Thread: Roller rockers

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Having never used rollers before, I plan on using a set of Harland Sharps on my 357, with 462 heads. Is there anything special in the way of pushrods , etc, that I need to be aware of? Obviously I have the option of going 1.5 across the board, or 1.6/1.5. Is there any benefit to this unless its a full out race motor? Thanks, I wanna get this puppy finished so I get the wifes surprise wrapped up. Get yer mind out of the gutter, I mean the engine is for her.

I don't know about those heads you may need guide plates. Hopefuly some one will catch this that knows

you will need guide plates installed into the heads, you can do the drilling but i recommend having a machinist do it since you're never done them before.... also you will need hardened pushrods or else the guide plates will eat right through them..... the 1.6/1.5 setup is good even for a non race motor, the rocker ratio affects cam lift, but it depends on what cam you already are using and what kind of valve clearance you have, if you have a stock to mild cam it can be an easy way to get a little more juice out of the motor, i've never done it myself though so i'd wait on someone with a little more knowledge on it...

Thats great, but if I use 3/8" studs, I wont have to drill, or are the original, pressed in studs? If so that makes sense. On the pushrods, why do they offer the +.100" rods, is that somehing you need to do to correct geometry or something, or can you renain at std. Are the +.100's for the 1.6's and the std for the 1.5's. Told ya this was new to me. Thanks.

I'm no expert on roller rockers, and luckily the two engines I have that have them were done when I got them, but I do know that when you install the guideplates they are secured by screw in studs, and that the heads need machined to accept these. I also remember that it is more than just tapping threads in most cases, you have to have some of the boss machined down to lower it a little. I think the guide plate kit will probably include directions??

As for different length pushrods, I didn't know these existed until I took my newly running 302 in my '27 in to have the exhaust system done. When it was all capped up and quiet, the guys at that shop (who build race engines) said it was not running right. Sounded ok to me, but they really know their stuff. I told them to fix it, so they installed shorter pushrods to correct the geometry and when I picked it up the car did sound much crisper and ran better. Maybe the head surfacing took off material that changed the length needed?

All this finite stuff is way beyond my pay grade, so I leave it to experts, like some of the guys we have on here.

Don

you do not need any guide plates.for 5/16 push rods. but you need to check the heads that the pushrods do not hit in the heads .they have cast slots in the heads somewhat a guid that the push rod runs thru the head. that holds the rocker track . the longer 1.6 will hold it the 3/8push rod at a dif angle then you need to drill out the guids / heads slots out and then you need guid plates and screw in studs the push rods need to be stock for the stock stuff to work that is 5/16 not 3/8 if you go 3/8 you will need much work. you allways should check the pushrod for the right length way to many things can throw this off and you can if they hit at the bottom of the slots with a small stone or bur in a dieginder just take out were it hits do not make it wide or your rocker will not track

Pat: Good info, so you don't always necessarily need guide plates when using roller rockers? I thought it was a matter of keeping them straight, and you needed the guide plates to act as a support.


Don

[quote=Itoldyouso]Pat: Good info, so you don't always necessarily need guide plates when using roller rockers? I thought it was a matter of keeping them straight, and you needed the guide plates to act as a support.[quote] no what would keep the old ones straight? the head has the guid casted in a slot the new gm head have rocker arms with a slot in the rocker that holds it on track and with hp guid plates you must run harden pushrods and this would change if dart or any HO head with screw in studs may need guid plates

Also depends on what type of studs you are using. Do your screw in studs have a nut on them to tighten them with? If so, you are going to have to have the stud bosses machined down to make them all flat and allow for the extra space the nut takes up, usually aroun .100" or something like that??? Maybe someone with a good memory will jump in here and remember that dimension....

Originally Posted by Dave Severson

Also depends on what type of studs you are using. Do your screw in studs have a nut on them to tighten them with? If so, you are going to have to have the stud bosses machined down to make them all flat and allow for the extra space the nut takes up, usually aroun .100" or something like that??? Maybe someone with a good memory will jump in here and remember that dimension....

well it dose not if you want steel guids then yes you need to cut them down if it is a stock head and you want steel guid plates if not stock then you need studs with a shoulder to hold the guid plates down and some guys go to a 7/16 BBC for a better stud and you can get the rockers for the bigger studs i have cut the sbc chevys and olds and Ford and drill them for it is about 125up from the spot face of the head bolt or so for the sbc for plates

[QUOTE=pat mccarthy]well it dose not if you want steel guids then yes you need to cut them down if it is a stock head and you want steel guid plates if not stock then you need studs with a shoulder to hold the guid plates down and some guys go to a 7/16 BBC for a better stud and you can get the rockers for the bigger studs i have cut the sbc chevys and olds and Ford and drill them for it is about 125 from the spot face of the head bolt or so for the sbc for plates[/QUOTE

Thanks for clarifying, Pat. Been about 20 years since I've done any automotive machine operations. Sometimes my memory of it is a bit fuzzy!!! Heck, I think it's a good day now if I remember my name!!!! Good thing the shop is now only 20 steps out the back door or I'd probably get lost on the way to work!!!!

dave do not be so hard on your self hell i will do that for free just kidding you know your my best ford friend come to think of it well ????anyways your one of the few i will talk to

That helps me a ton, but leaves me with one naked question. If I put the full rollers on, are you saying I can use the original studs or do I have to install screw ins? Even without the plate and using 5/16' pushrods. Sorry I hate not knowing this stuff, , "but I'm agettin lerned".

you can use the stock stud and no guid plates but if you go to 1.6 you need to check the push rods they do not bind in the head if so you need to do what i said or go to guid plates drill and tap the heads out the guild holes mill the heads down for the guid plates screw studs

Oh ya! Now I get it. Pat you ARE DA MAN! Thanks everybody.