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some manufacturers of the roller rocker recommend them. I thought I could get away without using them since the HiPo heads have guide slots in them instead of the usual round holes. But I was wrong and had a push rod & rocker damaged when they lost contact with each other at 6000 rpm. Guide plates were then installed, and no more drama over the past seven years. Just be sure your pushrods are of the hardened variety.

Z. Ray
 

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bnichols04 said:
is it necessary to install a push rod guide plate when converting to roller rockers?
That depends on the type of rocker system you have now. If you have a vintage engine/head combo using pressed in studs or a non-adjustable shouldered stud then the only option for roller rockers is to get the heads machined for screw in studs, and yes guide plates are required.

If you have newer heads with a pedastal style rocker system, there are bolt on roller rockers available from the aftermarket that will replace the stock stamped rockers and no guide plates are needed, however that still limits the rocker system to the stock non-adjustable pedastal mounting which may require shims for proper rocker geometry if you change cams. If you want to convert this type of head to an adjustable rocker system then machining for screw in studs and guide plates are necessary.
 

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if you are going to have to, or want to, replace the pressed in studs with the screw in type, be sure to go with the 7/16" studs & rockers. They are considerably stronger than the 3/8" variety & the 7/16" rocker arms won't cost any more than the 3/8" ones.

Z. Ray
 

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Discussion Starter #5
i have the newer style head with bolt in rockers. i was just wondering because i have a set of roller rockers laying around the house and i wanted to put them to use. i didn't know you had to shim the rockers i thought they were adjustable from the allen screw in the middle of the nut on top of the rocker? how do i know if my push rods are hardened or not?
 

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Pedestal mount rockers normally just have a bolt going thru the trunion to hold them down. If you have an allen set screw inside an adjusting nut to hold the rocker at the trunion (the rockers pivot shaft) then you have a stud mounted rocker, not a pedestal. Also, even if you have pedestals, you can't just bolt on any old set of rockers you happen to have laying around (and are you certain the rollers you have laying around are for the SBF?). The aftermarket rollers made for pedestal heads come with special hardware to fit those applications, specifically a sled and fulcrum that supports the rocker at the trunion. If you want to use a stud type, adjustable rocker (whether roller or not) on a pedestal head you have to buy a conversion kit from Crane (basically a stepped stud with threads small enough to fit the screw hole in the pedestal) or get the heads machined. Pedestal rollers won't fit on normal studs because the hole for the through bolt is made for a 5/16" bolt, not a 3/8" or 7/16" stud.

There is a rocker that has an adjusting nut with set screw over the pushrod cup (actually the screw is the adjusting part and the nut locks it in place). I have seen these on high end shaft type rockers like is used on the FE motors (a single pivot shaft spanning the length of the head that holds all 8 rockers for that head). I also seem to recall seeing rockers like this for the 302 pedestal heads as part of a shaft style rocker conversion meant for extreme high rpm use (meaning mega $$) but I don't remember seeing one like this for the small block pedestal heads outside of the shaft style conversion. That doesn't mean they don't exist, I just haven't seen them.

On the pushrods, AFAIK there isn't a fool proof way to ID hardened pushrods (unless the mfg has it stamped on the side of the pushrod with the part number) but the safe bet is that unless your heads have guide plates on them already chances are that the pushrods are not hardened.
 

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Discussion Starter #7
thanks for the great info. the allen screw i was talking about was in the box with the new roller rockers. should i just replace my push rods with the same length ones that come out that are not hardened? or do i need longer ones with the 1.6 roller rockers that i have here. they are new roller rockers from crane cams that have been in the box never opened just sitting in a corner for a while.
 

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If there are no other changes from stock except for the roller rockers, then the same length pushrods should work. However, if the change to rollers involves machine work to install screw in studs and guide plates then it would be best to measure the needed pushrod length with a length checking tool. They are available for less than $15, so it's cheap insurance to make sure you get the correct length.
 

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I believe it depends on whether or not they are rail or non-rail roller rockers. Most are non rail which require push rod guide plates.
 
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