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Author
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Topic: Valvetrain harmonics
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V8 Thumper
Gearhead Posts: 4044
From: Orange, Ca. United States of America
Registered: Dec 2001
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posted 02-05-2003 07:28 AM
   
I've been reading a bit about it... can someone give it to me in English?  ------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9" All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html [This message has been edited by V8 Thumper (edited 02-05-2003).]
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Just Strokin
Gearhead Posts: 754
From: Tuscaloosa, Alabama
Registered: Dec 2001
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posted 02-05-2003 09:14 AM
Here is one way to think of valve train harmonics in a way you can understand it maybe.....
Have you ever had a tire on your car that at a certain speed it would vibrate, but at other speeds it was smooth?
The valve train parts and pieces, specially the springs have a certain frequency at which they resonate (vibrate). ------------------
Larry No fast Fords at this time but one fine cruising 96 F350 CC DRW Power Strokin diesel.
And one rusty 64 Fairlane nick-named the Rust Bucket....And sometimes called the Money Pit... The sounds of a brain dropping into gear.....
"Buzzzzzz.......Click"
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Moneymaker
Administrator Posts: 21725
From: Lyons, IL, USA
Registered: May 99
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posted 02-05-2003 10:27 AM
Just picture your rocker arms moving side to side in addition to up and down at 7000 RPM.
Think about what that does to your push rods and lifters, and of couse what the cam is thinking at this time.  ------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00,'01,'02,&'03
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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bluestreek
Gearhead Posts: 1460
From: Athens,GA
Registered: Jul 2001
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posted 02-05-2003 12:13 PM
That's the very reason I'm building a shaft mount system for a set of AFR 185 heads. All that movement and vibration scares me!! ------------------
1966 Mustang Coupe: Custom glass hood and BIG scoop sits atop a 289 stroked to 331 c.i., Steel crank and girdle, 5.4 H-beams, Forged slugs, ported TFS alum. heads, ported Stealth 8020 intake, CompCams Xtreme Solid Roller, Holley 750 HP, long tubes, 4speed, 9" 3.50 posi, BFG Drag radials..
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JCQuinn@work
Gearhead Posts: 542
From: Lakewood, CO, USA
Registered: Jun 2001
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posted 02-05-2003 01:21 PM
Don't forget to add valve bounce to the harmonics picture. When the engine is spinning at 7000 rpm, each valve is banging against the seat 58 times per second. The more radical the cam profile, the more the valve setting down on the ceat is like a collision instead of a closing. Most valve train problems are caused by insufficient valve spring pressure to keep the valve from bouncing. John
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Moneymaker
Administrator Posts: 21725
From: Lyons, IL, USA
Registered: May 99
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posted 02-05-2003 01:24 PM
Absolutley John! ------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00,'01,'02,&'03
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
IP: Logged |
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