OEM Rocker Arm Side Play

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Yeah, I don't even think the factory heads had even stem heights when they were new......as important as it was with non adjustable valve train, but "somehow" they still ran well. lol
Ran well? yes...Unless you had the chance to test that theory. Back in '68 identical twins Jim and Jack Klaton walked into Sherm's Sales and ordered identical red 383 4 speed Coronets. Absolutely identical. They requested they be built sequentially and serial numbered as such. When they were delivered the cars were inspected by the twins and pronounced to be as ordered. A coin was flipped for the choice of cars. After a bit of cruising around town nose to tail making every teenage guy around drool they ran them off just to "see". Jim's car beat jacks by 3 car lengths in a roughly measured quarter mile. They traded lanes and did it again with the same result. Doing what twins do they switched cars and did it again twice with the exact same result. Jim's Coronet was always significantly faster than Jack's. Conclusion? Factory tolerances at the time sucked. Whether it was chamber volume, or deck height, or valve preload, or cam timing no one knew because nobody ever tore down and checked those engines to find out. Hell, at the time we were just kids who didn't have a clue. Now we know better, and strive to make things right that the factory didn't have the time, resources, or will to get right. Yes, both ran well, but one ran much better.
 
Ran well? yes...Unless you had the chance to test that theory. Back in '68 identical twins Jim and Jack Klaton walked into Sherm's Sales and ordered identical red 383 4 speed Coronets. Absolutely identical. They requested they be built sequentially and serial numbered as such. When they were delivered the cars were inspected by the twins and pronounced to be as ordered. A coin was flipped for the choice of cars. After a bit of cruising around town nose to tail making every teenage guy around drool they ran them off just to "see". Jim's car beat jacks by 3 car lengths in a roughly measured quarter mile. They traded lanes and did it again with the same result. Doing what twins do they switched cars and did it again twice with the exact same result. Jim's Coronet was always significantly faster than Jack's. Conclusion? Factory tolerances at the time sucked. Whether it was chamber volume, or deck height, or valve preload, or cam timing no one knew because nobody ever tore down and checked those engines to find out. Hell, at the time we were just kids who didn't have a clue. Now we know better, and strive to make things right that the factory didn't have the time, resources, or will to get right. Yes, both ran well, but one ran much better.
That's a great story. I have one similar. I got a 73 340 Rally charger when I was in high school. Summer of 1980. 79K original miles. 73 340. Low compression, low performance "comparatively" speaking. 2.76 8 3/4. Car already had a reputation before I got it. It was unruly quick for such a heavy car. We all "figured" maybe it left with a little more blueprinting or maybe "got lucky".

There were only like three other cars in school that had anything for it. Jeff Smith's tough *** 70 Camaro, small block 400, turbo 400 and 4.10 gears. David George's 71 LS6 4 speed Chevelle and Don Oldfield's 70 383 4 speed Challenger "sometimes". Robert Bankston (RIP) had a 70 SS396 Chevelle and we ran several times and he never could get that Charger. Pissed him OFF. lol That Charger was quicker and faster than it ever should have been.
 
Frankly, to my eyes..... the factory rockers are much nicer.

The Melling rockers have a bunch of added mass in areas that do nothing for strength, but are definitely adding to the moment of inertia.

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If the rest of the factory rockers looked as good as that one...... they’d have gone right on the new build.
 
Frankly, to my eyes..... the factory rockers are much nicer.

The Melling rockers have a bunch of added mass in areas that do nothing for strength, but are definitely adding to the moment of inertia.

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If the rest of the factory rockers looked as good as that one...... they’d have gone right on the new build.


I noticed that too, not overly concerned that much, but a valid point. I have wondered if these rockers are stamped for both small and big block, the same overall size but the pushrod dimpling is positioned differently depending? Awfully large flat area for that:

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my big takeaway from this thread is that I won’t be using/recommending the Melling SBM rockers.
And that if someone decides to use them, they really need to look them over very carefully and mock everything up before assembling.
 
And another area with more material is on the bottom side of the rocker, they are a good bit wider vs the oem’s

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my big takeaway from this thread is that I won’t be using/recommending the Melling SBM rockers.
And that if someone decides to use them, they really need to look them over very carefully and mock everything up before assembling.
No I would not recommend them either. It’s a budgetary issue and the only reason I’m fixing them. Bottom line, Don’t buy them unless you intend to fix them. Side clearances is not the issue which was the initial concern. And don’t buy Speedmaster heads already assembled and expect to run factory style rockers. :)
 
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Take pictures if you can of one, zoomed and clear.
Here’s an oem rocker and one of the good Mellings (ootb ready) My digital caliper battery is now dead but I’ll get some measurements ASAP. Do you have a caliper to measure things?
The Mellings are slightly thicker as I’ve mentioned earlier. It be interesting to see how they (and any others like Elgin etc) stack up to the MP’s

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I've got an ol El cheapo digital caliper.... Maybe could weigh them also
 
Spacers installed with approximately .040” side clearance on all sets of rockers. Tips centered over the valve stems pretty good. Pushrods clear the heads. Certainly better than it was

From this:



To This:

 
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Still surprisingly sloppy looking at .040.

Glad they sent you the ones made out of the “good” aluminum.
 
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