crank counter clockwise back to around 40d BTDC.
- Turn the crank clockwise slowly and stop when the dial indicator just begins to move.
- Read the wheel.

Are the steps I`ve taken to degree the cam correct.
Where would I be if I were to install with the marks aligned (25d BTDC) when the cam card states 19d.
What is a reasonable Òutage`on this particular cam.

Thanks for your help.

[b5blue]

  I used that same cam and a Mopar timing gear set. I wanted to degree it all but the shop I was using had it all together (Chuck has literally rebuilt over 100 B/RB's.) and ready to go. Later when I had some timing issues I asked about degreeing he said with all Mopar parts he never needed to. In my case it turned out to be all in the dizzy and it's fine now. Are you certain your checking it right? Ron will clear things up for you when he sees this! 

[StockMan]

Thanks for your reply.  Ron has been helping me with this and suggested that I use the intake centerline technique.  
I plan to try this but have not had the time yet so I wanted to check to see if this approach I`m using has any kind of accuracy (I`m certain Ron can verify this as well).

I checked the original cam using this technique, with the old timing chain-gear set and it measured in at around 19 as well.  
It seems that this MP cam might be out a few degrees.

Also, I would be interested to know if the cam card states that intake begins to open at 19 BTDC, and I align to that, does it mean that my centerline is to spec as well.

From what I`ve read on other posts cam timing being out a bit is not uncommon.  And I`ve heard that depending on where the MP cams are built there have been quality issues reported.

[b5blue]

Oh I'm with ya on it, when I get back in there I'll be checking, I was kinda in a rush back then. My son needed my other car for collage, the Charger had to go back to earning it's keep. It's always better to be certain! 

[BSB67]

1) you should not degree a cam from advertised specs. (advertised specs are at 0.006" lift).
2) you can use the 0.050" specifications ( does MP give you those?)
3) Use the centerline method, and do it at several different lift values to confirm the results.

Do you have a cam card and what are all of the specs?

[StockMan]

Hi

The card gives the following
Adv Duration         268-284
Duration at .05      214-225
Intake Centerline   113
Lift                        450-464
Overlap                 46

The factory manaul tells me that the intake should begin to open at 19d BTDC for the magnum cam.

Thanks

[b5blue]

My B/RB book shows Mopar P4452783 268/284* Centerline @ 115* and it does state production variances could result in centerline being off "several degrees". 

[StockMan]

Thanks for the quick response.  My card shows a list of MP Cams and mine is listed as P2806980 (single bolt), the one right after it is a three bolt (P4532098) and it reads the 115ICL.

Does the information you have specify the BTDC degree when the intake valve should begin to open.

[StockMan]

Sorry, I gave you the wrong #s, my cam is the P4452783, the 3 bolt is the P4529270.  So its odd that my sheet states the 113.
Is the method I used by confirming where intake opens/closes not an accurate means of checking the cam timing?

[StockMan]

After taking a look at more sites I find discrepancies on when the intake should open.  I now see 21 degrees reported, my factory 68 manual reports 19??
http://victorylibrary.com/mopar/mpcam-tech-c.htm

If it is 21 degrees and I'm at 25 would that be better than the 19?

I'm assuming value opening early would be referred to as advanced (more torque)?

[BSB67]

Not sure what to say without repeating myself.

If you insist on using advertised duration and associated intake opening event, take the measurements at .004", .005" and .006" lift as these are the values that the cam suppliers use, not when the lifter first moves.  You need to find out exactly which of these three values MP uses.  My memory says .006", but I could be mistaken.

A better way is to use the 0.050" duration from the cam card.  With a 113 ICL, the 0.050" intake lift is at 6 degrees ATDC on the opening side and 40 degrees ABDC on the closing side.

Again, the best way is using the ICL.

[firefighter3931]

Again, the best way is using the ICL.

Yep....the only reliable way.    Without knowing where the advertised duration is measured at it's just a guessing game. MP has never been forthcoming with reliable information. 



Ron

[StockMan]

I'm all setup to try the ICL method and I'm going to do that this morning.  I thought that measuring when the valves open/close would also be an accurate means of checking cam timing. 
But I guess if I don't have all of the information then that won't work.

Thanks for the help.

[StockMan]

I'm not seeing many positive comments on the MP cams, looking back I should have gone with Ron's recommendation (Lunati).

[b5blue]

There may be better but I like mine just fine!  It's the same profile as the 3 bolt six pack, just the taper is less on them.

[StockMan]

I checked the timing using ICL method and was way off with how I had the marks aligned.  I backed up to the factory marks and now read 113.5. 
So I should be good with only 1/2 degree off.  So the cam is pretty much bang on.

Here is what I did.
- Found TDC using piston stop.
- Rotate crank clockwise until I'm at top of intake valve lift.  Zeroed dial indicator.
- Moved to 0.05 after full lift took the number from the wheel (71)
- Moved to 0.05 before full lift and took the number from the wheel (156)
- Add the number together (227) and divided by 2 and ended up with 113.5

Just so I understand the terminology, advanced means the valve would open earlier than the factory spec, retarded would mean the valve would open later, correct?

Thanks again.

[firefighter3931]

Good work Robin 

See, the ICL method is much more accurate 

Advanced means earlier, retarded means later....you got it right 


Ron

[StockMan]

Thanks Ron, its a good thing I didn't put it back together the way I was doing it.  But with the info from BSB67 I would have been close.  With the way things are installed now, the intake opens at around 20degrees BTDC when the dial reads .006, which is close.  I didn't realize that with the way I was doing it that the .006 is required information, and, not alway provided or accurate.

Thanks
Robin