What is going on here. "Rocker Arm Geometry"

[bugzaper]

Changing valve cover gaskets to day and while looking at the rocker arms on #1 cylinder something just didn't look quite right.
I pulled the rockers and "T-Stand" off and here is what I found (see pics.).
Intake is not quite as bad but, still not as centered as I'd like.
I'm a bit afraid that the incorrect geometry of the rocker on the valve may have worn / is wearing the guide.

Not sure what is going on.

 

[8ad-f85]

Looks like the tip is scrubbing.
Is that valve tip hardened?
Stock heights, cam?

 

[bugzaper]

Looks like the tip is scrubbing.
Is that valve tip hardened?
Stock heights, cam?

Is the valve tip hardened?
Not sure about that, I'd think so, but just don't know.

Stock heights, cam?
"Yes" all stock rockers / T-Stands / Push-rods / Springs / Lifters.
Cam is a smallish "LUNATI" brand (see pic. of cam card).

When I built this engine I had it decked (don't remember how much...12 years ago).
I didn't change the push rods as I was thinking that the lifters had enough to take up the difference.
One thing I did have to do was to notch the guide plates (steel plates under the T-Stands) as a few were rubbing on the push rods.

 

[8ad-f85]

As I recall, there isn't enough (if any?) geometry change with a bolt down stand and minimal decking/pushrod length.
I could be wrong about that.
I'm thinking just as you are, the minor length differences would be taken up by the plunger in the lifter.
What can change is the relationship of the fixed rocker to the valve stem height from a valve job...or possibly a warbled out guide might start to scrub? (chicken-egg)
The hardened tip valves often have a darker portion or otherwise obvious stellite disc attached to the top, that can be seen from the side of the stem tip.

On (adjustable) fixed stand rockers, there can be problems screwing the adjusters too far out to make up for a short pushrod.
Too much sticking out can lead to breakage problems with so much unsupported leverage.

 

[8ad-f85]

What was going on that the pushrods rubbed the plates?
That might point to what's changing things.

 

[bugzaper]

What was going on that the pushrods rubbed the plates?
That might point to what's changing things.

I had "2" that were rubbing up against the plates causing them to cut grooves into the push-rods. (see pic)
What I found interesting is that none of the others were doing this.
Several were within app. 1/8" of guide plate but, not touching.
I checked the guide plates and they did not appear to be bent.
Maybe (I don't know) the "T-Stand" was slight off.
If I remember right (been 12 years) both were on the same cylinder.
I'm just lucky that the push-rods didn't come apart!!!
Building these engines require a complete different learning curve.

 

[bugzaper]

Additionally.
I found this push rod (see pic.) on the same day I found the cocked rocker / T-Stand.

 

[8ad-f85]

So far it sounds like the rockers were bolted down cockeyed, but then straightened out?
Could that have worn the guide some and gotten worse over time?
Is something moving, loosening, or off location?
Any very slight and nearly undetectable damage get worse with time?

 

[bugzaper]

So far it sounds like the rockers were bolted down cockeyed, but then straightened out?
Could that have worn the guide some and gotten worse over time?
Is something moving, loosening, or off location?
Any very slight and nearly undetectable damage get worse with time?

All the above is possible.

 

[8ad-f85]

Part of the spring clip is broken away?
That might let the rocker wiggle around a bit.

 

[bugzaper]

Part of the spring clip is broken away?
That might let the rocker wiggle around a bit.

I'm thinking about scraping the entire stock rocker system and going with the "MTS" or "-?-" non-adjustable, just have to convince myself the cost is worth it.
I'm learning that once you start modifying these engines the cost goes w..a..y up!

 

[8ad-f85]

There's probably reasonable cost lightly used ones around that fit the needs of a mild or intermediate build.
I'm not convinced that the rockers are the cause but it seems like good piece of mind.
Maybe before removing the head, pull that hole's springs and see if the stems wiggle too much?
I wonder if your particular spring used wanders about or has the slight interference problems that some other sbc types have?
I'm also noticing that there aren't low cost stock or mild rocker options out there.
The stock stuff isn't bargain priced either.

 

[bugzaper]

There's probably reasonable cost lightly used ones around that fit the needs of a mild or intermediate build.
I'm not convinced that the rockers are the cause but it seems like good piece of mind.
Maybe before removing the head, pull that hole's springs and see if the stems wiggle too much?
I wonder if your particular spring used wanders about or has the slight interference problems that some other sbc types have?
I'm also noticing that there aren't low cost stock or mild rocker options out there.
The stock stuff isn't bargain priced either.

I've got a home-made rocker set I purchased from a fellow a few years back (see pic) and think I'll give them a try after a bit more fitment and rounding of sharp edges.
Also, before tearing into it I think I'll run each piston up to T.D.C., pull the plugs, stuff the hole with cotton rope to hold the valve up, take off each spring and check for the side wobble.
I can't remember as it's been to long ago and I didn't keep any paperwork (big mistake) if the valve guides were replaced or just knurled (spell).
I think I can file the tops of those valve stems that are a bit mushroomed.

 

[8ad-f85]

I guess the main thing I'd worry about on an assembled engine is the mock up or modification aspect.
Using a non-roller tip rocker makes the geometry aspect of utmost importance.
If there's any scrubbing, you'll have to find a way to solve the geometry changes by shimming, milling or pushrod length.
If you have non-hardened valve tips, scrubbing would be a greater concern yet.

 

[bugzaper]

I guess the main thing I'd worry about on an assembled engine is the mock up or modification aspect.
Using a non-roller tip rocker makes the geometry aspect of utmost importance.
If there's any scrubbing, you'll have to find a way to solve the geometry changes by shimming, milling or pushrod length.
If you have non-hardened valve tips, scrubbing would be a greater concern yet.

Agreed.
Not to make any excuses, this was my first Cadillac engine build.
The next (if there is such) will be different.

 

[8ad-f85]

Nothing to feel self conscious of!
I don't think there's anyone alive that hasn't had a weird part issue slip by, problem with bolting something together feeling funny or who knows what.
There's so much we are not equipped to measure without ultra high buck equipment and all the time in the world to ponder.
Even the bellybutton brands have strange machining issues that are all but impossible to identify and the blame lies with whatever seems convenient.
There's lots of new parts out there that simply don't work, if that says something.
Sometimes these things remain a mystery, to be solved and long forgotten.
Much respect for anyone that takes responsibility of their influence to a project first.

 

[Darius]

About the only thing that comes to minds as a "wish I had done that differently" involves the valvetrain. I have never felt comfortable with the stock setup, though on my first build it gave my no problems whatsoever. On the current build I opted for one of Marty's shaft mounted non-adjustable roller setups. Now, I wish the extra bucks had been spend for the ADJUSTABLE unit.

Simply because of: possible production stack up variables, use of an aftermarket camshaft, a machine shop's valve job - I think the cost of the adjustable roller setup brings ease of use and peace of mind. No, they aren't cheap, but that peace of mind is worth a lot!!

best,

bro. b

 

[PJ McCoy]

The peace of mind is more than some can afford. Like me.
So slap it on and go for it!!
Wish I had used the "baby cam". A guy down the road has a T bucket with a 76 caddy.
Same can i have on the shelf due to stock rockers. Sounds mean pulls hard. Light weight, stops pulling around 4300 rpm
My revvy is limted to 47k, i should have saved the money on both cam and rockershaft.
PJ

 

[Darius]

The peace of mind is more than some can afford. Like me.
So slap it on and go for it!!
Wish I had used the "baby cam". A guy down the road has a T bucket with a 76 caddy.
Same can i have on the shelf due to stock rockers. Sounds mean pulls hard. Light weight, stops pulling around 4300 rpm
My revvy is limted to 47k, i should have saved the money on both cam and rockershaft.
PJ

JP,
I totally understand your point. When I did my first Caddy build funds were extremely low. Now, my finances are somewhat better, but they were not "better" enough at the time to buy the adjustable shaft mounted rockers. We do what we can, when we can.

I have long admired the common sense approach of your project. With that young, growing family of yours you have made wise choices.

Best,

bro. d

 

[PJ McCoy]

Sorry for mudding up your thread bugzapper. I "Appleagize"!
PJ