Re: Cam installed centerline question
[Re: 426runner]
#844366
11/02/10 06:09 PM
11/02/10 06:09 PM
|
Joined: Jan 2003
Posts: 9,826
las vegas
70AARcuda
master
|
master
Joined: Jan 2003
Posts: 9,826
las vegas
|
it will run better...lol
you are 3 degrees advanced...advancing the cam with help the low end performance...increase cylinder pressure by closing the instake valve sooner..
Advancing the camshaft means that you are starting the opening and closing process sooner in the cycle. It generally improves low-speed torque and mid-range power while sacrificing top-end hp. Conversely, retarding the cam detracts from low- and mid-range power in order to help top-end power. Generally, moving a camshaft a couple of degrees will not make dramatic changes to the engine's power curve
Last edited by 70AARcuda; 11/02/10 06:26 PM.
Tony
70 AARCuda Vitamin C
71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield)
71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas)
71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
|
|
|
Re: Cam installed centerline question
[Re: Stanton]
#844369
11/02/10 09:00 PM
11/02/10 09:00 PM
|
Joined: Jan 2003
Posts: 6,591
Canton, Ohio
Sport440
master
|
master
Joined: Jan 2003
Posts: 6,591
Canton, Ohio
|
Quote:
Your engine will be retarded !
The intake valve opens later and closes later. Since it closes ABDC that's a hair less compression the motor will make. Likewise the exhaust valve will open sooner, releasing combustion pressure sooner. All this equates to a loss of power.
You have it backwards. If the intake valve reaches peak lift earlier at 105* ATDC vs 108* ATDC
Then it is indeed advanced and not retarded.
For the OP, if thats where your at. Thats not a bad ICL area. IMO 101* to 106* for alot of engine combos is a good general ICL. mike
|
|
|
Re: Cam installed centerline question
[Re: 426runner]
#844371
11/02/10 09:54 PM
11/02/10 09:54 PM
|
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
|
yes it's confusing as a smaller # ie 105 vs 108 means sooner (advanced) as 5 o'clock is sooner than 8 o'clock. the intake valve reaches peak lift at 105 deg past TDC compression (which is sooner) than if it reached it at 108 deg past TDC compression (& therefore closes sooner). As said it shifts the power band lower & reduces the valve to piston of either the intake or ex valve (I forget which one). Cams I've advanced (street) which you'd be doing (to 105) have always benefitted from it (more torque)
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Cam installed centerline question
[Re: RapidRobert]
#844372
11/02/10 10:02 PM
11/02/10 10:02 PM
|
Joined: Dec 2008
Posts: 1,200
UK
602heavy
pro stock
|
pro stock
Joined: Dec 2008
Posts: 1,200
UK
|
Quote:
yes it's confusing as a smaller # ie 105 vs 108 means sooner (advanced) as 5 o'clock is sooner than 8 o'clock. the intake valve reaches peak lift at 105 deg past TDC INDUCTION stroke (which is sooner) than if it reached it at 108 deg past TDC INDUCTION stroke (& therefore closes sooner). As said it shifts the power band lower & reduces the valve to piston of either the intake or ex valve (I forget which one). Cams I've advanced (street) which you'd be doing (to 105) have always benefitted from it (more torque)
|
|
|
Re: Cam installed centerline question
[Re: GomangoCuda]
#844375
11/03/10 03:13 PM
11/03/10 03:13 PM
|
Joined: Oct 2003
Posts: 1,371
Costa Mesa, CA
chache876
pro stock
|
pro stock
Joined: Oct 2003
Posts: 1,371
Costa Mesa, CA
|
Heres a somewhat related question about cam timing...
If I have an adjustable timing chain with multiple keyways on the crankshaft gear, and they are marked 0, +1, +2, +3, -1, -2, -3, etc...
Lets say I have a lobe separation angle of 106*
If I set the timing gear so that it is in the +2 slot, does that mean I am advancing the camshaft 2 degrees so that its now 104* or does that mean that I am adding 2 degrees to the 106* number? 106+2=108?
|
|
|
Re: Cam installed centerline question
[Re: chache876]
#844376
11/03/10 03:40 PM
11/03/10 03:40 PM
|
Joined: Dec 2008
Posts: 1,200
UK
602heavy
pro stock
|
pro stock
Joined: Dec 2008
Posts: 1,200
UK
|
Quote:
Heres a somewhat related question about cam timing...
If I have an adjustable timing chain with multiple keyways on the crankshaft gear, and they are marked 0, +1, +2, +3, -1, -2, -3, etc...
Lets say I have a lobe separation angle of 106*
If I set the timing gear so that it is in the +2 slot, does that mean I am advancing the camshaft 2 degrees so that its now 104* or does that mean that I am adding 2 degrees to the 106* number? 106+2=108?
+ advance
- retard
'lining up the dots' is a no no , the only accurate way would be to use a degree wheel , some of those crank/cam gears are not always accurate. 
|
|
|
Re: Cam installed centerline question
[Re: GomangoCuda]
#844377
11/04/10 03:24 PM
11/04/10 03:24 PM
|
Joined: Apr 2004
Posts: 1,396
Mass
dgc333
pro stock
|
pro stock
Joined: Apr 2004
Posts: 1,396
Mass
|
Quote:
Quote:
double it and divided by two
 How long has it been since you had a basic math class?
I know exactly what I said, in my 30+ years as an engineer I have found that sometimes it helps to make things clear to state the obvious. I could have just said; "straight up centerline = lobe seperation angle" but I wonder how many more folks will remember why that is true because I added the silly little math expression.
|
|
|
Re: Cam installed centerline question
[Re: dgc333]
#844378
11/04/10 05:27 PM
11/04/10 05:27 PM
|
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
|
Quote:
I have found that sometimes it helps to make things clear to state the obvious.
I'm w you here as cam theory is (sort of) Greek to me & I need it (the obvious) spelled out so I can grasp it.
Last edited by RapidRobert; 11/04/10 05:46 PM.
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Cam installed centerline question
[Re: chache876]
#844379
11/04/10 06:51 PM
11/04/10 06:51 PM
|
Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
|
Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
|
Quote:
Heres a somewhat related question about cam timing...
If I have an adjustable timing chain with multiple keyways on the crankshaft gear, and they are marked 0, +1, +2, +3, -1, -2, -3, etc...
Lets say I have a lobe separation angle of 106*
If I set the timing gear so that it is in the +2 slot, does that mean I am advancing the camshaft 2 degrees so that its now 104* or does that mean that I am adding 2 degrees to the 106* number? 106+2=108?
Lobe seperation angle is not the installed centerline. Lobe sep angle is ground into the cam and cannot be changed. The installed centerline is where the cam grinder reccomends to put the intake centerline for best performannce. Ron
|
|
|
Re: Cam installed centerline question
[Re: 426runner]
#844381
11/11/10 02:33 PM
11/11/10 02:33 PM
|
Joined: Apr 2005
Posts: 12,271
Overpriced Housing Central
RobX4406
I Live Here
|
I Live Here
Joined: Apr 2005
Posts: 12,271
Overpriced Housing Central
|
Quote:
Another related question... It is always recomended to check the installation of the cam for the proper centerline as called for by the manufacturer. Most all write-ups or videos that show the process end up with the CL coming out correct. Mine didn't. My installation calculated out to 105 instead of 108 like the card said it should. Why would this happen? What factors could contribute to the cam not being as the manufacturer says it should be out of the box? And yes, there were 2 of us there during the degreeing process and we did it over and over and came up with the same 105 every time. 
Timing chain set variances, cam being ground slightly off, could be a couple issues to change the installed centerline.
|
|
|
Re: Cam installed centerline question
[Re: RobX4406]
#844382
11/11/10 02:52 PM
11/11/10 02:52 PM
|
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
Dodgem
master
|
master
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
|
 It's called the stacking effect. the key way on the crank may be of a bit. the key way in the bottom gear may be off a bit, the dowel hole in the top gear may be off a bit and the dowel placement in the cam may be off a bit as these things are less than perfect. sometimes it stacks up to 10 or more degree's off. I would leave your cam where it is you will like it with a tad more advance!
|
|
|
|
|
