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Adjustable Rockers

1K views 11 replies 5 participants last post by  Grusome Goat 
#1 ·
As of now, I'm running a set of cast 16 heads on my Pontiac. I'm running the stamped steel rockers still, which isn't a big problem (I don't have an incredible high light cam or any off the wall ramp rates to worry about). However, I am also using the 3/8" inch, screw-in non adjustable stud/nut combination. I'd like to be able to set my valves rather than just torque them to 20 ft-lbs, and was wondering what was required. Is it simply an adjustable type poly-lock, or do I need to change studs too? Thanks for the help.
 
#4 ·
The heads you have are the small valve small chamber and to convert to screw in studs you will have to have this work performed by a machine shop or a competent head shop. I ran a pair of heads like yours for years and started having problems with the pressed in studs pulling out after alot of severe high rpm use. My suggestion would be to try find some better heads with the screw in studs and with big valves.
 
#5 ·
Grusome Goat said:
The heads you have are the small valve small chamber and to convert to screw in studs you will have to have this work performed by a machine shop or a competent head shop. I ran a pair of heads like yours for years and started having problems with the pressed in studs pulling out after alot of severe high rpm use. My suggestion would be to try find some better heads with the screw in studs and with big valves.
Small valve heads? These heads are the small chamber (72 cc) heads with the LARGE 2.11/1.77 valve. They already have screw in studs, and all I am wanting to do is to make the heads, by either using the current studs or replacing them, have an adjustable valve train.
So, Machine Shop Tom, I searched Crane's site quickly, and couldn't come up with that part number. I'll look more a little later, but what I understand is that these are adjusting nuts that will fit my current studs? Just need some clarification?
 
#7 ·
My mistake I misread. I would recommend changing to ARP rocker studs and going with some better rockers (if you can afford it) i.e. Comp Magnum roller tips and polylocks. This will give you a fully adjustable valve train and the rocker ratios are more accurate. This is the setup I currently have on the 670's that I have on my 400 and find it more reliable than the stock setup.
 
#9 ·
Okay, well now, in lieu of getting new rocker arms, which I'd been cosidering, and assuming I've got valve cover clearance, would it be smart to look at a higher ratio rocker? I'm running Crane's blueprint "068" cam, with .408/.411 lift-not much obviously. I wasn't sure how much, if any, advantage I'd have with running a higher ratio rocker and thought maybe you'd provide some input as well.
 
#10 ·
If you go to change to a 1.65 ratio rocker you're going to have to pull the heads and have the pushrod holes elongagated for the pushrods to dome through right and not rub. Of course the 1.65 will increase your lift and at times may increase duration by a couple of degrees. Your lift will be right .458 on the intake with the 1.65's but the 068 is a really good street cam overall. If you go with roller rockers Harland Sharps are about the best you can get for a Pontiac and if you want to ratain your present valve covers you can double gasket to give a little more height. I'm presently using M/T's on my GTO and have not clearance problems with my polylocks with single gaskets and the Comp Magnum roller tips are some pretty heavy duty rockers. Also one more thing when you go to increasing valve lift is your springs, you'll have to check to make sure your not getting coil bind which is common with stock springs and higher lift. Goat
 
#11 ·
Okay, well, I guess I'll keep a higher ratio rocker in mind, but I don't want to pull the heads right now, so forget that. I'm running an old set of M/T valve covers now, so I guess I'd be safe with it huh? I guess I'll look at just a set of 1.5 ratio roller tip rockers, and hopefully be done with it. Thanks
 
#12 ·
Yes your M/T's will clear as tht is what I'm using on my GTO and have had no problems whatsoever. The Comp roller tips are a true 1.52 ratio and aren't as much as the full rollers. You can also get roller rockers in 1.52's as Harland Sharp makes them and in my opinion are the best on the market. Whatever you decide to go with change the rocker studs. Either way you go use ARP rocker studs with the 7/16 tops as that is what is recommended for Comp and Harland Sharp. Make sure every thing is clean and use a good threadlocker when you install the studs and use either the Crane Kool nuts or Mr Gasket polylocks and you will then have fully adjustable valve train tha twill net you a few more horses and add reliablity to you valve system.
 
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