Roller Rockers--Still Confused
Thread Starter
Instructor
Joined: Jan 2002
Posts: 153
Likes: 0
From: Essex Ont
Roller Rockers--Still Confused
I'm still a little confused on what exactly I would need to upgrade to 1.6's.
I have an '88 IROC L98 (iron heads). Do these have self aligning rockers in stock form?
What exactly would I need to upgrade to full rollers (other than the rockers and valve springs)? I will be replacing valve springs too but don't want to have to machine the heads to fit them.
Thanks
Bob
I have an '88 IROC L98 (iron heads). Do these have self aligning rockers in stock form?
What exactly would I need to upgrade to full rollers (other than the rockers and valve springs)? I will be replacing valve springs too but don't want to have to machine the heads to fit them.
Thanks
Bob
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Re: Roller Rockers--Still Confused (Irocan)
If your car doesn't have guide plates then it has self aligning rockers. You can use either, just remember that if you get normal rockers you HAVE to get guide plates, which will require hardened pushrods.
Other than that springs should just about do it.
Other than that springs should just about do it.
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Do yourself a favor and get non-self aligning rockers. They self-aligning ones eat up horsepower. It might cost you $50 more for some hardened pushrods and hardened guide plates, but it'll be worth it in the end. Even a set of new L98 springs SHOULD be ok with the added lift.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Roller Rockers--Still Confused (Irocan)
Comp Cams now has 1.6:1 ProMagnum full roller rockers in either self-aligning or non self-aligning to fit 3/8" studs. If you want to install 7/16" studs only non self-aligning ProMagnums are available.
Your engine has non hardened guide plates (they don't contact the push rods) with self-aligning rockers.
Either use the self-aligning ProMagnums w/o guide plates or the non self-aligning with hardened guide plates and hardened push rods.
You should replace push rods in either case.
You can use the Comp Cams #981 single spring with damper to give a little more spring rate and it fits the stock seat. Use a shim pack to get the desired installed height and so seat pressure. If you toss the tin oil shedders from atop the stock springs to lighten the valve train you will also need the shims to achieve even stock installed height.
Get a set of OEM lower valve seals and upper O-ring seals from your Chevy dealer.
Use new valve retainers (keepers) to assure you don't drop a valve later. Comp Cams has machined retainers.
Your engine has non hardened guide plates (they don't contact the push rods) with self-aligning rockers.
Either use the self-aligning ProMagnums w/o guide plates or the non self-aligning with hardened guide plates and hardened push rods.
You should replace push rods in either case.
You can use the Comp Cams #981 single spring with damper to give a little more spring rate and it fits the stock seat. Use a shim pack to get the desired installed height and so seat pressure. If you toss the tin oil shedders from atop the stock springs to lighten the valve train you will also need the shims to achieve even stock installed height.
Get a set of OEM lower valve seals and upper O-ring seals from your Chevy dealer.
Use new valve retainers (keepers) to assure you don't drop a valve later. Comp Cams has machined retainers.
Burning Brakes
Joined: Nov 2001
Posts: 812
Likes: 1
From: Sherman Texas
Re: Roller Rockers--Still Confused (Irocan)
You might have to slot the pushrod holes to use 1.6 rockers. I am not sure, but some iron GM heads have a problem with the pushrod hitting the casting when using 1.6 rockers. Check with a local shop, or call Summit Racing, they're techs might be able to tell ya. :cheers:
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Roller Rockers--Still Confused (thmupr)
The #113 Al castings won't have to be slotted.
However a little surgery is required inside the valve covers:
1) reduce/remove the drip tabs
2) narrow the bolt posts.
However a little surgery is required inside the valve covers:
1) reduce/remove the drip tabs
2) narrow the bolt posts.
Drifting
Joined: Mar 2001
Posts: 1,636
Likes: 3
From: Lafayette IN
Re: Roller Rockers--Still Confused (Nathan Plemons)
If your car doesn't have guide plates then it has self aligning rockers.
Cast iron heads in the early days used a "guide" that was machined into the head itself. It was a slot that would guide the pushrod. The factory setup with this style did not use self-aligning rocker arms.
Then Chevy started making some cast iron heads with a hole instead of a slot. These generally used guideplates and non-self aligning rockers.
When they came out with aluminum heads, they started using various combos of non-hardened guideplates and self-aligning rockers.
Good luck, -Matt-
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Thread Starter
Instructor
Joined: Jan 2002
Posts: 153
Likes: 0
From: Essex Ont
Re: Roller Rockers--Still Confused (Nathan Plemons)
I'm starting to get a clearer picture now.
What is the lift of the stock cam? Do you guys think this is a worthwhile mod? I have a superram base, AS&M LTR's and ported plenum as well. Edelbrock headers and Flowmaster exhaust.
I will not be able to get into heads and cam swap for quite a while (read a couple of years). I really need to get it painted this year.
If I can drop et's by a tenth or two I'd be happy for now.
Bob
What is the lift of the stock cam? Do you guys think this is a worthwhile mod? I have a superram base, AS&M LTR's and ported plenum as well. Edelbrock headers and Flowmaster exhaust.
I will not be able to get into heads and cam swap for quite a while (read a couple of years). I really need to get it painted this year.
If I can drop et's by a tenth or two I'd be happy for now.
Bob