Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Question About A 350 Roller Setup
View Single Post
  #19 (permalink)  
Old 11-30-2012, 04:29 PM
cobalt327's Avatar
cobalt327 cobalt327 is offline
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 60
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 598 Times in 547 Posts
Quote:
Originally Posted by ChevroletSS View Post
Ok can you explain rocker arms to me? What is 1.5, 1.6, 1.7 rockers and what are the differences. Are there others??? I am ging to post another thread on this to so others can comment
From here:

The rocker arm is a fulcrum. Its job is to turn the cam lobe's circular rotation into an up and down movement. This is able to be done because the rocker has a pivot point or fulcrum that allows the cam lobe to open the valve.

The rocker arm's pivot point is not in the center of the rocker; instead it is offset more towards the pushrod. The amount of offset is expressed as a ratio (1.5, 1.6, 1.7, etc.)

The stock small-block Chevy rocker arm has a 1.5:1 ratio. These rockers are called 1.5 ratio rockers or just 1.5 rockers for short. This means that the rocker arm tip at the valve end of the rocker moves 1.5 times the amount of movement seen at the pushrod end of the rocker- which is also the same amount as the camshaft's lobe lift.

Let's say your camshaft has 0.350" lobe lift. With a 1.5 rocker, the cam's lobe lift becomes 0.525" lift at the valve (0.350 x 1.5 = 0.525).

The same 0.350" cam lobe using 1.6 rockers would give you 0.560" lift (0.350 x 1.6 = 0.560), w/o having to remove and replace the cam. With the Chevy factory hydraulic roller cam and lifter set up, this will give you more lift before running into problems w/the dogbone retainers losing contact w/the stock lifters.

Changing the rocker ratio will also change the off-the-seat duration seen at the valve a small amount. However, seat-to-seat duration will not change.

Last edited by cobalt327; 11-30-2012 at 04:40 PM. Reason: Add link.
Reply With Quote