Crane Gold rocker mystery??

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KnuckleDuster

KnuckleDuster

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Working on a friends car and noticed what looks like five tiny holes drilled from underneath. There are raised ridges around them. This is only on one rocker. Why?

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looks like it hit something on the inside of vc oil deflector?
 
Just weird it's so uniform.

Are these rockers pretty good?
Seems like I've heard mixed reviews over the years. They are late 80's- early 90's vintage I believe.

He was told the engine was a 1973 340 with roller rockers and a mild cam, actually it is a 70 340 with X-heads and these, Weiand Action Plus intake and the rest is still unknown, including cam brand and specs, pistons and whether it has been overbored. It's got a 5 speed Keisler Tremec tied to it with a 9-1/4. out of a truck with 4.10 gears. He is getting drive line vibration at highway speeds. It has a custom driveshaft, but I noticed his pinion is angled a bit downwards, could that cause vibration?
Could it be gear mesh?
I was able to find his factory TDC mark was nowhere near TDC, so I found and marked true TDC so we could get his total timing to 36° and put an end to his detonation issues. Waiting on an FBO limiter plate to fully map it out.
Before that we have to address his crusty fuel system, though.
Car is a 74 Roadrunner. It's a mess, but he knows and still loves it. He is new to old Mopars but loves learning and has a great attitude, so I've been trying to help him get some of it sorted out.

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Crane golds were the defacto AL rocker arm. Pretty good under all but the stiffest springs.
 
Pinion angle can definitely cause vibration; Gear mesh probably not.
Too much timing possibly.
A slipped balancer ring for sure yes if the balancer is for externally balanced engine. That needs to be established and remedied ASAP
 
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Balancer is factory internal type.
Betting it's an earlier mismatch with 70-up timing cover unless it's slipped 6 inches or so. Ran out of time before I got to confirm.

What is the general rule of thumb for pinion angle?
It only hapoens at certain speeds. Will have to test more, but I think it's speed dependant, not rpm.
 
The balancers are 7.25 IIRC in diameter, making the perimeter 22.7766 inches and 90* would be 1/4 of that so 5.69 inches. I'm thinking you are on the right track, easy fix for sure.

As for the pinion, it has to be nose down relative to the the driveshaft. The driveshaft itself should be going downhill from the trans. This makes the two U-joints cycle in opposite directions and so if they were equal angles the vibration would cancel.
However, they cannot be equal and opposite under all conditions.The major compensation is for axle-wrap under power. This changes with the amount of power,the body weight, and with the stiffness of the springs. With lots of power and a single factory main leaf, you might need 7 degrees nose down, to prevent over-rotation of the rear end. Less power, and less traction, requires less compensation.
Cruising requires the least front to rear difference, for smooth sailing. Ideally they would be equal and opposite, perhaps 1.5 to 2 degrees. But if your power wraps the rear up from 1.5 to 2* nose down to 5* nose up, well, you cant have that! So cruising has to be sacrificed, or the springs have to be stiffer.
Ideally the rear angle will be slightly nose down under full power.
 
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The crane golds had issues with the hardness of the adjusters back around the late 90's. They would snap off flush with the rocker arm. I have a set in my 340 but I bought replacement adjusters. I think they came from smith brothers.
 
SSG_Karg said:
5 speed car eh? Possibly roached crank thrust bearing causing the bad vibes?
Click to expand...

I am not too familiar with the Tremec 5spd conversions at all. I glanced through the paperwork ,but we'll have to look further into it. The trans also makes a little noise in neutral until you step on the clutch. Between that and tge vibration, I was already thinking it might have a bad bearing and/or maybe need clutch adjustment.

The vibration is steady, not cyclic. Like a very deep hum, not like whomp whomp whomp. Hope that helps describe, lol!
 
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The Tremec conversions require cutting the entire trans tunnel out because they are so bulky. I'm betting this wasn't installed correctly and the trans is angled way down causing the u joints to be out of phase badly. One glance underneath should tell you all you need to know. Take a pic.

Oh and somebody labled that rocker for cylinder #5 with a center punch--no big deal just poor execution when a black Sharpie works the same.
J.Rob
 
RAMM said:
The Tremec conversions require cutting the entire trans tunnel out because they are so bulky. I'm betting this wasn't installed correctly and the trans is angled way down causing the u joints to be out of phase badly. One glance underneath should tell you all you need to know. Take a pic.

Oh and somebody labled that rocker for cylinder #5 with a center punch--no big deal just poor execution when a black Sharpie works the same.
J.Rob
Click to expand...

Thanks!
 
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Ok...just got off the phone. The tunnel is cut and fabbed. I also think I remember seeing they got within .0003 centering the input shaft to the bell housing from looking at the paperwork. He is on his way out of town for the week, so I won't know more or be able to take pics until he gets back. I think I remember noticing the trans yoke angled down a bit, regardless. If it is, at least maybe there won't be such major surgery involved to correct it. Thanks for the ideas so far!
 
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This post has certainly meandered a little from the original post. No idea why those punch marks would be there, you say they are marks from drill holes from underneath? So you are saying the holes go almost all the way through and those marks are from the drill almost breaking through? That's how I read it. Feel free to Kick my A if that has already been addressed in the discussion. In any case they look to be man made and pretty stupid thing to do on a highly stressed component. For my 2 cents, about Crane Gold rockers, half the ones I have seen on middle HP engines were pure junk. According to Mopar Mike above, they had some issues and my mechanic at around that time (late 90s to mid 2000s) used about three sets of them on his engines (360's) before giving up, as they kept failing. He kept replacing them individually as they failed and gave up in the end. So after seeing these things first hand, I would never buy them or use them. Change around the saying, "Not all that glitters is gold", for these rockers, it would be, "Not all that is Gold, glitters"
 
I think J Rob was right they were marked with a punch.
Yes the post has wandered, didn't see the need for a second post since I was getting good feedback.
Thanks for the advice so far y'all! The owner appreciates it as well!
 
not drilled from underneath. if stamped for #5, why is it at #2 now? run it, or remove all and inspect all
 
Marcohotrod said:
not drilled from underneath. if stamped for #5, why is it at #2 now? run it, or remove all and inspect all
Click to expand...

Question is why was it marked for #5 to begin with?
Perhaps the rockers or even heads have changed sides, it would be #5 on the other side.
We'll look into it next time he brings it by.
 
I didn't look at my own pic. Was thinking it WAS on #4. So much for that theory, lol...
 
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