Vortec rocker question

[Don W.]

My, new-to-me, Vortecs have what I would call pedestal mount rockers which I guess some call shaft mount rockers, mine even have roller bearings. Anyway, with a bit of searching it seems these are non adjustable which means when I assemble the engine I need to check pushrod length to make sure the lifters have the correct preload. Something I would do anyway but am I on the right track here or is more I should know?

Thanks

 

[dgoodhue]

Re: Vortec rocker question

Yes you are right on.

 

[Don W.]

Re: Vortec rocker question

Thanks !

 

[Windedv6]

Re: Vortec rocker question

Don

This is the setup I had been running for for the last several years. Depending on what lifters you are using it's easy to get the preload correct. I used the Crane lifters (11532-12 for the bowtie block and 10530-12 for the stock block) and they recommend .030 -.060 preload on the cup. I used .040 for my motor. For Comp 850lifers use .030. Do not use the Comp "R" as they are for high rpm race application and only use .0002 - .0004 preload. People tend to over perload these lifters cause unwant problems.

Just get an adjustable push rod, leave it lose on the number one cylinder (TDC) intake. Comp has an adjustable pushrod (pn#7702) that adjusts from 6.8" to 7.8". Be sure to get one that is not to long or you will not have any ajustment to play with. With the pushrod remaining loose, torque the rocker bolt to 26 foot lbs. Then adjust the pushrod until it just touches and you feel it sightly snug but not depressing the lifter cup. Take out he adjustable pushrod and measure the length. Add .040 to that length for the correct pushrod to get. Depending on your deck height and head gasket thickness the new length may not come out to a stock shelf size so round the length up or down to the next stock shelf size. The rule of thumb is on high rpm motors round down and on lower rpm motors round up.

Use this same length for all your pushrods and you are good to go. You don't need to do any other cylinders or valves as all the puch rods need to be the same length. What I always liked about these rockers is that you never have to adjust them again even if you have to replace head gaskets or wanted to retorque your heads. You just need to torque the rocker bolts back to spec.

John

 

[Don W.]

Re: Vortec rocker question

John,

Thanks for the note and the heads up on the lifters.

Since the heads will be trued and the block -0- decked I didn't figure the stock length was gonna work anyway. Although I didn't mention it originally I'll be making a "solid" lifter out of two of my original lifters to check valve to piston clearance as well.