1.6 rockers please explain.

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Kevin D.

Kevin D.

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Could someone explain 1.6 rockers.What they do.How they change valve geometry.Also what it takes to run them,Thanks Kevin.
 
Kevin D. said:
Could someone explain 1.6 rockers.What they do.How they change valve geometry.Also what it takes to run them,Thanks Kevin.
Click to expand...

the rocker arm pivots on the shaft....from the center of that shaft..the valve side is 1.5 time longer then the pushrod side...

with 1.6 rocker...the valve side does get longer since the rocker has to be over the valve stem..so the push rod side is shortened to create the 1.6 ratio...

if you have .500 lift cam with 1.5...you can actual cam lift at the lobe of .333

if you change to a 1.6 rocker...you take the .333 x 1.6 = .533...so in effect you have gain about .033 lift at the valve .....

the cam will open quicker with the 1.6 rockers...and you will have a net gain in lift...

problems...make sure you valve spring can handle the additional lift...make sure your retainers do not hit the top of the guide with the additional lift..

sometime the pushrod will rub on the pushrod tunnel in the head since the adjuster on the rocker is moved closer to the center of the shaft.....you need to check for clearance there also...
 
only thing i can add to that is make sure the valves dont hit the pistons and the retainers dont hit the rockers...

think that covers it...
 
Tony covered it real well but I'll ad a couple things. Running 1.6 rockers should have no effect on valve train geometry. When talking geometery you are referring to how the scrub pad or roller on the rocker arm (depending on the style of rocker arm) is centered over the valve stem. As Tony pointed out 1.6 rockers don't change that part, they only move the pushrod in toward the rocker arm fulcrum to increase the lift ratio. They are generally a direct bolt on but as it was already pointed out you need to make sure you have the clearances to run them.
 
Good topic, I would guess there are increased pressures on the cam, lifter, and push rod since you are moving the push rod towards the pivot point of the rocker with the 1.6's. Any adjustments as far as valve spring pressures required?

Is the 1.7 the same principal just a little more extreme?
 
yes, the force to open the valve will increase, and so the load on the related parts (pushrod, lifter, cam, rocker arm, shaft).

1.7`s are the same principle.

Michael
 
440outlawdart said:
say my 683 camshaft would turn into what lift with those
Click to expand...

What engine? If it's a small block with a 683 lift cam you don't have that much at the valve anyway because of the losses due to the complex angles of the lifter to the pushrod to the rocker arm. 1.6 rockers will possibly get your lift up to the .683 rating. Big blocks don't have that issue so a .683 lift will change to .728. Like Tony said in the 2nd post all you have to do is first divide what lift you have now by 1.5 and that gives you your cam lobe lift then multiply it by 1.6 (new rocker arm ratio). It's basic math

.683 divided by 1.5 (rocker arm ratio) = .455 cam lobe lift

.455 cam lobe lift times the new rocker arm ratio of 1.6 = .728 lift

You also gain a little duration. Approx. 2-3 degrees at .050"
 
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