NEWB pushrod rocker and valvespring ?s
02-25-2009, 06:18 PM
#1
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NEWB pushrod rocker and valvespring ?s i MIGHT be having to replace the above so i have a few questions.
1. what are the numbers 1.5-1.8 when describing roller rockers talking about?2. about the above numbers-which produces the most power and would i have to get a tune for them?
3. if i have to shim up the rockers, doesnt that mean that i should wait to order pushrods till i mount the rockers?
1. what are the numbers 1.5-1.8 when describing roller rockers talking about?2. about the above numbers-which produces the most power and would i have to get a tune for them?
3. if i have to shim up the rockers, doesnt that mean that i should wait to order pushrods till i mount the rockers?
02-25-2009, 07:08 PM
#2
See below.
i MIGHT be having to replace the above so i have a few questions.
1. what are the numbers 1.5-1.8 when describing roller rockers talking about?
That is the rocker ratio. For example, with a 1.5 ratio if the cam lift at peak is 0.300", then the valve lift is 1.5 X 0.300" = 0.450" of valve lift. LS1's come from the factory with a 1.7 rocker ratio.
2. about the above numbers-which produces the most power and would i have to get a tune for them?
There have been some who have seen an marginal increase going to 1.8 rockers, but there are trade-off's to this. If you never plan to install a cam, it might be worthy of further investigation.
3. if i have to shim up the rockers, doesnt that mean that i should wait to order pushrods till i mount the rockers?
Depends on the rockers. Crane rockers are fully adjustable so the pushrod determines both lifter preload and geometry (along with the adjustment procedure). Fixed fulcrum rockers such as Yella Terra and stock, the pushrod determines only lifter preload. Shimming is used in the fixed fulcrum rocker setup to determine correct geometry or wipe pattern.
1. what are the numbers 1.5-1.8 when describing roller rockers talking about?
That is the rocker ratio. For example, with a 1.5 ratio if the cam lift at peak is 0.300", then the valve lift is 1.5 X 0.300" = 0.450" of valve lift. LS1's come from the factory with a 1.7 rocker ratio.
2. about the above numbers-which produces the most power and would i have to get a tune for them?
There have been some who have seen an marginal increase going to 1.8 rockers, but there are trade-off's to this. If you never plan to install a cam, it might be worthy of further investigation.
3. if i have to shim up the rockers, doesnt that mean that i should wait to order pushrods till i mount the rockers?
Depends on the rockers. Crane rockers are fully adjustable so the pushrod determines both lifter preload and geometry (along with the adjustment procedure). Fixed fulcrum rockers such as Yella Terra and stock, the pushrod determines only lifter preload. Shimming is used in the fixed fulcrum rocker setup to determine correct geometry or wipe pattern.