Built in cam advance - Team Camaro Tech
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post #1 of 7 (permalink) Old Nov 23rd, 14, 10:46 AM Thread Starter
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Steve
 
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Built in cam advance

General engine/cam questions for you engine guru's.

I have seen that many aftermarket cam manufacturers state that they have 4 degrees of advance built in the grind.

1. Did all american car engines from the 60s and 70s have this too?

2. Does this mean in a perfect world (which I only visit occasionally), if the number one piston is at TDC and the balancer is on 0 degrees, the timing events are really 4 degrees advanced? Or put another way, at 0 you are really at 4 degrees?

Thanks,

Mr. Fixit
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post #2 of 7 (permalink) Old Nov 23rd, 14, 01:49 PM
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Re: Built in cam advance

The simplest method is during engine assembly to use adjustable cam chain gears...
But before we thinking going down that route
1/The engine as it is MUST be dialed in correctly for THAT cam setting 1st.. then maybe think about it.. and even then only if have stable idle issues because of big cams or over carbed or track car
2/The effectiveness of advancing / retarding is about changing the power curve rpmn range.. and the amount is either zero or a couple 100 rpms only depending on the cam profile, ramp speeds etc.
3/ppl who to go to messing around with cam advance, tend to be those who have not dialed in the tuning specs for their car correctly and are trying to patch fix something they have little understanding about ... and those who do have understanding tend to simply throw another cam in and have enough experience to set any advance that maybe needed then and there... then re dial in the new tuning specs.

My Spelling is not incorrect...it is creative

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post #3 of 7 (permalink) Old Nov 23rd, 14, 04:16 PM Thread Starter
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Re: Built in cam advance

Quote:
Originally Posted by Mr. Fixit View Post
General engine/cam questions for you engine guru's.

I have seen that many aftermarket cam manufacturers state that they have 4 degrees of advance built in the grind.

1. Did all american car engines from the 60s and 70s have this too?

2. Does this mean in a perfect world (which I only visit occasionally), if the number one piston is at TDC and the balancer is on 0 degrees, the timing events are really 4 degrees advanced? Or put another way, at 0 you are really at 4 degrees?
If anyone can answer either of these questions, that would be awesome.

Thanks,

Mr. Fixit
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post #4 of 7 (permalink) Old Nov 23rd, 14, 05:58 PM
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Re: Built in cam advance

Quote:
Originally Posted by Mr. Fixit View Post
General engine/cam questions for you engine guru's.

I have seen that many aftermarket cam manufacturers state that they have 4 degrees of advance built in the grind.

1. Did all american car engines from the 60s and 70s have this too?

2. Does this mean in a perfect world (which I only visit occasionally), if the number one piston is at TDC and the balancer is on 0 degrees, the timing events are really 4 degrees advanced? Or put another way, at 0 you are really at 4 degrees?
1. There isn't enough info to determine if 'all' had cams ground advanced.

2. No. The timing events are where they are designed to be.
Quote:
By using special timing sets, you can change the angle of the cam relative to the crankshaft. Spinning the cam forward so that the valve opening events happen sooner is called advancing the cam. Retarding the cam is just the opposite. Most camshaft manufacturers grind in around 4 degrees of advance into their cams so that it is automatic when you install your cam with the zero marks on the timing set. This is very common with street cams but varies with different race cams. Make sure you know what you have.

"Typically, engines respond better with a few degrees advance," Godbold explains. "This is likely due to the importance of the intake closing point on performance. Earlier intake closing leads to increased cylinder pressure and better responsiveness." As a general rule of thumb, advancing the cam will help low-end torque, but if your engine is dying by the flag stand, retarding the cam a few degrees should help extend high-rpm power a bit.
http://www.hotrod.com/how-to/engine/...esign-science/

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post #5 of 7 (permalink) Old Nov 23rd, 14, 06:18 PM
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Re: Built in cam advance

the way i understand it goes by what lobe separation the cam has. lets use a cam with 110 degree lobe separation as a example. if this cam was installed "straight up", the intake center line would be 110 degrees. most cams would be installed at 106 degrees wich is 4 degrees advanced. the part of being ground in means in a perfect world, with a adjustable timing set the center setting would net you 106 degrees in this example. of course we have to check this becaust varibles and tollerances it many times isnt dead on. if im not right on this some one please say so!
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post #6 of 7 (permalink) Old Nov 23rd, 14, 06:26 PM Thread Starter
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Re: Built in cam advance

Quote:
Originally Posted by onovakind67 View Post
1. There isn't enough info to determine if 'all' had cams ground advanced.

2. No. The timing events are where they are designed to be.


http://www.hotrod.com/how-to/engine/...esign-science/
Thank you for the great explanation, I do appreciate it.. Very comprehensive.

Thanks,

Mr. Fixit
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post #7 of 7 (permalink) Old Nov 23rd, 14, 06:35 PM
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Re: Built in cam advance

You are confusing the TDC of the engine with the cam position within the engine.
Everything is referenced off of TDC, & it will still be 0 on the balancer.

Not sure how many factory applications have built in advance.
I would assume quite a few.

Typically cams are designed for best performance through testing.
Would you benefit from further tuning??? Not sure & experimentation is the only way to tell.

Advance is the difference in degrees that the cam (IC or installed centerline) is installed from the LSA setting. If your cam is ground on a 110LSA (the degrees between peak intake & exhaust lift as ground) & you get peak intake cam lift at 106 it is 4 degrees advanced.

There is no right or wrong, only where it works the best.
Rest assured, most manufacturers will try to design it for best performance.
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