Solid Roller Lash Question
Thread Starter
Melting Slicks
Joined: Nov 2000
Posts: 2,738
Likes: 53
From: Bogart GA
Solid Roller Lash Question
Comp Cams cant seem to answer this question so I thought I would post it here.... My cam card hot lash values are based on 1.5 rockers. I have 1.7 rockers. Should the lash values be adjusted for the 1.7 ratio?
Drifting
Joined: Oct 2006
Posts: 1,875
Likes: 779
From: Persona Non Grata
2022 C3 of the Year Finalist - Unmodified
I await a knowledgeable party.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Lash apparently does change because of the r ratio So according to the experts you add a couple of thousands going from 1.5 to 1.7
Modern sr cams us less lash use the biggest dia ARP studs and the crane cams gold stud girdle
Allen locking nuts and lash caps on the valve stem tips
Use a dial indicator or angle feeler gauges
Do them hot and use the min spec
Modern sr cams us less lash use the biggest dia ARP studs and the crane cams gold stud girdle
Allen locking nuts and lash caps on the valve stem tips
Use a dial indicator or angle feeler gauges
Do them hot and use the min spec
Last edited by gkull; Dec 2, 2016 at 11:44 AM.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I'm using 1.7 on my 434 ci. I have +200 push rods and the taller ARP studs to clear my bigger diameter valve springswith cc steel rrs
My valve stems are also. 100 over to use the 2.05 installed height springs
Go to the cc spring charts and you can see the closed pounds at different installed heights.
So for example a spring might be 240# at 2.00 inches. A sub 7500 rpm only needs. 205 pounds
So you raise the installation height to get the lower pounds and make the springsand rollers last longer
My valve stems are also. 100 over to use the 2.05 installed height springs
Go to the cc spring charts and you can see the closed pounds at different installed heights.
So for example a spring might be 240# at 2.00 inches. A sub 7500 rpm only needs. 205 pounds
So you raise the installation height to get the lower pounds and make the springsand rollers last longer
Safety Car
Joined: Apr 2005
Posts: 3,624
Likes: 431
From: Dale City VA
Lash should indeed change according to rocker ratio.
You want the lash point to be at the end of the lash ramp on the cam lobe.... A higher ratio rocker arm opens the valve... or in this case closes up the lash faster/sooner, so in the case of replacing 1.5 rockers with 1.7 rockers you need to increase lash to make this happen.
Mike Jones of Jones Cams and Dick Jones of Controlled Induction explain the formula to determine how much lash should change based on rocker ratio and the parameters involved in how/why you should adjust valve lash values based on rocker ratio in this thread.
http://www.yellowbullet.com/forum/sh...d.php?t=721186
Will
You want the lash point to be at the end of the lash ramp on the cam lobe.... A higher ratio rocker arm opens the valve... or in this case closes up the lash faster/sooner, so in the case of replacing 1.5 rockers with 1.7 rockers you need to increase lash to make this happen.
Mike Jones of Jones Cams and Dick Jones of Controlled Induction explain the formula to determine how much lash should change based on rocker ratio and the parameters involved in how/why you should adjust valve lash values based on rocker ratio in this thread.
http://www.yellowbullet.com/forum/sh...d.php?t=721186
Will
Thread Starter
Melting Slicks
Joined: Nov 2000
Posts: 2,738
Likes: 53
From: Bogart GA
Lash should indeed change according to rocker ratio.
You want the lash point to be at the end of the lash ramp on the cam lobe.... A higher ratio rocker arm opens the valve... or in this case closes up the lash faster/sooner, so in the case of replacing 1.5 rockers with 1.7 rockers you need to increase lash to make this happen.
Mike Jones of Jones Cams and Dick Jones of Controlled Induction explain the formula to determine how much lash should change based on rocker ratio and the parameters involved in how/why you should adjust valve lash values based on rocker ratio in this thread.
http://www.yellowbullet.com/forum/sh...d.php?t=721186
Will
You want the lash point to be at the end of the lash ramp on the cam lobe.... A higher ratio rocker arm opens the valve... or in this case closes up the lash faster/sooner, so in the case of replacing 1.5 rockers with 1.7 rockers you need to increase lash to make this happen.
Mike Jones of Jones Cams and Dick Jones of Controlled Induction explain the formula to determine how much lash should change based on rocker ratio and the parameters involved in how/why you should adjust valve lash values based on rocker ratio in this thread.
http://www.yellowbullet.com/forum/sh...d.php?t=721186
Will
Race Director
Joined: Jan 2000
Posts: 13,025
Likes: 2,266
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Shouldn't add any noise since all you're doing is putting the lifter back on the proper part of the opening ramp as it would have been with the 1.5's.
That said...for longevity, less lash is good. My stuff is always set pretty tight.
JIM
That said...for longevity, less lash is good. My stuff is always set pretty tight.
JIM
Thread Starter
Melting Slicks
Joined: Nov 2000
Posts: 2,738
Likes: 53
From: Bogart GA
Just heard from comp cam, they said to just use the value for 1.5.
Last edited by KJL; Dec 2, 2016 at 10:55 AM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Corvette & Porsche 911: How Two Icons Conquered the Last 25 Years
Joe Kucinski
2027 Chevrolet Silverado 1500 First Look: Everything You NEED to Know!
Michael S. Palmer
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
Drifting
Joined: Jul 2013
Posts: 1,299
Likes: 93
From: Tri-Cities TN
Yes it needs to change. Take your hot lash and divide by 1.5. That number is the clearance lash for the ramp. Now take that number and x by 1.7 and that will be your lash based on you using 1.7 rockers.
Drifting
Joined: Jul 2013
Posts: 1,299
Likes: 93
From: Tri-Cities TN
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Le Mans Master
Joined: Mar 2001
Posts: 6,242
Likes: 1,014
From: Watkinsville, GA and Glen Cove, NY
I think Chris said on another forum those lifters are $1300.00. I bought a set of the Morel bushed solids from Chris a couple months ago. If these had been out then, probably would have gone with these. Looks promising.
Last edited by 69ttop502; Dec 4, 2016 at 08:01 AM.
Drifting
Joined: Jul 2013
Posts: 1,299
Likes: 93
From: Tri-Cities TN
They are just under the above number. Availability is now. Will have at PRI show.