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Couple of questions - degreeing my camshaft

Posted By: capac

Couple of questions - degreeing my camshaft - 06/08/13 05:10 PM

Let me start off by saying that this is the first time I've ever degreed a camshaft. Having said that, I feel like I have a really good understanding of what I'm doing and the proper procedures. Almost all of the specs on the cam card match the actual measuerments. The only variance (might not be the camshaft...) is the centerline. The cam card says 109, but my measurements come out to 114.5. My first question is: would this have the same effect as advancing the cam 5.5 degrees?

I bought a timing set that has 7 different adjustments (3R,2R,1R,0,1A,2A,3A), so I'm hoping to get this cam dialed in where it needs to be. The guy I bought the cam (and heads) from recommended 2 - 4 degrees of advance for my setup. What I'm not sure of, is did he account for the 3 degrees that are allready built into the cam. So addintionally, maybe you folks in the community can recommend what I should do. As always, let me know if I left out any crucial info (I usually do).

Car
- Street car with occasional trips to the strip.
- A body car, so 3200 - 3400lbs?
- Manual transmission
- Probably 3.91 gear

Engine
- 318 stroker (390)
- 9.877:1 static compression
- RHS heads ported, flow 288 @0.550/287 @0.600 lift
- Hughes 1.6 roller rockers
- Edelbrock RPM intake
- Quickfuel 750cfm
- Headers of some kind

Camshaft
- Hydrolic roller (Comp Cams)
- .586 Intake lift @.050 (1.6 ratio)
- .581 Exhaust lift @.050 (1.6 ratio)
- 242 Intake duration @.050
- 248 Exhaust duration @.050
- Intake centerline 109
- Lobe separation 112
- Intake open 12 degrees BTDC @.050
- Exhaust open 59 degrees BBDC @.050
- Intake close 50 degrees ABDC @.050
- Exhaust close 9 degrees ATDC @.050
Posted By: MR_P_BODY

Re: Couple of questions - degreeing my camshaft - 06/08/13 05:18 PM

They are telling you to put it in at 109... I would
move it to 107 with the 9.8 compression you have
Posted By: capac

Re: Couple of questions - degreeing my camshaft - 06/08/13 05:30 PM

Quote:

They are telling you to put it in at 109... I would
move it to 107 with the 9.8 compression you have




So that would be a total of 5 degrees advance? Just making sure I understand this properly. Also, if I can't get right at 5; what would be better 4.5 or 5.5?
Posted By: BSB67

Re: Couple of questions - degreeing my camshaft - 06/08/13 05:52 PM

5° degrees advanced is an installed intake center line of 107° for the cam you have.
Posted By: 451Mopar

Re: Couple of questions - degreeing my camshaft - 06/08/13 06:58 PM

Because you said this is your first time, make sure you are measuring off the SECOND lifter on the drivers side. The first lifter is the exhaust, the second is the intake.
Posted By: capac

Re: Couple of questions - degreeing my camshaft - 06/08/13 07:18 PM

Quote:

Because you said this is your first time, make sure you are measuring off the SECOND lifter on the drivers side. The first lifter is the exhaust, the second is the intake.



I am, thanks for that though! That is the type of mistake I could easily see myself making! Since the heads are still boxed away, I looked at the valve reliefs to determine which one was the intake.
Posted By: RobX4406

Re: Couple of questions - degreeing my camshaft - 06/08/13 07:21 PM

How are you determining TDC of the piston?

That throws lots of people off. I use the the .050 down from the high spot going each direction.
Posted By: capac

Re: Couple of questions - degreeing my camshaft - 06/08/13 07:29 PM

I made a piston stop that bolts directly to the deck. At first I just used a dial indicator on the piston itself, but quickly realized that there was about a 3 degree (guessing) period where the piston didn't move. So for best accuracy, I made the stop. I'm not sure exactly how far down in the hole the piston was stopping, but I know that it was hitting the stop 34 degrees on either side of TDC. Hopefully that made sense...
Posted By: MR_P_BODY

Re: Couple of questions - degreeing my camshaft - 06/08/13 08:25 PM

Quote:

I made a piston stop that bolts directly to the deck. At first I just used a dial indicator on the piston itself, but quickly realized that there was about a 3 degree (guessing) period where the piston didn't move. So for best accuracy, I made the stop. I'm not sure exactly how far down in the hole the piston was stopping, but I know that it was hitting the stop 34 degrees on either side of TDC. Hopefully that made sense...



Doesnt matter how far in the hole it is... put the
damper on and roll it up till it hits and take a reading
on the damper.. roll it the other way till it hits
and take a reading.. split the 2 numbers.. thats zero
Posted By: Cab_Burge

Re: Couple of questions - degreeing my camshaft - 06/08/13 10:15 PM

Most SB Mopar cams ground on a 112 lobe seperation angle are ground that way for a power adder or for extremely high RPM drag racing like a stick shift drag cam with a lot of different motor specs than your motor has or a high RPM roundy rounder motor, some application where the motor never sees a load under 5500 RPM at the track That being said you have the cam so try checking both lobes on the cam for lobe seperation angles at max lift. Check the intake first and then the exhuast, if you find the marks on the crank sprocket that actaully get the cam in with no advance or retard then the intake lobe max lift should be at 112 after top dead center and the exhaust lobe max lift should be at 112 before top dead center Once you deteremine if it is ground on 112 then find the mark (by trying and degreeing until you get what you want) on the crankshaft sprocket that will get the intake lobe center(max lobe lift at)at 105,106 or 107 after top dead center. If you get 106 max lobe lift ATDC on the intake then check the exhaust lobe, it should be in at 117 The exhaust lobe has to follow the intake lobe centers, moving the max lift on the intake lobe closer to TDC advances both the intake and exhaust, moving the intake max lobe lift away from top dead center retards the cam. Advancing the cam normally will increase the power at the lower RPM, retarding the cam is suppose to increase top end power as well as kill bottom end, I have never had a N/A drag car, BB, Hemi or SB Mopars that like the cams retarded IHTH BTW, I like to check the lobe seperation angles with the heads on with all the rocker gear with some light checking springs on both the valves so I can check piston to valve clearances while indexing the cam, I set the lash at zero and go from there BTW, you should do that checking with a solid roller lifter, not a hydrastic roller lifter That eliminates the chance of the lifter collapsing while checking the cam, which will skew the readings and clearances
Posted By: RobX4406

Re: Couple of questions - degreeing my camshaft - 06/09/13 01:25 AM

Quote:

I made a piston stop that bolts directly to the deck. At first I just used a dial indicator on the piston itself, but quickly realized that there was about a 3 degree (guessing) period where the piston didn't move. So for best accuracy, I made the stop. I'm not sure exactly how far down in the hole the piston was stopping, but I know that it was hitting the stop 34 degrees on either side of TDC. Hopefully that made sense...



That why you set the indicator at your high point then go down in the hole a set amount, up stroke both direction, same technique as a piston stop. That 3-4 degrees of dwell time can play havoc.

Sounds like you have a good handle on it.
Posted By: capac

Re: Couple of questions - degreeing my camshaft - 06/09/13 02:02 AM

Quote:

Most SB Mopar cams ground on a 112 lobe seperation angle are ground that way for a power adder or for extremely high RPM drag racing like a stick shift drag cam with a lot of different motor specs than your motor has or a high RPM roundy rounder motor, some application where the motor never sees a load under 5500 RPM at the track That being said you have the cam so try checking both lobes on the cam for lobe seperation angles at max lift. Check the intake first and then the exhuast, if you find the marks on the crank sprocket that actaully get the cam in with no advance or retard then the intake lobe max lift should be at 112 after top dead center and the exhaust lobe max lift should be at 112 before top dead center Once you deteremine if it is ground on 112 then find the mark (by trying and degreeing until you get what you want) on the crankshaft sprocket that will get the intake lobe center(max lobe lift at)at 105,106 or 107 after top dead center. If you get 106 max lobe lift ATDC on the intake then check the exhaust lobe, it should be in at 117 The exhaust lobe has to follow the intake lobe centers, moving the max lift on the intake lobe closer to TDC advances both the intake and exhaust, moving the intake max lobe lift away from top dead center retards the cam. Advancing the cam normally will increase the power at the lower RPM, retarding the cam is suppose to increase top end power as well as kill bottom end, I have never had a N/A drag car, BB, Hemi or SB Mopars that like the cams retarded IHTH BTW, I like to check the lobe seperation angles with the heads on with all the rocker gear with some light checking springs on both the valves so I can check piston to valve clearances while indexing the cam, I set the lash at zero and go from there BTW, you should do that checking with a solid roller lifter, not a hydrastic roller lifter That eliminates the chance of the lifter collapsing while checking the cam, which will skew the readings and clearances



Thanks for all of the info Cab. I'll probably measure the lobe separation tomorrow to make sure it is correct. I didn't ask too many questions about the cam when I was purchasing it, I just told them what I wanted (Brian @ IMM). I feel pretty confident that his recommendation is good.

I didn't do any of this with the heads on because I don't have any pushrods, or a solid lifter(s). I have to measure the pushrod length once everything is assembled since the machine shop I used can't tell me how much material was removed when they zero decked it...
Posted By: Cab_Burge

Re: Couple of questions - degreeing my camshaft - 06/09/13 03:14 AM

It's always better to measure for the pushrods with the rocker arm set up your going to run on that motor You can check the lobe center timing at the lifters, make sure and get the dial indicator stem as close as you can to duplicate the angle of the lifters in thier bores, front to back and side to side
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