Ls3 with 1.8 rockers install
Burning Brakes
Joined: Jun 2000
Posts: 1,148
Likes: 47
I installed 1.85 Yella Terra rockers on my 2010 Grand Sport with ARP rocker studs, comp cams pushrods ( I think 7400s ) and STOCK valve springs!! I could REALLY feel the difference and would shift ( manual trans ) flawlessly at 6700RPMS!!
I then added Z06 manifolds/exhaust on stock NPP muffs, Haltech CAI and a mail order ECS tune.
Without a cam, headwork or headers the car went 11.7@121MPH on a soft 1.8 60ft launch.
9 years and 60,000 miles later, the car still runs strong without a single hiccup.
I then added Z06 manifolds/exhaust on stock NPP muffs, Haltech CAI and a mail order ECS tune.
Without a cam, headwork or headers the car went 11.7@121MPH on a soft 1.8 60ft launch.
9 years and 60,000 miles later, the car still runs strong without a single hiccup.
Last edited by Vette Threat; Aug 24, 2020 at 01:53 PM.
Racer
Joined: Sep 2018
Posts: 314
Likes: 81
From: Virginia
That would explain a lot. I didn't realize there were std and tall versions. i bought mine used off this forum.
Intermediate
Joined: Oct 2016
Posts: 34
Likes: 1
I installed 1.85 Yella Terra rockers on my 2010 Grand Sport with ARP rocker studs, comp cams pushrods ( I think 7400s ) and STOCK valve springs!! I could REALLY feel the difference and would shift ( manual trans ) flawlessly at 6700RPMS!!
I then added Z06 manifolds/exhaust on stock NPP muffs, Haltech CAI and a mail order ECS tune.
Without a cam, headwork or headers the car went 11.7@121MPH on a soft 1.8 60ft launch.
9 years and 60,000 miles later, the car still runs strong without a single hiccup.
I then added Z06 manifolds/exhaust on stock NPP muffs, Haltech CAI and a mail order ECS tune.
Without a cam, headwork or headers the car went 11.7@121MPH on a soft 1.8 60ft launch.
9 years and 60,000 miles later, the car still runs strong without a single hiccup.
Intermediate
Joined: Oct 2016
Posts: 34
Likes: 1
I am bringing this 2016 thread back to life since I just replaced my stock 1.7 ratio stock rocker arms in my LS3 with a set of Comp Cams 'Ultra-Pro Magnum' 1.8 ratio rocker arms. (P/N 1678-16).
These full-roller rocker arms are Investment-Cast 8650 Chromoly Steel and the trunnion needle bearings are held in place with Circlips so they cannot fall out like the stock rocker trunnion bearings have been known to do.
The stock LS3 cam has a lift of .551 / .525 when the stock 1.7 ratio rocker arms are used ... When using the 1.8 ratio rocker arms, the cam lift increases to .583 / .556 (an increase of .032" on both the intake and exhaust)
I was worried that if I continued to use the stock LS3 valve springs, they would be very close to coil bind with this increase of lift, so I installed a set of PAC 1218 beehive springs. These springs are a drop-in replacement, so I used my stock valve locks and retainers .... The PAC 1218 springs are good for a max of .600" valve lift, so they are ok when used with the new 1.8 ratio rocker arms.
I also replaced my stock pushrods with a set of Brian Tooley 7.375" hardened rods. These rods are .025" shorter than the stock 7.40" rods, but I needed this slightly shorter pushrod in order to get the correct lifter preload.
My engine only has 21,000 miles on it, but since it's now 9 years old, I installed a new set of the 'hat' type valve stem seals too.
I haven't been to the dyno to see how much HP the extra valve lift added, but I can say that in my supercharged engine, it does run stronger ... I was hoping for maybe something like a 20 HP increase since my engine is boosted.
Sure, a cam change would be the best bet as far as a HP increase, but I don't want to go inside my engine ... I also don't want to go through the pain in the *** trouble it is to replace the cam in these cars.
1.8 Rocker Arms for rectangular port heads: . https://www.summitracing.com/parts/cca-1678-16
1.8 Rocker Arms for cathedral port heads: . https://www.summitracing.com/parts/cca-1677-16
Anyway ... Just posted this as a FYI for anyone here thinking about 1.8 ratio rockers
These full-roller rocker arms are Investment-Cast 8650 Chromoly Steel and the trunnion needle bearings are held in place with Circlips so they cannot fall out like the stock rocker trunnion bearings have been known to do.
The stock LS3 cam has a lift of .551 / .525 when the stock 1.7 ratio rocker arms are used ... When using the 1.8 ratio rocker arms, the cam lift increases to .583 / .556 (an increase of .032" on both the intake and exhaust)
I was worried that if I continued to use the stock LS3 valve springs, they would be very close to coil bind with this increase of lift, so I installed a set of PAC 1218 beehive springs. These springs are a drop-in replacement, so I used my stock valve locks and retainers .... The PAC 1218 springs are good for a max of .600" valve lift, so they are ok when used with the new 1.8 ratio rocker arms.
I also replaced my stock pushrods with a set of Brian Tooley 7.375" hardened rods. These rods are .025" shorter than the stock 7.40" rods, but I needed this slightly shorter pushrod in order to get the correct lifter preload.
My engine only has 21,000 miles on it, but since it's now 9 years old, I installed a new set of the 'hat' type valve stem seals too.
I haven't been to the dyno to see how much HP the extra valve lift added, but I can say that in my supercharged engine, it does run stronger ... I was hoping for maybe something like a 20 HP increase since my engine is boosted.
Sure, a cam change would be the best bet as far as a HP increase, but I don't want to go inside my engine ... I also don't want to go through the pain in the *** trouble it is to replace the cam in these cars.
1.8 Rocker Arms for rectangular port heads: . https://www.summitracing.com/parts/cca-1678-16
1.8 Rocker Arms for cathedral port heads: . https://www.summitracing.com/parts/cca-1677-16
Anyway ... Just posted this as a FYI for anyone here thinking about 1.8 ratio rockers
Race Director
Joined: Mar 2011
Posts: 13,262
Likes: 3,150
From: SW Florida
2021 C6 of the Year Finalist - Modified
Your welcome ... My GS has not had any problems at all with these 1.8 ratio rocker arms and the valvetrain is very quiet.
No extra tuning is needed since all you are doing is increasing the cam's lift (cam duration remains the same as it was with the stock 1.7 rocker arms)
No extra tuning is needed since all you are doing is increasing the cam's lift (cam duration remains the same as it was with the stock 1.7 rocker arms)
