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Discussion Starter · #1 ·
I am considering putting in 1.6 roller rockers on a 355 sbc. It presently has stamped 1.5 rockers. My lift is .454 @ .050 so this will up my lift to about .484, Duration is 216 @ .050. I believe this has a little effect on duration as well. Will this increase hurt lower torque of the motor and if so by how much? I have a heavy 4 speed manual car so I need the low end torque. It is about 3600lbs.
 

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1.6 rockers

I would advise not to install the higher ratio rockers. Small block chevy heads will flow just as much air at low rpms with the factory rockers as they will with the higher ratio rockers. If you were to install the new rockers, it would have a negligible effect on torque. The higher lift is only necessary at high rpms because the time the valve stays open becomes so short. Also, changing to a higher ratio rocker arm will put more stress on your lifters, and it will change your valvetrain geometry for the worse. Chevy used 1.5 ratio rockers on the small blocks for a reason. If you were to build a high revving small block for a light car, I would encourage the higher lift, and higher ratio rockers, but not for a heavy car where torque is more desirable. You can save yourself the money and the headache by just running the factory rockers. You already have excellent lift and duration for a torquey motor.
 

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Higher ratio's will always help short of the point where heads give up flow.

Spring and retainer clearnace is common, so is needing longer pushrods, No lifter problems I've ever encountered.
 

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Are your stamped rockers stock that are on it right now?? If so they probably have less than a 1.5 ratio. You may be better on buying a full roller rocker with a true 1.5 ratio or the roller tipped ones with a 1.52 ratio.
 

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Rockers do not change the duration since all duration figures are given as per lobe/lifter lift, which does not see the rocker/valve.

1.6 rockers will lift the valve 6.66% higher at every "off-the-seat" point, which will allow more volume into the cylinder sooner, therefore more power across the board. Area under the curve.

Because camshaft ramp steepness and total lift is limited by the lifter type, increased rocker ratio is the only way to get more lift.

1.6 rockers are a fine idea. With the lift you will have, roller tip rockers are not necessary, but always desireable.
 

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What are you running for heads? You have to be careful and check to make sure the push rod won't contact the head where it passes through the push rod hole when using 1.6 rockers. It is possible that you may have to elongate the push rod holes.
 

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I agree with Xntrik...

Most head flow curves increase up to a certain lift point, then level off, and then start falling off slightly. The sooner you get the valve open, the sooner you get it to the peak flow point and the more time it spends "over the hump" of peak flow. The average time the valve spends at or around the peak flow point is increased and there are few or no drawbacks to the upgrade. Rest assured that it rarely hurts power.
 

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Discussion Starter · #10 ·
great help everyone thanks. A mechanic I know did mention he would have to check to make sure the pushrods did not hit the holes as well. I have the older trickflow aluminum heads. The machinist who replaced my springs last spring said the springs were good for .500 lift. Might I still have the issue with push rods hitting if I do go to the 1.6 roller or roller tip. Still considering the 1.5 rollers or roller tips as well.
 

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Trick Flows should have no problem with 1.6 rockers. This is a common upgrade that they planned for.

Your lift is fine for your springs. Most people reuse their old springs with no problems.
 
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