Predict Cam Characteristics...

N

NicD

Member

Mar 4, 2004

57

0

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Oct 27, 2005

#1

• Oct 27, 2005

• #1

0.510/0.534 222/223 @ 0.50" 112 lobe sep

How would this cam act in a N/A 347 with AFR 185's in terms of:

1. Idle
2. Performance
3. Emissions

Thanks in advance...

 

F

fiveohGT

New Member

Jun 22, 2004

353

1

0

Fairfax Virginia

Oct 27, 2005

#2

• Oct 27, 2005

• #2

Which cam is that?

 

Modular2v

Founding Member

Jun 30, 2002

3,222

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99

oklahoma

Oct 27, 2005

#3

• Oct 27, 2005

• #3

well i can tell you that you are not taking full advantage of the afr's flowing capabilities with that small of a cam

 

N

NicD

Member

Mar 4, 2004

57

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Oct 27, 2005

#4

• Oct 27, 2005

• #4

fiveohGT said:

Which cam is that?

Click to expand...

It's a Pro Mustang 4018, the cam that CHP uses in it's 347e short and long blocks...

 

vristang

15 Year Member

Mar 31, 2005

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Seattle

Oct 27, 2005

#5

• Oct 27, 2005

• #5

Is the 347e smog legal? Sounds like a smog legal cam to me.

As a general rule big duration and passing emissions don't go together. Once the overlap gets to the point where it causes a rougher idle (which everyone seems to want) it will be tough to pass.

 

N

NicD

Member

Mar 4, 2004

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Oct 27, 2005

#6

• Oct 27, 2005

• #6

vristang said:

Is the 347e smog legal? Sounds like a smog legal cam to me.

As a general rule big duration and passing emissions don't go together. Once the overlap gets to the point where it causes a rougher idle (which everyone seems to want) it will be tough to pass.

Click to expand...

Exactly - 347e is their smog legal stroker...

I'm using this as a starting point to try to determine how much bigger i can go and still be smog legal...Any ideas?

 

CoupedUp

Banned

Aug 26, 2005

260

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Gone Fishing

Oct 27, 2005

#7

• Oct 27, 2005

• #7

Those specs aren't bad for a "street car".
I would go with a little more valve lift (.550 area) and kept the duration and lsa right where it is. The 185's flow peak around the .550" lift area.

The idle will have a little lope to it, so you will know the engine has a cam, but not at all too choppy.

It will make power from about 1800-5800 and shouldn't have a problem passing emissions.

It sounds like a good street cam to me ... although point specific numbers don't tell the whole story of the lobe profile.

Good Luck

 

Modular2v

Founding Member

Jun 30, 2002

3,222

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oklahoma

Oct 27, 2005

#8

• Oct 27, 2005

• #8

what if you put a cam in a with over 550 lift with afrs? would it be too much cam for the heads?

 

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IntenseBlue

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Jul 10, 2005

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Oct 27, 2005

#9

• Oct 27, 2005

• #9

No, it wouldn't.

 

vristang

15 Year Member

Mar 31, 2005

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Oct 27, 2005

#10

• Oct 27, 2005

• #10

If you need to stay smog legal all you can really play with is the lift. However, this may still have an affect on emissions as the ramp rates will probably change.

It may be better to bump to a 114lsa if opening the lift and/or duration? I am by no means an expert though. I am just throwing the idea out to see what others think. I suppose that if going for max power in an emissions legal combo one would have to look more closely at the exact valve timing events, as opposed to the very general duration at .050" and max lift numbers.

 

N

NicD

Member

Mar 4, 2004

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Jan 13, 2006

#11

• Jan 13, 2006

• #11

In terms of idle and performance, what would be the difference between a cam with 230/235 dur and .535 lift with 1.6 rockers vs. a cam with 230/235 duration with .568 lift with 1.7 rockers?

Again this is for a daily driver...

 

Cobra4075

Founding Member

Feb 18, 2002

286

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17

Tinley Park, IL

Jan 13, 2006

#12

• Jan 13, 2006

• #12

You could put a higher ratio rocker like 1.7's to get a higher lift. I have a custom cam i just took out of my stock block 302 w/ afr's. The lift was around .580 and i didn't have clearence issues. Also, it would not come close to passing emissions no matter what i tried.

 

1

1SLO306

My 97 GTP owns you ALL!

Mar 31, 2005

904

1

17

Muhlenberg, ky

Jan 13, 2006

#13

• Jan 13, 2006

• #13

there is a formula to figures out how much lope u will get out of it
intake DUR@.50+exhaustDUR@.50/4-LSA*2

In figured that cam up and comes out to a negative #(-1.5) so u prolly wont tell much diff in idle

 

Grn92LX

Fidanza Man!

Founding Member

Jan 14, 2001

6,819

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129

New York

Jan 13, 2006

#14

• Jan 13, 2006

• #14

Why spend THOUSANDS on a 347 only to put a junk guessing game camshaft in?!!?!?!!?!?! Put the RIGHT cam in to give you what you want. I can tell you my custom FTI cam is MUCH bigger and it drives awesome.

 

QDRHRSE

New Member

Dec 31, 2002

1,590

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Palmdale, CA

Jan 14, 2006

#15

• Jan 14, 2006

• #15

That cam has a lot of lift for that duration. Truthfully, the AFR 185 will flow almost the same with .500 lift and .534 . Other than the fairly high lift, that cam might as well be a broomstick for a 347. I realize that CHP builds a lot of engines but that doesn't sound like the greatest cam. I even question the LSA. It's quite short for a motor that will naturally make power down low. That souns like a cam for a smaller motor that needs more tq- sooner than later. Just me thinking.......

 

N

NicD

Member

Mar 4, 2004

57

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6

Jan 17, 2006

#16

• Jan 17, 2006

• #16

Grn92LX said:

Why spend THOUSANDS on a 347 only to put a junk guessing game camshaft in?!!?!?!!?!?! Put the RIGHT cam in to give you what you want. I can tell you my custom FTI cam is MUCH bigger and it drives awesome.

Click to expand...

It's not a guessing game, more of a learning game...Even if I had FTI do a custom cam, I'd still want to know the specs and I'd still want to understand what was going on and why my car performs the way it does...

BTW, I've have chatted with Mr. Curtis, he'll likely be doing my cam once my combo is complete, but the motor will possibly be going in with stock intake and exhaust...This cam will likely be temporary, but in the car while doing final mods...

As far as cams go, I understand the concepts but not the applications - that is - from reading, I know what lift, duration and lobe separation are, but I don't know how they relate to idle, power, and emissions...

It's kinda like knowing what passes, runs, and 1st downs are, but not having any idea how to put a drive together for a touchdown...Some guys are satisfied watching the hits and the great plays...I want to know what made the plays work...

Can anybody maybe refer me to some reading material? Maybe provide a link? I've searched quite a bit but haven't come up "cams for dummies" yet...

 

vristang

15 Year Member

Mar 31, 2005

4,933

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124

Seattle

Jan 17, 2006

#17

• Jan 17, 2006

• #17

Here a a few of the useful sights I have found.

Still did not answer the questions I had the way I wanted them answered.

http://www.hotrod.com/techarticles/18218/index.html
http://www.hotrod.com/techarticles/113_9804_cam/index.html
http://www.hotrod.com/techarticles/113_0209_cam/index.html
http://www.hotrod.com/techarticles/49598/index.html


jason

 

N

NicD

Member

Mar 4, 2004

57

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Jan 17, 2006

#18

• Jan 17, 2006

• #18

^ Some good stuff...Takin it home with me tonight...Thanks Jason...

Keep it comin...Any info is good info...

 

vristang

15 Year Member

Mar 31, 2005

4,933

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Seattle

Jan 19, 2006

#19

• Jan 19, 2006

• #19

I liked this book too. It does provide a little more detail than what you get in the mags. Pretty good stuff on oil systems as well.

Four-Stroke Performance Tuning by A. Graham Bell