I had my 083's done at the machine shop... 3 angle, screw in studs and guides, larger springs etc.

Valvetrain Breakdown
1.6 Roller Rockers
LT4 Hotcam
LS7 lifters
Stock length push-rod's

I used the stock push-rods because on a previous thread about my build, I asked if I needed longer rods. The consensus was that if I wasn't going to a smaller base circle cam then my stock push rods would work.

However I question this due to the fact I am trying to set my preload and it seems as if the rocker bottoms out on the hex of the stud. I turn the rod back and forth and up and down until slack is taken from up and down, and side to side isn't sloppy but has some resistance. When I get to this point I take it one full turn which is what I have read on multiple threads on new valvetrain parts. Upon doing it this way, on some of the valves, the rocker sits on the hex of the stud and when I rotate the assembly I have heard a "click" sound from some where that wasn't present prior to adjustment.

So my question is this, is the clearance between the hex on the stud and the curved part of the roller rocker really supposed to be close? I haven't measured and I don't know in thousands, but upon a quick look on most valves it's less than a 1/8th inch clearance there. I just don't want to fire this bad boy up and ruin something or have something bind, rub or break.

Thanks in advance.

 

I've encountered the same thing and have had to machine the stud boss down a bit to make clearance, just as you would for guide plate spacing.



If you are using a stud with a radius above the hex it can be even more of an issue since the interference is not always obvious. If you are using the factory type screw-in studs and are bottoming, push rod length change and/or head machining are about your only options. Remember that the valvetrain geometry, and not the stud clearance, should dictate push rod length.

 

I had the boss machined down, kinda have to on screw in studs with the hex. It really just seems like my pushrod needs to be just a tad taller. I ordered a pushrod length checker so when it comes in I will check it that way.

 

I'm no engine builder by any means, but something tells me the fact the push rod in the photo's sitting back against the guide with barley any clearance there isn't correct. All the other pictures I see online the pushrod no matter where in the cycle has the pushrod about the middle of the guide plates front to back and centered side to side.

Also, these pushrods IMO are still pretty loose. However if I take it even a 1/2 turn more on most of them it bottoms out.

 

Your stud bosses probably weren't milled down far enough.

Take em back to the machine shop and have em cut down some more. Looks like, by about the thickness of the plates. (.100" - .125")

 

i have theese same exact rockers on my 89 305 carbed..... check your geometry amd try going with a longer pushrod

 

Well, here is what I found out today doing some measuring. My LS7 lifter cup is not as deep as a stock L98 cup. Matter of fact, if I put the L98 lifters in, the rocker bottoms out real fast, almost before I can even tighten it down half way.

The head boss's do appear to have been milled down for the proper specs to cover the hex and the guide plates. I marked cylinder 1 so I could get an idea of how the valve train geometry is and I snapped some images. You guys tell me what you think about this. It seems to me that the intake is a tad crooked and the exhaust valve is a tad over center. I also snapped a picture of the lifters at base circle. There flush with the dogbone which is the same as with the L98 lifters. So really the only difference in the LS7 and L98 lifters is the L98 appears to have a deeper cup by roughly .125. Which shocks me as I read several places that the LS7 lifter is supposed to have a deeper cup.

 

.

 

The only way (100% reliable way that is) is to measure and verify using the rocker arm pivot points (roller tip axle centre and trunnion centre) and ensure they are 90 degrees to the valve at mid lift.
There's a fairly concise procedure written using what's called the mid lift method for valve train geometry.

You made an extremely valid point regarding the different pushrod cup seat heights for different lifters. That and a myriad other things will affect the final pushrod length.

You may find that once you've dialed in the correct length with an adjustable push rod, you'll have sufficient clearance at the rocker stud.

Not sure how reliable the plastic pushrod tool is.

 

Old thread but I had this problem with some 305 heads that weren't machined down enough. I used lash caps and a longer pushrod to make it work.

 

I'd be concerned that that would mess up the geometry.
With a .100" longer valve in my heads, it pushed the contact towards the exhaust side. So much so, that proper geometry couldn't be achieved without other changes.

That said, if this is average everyday 305 with nothing special in terms of performance hardware (like a cam) and a factory valvetrain then it may not make a appreciable difference other than accelerated wear perhaps.