L98 Rocker Install
Thread Starter
Intermediate
Joined: Nov 2022
Posts: 34
Likes: 7
From: Buffalo, NY
L98 Rocker Install
I’ll soon be swapping out my stock TPI for a high flowing intake (BigMouth base, AS&M runners, port matched plenum).
While I already have that area apart, I was going to swap my stock rockers with a set of 1.6 roller rockers. I already have them, so why not?
I know that I have to shave the drip tabs off the covers, And that my stock valve train will suffice using the stock camshaft.
But do I need to adjust anything before/during/after, like lash, etc? Or can I just swap them and “done”?
While I already have that area apart, I was going to swap my stock rockers with a set of 1.6 roller rockers. I already have them, so why not?
I know that I have to shave the drip tabs off the covers, And that my stock valve train will suffice using the stock camshaft.
But do I need to adjust anything before/during/after, like lash, etc? Or can I just swap them and “done”?
Drifting
Joined: Apr 2011
Posts: 1,925
Likes: 441
From: Albuquerque NM
Ooh have you done a baseline dyno?
Exhaust mods?
I have been curious what a big mouth TPI intake manifold base, plus Arizona Speed long tube runners, and 1.6 full roller rockers can result in as far as rwhp gains on a MAF L98 car.
Grind down the drip tabs, keep an eye and ear on clearance, and the roller rockers should be bolt on, plus lash procedure.
Lash procedure is pretty well documented.
What year are you working ongoing?
Full roller rockers or just roller tip?
What heads? You gotta make sure your valvetrain and valvespring and retainer and guide clearance can handle the extra lift.
Hopefully others chime in!
Exhaust mods?
I have been curious what a big mouth TPI intake manifold base, plus Arizona Speed long tube runners, and 1.6 full roller rockers can result in as far as rwhp gains on a MAF L98 car.
Grind down the drip tabs, keep an eye and ear on clearance, and the roller rockers should be bolt on, plus lash procedure.
Lash procedure is pretty well documented.
What year are you working ongoing?
Full roller rockers or just roller tip?
What heads? You gotta make sure your valvetrain and valvespring and retainer and guide clearance can handle the extra lift.
Hopefully others chime in!
Race Director
Joined: Sep 2003
Posts: 16,836
Likes: 337
From: Database Error Indiana
If you change rockers you will have to adjust the lash. It is easy if you do it when the intake is off. You can see which valves are closed. Rotate the motor and get the timing mark to zero° and do the ones that are closed. Then rotate the motor 1 turn and do the others.
Thread Starter
Intermediate
Joined: Nov 2022
Posts: 34
Likes: 7
From: Buffalo, NY
I haven’t dyno’d it, but it does a 13.4 @ 104 with full exhaust as the only mod.
I will also bring adding TPiS longtube headers along with the intake.
Everything else is stock. I’ve been told by many TPI “experts”, including Jim at TPiS, that as long as I have stock heads and cam, my stock valvetrain parts are sufficient for 1.6 roller rockers.
Well I guess I’ll have to dust off the ‘ol GM service manuals to get the proper procedure. I was hoping I could just unbolt the the old, and install the new seeing as I wasn’t actually going to mess with the springs or valves.
I will also bring adding TPiS longtube headers along with the intake.
Everything else is stock. I’ve been told by many TPI “experts”, including Jim at TPiS, that as long as I have stock heads and cam, my stock valvetrain parts are sufficient for 1.6 roller rockers.
Well I guess I’ll have to dust off the ‘ol GM service manuals to get the proper procedure. I was hoping I could just unbolt the the old, and install the new seeing as I wasn’t actually going to mess with the springs or valves.
Thread Starter
Intermediate
Joined: Nov 2022
Posts: 34
Likes: 7
From: Buffalo, NY
Don't take this wrong. You obviously don't know what is involved; or how to change rockers.
You have to set the lash, pre-load, "adjust", what ever you call it. If you don't have the experience or knowledge of this simple requirement, there are going to be a lot of things you'll be doing for the first time in conjunction with these mods. We have had several recent threads on here where peeps have had difficulty with setting the valve train up after repairs because they hadn't done it before, (or it may have been so long they forgot how to do it?). These guys had significant difficulty with a task that experienced DIY'rs have no trouble with at all.
See if you can recruit a buddy that knows how to do it to help you with the lash. Learn. It is not rocket science to do it correctly, but there are a whole bunch of ways to get it wrong and it will be frustrating in the least, and you'll have broken/bent parts at the worst.
Just an observation.
You have to set the lash, pre-load, "adjust", what ever you call it. If you don't have the experience or knowledge of this simple requirement, there are going to be a lot of things you'll be doing for the first time in conjunction with these mods. We have had several recent threads on here where peeps have had difficulty with setting the valve train up after repairs because they hadn't done it before, (or it may have been so long they forgot how to do it?). These guys had significant difficulty with a task that experienced DIY'rs have no trouble with at all.
See if you can recruit a buddy that knows how to do it to help you with the lash. Learn. It is not rocket science to do it correctly, but there are a whole bunch of ways to get it wrong and it will be frustrating in the least, and you'll have broken/bent parts at the worst.
Just an observation.
While OHC engines still have rocker arms, they’re not just sitting on top with a single nut holding them on.
Instructor
Joined: Dec 2019
Posts: 120
Likes: 35
From: Texas
Derek of Vice Grip Garage has a fantastic video about setting hydraulic valve lash on YouTube. His method is what I used to learn and have done it numerous times with success. It’s extremely easy and almost fool proof.
Thread Starter
Intermediate
Joined: Nov 2022
Posts: 34
Likes: 7
From: Buffalo, NY
Instructor
Joined: Dec 2019
Posts: 120
Likes: 35
From: Texas
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Drifting
Joined: Jan 2021
Posts: 1,312
Likes: 383
From: Northern California
I used that method on mine last year and it worked perfectly.
Melting Slicks
Joined: Aug 2003
Posts: 3,389
Likes: 391
From: Lakeville MI
Don't forget that you will need guideplates and hardened pushrods (if using non self-aligning rocker arms), and maybe even longer studs for a better fit with the poly locks. If replacing the studs, consider going to 7/16" studs unless the rockers that you already have are intended for 3/8" studs.
What rocker arms do you actually have now? Must be a narrow body design to fit centerbolt valve covers.
What rocker arms do you actually have now? Must be a narrow body design to fit centerbolt valve covers.
Thread Starter
Intermediate
Joined: Nov 2022
Posts: 34
Likes: 7
From: Buffalo, NY
Don't forget that you will need guideplates and hardened pushrods (if using non self-aligning rocker arms), and maybe even longer studs for a better fit with the poly locks. If replacing the studs, consider going to 7/16" studs unless the rockers that you already have are intended for 3/8" studs.
What rocker arms do you actually have now? Must be a narrow body design to fit centerbolt valve covers.
What rocker arms do you actually have now? Must be a narrow body design to fit centerbolt valve covers.
Thread Starter
Intermediate
Joined: Nov 2022
Posts: 34
Likes: 7
From: Buffalo, NY
https://youtu.be/XR4W-MWjEyI?si=GZDpZKS0MtI8BAC2
https://youtu.be/YIitbcf0IWA?si=NargLc4ozzSmT6jC
Start the second one around 14:30. Great explanation of what you’re doing and the geometry you’re trying to achieve. He also goes through setting lash again here.
https://youtu.be/YIitbcf0IWA?si=NargLc4ozzSmT6jC
Start the second one around 14:30. Great explanation of what you’re doing and the geometry you’re trying to achieve. He also goes through setting lash again here.