Cam/Valvetrain Issues

What I meant is I have read that there is an exhaust crossover in the intake manifold. A bad welch plug in this area would produce an exhaust leak when cold and diminish as the engine warmed up. Just a thought.
 
cheese1 said:
what I meant is I have read that there is an exhaust crossover in the intake manifold. A bad welch plug in this area would produce an exhaust leak when cold and diminish as the engine warmed up. Just a thought.
Click to expand...

Should see evidence that an exhaust leak exists from black discoloration near the plug or on the valley cover.
 
Good pics Robert!

If ya go to the sonja motor thread, you will see how I installed the rear cam bearing also, and then created an "match" in the bearing shell to eliminate any oil flow restriction.

Simply because of the way the lubrication system is set up on these motors, exact cam bearing positioning is very critical! Probably more so than on any similar engine from other oems, so a machinist has no leeway in bearing installation, it must be done very carefully with complete visual verification all the way! Ya can't just slam 'em in and move on! And even if all oil holes line up, any mis-alignment/overhang must be corrected by alignment drilling through the block or saddles and then hand-finishing with a die grinder.

Also...if the cam bearings are installed backwards (very easy to do), the oil holes will never align! If the bearing installer just pulled just one out of the set and loaded on the tool the wrong direction, then the system is scruud!

I have two boxes of new cam bearings here now that came to me with a bunch of throwaway parts. Both sets had obviously been installed wrong, then discovered and removed. These are one-shot items, ya can't just slam 'em in, then realize they are wrong, remove 'em and use again!

These boat rockers are not worth having "repaired", simply replace with new if there is any doubt as to servicability.

Regarding the rotten welch plug syndrome...those should always be removed before a bake and blast or hot tank. Then new ones installed. Depending upon your exact manifold, not someone else's, you could have none, two or five welch plugs present. Definitely five if the manifold is an egr unit. Only two of the pugs block escape of exhaust gas (the noise referred to in the other thread is an exhaust leak), the other three clock coolant jacket access.

If you suspect an exhaust leak under the intake manifold, stick one end of a piece of vacuum hose in your ear, and slide the other end under the manifold while the motor is running and you will hear an exhaust leak very clearly. And if there is an exhaust leak, that won't show up as a vacuum leak point since the exhaust gas masks it unless you used propane intake manifold gaskets which block the crossover.

You can use the same piece of vacuum tubing and slide down into each pushrod hole while the motor is running and listen to any lifter tick that might be present, works much better than a long-probe stethoscope.
 
I May have found the problem. After reading through this thread and thinking I would hate to pull the motor I figured I would pull the rockers on each head and check things out one last time.
I bolted the rockers back into place tightening from the center and working outward. When I started the engine the noise moved from the #6 cylinder to the #1 cylinder.
I thought this was odd, how could the noise move from one head to the other head?
I figured I would try an experiment. With the motor running I loosened the bolts on the rocker stand on cylinder #1 and the noise went away. I played around with the tightening sequence and found out that the noise would increase or recede by which order the rocker stands were tightened.
I now believe the problem to be screwed up rocker stands. Not knowing the history of this motor. I now have some questions.
What is the height of the rocker stands?
Are the boat style stands the same as the welded stands? Can they be mixed together?
Is there a factory torque sequence? I didn't see one in the service manual.
 
All sv rocker shaft stands are the same height. I measuredusing calipers, a virgin stand and I get 1.313 from the bottom to the lower part of the shaft bore. If they have been rebuilt the bore May be slightly bigger. As long as they are close to the same ground parallel to the bore cl. I would think you are good to go.

As for tightening sequence. I pull them down from the center out and evenly so they all meet the head at close to the same time. Then torque to 16 ft/lb again evenly from the center out.

I don't know why loosening the stand bolts would make a differance unless you have a binding situation.
 
cheese1 said:
I May have found the problem. After reading through this thread and thinking I would hate to pull the motor I figured I would pull the rockers on each head and check things out one last time.
I bolted the rockers back into place tightening from the center and working outward. When I started the engine the noise moved from the #6 cylinder to the #1 cylinder.
I thought this was odd, how could the noise move from one head to the other head?
I figured I would try an experiment. With the motor running I loosened the bolts on the rocker stand on cylinder #1 and the noise went away. I played around with the tightening sequence and found out that the noise would increase or recede by which order the rocker stands were tightened.
I now believe the problem to be screwed up rocker stands. Not knowing the history of this motor. I now have some questions.
What is the height of the rocker stands?
Are the boat style stands the same as the welded stands? Can they be mixed together?
Is there a factory torque sequence? I didn't see one in the service manual.
Click to expand...

Again...not an unusual situation when you deal with many of these engines with all the issues related to the rocker system lubrication!

There are at least five distinctly different rockers stands used, but all are dimensionally identical. Those are:

1) the "oiler" stands of which there are at least three variations over the years but all interchange perfectly.

2) the non-oiler stands (no oil feed hole) of which there are at least two variations, one with the "cutaway" foot to allow head bolt clearance at some positions.

They are easily distorted if over-tightened or the incorrect hardened washer is used under the head of the retaining bolt. It's not uncommon to find 'em cracked right down through the shaft hole! If distorted, then become shorter by just a few thousandths...that can then lead to oil bypass on the oiler stand when re-installed, that in turn starves the rocker shaft...not uncommon. We have other threads in this series that allude to that issue.

There is no torque spec for that assembly as it's so easily distorted, ya cannot use a standard torque table for that fastener. Since we seal all the threads on the bolts, then they just get snugged from the inside to the outside alternately and then tightened with an educated elbow!

I've also shown distorted stands and "short" ones in other threads on this sub-forum!

There are no differences between the welded rocker system or the boat rocker system other than what we have discussed, other wise we would have advised of that. The rocker shaft, the rocker arms, and the spacer springs are the differences!

There were some nine stand assemblies used with the boat rocker/pushrods that did not use the spacer springs! But those don't show up in the parts literature. And then over the years as folks worked on this stuff, they have mis-matched all these parts because they don't know how to do this and the nuances to look for!

I've found that new, current production boat rocker shafts from various manufacturers can have as much as 0.005" "bow" in 'em when checked end-to-end. That in turn makes the tighten-down of the rocker stands very interesting (and tedious!!). Some folks think the problem is the stand "length" is wrong...in actuality, the rocker shaft is the problem!

But overall, this one more reason that I do not like to use the five stand/boat rocker assemblies! It works ok when everything is new (such as the conversion "kits" ihc offered back in the day). But mixing and matching old parts from different applications/eras is not the best way to build an engine! And this kind of tolerance stack is just what you are encountering!

I know this is easy for me to describe as I have well over 100+ rocker stands that I have cleaned/inspected and honed for recycling. Most folks don't have that luxury, but I've spent hundreds of hours scruuin' with this stuff to come up with all these nuances, ya won't find that inna book! And frankly...what you are encountering is actually very unusual but does occur...I've run into the same situation myself.

What I do for the matched sets of used rocker stands that we supply as reconditioned parts for customer use, is to go through all of 'em and using a perfectly straight rocker shaft on a surface plate, I match a set of nine (or five) that are identical in height when un-compressed by the retaining bolt. We've discovered this through alotta trial and error, along with feedback from customers. If we could still source all these parts new, we would not have to go through all this kinda stuff...but we can't!

Just for shits and giggles, if you have a functional nine stand/welded rocker assembly that is clean internally, what not mount it on the problematic side with the correct pushrods?

Also...we normally think of lifter noise as being the result of not pumping up or not being properly preloaded. But...if the "installed valve height" is really off (too "high"), then the lifter(s) could very well be bottoming out and creating the noise! Loosening the rocker stand bolts allows compensation for that.

It's my firm belief that what you are encountering with this somewhat "unknown quality" engine is tolerance stack! And that is a very unusual situation which is not the norm!
 
I took apart both rocker assemblies and thoroughly inspected everything. When I checked the shafts to see if they were straight, low and behold they have a bow in the center. Probably about a 1/16th of an inch. I'm going to pick up my welded rockers from the farm and get them cleaned up. I'll post back with details after the switch is made.
You guys have been great. Thanks for all the help.
 
A 16th of an inch??? That's a texas football field man!

Was that rocker shaft used as a prybar?

I've been drilling those shafts with a carbide bit and they are hard! And...I recently cut one into chunks to use for some spacers using a gizzwheel, they are still hard!

I first discovered this "bent" (if we can call it that) rocker shaft deal when inspecting a new five stand shaft (fairly recent production I assume) when I set up a fixture for inspecting and "grading" these rocker stands into matched sets. Every time I set up a set of nine in the fixture nothing would match. I was blown away!

So after carefully hand checking each one as Robert described, I could find no discrepancy amongst 'em. I had laid the new rocker shaft on the surface plate (a chunk of granite) and it I couldn't believe how "crooked" it was!!!

So then I pulled out all the used shafts I had (about 25 in various conditions) and checked those...all the badly worn nine stand shafts were perfect! About five of the five stand/boat shafts (slightly used) showed some degree of "bow". I have no way of determining whether the five stand/boat shafts I was checking were IH oem or an aftermarket replacement like we're forced into now.

Once I started using a "straight" rocker shaft for the fixture, then all the rocker stands were real easy to match up simply by eyeball!
 
Update - whent to the farm and picked up the old rockers. Cleaned up the old welded style rockers and found the shafts are worn really bad. So here's what I tried. I took the boat style rockers and shaft and removed the boat style and replaced with the welded. I flipped the shaft so the notch is facing up and it still raps at start up. So it seems that I either have screwed up shafts or the "tolerance stack" issue you had mentioned. Any ideas how to check the tolerance stack and is there a remedy?
 
Don't get discouraged, we will get there! And what you have done now is just one more step!

You did swap the pushrod set when ya changed back to the welded rockers??? Welded rockers must use cup and ball pushrods, but that is dam obvious...I just had to ask!

Are all the cup and ball pushrods the same length? Did the noise shift to another hole or is the same lifter/pushrod/rocker/valve involved?

Have you watched it oil on the noise side since swapping rockers? Every rocker must produce oil along the "slot" on the top in order to feed both the pushrod socket and the valve tip.

Robert has developed some "adjustable" pushrods just for use when working through issues like this that May involve suspect lifter travel or a "short" valve train stack. That is the method for changing lifter pre-load as far as diagnostics go.

Another method you can try, use a feeler gauge blade (start off with a 0.010") and insert between the valve tip and the rocker while the engine is running, same process as you would use when setting valve clearance on a "hot" engine with it running that has solid lifters. You will have to kinda "force" the gauge blade into position and hold it there.
 
I did use the ball/cup pushrods. They came off the original motor and are all the same size. I have managed to manipulate the noise by the tightening sequence on the rocker bolts around cylinder #1. The noise is very faint on #1 now. The noise has now become louder on cylinder #2. I've played with the tightening sequence and it goes away once the engine is warm. On cold start up it is loud again. So on cold start up I have about 5 minutes to play with the tightening sequence.
I was really hoping the rocker shafts that I picked up from the farm were in good shape. At least then I could determine if I'm dealing with wacked out shafts. I'll try the feeler gauge this weekend. By the way, what would 2 good used 9 stand shafts go for? You can pm me if you prefer. I'm sure there is a solution to this madness.
 
I have quite a few take-off rocker assemblies to go through yet and break down into parts for grading. A mixture of five stand and nine stand, boat and welded, some are assembled incorrectly. I have a couplea enrollees on their way to binder u. Right now, I'll have them break these parts out and supervise the inspection process and see what we have here. Jeff May also have some at his location.

But, I think the feeler gauge trick will tell ya something and will also prove or disprove the tolerance stack deal, that is not a cure of course, but does narrow down the root cause even more.
 
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