stock rocker spacing.

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stupidasso

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Hey all,
I'm about to put in my new springs and cam, but before I did that I noticed that the rocker arm was a little off center from the valve, then I noticed that I have about .09 inches of gap between the two rocker arms on the number one cylinder. Lot of slop there I'm able to move the rockers back and forth. I dont see any shims present either. Should there be shims in there to make sure that the stock rocker arms are centered on the valve and don't have any left to right movement?

Thanks,
Stu
 
Theres a left and right rocker arm.
There should be no free play in the rocker when it is depressing the spring. There is some present when the lifter is on the base circle of the cam and the rocker is not pressing on the spring much.
There should be no gaps of light ever.

MP makes HD versions of the rocker. $80
 
Hi Rumble,
this is side to side gaps between the intake and exhaust rocker. Essentially with everything installed, and number one at TDC, I can slide the rockers on the shaft. so the slop as I call it is horizontal, not vertical.

Thanks.
Stu
 
I think what Rumble is saying(not to butt in) Is that your rockers should never be loose enough to slide back and forth easily. There should always be pressure on the rockers even at tdc.(that would be the preload). You may have some worn lifters, rockers,pushrods, or springs.....(Check the ball area of the rocker arm and the pushrods first)I have ran the stock rockers on a 318 and a 360. I always had a little clearance between the rockers, I don't think it's a big issue on street cars. Just make sure you have the rockers on right and the hold down spacers in the right places. For the most part if everything is on right and in good order I believe the rockers and valves pretty much self align. If you can move those rockers from side to side easily then you probably don't have enough preload and will most likely make for a noisy valve train. There are also places that sell the rocker arm shims to eliminate the play your talking about.

P.S. Mellings MPR-324 pushrods are 30 thousandths longer than stock and have the same ball/ball ends. I used these to add preload with good results.
 
63dartman, there won't be pressure on the valve stem if you have a mechanical cam, or at least I hope there isn't.


Stupidasso, try another pair of rockers in that spot, it might be that you happen to have two rockers that are not as wide as the rest. After all they are mass produced. You can have some movement but .090 seems a bit much.

At one time MP made shims for this, I do not know if they are still available.

Chuck
 
I think what Rumble is saying(not to butt in) Is that your rockers should never be loose enough to slide back and forth easily.
Click to expand...
No no no, do butt in. Your right, that's what I'm saying in a up and down manor, not side to side, but it still applies. It should have been mentioned with my reply.
However, when the lifter is on the base circle of the cam, that's when there is the most play. Some is normal. I just do not have a measurement to say OK or to much.

340, I don't think shims under the bar, the only ones I know of, is the answer. It would provided more room. The Mech. rocker gear has spacers. You can get them in different widths. Or used to.

I still think this
MP makes HD versions of the rocker. $80
Click to expand...
is the best option across the board and it is very inexpensive.
 
I don't think you guys understand his concern, it is side to side rocker movement on the shaft not rocker to pushrod/valve stem movement. Lifter preload/valve clearance has nothing to do with side to side movement. This should be checked before you even put pushrods in the motor.


Chuck
 
O.k. Yes I assumed he was running a hydraulic cam. Maybe we should ask that question first. If it's a solid cam yeah you will be able to move the rockers side to side a bit since there is no preload. For the side to side movement. .090 Is probably too much play for the solid rockers. They make shims for the solid though. If your running a solid cam with adjustable rockers there are supposed to be spacers in between the rockers. Alot of times they are sold used with out them because they were lost or misplaced.

If it's a hydraulic cam.....There may be a little side to side play, I know all the stock rockers I have ran had some play side to side.(not sure if it was .090 though) But!!! You should not be able to move the rockers side to side easily just like I said before. I know the issue is the the rocker arm spacing and side to side movement. If your rockers have the right preload they should not slide on the shaft easily to begin with. If the spacing is a concern I do believe you can use the same shims for the solid cam to fix that issue. They make shims in varying widths or you could just find the dimensions of the stock shims and make your own. I could probably post the dimensions if you need them. I have stock shims in the garage that I could measure.

personally I think the correct preload or gap on the rockers is more of a concern. You could possibly throw a pushrod and there is a wear issue on both the solid and hydraulic if it's not set up right.
 
mopar sells shim for that purpose...or they used to...i bought some for my 340 a few years ago
 
Hey guys, thanks for all the replies.
Here's my setup.

Stock 360 from a 77 truck (could tell because of the pan).
I bought this from a rebuilder as a fully rebuilt long block.

Hyd lifters and such.

I bought the Mancini cam kit
Purple shaft 340 grind
MP lifters
MP push Rods
MP HD Springs
Comp retainers, etc.

I have the #1 at TDC and am able to slide my stock rocker arms side to side. I didn't measure the Up and Down movement that I have.
I'm just getting ready to dissassemble to install my new valvetrain parts and was concerned that I may have a problem and was wondering if this was normal. sounds like it isnt. I think I should go with new rocker arms and shaft and spacers with all the other work I'm putting into this, huh?

Thanks again guys, you've all been a real help. Hope to meet some of you at fling in May.

- Stu
 
You can use machine bushings for the side slop, you can get them in varying thickness and are available at most hardware stores/AZ/Napa/etc. I get them at the local Tractor Supply store, like $2.99 a 10 pack.
 
With new rockers, you may end up with the same thing. As said, they are mass produced and that side-to-side tolerance is not controlled. I have measured that much with the hydraulic rockers. Use shims to tighten up the slop if you like, but these ran with some side-to-side slop. The shims will be a bit larger than .875" ID. I personally would not swap around used rockers on a used shaft as they tend to wear in together.

Check your shafts for excess wear where the rockers ride with a caliper. I would consider changing the shaft for more than .003-005" wear or thereabouts for an engine I cared about.

Up and down should be zero with everything setup AND the engine run in, or pre-oiled and turned over a few times so that the lifters are pumped up. With fresh lifters that have never been pumped up, you are going to find the piston movement inside the lifters gives an up and down movement on the rocker. You may also find that with any lifter that leaks down after being run. So the only way to check that IMO is to look at the pistons inside the lifters on each cylinder one at a time with that cylinder at TDC of the compression stroke (not at overlap) and look to see that the lifter piston is pushed down into the cylinder body from the retaining clip by a short distance, perhaps 1/16".
 
nm9stheham said:
With new rockers, you may end up with the same thing. As said, they are mass produced and that side-to-side tolerance is not controlled. I have measured that much with the hydraulic rockers. Use shims to tighten up the slop if you like, but these ran with some side-to-side slop. The shims will be a bit larger than .875" ID. I personally would not swap around used rockers on a used shaft as they tend to wear in together.

Check your shafts for excess wear where the rockers ride with a caliper. I would consider changing the shaft for more than .003-005" wear or thereabouts for an engine I cared about.

Up and down should be zero with everything setup AND the engine run in, or pre-oiled and turned over a few times so that the lifters are pumped up. With fresh lifters that have never been pumped up, you are going to find the piston movement inside the lifters gives an up and down movement on the rocker. You may also find that with any lifter that leaks down after being run. So the only way to check that IMO is to look at the pistons inside the lifters on each cylinder one at a time with that cylinder at TDC of the compression stroke (not at overlap) and look to see that the lifter piston is pushed down into the cylinder body from the retaining clip by a short distance, perhaps 1/16".
Click to expand...

Yeah I believe the shim ID is 25/32" or something, technically. But iirc the last shims I used were packaged as 7/8" and they worked fine. OD is 1 1/4" or 1 3/16", either way....:)
 
Stock paddle rockers are like that. Some say they're junk, but they've worked pretty good for 50 years.
 
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