Degree Cam Question
Thread Starter
Racer
Joined: Jan 2012
Posts: 321
Likes: 16
From: Ontario
Degree Cam Question
Hey I degreed my Comp Cams 08-466-8 268XFI camshaft. Cam card says says to install the cam so that the intake center line is at 109 degrees ATDC. The LSA is 113.
When I installed the cam dot to dot I found the intake center line to be at 104.5 degrees ATDC. So it was advanced by about 4.5 degrees. This seems like a lot?
I retarded the cam 4 degrees and checked the intake centerline and measured 109 degrees ATDC.
4 degrees off seems like a lot? And is what I did correct? First time degreeing a cam.
I think 4 degrees advanced is built in to the cam, so retarding the cam 4 degrees would match the cam card?
Thanks.
When I installed the cam dot to dot I found the intake center line to be at 104.5 degrees ATDC. So it was advanced by about 4.5 degrees. This seems like a lot?
I retarded the cam 4 degrees and checked the intake centerline and measured 109 degrees ATDC.
4 degrees off seems like a lot? And is what I did correct? First time degreeing a cam.
I think 4 degrees advanced is built in to the cam, so retarding the cam 4 degrees would match the cam card?
Thanks.
Pro
Joined: May 2016
Posts: 708
Likes: 149
From: Minnesota
Hey I degreed my Comp Cams 08-466-8 268XFI camshaft. Cam card says says to install the cam so that the intake center line is at 109 degrees ATDC. The LSA is 113.
When I installed the cam dot to dot I found the intake center line to be at 104.5 degrees ATDC. So it was advanced by about 4.5 degrees. This seems like a lot?
I retarded the cam 4 degrees and checked the intake centerline and measured 109 degrees ATDC.
4 degrees off seems like a lot? And is what I did correct? First time degreeing a cam.
I think 4 degrees advanced is built in to the cam, so retarding the cam 4 degrees would match the cam card?
Thanks.
When I installed the cam dot to dot I found the intake center line to be at 104.5 degrees ATDC. So it was advanced by about 4.5 degrees. This seems like a lot?
I retarded the cam 4 degrees and checked the intake centerline and measured 109 degrees ATDC.
4 degrees off seems like a lot? And is what I did correct? First time degreeing a cam.
I think 4 degrees advanced is built in to the cam, so retarding the cam 4 degrees would match the cam card?
Thanks.
If it's too retarded it will still run, but you'll lose the low end torque that you probably chose this cam for. Just my opinion. I think it's probably unlikely that a high production comp cam came out of the box ground advanced by 4 degrees. Anything is possible, though.
Last edited by JoeMinnesota; May 1, 2017 at 09:40 PM.
Thread Starter
Racer
Joined: Jan 2012
Posts: 321
Likes: 16
From: Ontario
Thanks. I did check everything several times.
I did a lot of reading and my understanding is that most aftermarket cams have 4 degrees advanced ground in to the cam.
I guess I'm asking if I need to retard the cam to match the cam card specs.
I'm thinking now I should set the degree wheel and dial indicator up again to check the cam event timing to see at what degree valves open and close now with the 4 degree retard to see how that matches the cam card.
I did a lot of reading and my understanding is that most aftermarket cams have 4 degrees advanced ground in to the cam.
I guess I'm asking if I need to retard the cam to match the cam card specs.
I'm thinking now I should set the degree wheel and dial indicator up again to check the cam event timing to see at what degree valves open and close now with the 4 degree retard to see how that matches the cam card.
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Team Owner
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Trust your degree wheel and set it up like the cam card asked
Out of the above posters ask how many have ever degreed in a cam and how many times do they do it a year
I've been very dissapointed in comp cams billet steel custom rollers. My last one was 3.5 wrong. So you could not match it because the timing set has 2 degree incremental changes
When you talk about 4 degrees ground in. That is the actual valve event numbers from your cam card and yes CC tends to do this compared to other cam companies
Out of the above posters ask how many have ever degreed in a cam and how many times do they do it a year
I've been very dissapointed in comp cams billet steel custom rollers. My last one was 3.5 wrong. So you could not match it because the timing set has 2 degree incremental changes
When you talk about 4 degrees ground in. That is the actual valve event numbers from your cam card and yes CC tends to do this compared to other cam companies
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Pro
Joined: Jan 2016
Posts: 502
Likes: 103
From: Reno Nevada
If you do this, you have no idea if the cam is installed correctly or not. You have to check and it is a pretty easy process. Regardless of manufacturer, always degree in a cam.
Drifting
Joined: Jul 2013
Posts: 1,299
Likes: 93
From: Tri-Cities TN
Your chain set, your lifter bore angle, your keyway on the crankshaft can all affect camshaft phasing. We do not use centerline method here. We use duration method and phase the cam in by using the valve events. Centerline method is based on the opening side of the lobe being the same as the closing side. In todays's world with asymetrical lobes centerline method can be off quite a bit.
We print duration method on the cam card. If you are not familiar with it, Crane has it on their website.
We print duration method on the cam card. If you are not familiar with it, Crane has it on their website.
Drifting
Joined: Jun 2008
Posts: 1,565
Likes: 111
I've degreed a Comp solid flat tappet and a Cam Motion solid roller. Both were within 1 degree. If the advance was ground into the cam, the cam card valve events will already reflect that. Don't forget that the quality of your timing chain/sprockets, crank keyway, the size of your degree wheel, and the accuracy of your TDC measurement all affect your measured intake centerline.
Last edited by Neil B; May 2, 2017 at 10:29 AM.
Racer
Joined: Jan 2013
Posts: 302
Likes: 2
From: Sayville New york
with a professional 24" degree wheel my lunati roller cam was 4 degrees advance i retarted it 2 degrees by way of made in west germany roller chain used by world champ that has 8 advance slots and 8 retard slots in 1 degree increments a truly perfect machine piece of technology.
Drifting
Joined: Jun 2008
Posts: 1,565
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Thread Starter
Racer
Joined: Jan 2012
Posts: 321
Likes: 16
From: Ontario
I checked cam event timings and the PTV, and push rod length I needed.
Cam card says:
IO 25 BTDC / IC 63 ABDC
EO 75 BBDC / EC 21 ATDC
I measured (With cam retarded 4 degrees):
IO 25 BTDC / IC 63 ABDC
EO 71 BBDC / EC 23 ATDC
Intake is right on, exhaust is off a bit. Exhaust opens 4 degrees late from the cam card. I checked this several times, both at the lifter and at the valve spring retainer. This cam seems a bit messed.
PTV was about .110" intake and .250" exhaust. Using play dough method.
Think this all sounds ok enough to bolt it all down?
Cam card says:
IO 25 BTDC / IC 63 ABDC
EO 75 BBDC / EC 21 ATDC
I measured (With cam retarded 4 degrees):
IO 25 BTDC / IC 63 ABDC
EO 71 BBDC / EC 23 ATDC
Intake is right on, exhaust is off a bit. Exhaust opens 4 degrees late from the cam card. I checked this several times, both at the lifter and at the valve spring retainer. This cam seems a bit messed.
PTV was about .110" intake and .250" exhaust. Using play dough method.
Think this all sounds ok enough to bolt it all down?
Melting Slicks
Joined: Mar 2008
Posts: 2,666
Likes: 289
From: Spring Park MN
I checked cam event timings and the PTV, and push rod length I needed.
Cam card says:
IO 25 BTDC / IC 63 ABDC
EO 75 BBDC / EC 21 ATDC
I measured (With cam retarded 4 degrees):
IO 25 BTDC / IC 63 ABDC
EO 71 BBDC / EC 23 ATDC
Intake is right on, exhaust is off a bit. Exhaust opens 4 degrees late from the cam card. I checked this several times, both at the lifter and at the valve spring retainer. This cam seems a bit messed.
PTV was about .110" intake and .250" exhaust. Using play dough method.
Think this all sounds ok enough to bolt it all down?
Cam card says:
IO 25 BTDC / IC 63 ABDC
EO 75 BBDC / EC 21 ATDC
I measured (With cam retarded 4 degrees):
IO 25 BTDC / IC 63 ABDC
EO 71 BBDC / EC 23 ATDC
Intake is right on, exhaust is off a bit. Exhaust opens 4 degrees late from the cam card. I checked this several times, both at the lifter and at the valve spring retainer. This cam seems a bit messed.
PTV was about .110" intake and .250" exhaust. Using play dough method.
Think this all sounds ok enough to bolt it all down?
You are close enough on your cam. Run it.
Mike