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How many rpms does a advanced cam change

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4.9K views 46 replies 15 participants last post by  Aaron  
#1 ·
In reference to advancing a cam. How many rpms change when you advance it say a total of 4 degrees? In other words, if you advance it 4 degrees and redline was at 6500, where will that redline now be?
 
#6 ·
Aaron - in your situation, I (personally) would degree the cam and install it exactly the way Harold recommended....and then live with it.
Degree-ing a cam with the engine out of the car and on an engine stand is easy enough. In the car is kind of a PITA b/c of all the "stuff" you have to remove.
Simply a hunch on my end, but if your cam is retarded and you're not getting the 60 foot times you'd expect with your combo, that's the likely place to start.....IMHO.
As previously mentioned, always be mindful of piston to valve clearance. Doubt it will be an issue....but just keep that in the back of your mind.

p.s. - If Harold ground some advance in that cam (likely), you're fighting/offsetting that by having it installed "retarded".
 
#10 ·
Not all professional engine builders are created equal, FWIW.

There's nothing wrong with questioning why the retard was used in the cam install.

Not sure that last sentence could be written anywhere else but here in 2024 and in this proper context.........
 
#12 ·
Not all professional engine builders are created equal, FWIW.

There's nothing wrong with questioning why the retard was used in the cam install.

Not sure that last sentence could be written anywhere else but here in 2024 and in this proper context.........
Thanks. Agreed again.
 
#14 ·
From what I was told it only moves the rpm power range up and down alittle. I can never remember which way it moves. If advancing it moves it down, why would you want that in a race application? You have a 5000 ish stall? Lower rpm increase for something it will never see?
For the hassle it is to change it, I would leave it and focus on other things.
 
#20 ·
From what I was told it only moves the rpm power range up and down alittle. I can never remember which way it moves. If advancing it moves it down, why would you want that in a race application? You have a 5000 ish stall? Lower rpm increase for something it will never see?
For the hassle it is to change it, I would leave it and focus on other things.

George your about the only one advocating for leaving it along.
 
#15 ·
Didn't realize the motor was out of the car. Degree away!!!! :)

Could think about using a two piece timing cover, in case you have to degree the cam again with the motor back in the car. Make things a little easier.

Also, please keep in mind that this car is not getting the 60 foot times that it should. Combine that with a cam that may be installed six degrees more retarded than need be and I think the OP has a legitimate question.....FWIW.

Assuming the OP has traction, that is............
 
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#16 ·
Everything you never wanted to know about camshaft timing....

 
#18 ·
where will that redline now be?
Aaron,

I think the terminology might be a little confusing. I always considered the "redline" to be determined more by the components used to build the engine. Basically I have always considered the "redline" as the rpm that you dont want to go above because valves will start floating or parts will start exiting the engine :)

Changing the cam timing will affect the overall power curve as you know but not what I consider the redline.

I think what you are calling redline is what I would call the shift point.
 
#21 ·
Aaron,

I think the terminology might be a little confusing. I always considered the "redline" to be determined more by the components used to build the engine. Basically I have always considered the "redline" as the rpm that you dont want to go above because valves will start floating or parts will start exiting the engine :)

Changing the cam timing will affect the overall power curve as you know but not what I consider the redline.

I think what you are calling redline is what I would call the shift point.
Correct Bill. Im using the term "redline" to indicate shift point. Seem like advancing the cam will push it down.
 
#19 ·
bottom line is is how correct is the cam in it? I've seen advancing the cam hurt power, decrease max rpm, increase max rpm, and do nothing.
 
#27 ·
I sifted quicky through this thread and I didn't see any post that mentioned what engine, heads, and cam specs. So IDK if I missed that, or if the question is merely a hypothetical one. But if this is concerning a specific engine combo that you have, and it's a fairly aggressive or "large" camshaft, then be advised that advancing or retarding the cam will change the piston to valve clearances, so you need to check it after you change the timing of the cam.