Charlie, i had exactly the same problem you illustrate in the pictures, broken pushrod cups with the Dove rockers, by chance have you got stainless valves with longer tips that make the rocker arm angle deeper at the adjuster end and then the adjuster ball is closer to underside of rocker where there is little p/rod cup clearance? I,m not sure of the above but i went back to cast rockers. best regards  aussie bill.

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

I think I am going to have to disagree with you and JM. I am sure that your both smarter than me so please respond, but I have read a lot on this and I believe Comp Cams agrees with me.



Reference #2 http://www.compcams.com/Technical/FAQ/ValvetrainGeometry.asp






Johnson Rod



Southern California

Charlie is being kind enough to not mention that I was riding with him when the pushrod broke! Yeah me Chuck with the  bad luck! He was stopped at a light and lightly whacked the gas, thats when it let go. Must be my fault. I agree that the dark area would suggest a previous crack in the rod. Charlie has a real attention to detail so if he says he checked the clearances I'm sure they were right on. He is also using the larger diameter Mummert pushrods. So other than my black cloud being around I don't know what else caused it! Chuck in NH

PS: I did get to be the first Columbus dude to ride in Charlie's truck. Sounds hard!

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

That is a possibility. Perhaps I should think about looking at my geometry soon.

I, too would like to hear how the pushrod length affects the contact patch. I know I've read that it will move the patch.

I'll make a conjecture. The only way I can see that it will change, is that the adjuster needs to be turned in or out, depending on the length of the pushrod, and that changes the rocker ratio slightly. The angle of the adjuster to the pushrod may cause what I will call the the effective ratio (actual valve lift / lobe lift) to vary with the lobe lift which will cause the patch to drift to one side or the other of center.



Chuck, I guess you haven't got to This n That yet? It was good to see you. 3 more months! Oh, wow, only 3 more months.


Lawrenceville, GA

Shaft rockers are not to be confused with those rockers that are supported by a rocker arm stud and the height of which are fixed by the length of the pushrod.  Shaft rockers are at a fixed location or pivot point which makes geometry at the valve dependent upon the rocker stand height and not the length of the pushrod.  The length of the pushrod on a shaft rocker arm setup simply alters the rocker arm ratio.  That’s the simple explanation.  More detail on these subjects can be found at the following links.

Rocker arm geometry for shaft mounted rockers

Altering the rocker ratio by changing the pushrod length

Lorena, Texas (South of Waco)

Charley.  Your rocker arm is reusable as long as the adjuster screw still works freely.

 

I’m voting on defective cups on the pushrods and suspect that the problem will not end until all the pushrods have been replaced.  I observed a similar problem two weeks ago when breaking in a Y engine that was also Dove rocker equipped prior to performing a dyno session on that engine.  The pushrods I had trouble with are similar in manufacturing appearance to yours for what it's worth.

 

At ten minutes into the camshaft breakin period on the engine in question, one of the pushrods had chipped out the side of its cup.  It was subsequently replaced and camshaft breakin then completed.  At that point, two more pushrods also had chipped ends.  A hard look at the remainder of the pushrods showed four more with visible cracks in the cups.  At this point, all the pushrods were replaced with a stock tubular set of the same length (8.00”) and the problem was resolved.  Eleven dyno pulls and three intake manifolds later, the stock pushrods are still holding up just fine.  The final analysis on the broken pushrods was that the cups were slightly undersized allowing the rocker adjusters to not seat far enough down in the cup and that was simply putting too much pressure on the upper portion of the cup.  The Dove roller rockers in this case received a clean bill of health and were absolved of being the problem.

 

Here’s pics of the faulty pushrods, both the ones with chipped cups and those found with cracks.

 

    

 

And here’s a pic of the stock pushrod style that replaced the set in question and also a picture of some Smith Brothers pushrods going into another Y.

   

Lorena, Texas (South of Waco)

  Charlie, the spring wouldn't look any lower.  If you can imagine putting a huge shim under the spring, you would effectively restrict valve travel because the spring would collapse sooner.  Pulling the shim out would give more valve travel.  So would using springs with smaller diameter wire.  I have seen this problem before.

It's easy to check each spring by inching the crank and checking for more valve travel when each valve is fully open (down).  Rocker ratios, fulcrum points, and valve stem heights are secondary to valve stem stroke limits.  Some guys machine the tops of their guides to accommodate more travel (provided the spring has more travel left).  It's easy to see, when we marry different brands of parts, they may not be compatible when stacked.  Hope this helps, and I hope you check your other spring Shut-heights.

Dave

Royal Oak, Michigan (Four miles north of Detroit, and 12 miles NORTH of Windsor, Canada).  That's right, we're north of Canada.

Ford 292 Y-Block major overhaul by simplyconnected

Looking at both Teds and Charlies pushrods they do have a noticeable shiny area at the top of the cup, then the stock type cup that Ted posted has the shiny area in the bottom of the cup. the problem seems clear to me.

 By the way Ted, thank you for the pics of the Flathead pump. I sent you an email but it came back to me, I seem to have that problem everytime i send you something might want to look into that.

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

Dave

The heads were built by John Mummert. I'm sure they are designed to handle more aggressive cams than I'm using. He knew which cam I was using and so I'm sure the components he used will allow it to function as necessary. Combine that with the fact that I can see that the spring is not binding when the valve is all the way open. I probably have 5000 miles on the heads. If it is something to do with coil bind or inadequate clearance for valve travel, it wouldn't have lasted this long.



Tim and Ted, thanks for sharing your experiences and opinions. It looks like I should check my geometry and get a new set of pushrods. I'm going to look at the remaining pushrods of my old set and see how deep in the cup the wear pattern is.



Ted, the part number stamped on the pushrods is MVP - 73 or MPV - 73 or some variation of that. Do you what yours were and from where they were sourced?


Lawrenceville, GA

Johnson Rod,

You and I are alike.  We look for the professional written word before we speak.  I too was armed with the CompCams info on rocker geometry before I talked to JM.  Ted made the long story short by explaining the CompCams info was based on stud mounted rockers.

By the way Ted and Tim, thanks for agreeing with me on Charley's problem.

Charlie Burns Laton, Ca (South of Fresno)



BurnsRacing981@gmail.com