Which pushrods to use
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Teching In
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Which pushrods to use Hi,
here is my plan for some more power
CheaTR cam
Yealla Terra 1.7 ratio rockers (1.8 not recommended by Thunder)
PP Gold dual springs
Now the question is which lenght rods to use ?
I have read that the stock lenght will be noicy so I'm also trying to minimize that (that's why I chose the new rockers).
I already have LS6 intake, G2 lig etc. bolt ons.
The car is 98 Z w/T56, 38k miles
here is my plan for some more power
CheaTR cam
Yealla Terra 1.7 ratio rockers (1.8 not recommended by Thunder)
PP Gold dual springs
Now the question is which lenght rods to use ?
I have read that the stock lenght will be noicy so I'm also trying to minimize that (that's why I chose the new rockers).
I already have LS6 intake, G2 lig etc. bolt ons.
The car is 98 Z w/T56, 38k miles
Thread Starter
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Originally Posted by PREDATOR-Z
Order the Crane 1.7, they come with p-rods and you'll benefit from added power below the curve. (variable lift)
Wouldn't Yella, or any other roller rocker (Comp, Harland etc.), do the same though.
How about the noise then. Crane specially advertize the quietness of the rockers but I can't see why the rest of them wouldn't do the same for less money ?
These are probably very stupid questions but I'll ask anyways
TECH Senior Member
Joined: Mar 2004
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From: BFE
Crane has variable lift rockers. Different design.
This is literature on the rockers and what they do:
VHP new “ACCELERATED LIFT” rocker arm geometry has opened the door to a new area of valve train development and cam lobe design that is producing impressive results. The “ACCELERATED LIFT” geometry is not magic; it is simply a new design of the rocker arm body that locates the pushrod seat low in the body with respect to the center of rotation about the shaft. Because the pushrod seat area travels in an arc as the lifter/pushrod moves upward during the lift event, the pushrod seat moves slightly away from the center of rotation around the shaft. This movement of the seat through its operating arc causes the effective rocker arm ratio to decrease. The end effect is this: a 1.6 ratio “ACCELERATED LIFT” rocker arm actually starts opening the valve at a ratio of 1.7. As the valve opens, the rocker ratio decreases to the 1.6 advertised ratio (this occurs at about .250” - .300” valve lift) and then maintains the 1.6 ratio through the rest of the lift cycle until it starts back on the seat. It goes back on the seat at a 1.7 ratio. This new geometry provides increased airflow earlier in the lift cycle and maintains it longer into the closing event. More flow equals more power! There are additional benefits. The “ACCELERATED LIFT” design applied to computer managed engines means that short seat-to-seat timing can be maintained to provide high vacuum at idle and low speed, but duration at .100”, .200” etc. is equal to camshafts having .050 durations 8 to 10 degrees bigger. This means great power increases and ease of tuning the engine management system. “ACCELERATED LIFT” geometry is the future for pushrod engines and VHP has it for you today!
VHP has also designed new camshaft lobes to maximize the advantage of these rockers. The new “ACCELERATED LIFT” lobes are being used in all of our new racing profiles, as well as our new LS1 family of cams for GM cars and trucks. Performance enthusiasts have known for over 25 years that the best lobe design to maximize “area under the lift curve” is the “inverted flank roller lobe:” However, the “inverted flank design” creates several manufacturing headaches which cause the price of these designs to be quite high. VHP'S new “ACCELERATED LIFT” Rocker body design and new complementary “ACCELERATED LIFT” cam lobe designs have produced a valve lift profile that exceeds the power potential of the “inverted flank” designs. These new profiles are available on all of the latest LS1 cams, including the “Truck Power” cams and many of the new racing cams. Most of our future pushrod camshaft designs will incorporate the “ACCELERATED LIFT” technology.
This is literature on the rockers and what they do:
VHP new “ACCELERATED LIFT” rocker arm geometry has opened the door to a new area of valve train development and cam lobe design that is producing impressive results. The “ACCELERATED LIFT” geometry is not magic; it is simply a new design of the rocker arm body that locates the pushrod seat low in the body with respect to the center of rotation about the shaft. Because the pushrod seat area travels in an arc as the lifter/pushrod moves upward during the lift event, the pushrod seat moves slightly away from the center of rotation around the shaft. This movement of the seat through its operating arc causes the effective rocker arm ratio to decrease. The end effect is this: a 1.6 ratio “ACCELERATED LIFT” rocker arm actually starts opening the valve at a ratio of 1.7. As the valve opens, the rocker ratio decreases to the 1.6 advertised ratio (this occurs at about .250” - .300” valve lift) and then maintains the 1.6 ratio through the rest of the lift cycle until it starts back on the seat. It goes back on the seat at a 1.7 ratio. This new geometry provides increased airflow earlier in the lift cycle and maintains it longer into the closing event. More flow equals more power! There are additional benefits. The “ACCELERATED LIFT” design applied to computer managed engines means that short seat-to-seat timing can be maintained to provide high vacuum at idle and low speed, but duration at .100”, .200” etc. is equal to camshafts having .050 durations 8 to 10 degrees bigger. This means great power increases and ease of tuning the engine management system. “ACCELERATED LIFT” geometry is the future for pushrod engines and VHP has it for you today!
VHP has also designed new camshaft lobes to maximize the advantage of these rockers. The new “ACCELERATED LIFT” lobes are being used in all of our new racing profiles, as well as our new LS1 family of cams for GM cars and trucks. Performance enthusiasts have known for over 25 years that the best lobe design to maximize “area under the lift curve” is the “inverted flank roller lobe:” However, the “inverted flank design” creates several manufacturing headaches which cause the price of these designs to be quite high. VHP'S new “ACCELERATED LIFT” Rocker body design and new complementary “ACCELERATED LIFT” cam lobe designs have produced a valve lift profile that exceeds the power potential of the “inverted flank” designs. These new profiles are available on all of the latest LS1 cams, including the “Truck Power” cams and many of the new racing cams. Most of our future pushrod camshaft designs will incorporate the “ACCELERATED LIFT” technology.
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Will these clear the valvecovers ?
based on this thread https://ls1tech.com/forums/generation-iii-internal-engine/447463-1998-ls1-roller-rockers.html
some of the rockers do not clear the valve covers.
I'm just wondering, will I get in trouble with these ?
based on this thread https://ls1tech.com/forums/generation-iii-internal-engine/447463-1998-ls1-roller-rockers.html
some of the rockers do not clear the valve covers.
I'm just wondering, will I get in trouble with these ?
They will clear the center bolt valve covers without modification. I am currently running the Crane 1.8's on my car but will likely install their 1.7's with the Dart heads I am preparing 
