Pushrod length question
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Teching In
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Pushrod length question Hey,
Going to be installing a Comp XER281HR, Pro Magnum 1.75 roller rocker kit, and PRC valve springs on stock 241 heads on an LS1. I'm also getting a set of cm pushrods to go with, they say the rods are 'matched' to the rockers, but I'm thinking can they tell the right length just from a list of components or will I be ordering a new set afterwards? Any experience with this combo? or will the stock length be okay too? The 281 is .595/.598 with 1.7's and .613/.616 with the 1.75's as far as I've read.
Thanks
Going to be installing a Comp XER281HR, Pro Magnum 1.75 roller rocker kit, and PRC valve springs on stock 241 heads on an LS1. I'm also getting a set of cm pushrods to go with, they say the rods are 'matched' to the rockers, but I'm thinking can they tell the right length just from a list of components or will I be ordering a new set afterwards? Any experience with this combo? or will the stock length be okay too? The 281 is .595/.598 with 1.7's and .613/.616 with the 1.75's as far as I've read.
Thanks
Are these stud mounted rockers? If yes, the pushrod length sets both wipe and preload. If no, you need to check wipe then measure for preload as any shimming of a fixed rocker will alter the pushrod length.
Thread Starter
Teching In
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Hey, thanks for the reply.
They are adjustable stud mounted rockers. As far as they tell me the length is changed to compensate for the longer 1.75 rocker ratio. Just my basic thinking, with the rockers being adjustable a few thou isn't that crucial becasue it can be made up in the adjustment... correct?
They are adjustable stud mounted rockers. As far as they tell me the length is changed to compensate for the longer 1.75 rocker ratio. Just my basic thinking, with the rockers being adjustable a few thou isn't that crucial becasue it can be made up in the adjustment... correct?
The measurement for adjustable rockers is not the same. I used stud depth to figure mine out before measuring with the adjustable pushrod. If you are starting from scratch then you first need to find out what rocker height provides the correct wipe pattern. If the heads are on the car you need check springs to do this.
Thread Starter
Teching In
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Thanks for the offer, unfortunately I'm in Canada so the drive's a bit much heh I might pick one up though. My project is starting to cost as much in tools as it is in parts.
Main reason I'm asking about the rod length is to see if this can be done over a weekend with all the parts on hand or should I expect hang-ups like the rods. I'd probably have to special order them. Shops around here don't seem to wanna carry alot of LS stuff for some reason. Now if I wanna build a 5.0 that's a different story... But I wanna go fast.
Main reason I'm asking about the rod length is to see if this can be done over a weekend with all the parts on hand or should I expect hang-ups like the rods. I'd probably have to special order them. Shops around here don't seem to wanna carry alot of LS stuff for some reason. Now if I wanna build a 5.0 that's a different story... But I wanna go fast.
Thread Starter
Teching In
Joined: Oct 2009
Posts: 21
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The measurement for adjustable rockers is not the same. I used stud depth to figure mine out before measuring with the adjustable pushrod. If you are starting from scratch then you first need to find out what rocker height provides the correct wipe pattern. If the heads are on the car you need check springs to do this.
Appologize for my ignorance, it's making me feel like a real noob, but to confirm the 'wipe' pattern is the tip contact to the end of the valve correct? and what are the check springs? I do have the install guide from Comp for the RR's so as long as I follow that I should be fine, eh? I guess my theory of an easy install with a minor adjustment and preload set is out the window thou.
