Jump to content
Forums Gone... but not forgotten!
Pontiac of the Month

Keane165's 1970 LeMans

2022 June
of the Month

  • Welcome!

    Welcome to Forever Pontiac, where we keep the memory of Pontiac alive with great discussion, maintenance tips, restoration/modification progression "blogs" and help from professional & DIY mechanics. Also, wonderful competitions that occur regularly. Please register for an absolutely free account to join in!

1,6 rocker arms

Recommended Posts

does anyone know if you can change the rocker arm ratio from 1.5 to 1.6 on a basically stock 69 400 to increase the lift.  I have done this on chevrolet motors in the past but am new to the pontiac motors and don't know how well this works. thanks in advance

Link to comment
Share on other sites

Tired of these Ads? Register Today!

Here are a couple of articles on this very subject. Rocky Rotella and Jin Hand are established Pontiac enthusiasts and writers. 



Link to comment
Share on other sites

  • 3 months later...

It all depends on the clearance you have at the valves. All Pontiacs have around .420 lift and most have non adjustable valve trains except on RA2 & 4 & 455SD engines. While they will physically fit on the engine rocker stud, Pontiac did a few things to ensure their 400 RA4 engines didnt blow up with 1.6 rockers. The push rod holes typically need to be enlarged to ensure the pushrod doesn't contact the head. And adjustable rocker studs are will be necessary so you can lash the valves. The factory valve springs will bind if not replaced, and the taller springs need their location milled to accept tall springs to prevent binding.  Other than that its a go. 1.6 are hard on pushrods, many replace theirs with better ones. The best working fix is a cam with more lift ground into the cam, and then use 1.5 rockers for reliability.  1.6 rockers will add about 3 degrees of duration and around .040 " lift to a stock cam. Dropping them on a stock motor will very likely result in a broken valve springs, bent pushrods, and a walk home...

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Tired of these Ads? Purchase Enhanced Membership today to remove them!
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.