Engine: V8 pushrod wear theory and practice

[PackardV8]

I've got a project going and recently I asked our members here for any '51-61 pushrods which were never going to be used. Several of you responded and I received the first batch this week.

Naturally, they were from pre-detergent oil engines, covered with crud. After a trip through the pressure hot cleaning and the shot blast cabinet, I examined them carefully. Some had to be discarded because of serious rust pits. A couple were bent.

Holding more than fifty clean used pushrods and inspecting the ends is enlightening. Some have definitely worn more than others. There are substantial length differences. (Stude allows a .048" difference in max/min length; that's huge!)

The good news is Studebaker chose a 3/8" diameter tip. That's much larger than the Packard/early Mopar 1/4" tip or most later V8s with 5/16" tips. The larger diameter spreads out the load.

Bottom line - in all my reading and in all my years of building Stude V8s, I've never seen any published data nor personal experience which definitively identifies when a pushrod has to be replaced. Naturally, in this exercise, I chose what seemed to be the best ones, but other than the subjective eyeball, anyone else have a reference or a method?

The mating surfaces, lifters and rockers, are even more difficult to examine and determine. I use new lifters, but there are no new rocker arms. Same question, what are our criteria and how do we determine go/no go.

jack vines

[RadioRoy]

Definitely if it is bent, it has to go. Straightening it would probably leave it in a weakened state and liable to be bent again.

Are the ball ends hardened? Could any ridges in them be smoothed out, or would that make them too short?

Are there any shot peening process to be used, such as with connecting rods?

[PackardV8]

Definitely if it is bent, it has to go. Straightening it would probably leave it in a weakened state and liable to be bent again.

Only if the side of the tube is kinked. If it's a simple curved bend, straightening it would not leave it weakened. We straighten rods, cams, cranks all the time. Only reason not to spend labor straightening pushrods is they're a low-value part. I definitely toss the rusty ones.

Are the ball ends hardened?

Yes, they're hardened

Could any ridges in them be smoothed out, or would that make them too short?

Not really practical.

Are there any shot peening process to be used, such as with connecting rods?

No, ends are already hardened and tubes are not forged, so shot peening doesn't really help them.

For my really high performance engines, I have custom pushrods made up. They're about $200 a set installed.

jack vines

[fatboylust]

A suggestion: using a new rod/lifter/rocker (from a brand X of your choice) and Dykem-blue high spot paste with the spray developer test the fit between the mating parts. Using this reference check the old parts looking for similar contact. Use the best of the bunch. Spherical tolerances during manufacture are among the most challenging needing specialized tooling so I am not surprised the data is not readily available . This would be similar to blue checking valve seats just in more three dimensions at once. Hope this helps.

[Mike Van Veghten]

fatboy -

Not neaarly as simple as that. NOTHING...from other makes is a snap-in situation...!

All one can do is what Jack has stated -
1. check for bends

2. check the balls (both ends) for odd wear NO...wear on the "end" would be allowed. They should wear on a diameter just slightly larger than the "exact" same dimeter as the rocker or lifter. The rocker cups normally have a second smaller diameter machined spot right at the center of the wear area

3. check for bad rust (some small pits woud not make it a throwaway for anything but the real hot rod engine.

4. make sure the ball is tight in the shaft/tube.

5. sort per length.

At that point, clean, lube and install.

Mike

[fatboylust]

Mike, I think maybe you misunderstood. I am not suggesting using the new brand X parts in place of the Studebaker parts. Only to gain a sample as to what the fit looks like for new parts intended for similar duty. Then checking the Studebaker parts to determine if they show similar contact patterns. I am not making this up, this method is used to check the fit of high pressure steam throttle valve disk/seats, push rods ends are just smaller. The steam valves have a defined acceptance criteria. The Brand X check is just a way to establish some basis of comparison.

[PackardV8]

Dykem-blue high spot paste with the spray developer test the fit between the mating parts. Using this reference check the old parts looking for similar contact. Use the best of the bunch.

Actually, that's what I just did on a recent build, checking the new custom pushrod fit into the used rocker arm adjuster socket.

On the '56J front, our friend Joe Hall just had a problem with a high-miles Packard V8. He noticed the pushrods weren't rotating. His first thought was incorrect taper on the reground cam. I sold him another reground cam and still no rotation. I sent him new lifters, still no rotation. All that was left were the rocker arms. The Packard V8 pushrod uses a too-small 1/4" tip. Over 250,000 miles, the tips had worn into the rocker socket enough to be captured so they couldn't rotate. He replaced them with lower mile rockers and was rotating.

jack vines

[PackardV8]

Big thanks to Gord Richmond and StudbakerCenterofOregon for digging out some early V8 pushrods I'm passing a couple along to Neil Wollam for a build he's doing.

jack vines

[Bills R2]

The market for new Stude rockers has to be a no-brainer. 16 per engine?
+ all the Caddie V8s being built.
Somebody is doing roller rockers for the IH V8 for God's sake!
A batch of 1600 would not last long.

[PackardV8]

The market for new Stude rockers has to be a no-brainer. 16 per engine?
+ all the Caddie V8s being built.
Somebody is doing roller rockers for the IH V8 for God's sake!
A batch of 1600 would not last long.

First set of roller rockers I ordered from Harlan Sharp in 1990 or so was $250. Most recent set was $500. They've always been available, just not at CASO prices.

jack vines

[427mike]

Jack,

Do you happen to know the radius on the stock studebaker pushrods (1961 and up) I am building a 1961 289 and had the cam reground to R1 specs. The push rods seem to be too short because I have about 4 to 6 threads showing under the rocker arm when adjusted at .026. I talked with Smith Brothers and they need to know the diameter and radius. Also, do you happen to know the wall thickness, they recommend a .083 wall I think. (i will have to check) I do have the longer pushrods approx. 11 3/8.

http://s189.photobucket.com/user/mikebeth_2007/library/Studebaker?sort=3&page=1#/user/mikebeth_2007/library/Studebaker?sort=3&page=1&_suid=139774732270105671904709625861

Here is a link to my pictures. I have a current post on this you might have read.

Thanks Mike D.

[gordr]

Doesn't the speed parts industry make roller rockers for Chevy, Ford, and Oldsmobile engines? How hard would it be to adapt some brand X roller rockers to a Studebaker head? If the overall length, and lift ratio were in the ballpark, wouldn't it just be a matter of making the necessary adaptations to fit the fit the roller rocker shaft to the Stude rocker arm stands?

[PackardV8]

Do you happen to know the radius on the stock studebaker pushrods (1961 and up)

Stude uses 3/8" tube and 3/8" balls. Never order pushrods by phone or e-mail, because the way they measure length is something only they understand. I'd send Smith Bros a sample and say. Make mine .0XX" longer than this. That way, there's no possibility of misunderstanding.

Doesn't the speed parts industry make roller rockers for Chevy, Ford, and Oldsmobile engines? How hard would it be to adapt some brand X roller rockers to a Studebaker head? If the overall length, and lift ratio were in the ballpark, wouldn't it just be a matter of making the necessary adaptations to fit the fit the roller rocker shaft to the Stude rocker arm stands

Yes, Gord, over the years, many different rocker arms have been adapted to the Stude head, including the big block Chevrolet stud mounts. If a CASO also is an engineer and understands all the very complex interrelation of valve train geometry, it can be done. However, I've seen more which made things worse than better. It's not as simple as it may look at first.

No, I'll never go that way again. Even the $500 cost, Rocker Arm Supply and Harlan Sharp are a better deal than roll-your-own.

Maybe, one should be defining the goal. Both the Rocker Arm Supply and Harlan Sharp are roller tip, but plain shaft bushing. GM, on their new 600hp supercharged LS engines, chose to go with a needle bearing on the shaft, but a plain tip rocker instead of a roller tip. They say roller tip rockers don't add any horsepower, but are a major wear point. It's the shaft which needs the needle bearings.

jack vines

[427mike]

Thanks for the help Jack. How many threads do you recomend seeing under the rocker arm after adjustment. I want to get my pushrod length correct the first time.

Mike D.

[Mike Van Veghten]

All this swap talk, even with the stock rockers, another thing most don't realize, it the rocker "location", rotation wise.

After taking apart a virgin 259, I noticed that the wear pattern is at the very "tip" of the rocker. Notice I said a "virgin". It's documented that this engine has never been apart past one rocker adjustment...until I got ahold of it... right at 30,000 miles !
Anyway, the wear pattern "suggests" that the geometry is/was off. This will throw off the lift of the valve.
BUT...since these rockers are so rough in design and machining, without drawings, I don't know where the actual "as designed" center of the rocker (valve end) pad is supposed to be..!
I can do some measuring and lay it out in a computer program (AutoCAD), and or just do the math, but for a daily driver is it worth the time to find the designed center to make sure my geometry is where it's supposed to be to get full valve lift....yaaaa...maybe, we'll see !?!

If the rockers aren't at the correct angle in the "as run position", you will be loosing valve lift.

Right now, after porting the heads on the above engine, the heads are just "sitting" on the block (not torqued) until I get a few other things worked out. I took one rocker assembly apart for cleaning, deburring and reasembly. I'll probably mess with finding the location of the 1.5 ratios location on the rocker pad and shim the rocker stands to suit. Unfortunatly, it's kind-of-a time consuming project..and I seem to have misplaced my 3lb valve springs..!

Mike