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Installing unknown cam

Posted By: cudaman1969

Installing unknown cam - 08/13/20 03:19 PM

I have 3 cams with no cam cards and I know I’ve seen on different sites on how to determine centerline but just can’t remember all the details how, can I get some insight from you guys on this? Thanks in advance
Posted By: CSK

Re: Installing unknown cam - 08/13/20 03:25 PM

Originally Posted by cudaman1969
I have 3 cams with no cam cards and I know I’ve seen on different sites on how to determine centerline but just can’t remember all the details how, can I get some insight from you guys on this? Thanks in advance


would have to install it with a degree wheel to find that out
Posted By: cudaman1969

Re: Installing unknown cam - 08/13/20 04:13 PM

Originally Posted by csk
Originally Posted by cudaman1969
I have 3 cams with no cam cards and I know I’ve seen on different sites on how to determine centerline but just can’t remember all the details how, can I get some insight from you guys on this? Thanks in advance


would have to install it with a degree wheel to find that out

Yes I know, what’s after that?
Posted By: CSK

Re: Installing unknown cam - 08/13/20 04:17 PM

Originally Posted by cudaman1969
Originally Posted by csk
Originally Posted by cudaman1969
I have 3 cams with no cam cards and I know I’ve seen on different sites on how to determine centerline but just can’t remember all the details how, can I get some insight from you guys on this? Thanks in advance


would have to install it with a degree wheel to find that out

Yes I know, what’s after that?


Posted By: polyspheric

Re: Installing unknown cam - 08/13/20 05:51 PM

You can do it from the valve stems as shown, but that incorporates any rocker arm asymmetry into the results. The video (no, I didn't watch it) should also mention that if the dial indicator quill is not parallel to the stem axis (not the bore axis or 90° to the deck) the reading is wrong. Any engine you're going to work on has stems angled to the bore.
If you can, safer to do it from the tappet. Yes, it's a PITA. The pushrod is also safe, but you need to bodge up some alignment fixture top be sure of getting exactly vertical motion. I would try a short section of tube with ID equal to PR OD and held in place with a magnet or clamp.
Posted By: cudaman1969

Re: Installing unknown cam - 08/13/20 06:17 PM

Yes I’ve done that many times. I guess I need to redefine my question. Now this is going on bad memory but..
Find the peak of ex and in then that is the centerline? Assuming both are the same not a duel pattern. Or are all just centered off the intake, .050 up and .050 down to get the centerline? I’m thinking one would need to know the exhaust also to see where it was ground? I don’t care where they close or open just that I’m not sticking it at 104 and supposed to be 115
Posted By: Cab_Burge

Re: Installing unknown cam - 08/13/20 07:31 PM

I would install all three cams and check them at .050 lifter rise opening and closing on both lobes and then check both lobe centers on both lobes at .050 before and after max lift, and then .100 and finally at .200.
I'm a little anal on cam timing so I check it at all three lifts for LSA before and after Max Lift scope If it varies less than 2 degrees at all three positions I'll use it up If it is more it goes back twocents
Posted By: BSB67

Re: Installing unknown cam - 08/13/20 07:49 PM

I'm still not sure I understand your question.

The cam grinder grinds in the LSA, and there is nothing you can do about that, and that you can simply measure with typical cam degreeing techniques. You'll need to do the exhaust as well. On asymmetrical lobes, the LSA number will change from top to bottom, depending on what reference lobe lift you use.

The recommended intake "centerline" is what the grinder chose and it is the relationship between the intake and exhaust events relative to the piston. No matter how they grind the ICL you can put the ICL anywhere you want. Like LSA, the ICL will change from top to bottom on asymmetrical lobes. Realistically, you cannot tell what the manufacturer intended for ICL by measuring the cam with typical cam degreeing tools.

That said.if you want the cam installed 4 degrees advanced (which seem to be the popular choice on all Mopar forums) Simply measure the LSA and subtract 4 degrees.
Posted By: cudaman1969

Re: Installing unknown cam - 08/13/20 08:01 PM

Let me ask another way, say I did the intake at .050 and came up with 108 degrees then did the exhaust at .050 and it came up at 116 degrees. Would I add the two (224) then divide to get the cams actual centerline of 112 degree?
Posted By: BSB67

Re: Installing unknown cam - 08/13/20 08:09 PM

No,

The LSA is 112°

The ICL is 108°

The cam is advanced 4°
Posted By: fast68plymouth

Re: Installing unknown cam - 08/13/20 08:13 PM

Originally Posted by cudaman1969
Let me ask another way, say I did the intake at .050 and came up with 108 degrees then did the exhaust at .050 and it came up at 116 degrees. Would I add the two (224) then divide to get the cams actual centerline of 112 degree?


The 112 would be the LSA, not the centerline.

The 108/116 are the centerlines.

In your scenario, the cam is a 112lsa, installed 4deg advanced.
Posted By: BSB67

Re: Installing unknown cam - 08/13/20 08:19 PM

Originally Posted by fast68plymouth
Originally Posted by cudaman1969
Let me ask another way, say I did the intake at .050 and came up with 108 degrees then did the exhaust at .050 and it came up at 116 degrees. Would I add the two (224) then divide to get the cams actual centerline of 112 degree?


The 112 would be the LSA, not the centerline.

The 108/116 are the centerlines.

In your scenario, the cam is a 112lsa, installed 4deg advanced.


Copy Cat grin
Posted By: fast68plymouth

Re: Installing unknown cam - 08/13/20 08:20 PM

You just type faster than I do. up
Posted By: cudaman1969

Re: Installing unknown cam - 08/13/20 10:10 PM

Thanks I got what I needed to know
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