Anyone here installed roller rockers with guide plates?

[wlee]

I'm in the process of installing new black moly roller rockers with screw in studs and push rod guide plates. I've had the studs pulled and the stud bosses tapped and am using the black moly push rods that came with the rockers.

My problem is - the push rods appear to be too short for this set-up, although they measure the same as stock rods. Does the nut on the screw-in studs combined with the guide plate require a longer push rod, or does the stud boss need to be milled?

Is there an easy solution?

Thanks! Lee

[mikep]

Uh Oh ... I hate to be the bearer of bad news but you have to mill off the top of the bosses that the studs mount into. Its best to do this before they are tapped as you get a better registration with the cutter. Crane sells a cutter made to do just that that drops into the hole left by the departed pressed in stud . Its not the end of the world. You can do it or have it done on a mill. you need to have the base of the threads in the same position relative to the gasket surface that the were before. You dont have to take a hell of a lot off but each stud boss has to be the same heighth so your pushrods dont bind in the guide plates.

[bigjimzlll]

there may be hope...Mike is right, but they do make a boss less screw in stud that dosent rquire milling the head....you cant use guide plates though

[wlee]

OUCH - Thanks for the reply . . . I think.

I read that the boss needs to be milled 0.30 for the screw-in stud - that doesn't seem like much to mill, and I wonder if that small of a milling will really fix my problem. The guide plates are pretty thick and I'm not married to them. Will leaving the guide plates off give me the extra stud length needed for the adjustment?

[bigjimzlll]

I dont think so... .30 is a mile in engine speak...almost a 1/3 of an inch...my machine shop wanted a 100.00 to do my bosses...I still think thats too much..I couldnt find the part number for the bossless studs...they would work if you can find them

[dmec]

if you use bossless studs you dont have to mill the heads, and you dont use guideplates. you also dont need hardened push rods.

[mikep]

I hate to ask but how did you keep the tap straight? It would be nearly impossible to tap the holes straight unless you had a tapping jig or even had the heads mounted in a good drill press. I only ask because a few thousandths ( which would be really easy to do by unassisted hand tapping and difficult to see with the naked eye ) off at the top of the studs will put your pushrods at a bad angle and will cause wear on the pushrod guide slots and eventual binding or wear and failure of the pushrods. Crane makes a reasonably priced tapping fixture designed to prevent just that. I hope you used one.

[Mike C]

You can buy a tap jig from Proform to pull the press in studs and keep the tap square. Be forewarned that if you use guide plates you have to drill out the cylinder head where the cast iron is used to guide the pushrod in the heads with press in studs. You could drill out the head and use the flangless studs and "upgrade" to self-aligning rockers. I have a set of heads on my Jimmy where some whack failed to get one of the studs in straight. I run Comp Magnum roller tips and put a lash cap along with a .100 long pushrod on that valve to keep the roller tip on the valve. I bought the heads tapped but without studs, had them rebuilt and only discovered after I was A$$ deep into the project... It has over 50k miles on it now, but I'm not sure what kind of damage has been done to the rocker stud by the side of the rocker...

[wlee]

Well, my problems have been solved . . . thanks for the info to all you who replied.

First, the old studs are pretty easy to pull - just stack nuts & washers on the stud and run the rocker nut down until the stud pops out. That was the easy part. A machinish buddy of mine had a neat little tool that fit in the adjoining boss & kept the tap square - sounds like the tool Mike C referred to.

I ended up at my local machine shop this morning and fortunately I do enough business there that they pretty much dropped everything they were working on to mill my bosses for me - well, that and the fact that they just got a new carbide cutter specifically for this job and hadn't gotten to use it yet. All three guys that work there came over & watched the process - pretty exciting for the little shop It took 2 hours & cost me $40 . . . not too bad for a rush job.

The engine is done and everything works great - no binding on any push rods, so I doubt I'll have any problems. Once again the board saved the day for me - thanks again guys!

[wlee]

Oh - I forgot . . . the bosses had to be milled 0.380 to accomodate the guide plate and nut on the screw-in stud.

It was pretty spooky to see that much metal coming off!