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Author
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Topic: Super Stock Cams...
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n2oMike
Gearhead Posts: 2831
From: Spencer, WV
Registered: Jan 2001
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posted 06-20-2002 11:18 AM
   
I was speaking with an engineer at Comp, and we were discussing a few issues about valve lash...He mentioned that some of the Super Stockers were running cams that speced out larger than what they actually needed... and were setting the valve lash extremely loose, around 0.040". The was done because the first part of the opening ramp is very gentle... If you set the valve lash really loose, this gentle opening ramp is avoided, and the valve literally gets YANKED open incredibly quickly. And the extra valve lash takes care of the excessive duration of the extra large cam. Seemed to make sense to me... Comments? Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
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jkilroy
Gearhead Posts: 1808
From: Vicksburg, MS
Registered: Dec 99
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posted 06-20-2002 02:07 PM
I would expect a lot of valve seat bounce with a setup like that. Maybe they are just trying to literally 'throw' the valve open beyond the set lift of the cam? No doubt that kind of thing is hard on parts, the lifters would be very loose on the cam when not under lift, that can't be all that good.------------------
Jay Kilroy
68' Fastback GT 390
"No such thing as a cam thats too big"
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JCQuinn@work
Gearhead Posts: 935
From: Lakewood, CO, USA
Registered: Jun 2001
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posted 06-20-2002 02:17 PM
This is an old (very old) racers trick. It is usually done on a temporary basis to see if the car likes more (tighter lash) or less duration (looser lash) than the installed cam has. Some guys run this way all the time but it is very hard on valve train parts. The clearance ramps are ground into the cam to let the valve motion begin and end the lift cycle in a manner that will not destroy lifters, rockers etc. People who run like this all the time have to constantly check the valve train and replace a lot of springs.John Quinn
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JCQuinn@work
Gearhead Posts: 935
From: Lakewood, CO, USA
Registered: Jun 2001
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posted 06-20-2002 02:20 PM
One more thought, while yanked open might sound good, how does slammed down on the seat sound?John Quinn
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 06-20-2002 03:13 PM
That's why we only do it when we want to go real fast. 
Been doing it for years and years. 
The trick will work on any solid flat tappet or roller cam.  ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
Professional Manwhore
The Barry of BarrysGrrl
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 06-20-2002 03:19 PM
The wide spread use of this is one of the reasons there are several different qualities of roller lifters now available. A few years ago there were roller lifters or there were roller lifters. Now we have "Pro series", "Severe duty series", "HI Tech" series etc. The standard "race" lifters cannot take the beating. Trust me on this one as I know first hand.  ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
Professional Manwhore
The Barry of BarrysGrrl
IP: Logged |
n2oMike
Gearhead Posts: 2831
From: Spencer, WV
Registered: Jan 2001
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posted 06-20-2002 05:45 PM
It looked like a good way to get more "area under the curve" in a given duration... at the expense of valvetrain abuse. Extra big and aggressive cam, combined with extra large lash gas to avoid the gentle initial opening and closing ramps has GOT to be REALLY tough on things. Doing this with a ROLLER would be insane! Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 06-20-2002 05:56 PM
Yeah well, I have been called much worse. INSANE is pretty tame by comparison. ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
Professional Manwhore
The Barry of BarrysGrrl
IP: Logged |
R&J MOTORSPORTS
Journeyman Posts: 94
From: Tampa,Fl.
Registered: Aug 2000
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posted 06-21-2002 02:15 PM
Interesting point. I am running a 289 in SS now and was told to set valves at .035 int. and .030 exh. Sounded like alot,now I know why. Does this sound right for my application? I am planning on changing to see what the results would be, what is the norm? Thanx, Joe------------------
Joe Strunk
NHRA SS/MA 2890
1964 SS/MA Comet
1965 PRO-Street Fairlane
1966 Fairlane Conv.
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n2oMike
Gearhead Posts: 2831
From: Spencer, WV
Registered: Jan 2001
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posted 06-21-2002 02:34 PM
The guy at Comp is named Mark. I don't have his extension offhand, but seemed quite knowledgable, and is their resident Ford guru. I'll post the extension later. He was MUCH more helpful in selecting a custom ground cam for a stroker FE I'm building for a friend than any of the other bozo's working there. He's generally there from 9-6 eastern time, and can be reached from their 'cam help' number. 1-800-999-0853Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
IP: Logged |
JCQuinn@work
Gearhead Posts: 935
From: Lakewood, CO, USA
Registered: Jun 2001
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posted 06-21-2002 03:18 PM
Joe
I've known people to run from zero to about .080 lash on competition engines. Just don't run these extremes too long. See Alex's post above about roller lifters.John Quinn
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