L-81 Cam selection advice (again)
Thread Starter
Le Mans Master
Joined: Feb 2011
Posts: 5,943
Likes: 61
From: Southern NH
L-81 Cam selection advice (again)
I've been talking about a cam swap for years, and thinking about doing it this summer.
How would the Crane Cams 113801 cam work with my set up and the stock computer and carb? cam specs: Duration @ .050" Lift 222° Intake/234° Exhaust. Lift: .467" Intake/.494" Exhaust, 114 LSA
Heads: stock ZZ4. Will be about 9.8 cr . Exhaust: Hedman Long tube headers and custom sidepipes I welded up. Transmission: Richmond 5 speed with 3.36 first gear and 2.87 rear gears (equates to a muncie with 4.11s in the rear)
Thanks.
How would the Crane Cams 113801 cam work with my set up and the stock computer and carb? cam specs: Duration @ .050" Lift 222° Intake/234° Exhaust. Lift: .467" Intake/.494" Exhaust, 114 LSA
Heads: stock ZZ4. Will be about 9.8 cr . Exhaust: Hedman Long tube headers and custom sidepipes I welded up. Transmission: Richmond 5 speed with 3.36 first gear and 2.87 rear gears (equates to a muncie with 4.11s in the rear)
Thanks.
Last edited by qwank; Apr 13, 2019 at 11:00 PM.
Race Director
Joined: May 2006
Posts: 18,740
Likes: 2,583
You want a cam with an operating range of 2,200 to 6,200 rpm? Are you seeing that kind of engine speed? For street usage looking at the Summit Racing site it does not show that cam.
Here are two with a slightly lower max rpm.
https://www.summitracing.com/search/...4%2B4294891014
Here are two with a slightly lower max rpm.
https://www.summitracing.com/search/...4%2B4294891014
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
OP Qwank
Must you use L81 carb, dist & computer?
If YES, I'd ask Crane and tell them exactly what you're working with.
Also, there's a few guys on here who've done similar L81 upgrade ... wait for their feedback.
Must you use L81 carb, dist & computer?
If YES, I'd ask Crane and tell them exactly what you're working with.
Also, there's a few guys on here who've done similar L81 upgrade ... wait for their feedback.
Thread Starter
Le Mans Master
Joined: Feb 2011
Posts: 5,943
Likes: 61
From: Southern NH
You want a cam with an operating range of 2,200 to 6,200 rpm? Are you seeing that kind of engine speed? For street usage looking at the Summit Racing site it does not show that cam.
Here are two with a slightly lower max rpm.
https://www.summitracing.com/search/...4%2B4294891014
Here are two with a slightly lower max rpm.
https://www.summitracing.com/search/...4%2B4294891014
As long as I make around 15 inches of vacuum the computer should be happy.
Racer
Joined: Oct 2001
Posts: 474
Likes: 64
From: Portage La Prairie Manitoba
I don't think your computer will be happy with that cam.
I tried a comp cams he 268 on mine once.
Stock heads with headers ,intake..... could not get it to idle right very lopey.
Had to unplug computer and change carb and distributer to make it work
I tried a comp cams he 268 on mine once.
Stock heads with headers ,intake..... could not get it to idle right very lopey.
Had to unplug computer and change carb and distributer to make it work
Thread Starter
Le Mans Master
Joined: Feb 2011
Posts: 5,943
Likes: 61
From: Southern NH
https://www.summitracing.com/parts/c...waAseHEALw_wcB
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
This would be a great candidate for a stock L-82 cam....some roller rockers and real pushrods......
The L-82 is a great street cam......the issue on the L-81 as well as older 350's back to 69' were the crap intake and exhaust.....
On the ZZ4 heads.....make sure you have the right flat tappet spring......Elgin and Isky both make a version of the "Z-28" spring that is great to .525 lift.
Jebby
The L-82 is a great street cam......the issue on the L-81 as well as older 350's back to 69' were the crap intake and exhaust.....
On the ZZ4 heads.....make sure you have the right flat tappet spring......Elgin and Isky both make a version of the "Z-28" spring that is great to .525 lift.
Jebby
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Thread Starter
Le Mans Master
Joined: Feb 2011
Posts: 5,943
Likes: 61
From: Southern NH
This would be a great candidate for a stock L-82 cam....some roller rockers and real pushrods......
The L-82 is a great street cam......the issue on the L-81 as well as older 350's back to 69' were the crap intake and exhaust.....
On the ZZ4 heads.....make sure you have the right flat tappet spring......Elgin and Isky both make a version of the "Z-28" spring that is great to .525 lift.
Jebby
The L-82 is a great street cam......the issue on the L-81 as well as older 350's back to 69' were the crap intake and exhaust.....
On the ZZ4 heads.....make sure you have the right flat tappet spring......Elgin and Isky both make a version of the "Z-28" spring that is great to .525 lift.
Jebby
I also heard I should use a dual pattern cam with the ZZ4 heads since the exhaust ports were so poor, that's why I've been trying to find something close to the L82 cam on the intake side, but a little larger on the exhaust.
And I didn't know flat tappet cam used different springs than roller cams? the ZZ4 springs are good for about .510 lift, some say .525 but I'm not sure about that.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
I'm not going to do roller rockers, I have the stock self aligning rockers from the ZZ4 so I'm going to use those, I don't think the cost for roller rockers is worth is for the setup I'm doing.
I also heard I should use a dual pattern cam with the ZZ4 heads since the exhaust ports were so poor, that's why I've been trying to find something close to the L82 cam on the intake side, but a little larger on the exhaust.
And I didn't know flat tappet cam used different springs than roller cams? the ZZ4 springs are good for about .510 lift, some say .525 but I'm not sure about that.
I also heard I should use a dual pattern cam with the ZZ4 heads since the exhaust ports were so poor, that's why I've been trying to find something close to the L82 cam on the intake side, but a little larger on the exhaust.
And I didn't know flat tappet cam used different springs than roller cams? the ZZ4 springs are good for about .510 lift, some say .525 but I'm not sure about that.
The ZZ4 was a hydraulic roller engine so the springs cannot be used...period. Elgin makes a set for flat tappet with springs,lock,retainers for $70. Actually the ZZ4 exhaust was the improvement.....the intake remained exactly the same....or worse. The ZZ4 heads will need a proprietary head bolt kit for the aluminum.
If you have them....fine, but I would not mess with them.....find a pair of used Dart Iron Eagle heads and bolt those on......those will show REAL gains.......you could pocket port and bowl blend them but you will still be 30 horses off an out of the box Dart head.
Jebby
Last edited by Jebbysan; Apr 20, 2019 at 05:00 PM.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
JMO
Most upgrades need to be done in concert with adjunct upgrades; otherwise, piece-meal approach often ends up a real disappointment (turd).
Perhaps, save toward bundled FI & cam swap budget; run whatcha got 'till then.
As said, call Crane ... but there's more than one comp 268H ... there's also an HE268H ... gentler high energy HE series not same as extreme energy XE
call Both crane & comp ... tell em what you have and what you want to do.
those OE stamped self-align rockers serve quite well in ZZ4 crates and x603 aka CT 355 crate race motors.
Those motors all have same heads and their roller springs are
pn 12551483, Single, 1.320" OD, 101 lb @ 1.780", 332 lb @ 1.22" (rather puny for a "roller" spring conventional wisdom/intuition)
Actually, pressures@heights not so different than Z28 springs.
Elgin single Z28 springs std & +0.100" longer free length
RV-943X 1.250 OD, 110 @ 1.700, 285 @ 1.210, coil bind 1.160, max lift .490
RV-1943X 1.250 OD, 125 @ 1.750, 325 @ 1.200, coil bind 1.160, max lift .550
Most upgrades need to be done in concert with adjunct upgrades; otherwise, piece-meal approach often ends up a real disappointment (turd).
Perhaps, save toward bundled FI & cam swap budget; run whatcha got 'till then.
As said, call Crane ... but there's more than one comp 268H ... there's also an HE268H ... gentler high energy HE series not same as extreme energy XE
call Both crane & comp ... tell em what you have and what you want to do.
those OE stamped self-align rockers serve quite well in ZZ4 crates and x603 aka CT 355 crate race motors.
Those motors all have same heads and their roller springs are
pn 12551483, Single, 1.320" OD, 101 lb @ 1.780", 332 lb @ 1.22" (rather puny for a "roller" spring conventional wisdom/intuition)
Actually, pressures@heights not so different than Z28 springs.
Elgin single Z28 springs std & +0.100" longer free length
RV-943X 1.250 OD, 110 @ 1.700, 285 @ 1.210, coil bind 1.160, max lift .490
RV-1943X 1.250 OD, 125 @ 1.750, 325 @ 1.200, coil bind 1.160, max lift .550
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Thread Starter
Le Mans Master
Joined: Feb 2011
Posts: 5,943
Likes: 61
From: Southern NH
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
spring specs mid-page
https://chevroletperformanceparts.co...e_vsprings.pdf
brand new set of those 12551483 ZZ4 springs for $51 delivered
https://www.ebay.com/itm/NOS-Genuine...75.c100623.m-1
https://chevroletperformanceparts.co...e_vsprings.pdf
brand new set of those 12551483 ZZ4 springs for $51 delivered
https://www.ebay.com/itm/NOS-Genuine...75.c100623.m-1
Last edited by jackson; Apr 22, 2019 at 06:41 PM.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Roller Spring at 80 lb on seat
FWIW ... all iron head production (RPO L31 vin code 8) 5.7L Vortec motors came with small (.414"/.428") Roller Cam-Roller Lifters ...
... all those production Vortec heads came with this small Roller Spring pn 10212811 ... which is all of 80 lb on seat.
That's right ... GM pn 10212811 ... an 80 lb "Roller Spring"
... all those production Vortec heads came with this small Roller Spring pn 10212811 ... which is all of 80 lb on seat.
That's right ... GM pn 10212811 ... an 80 lb "Roller Spring"