1.6 vs 1.7 rocker arms
#1
1.6 vs 1.7 rocker arms
On an Olds 455 does changing the rocker arm geometry from 1.6 to 1.7 cause and negative effects on the valvetrain?
The advantage of a 1.7 would be higher lift on a cam vs 1.6 which would have a lower lift.
The advantage of a 1.7 would be higher lift on a cam vs 1.6 which would have a lower lift.
#3
A 1.7 ratio basically makes the cam act more aggressively in all aspects than a 1.6 ratio. You gain both lift and effective duration. It doesn't have any more negative effect than having a cam ground with the additional lift and slightly more aggressive lobes.
#4
I did it on an under cammed Olds 350. I went from 1.6 Comp roller tips to 1.72 Scorpion SBF full roller rockers. They were quieter under the aluminum valve covers. The motor was still tempermental on 91 octane. I plan on trying them with the iron heads on my current build,will see how the geometry looks.
#7
You're definitely going to want to check pushrod to head clearance... to increase the ratio, the pushrod cup moves closer to the pivot. Not a big deal to clearance when the heads are off the car, but not something you really want to do with it in the car. I tried a Harland Sharp 1.7 many years ago as a sample piece (motor together in car) and decided against it since I would have to perform clearancing.
#8
On my Edelbrocks, to go froma 1.6 to a 1.7 rocker the pushrod holes had to be elongated on the top and bottom of the holes. Like Luke said, the pushrod cup location in the rocker arm moves and you may have to make room.
#9
Just make sure when you buy, you get the rockers, pedestals, bolts, and slotted mounts.
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