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Discussion Starter · #1 ·
Will idle vac always go up when advancing the cam?

Can it decrease but your DCR comes on sooner?


my answers are No, and Yes. Am I wrong? Please discuss.
 

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Will idle vac always go up when advancing the cam?

Can it decrease but your DCR comes on sooner?


my answers are No, and Yes. Am I wrong? Please discuss.
No idea about vacuum.

Advancing the cam increases DCR because it closes the intake valve earlier and DCR calculators use the intake closing point as a main componet to their calculations. The earlier the intake valve closes to sooner the compression stroke begins... the higher the DCR.
Will
 

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Discussion Starter · #3 ·
Any thoughts about diminishing returns?

what reading to watch for besides dyno output?

Cranking pressure won't always go up, will it?

just a general topic before specifics.
 

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Discussion Starter · #4 ·
will advancing the lobes give me more exhaust energy?

I would say yes? With an earlier EVO happening?

all at a lower rpm with sacrifice to upper rpm potential?
 

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Did you try a search on ICL?
 

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will advancing the lobes give me more exhaust energy?

I would say yes? With an earlier EVO happening?

all at a lower rpm with sacrifice to upper rpm potential?
Yes, I'd like to know the thoughts on this as well. Most conversations regarding advancing the ICL are about an increase in DCR. Not much is said regarding how moving the cam forward affects the exhaust. I would say yes as well, given that the exhaust valve is now opening sooner.

This could benefit some turbo guys if that is the case right?
 

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You will also be bringing the exh valve further away from the piston and the intalke valve closer to the piston.
 

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Discussion Starter · #8 ·
Yes, I'd like to know the thoughts on this as well. Most conversations regarding advancing the ICL are about an increase in DCR. Not much is said regarding how moving the cam forward affects the exhaust. I would say yes as well, given that the exhaust valve is now opening sooner.

This could benefit some turbo guys if that is the case right?

an earlier evo, slapping a turbine wheel
harder.

imagine that?
 

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Discussion Starter · #9 ·
Kaase in the 90s with his intake centerlines.

He pretty much wins those little ol EMC shows with an "early opener"

Thoughts on that?
 

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Discussion Starter · #10 ·
I see a lot of views on this topic. It'd be beneficial

to maybe have some discuss how an advance or

a custom grind with a more aggressive centerline

helped their program out.

Do the tweaked out heads available today give

more fudge room for ICL angles?

Even if you went too far with it, explain how

it acted but what you were thinking at the time.
 

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Discussion Starter · #13 ·
if my numbers are right, it makes the exhaust act like its on about a 109 LCA, but you still have 114* LCA between the lobes.

that sounds good for many many things.
and yes, I'm turbo, but I'm also NA until mid-load 3800rpms.
on a short stroke 306
 

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In my case, I am on a 114 and put the cam on a 105 ICL
if my numbers are right, it makes the exhaust act like its on about a 109 LCA, but you still have 114* LCA between the lobes.

that sounds good for many many things.
and yes, I'm turbo, but I'm also NA until mid-load 3800rpms.
on a short stroke 306
114 LSA with a 105 ICL puts the ECL @ 123

Stan
 

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If it's personal experience you want...
I have a street car with occasional track duty and S-480 turbo.
I was using an off the shelf street solid roller 249/255 with a 110 lobe installed on a 106 centerline. It sounded great, was strong and responsive while out of boost, and coming into boost was a beast! (remember street car)
The trend at that time with turbo cars was to go to a slightly shorter duration single pattern with a wide lobe seperation. N/A cams were frowned upon.
Searching for more power (as always) I had one made 237/237 on a 115 on the suggestion of a well respected individual and installed it on a 111 ICL and the results out of boost (N/A) were dissapointing. It idled and performed like Grandma's station wagon.:-gay It was a turd until boost came in. Boost was much more controllable with the throttle application though and did not come on like a light switch.
I preferred the light switch hahaha!:smt081
In my personal experience, grinding a cam with a tighter lobe seperation like a 112 or a 110 would probably have been more agressive while out of boost and the ICL could still have been adjusted to move the DCR where needed to help spool. Hope my mistakes help you out!
 

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Discussion Starter · #18 ·
114 LSA with a 105 ICL puts the ECL @ 123

Stan
right Mr. Weiss, I explained that the wrong way.

which 123 is actually stock coyote ECL at park angle.
 

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Discussion Starter · #19 ·
does anyone know typically how much retard you get from a belt driven cam at 6000 rpm?
 

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Discussion Starter · #20 ·
If it's personal experience you want...
I have a street car with occasional track duty and S-480 turbo.
I was using an off the shelf street solid roller 249/255 with a 110 lobe installed on a 106 centerline. It sounded great, was strong and responsive while out of boost, and coming into boost was a beast! (remember street car)
The trend at that time with turbo cars was to go to a slightly shorter duration single pattern with a wide lobe seperation. N/A cams were frowned upon.
Searching for more power (as always) I had one made 237/237 on a 115 on the suggestion of a well respected individual and installed it on a 111 ICL and the results out of boost (N/A) were dissapointing. It idled and performed like Grandma's station wagon.:-gay It was a turd until boost came in. Boost was much more controllable with the throttle application though and did not come on like a light switch.
I preferred the light switch hahaha!:smt081
In my personal experience, grinding a cam with a tighter lobe seperation like a 112 or a 110 would probably have been more agressive while out of boost and the ICL could still have been adjusted to move the DCR where needed to help spool. Hope my mistakes help you out!
Hindsight, it looks like you had some good early exhaust events happening and then you traded for some late, smaller exhaust events happening?
 
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