451 Road Runner woes

[lewtot184]

picture of all the adjusters i've seen or used with the exception of harlin-sharp. the top adjuster is the interference thread used on 318 poly engines. the second is the early slotted head that has been obsolete for years and i believe to be the one that needs a couple of threads showing. the last two are what is currently availiable, to the best of my knowledge, and doesn't need threads showing due to it's extended length. if you compare the balls between the second and third you can understand why the second needs to be extended further below the rocker to clear higher lobe lifts. the second isn't an actual ball either. the third type was probably introduced due to higher lobe lifts and to keep the push rod cup from binding at steeper angles. anyhow, thats my take on the whole thing.

 

[cdr]

the adjuster did not cause the rocker arm body to break, it is a lack of oil through the shaft. if it was an adjuster problem all of them would be toast.

 

[747mopar]

the adjuster did not cause the rocker arm body to break, it is a lack of oil through the shaft. if it was an adjuster problem all of them would be toast.

Agreed, that many discolored rockers really points to friction which could be clearance issues but most likely an oiling problem. I really think the cam bearing needs to be checked for proper alignment and the shafts checked as well.

 

[Jeremiah]

I agree that the adjusters are out of whack but I'd also like to see the bottom of the broken rocker, specifically on the side towards the valve spring. Also look for signs on other cylinders of the rockers hitting the valve spring retainers, etc.

 

[lewtot184]

i posted the adjuster pictures for reference only. i do believe there's an oiling issue and with the "hot" looking rockers i wonder if there's a restriction in the heads. after looking at the first photo more carefully i can see what may be too long of a push rod. if i were hunt2elk i'd go back to the builder person to make sure no restrictors were put in the heads or block and re-do the whole valve train.

 

[Shorthorse]

The actual number count of threads exposed is not really the issue. The objective is to have the push rod in a position to accept oil from the rocker arm. That's why some manufacturers have a recommended thread exposure. Because of modifications to the heads such as milling, thinner head gaskets etc, the push rod length is the final determination made when assembling the valve train. If the push rod is too long it will not get oil and like lewtot184 said the cup can bind on the rocker at full open. Binding will result in bent push rods. If the push rod is too short it will put undo stress on the adjuster. Checking for proper push rod length is a must. I have two checkers. One for intake and one for exhaust. Forty bucks is a whole lot cheaper than a new set of rockers. You might get lucky with across the counter push rods but companies like Manton and Smith Brothers provide an excellent product and great customer service.

 

[Shorthorse]

Agreed, that many discolored rockers really points to friction which could be clearance issues but most likely an oiling problem. I really think the cam bearing needs to be checked for proper alignment and the shafts checked as well.

View attachment 277524

If that's so, it will be easy to tell by the condition of the rocker bushings and shaft when the unit is disassembled.

 

[lewtot184]

i have a new performance hydraulic flat tappet cam that upon inspection the intersecting oil passages at the #4 journal were not completely drilled thru. if this cam had been installed i'm sure the valve train would've been smoked.

 

[GrabberOrange69]

Isn't the Proforms the ones that are not recommended on Mopars? I've used the 'old' 1604 Isky's for years and turned one engine 7300 and 660 lift with them. They are ductile iron rockers and non needle bearing. What's out there these days that is similar to them?

Those ductile iron jobs are great. I have a few sets of them and personally avoid aluminum rockers on my street car. Aluminum has no regular fatigue limit and can break at any time.

"Ferrous alloys (a.k.a. steel) and titanium have a threshold below which a repeating load may be applied an infinite number of times without causing failure. This is called the fatigue limit, or endurance limit. Aluminum and magnesium don't exhibit an endurance limit, meaning that even with a miniscule load, they will eventually fail after enough load cycles"

 

[HT413]

Those ductile iron jobs are great. I have a few sets of them and personally avoid aluminum rockers on my street car. Aluminum has no regular fatigue limit and can break at any time.

"Ferrous alloys (a.k.a. steel) and titanium have a threshold below which a repeating load may be applied an infinite number of times without causing failure. This is called the fatigue limit, or endurance limit. Aluminum and magnesium don't exhibit an endurance limit, meaning that even with a miniscule load, they will eventually fail after enough load cycles"

Bingo. That's why my 451 will be running ductile iron; aluminum is great for bulk items like pistons and heads, but high stress areas need iron (IMHO).

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And for me, on a street car a non roller rocker is every bit as efficient as a roller... so long as it is well oiled.

 

[lewtot184]

i like the crane ductile irons and have used several sets. but, there ain't no free lunches. the limits to the ductile iron are geometry issues at high lift and galling at the fulcrum point. when using ductile iron on stock shafts the fulcrum points will gall up and erode and i think this is due to similar metals in contact with each other. induction hardened shafts with oiling grooves do help. keeping lifts at the valve at moderate levels helps geometry and using moderate spring pressures adds to durability.

 

[dvw]

In my opinion push rods didn't cause any of this. Even if the length was off a little it wouldn't have caused the rockers to turn color. This is a lack of lubrication between rocker and shaft. Rather than talk about who did what lets get the rockers off the shafts and see why they got hot. Are the oil holes plugged or open? Since the entire shaft feeds all the rockers why are some in the middle hot? If the shaft had no oil it would've taken them all out. How do the other rocker bores look? I've never seen an engine diagnose itself without disassembly. Also why is the adjuster on the broken rocker backed out so much further than the one in the picture next to it?
Doug

 

[hunt2elk]

Got a little time this afternoon to mess with the car. I pulled the rocker assembly and turned the oil pump with a drill. While doing this, I turned the crank to try to find the oil passage. Not a drop of oil came up to either head. I accidentally had the sender unit out and oil did spray out there as soon as I hit the drill. I am positive I never lost pressure on the gauge when the motor was last run.

 

[dvw]

You need to align the cam passageways exactly or you will not have any oil to the heads. Only one head passage will line up at a time. Run the drill and move the crank
a little at the time. If there is no oil the #4 cam bearing may have spun.
Doug

 

[hunt2elk]

You need to align the cam passageways exactly or you will not have any oil to the heads. Only one head passage will line up at a time. Run the drill and move the crank
a little at the time. If there is no oil the #4 cam bearing may have spun.
Doug

Yep, that is what I did. My son kept the drill going and I slowly turned the crank. I turned the crank around at least 3 revolutions. So the #4 bearing controls all the oil to the heads?

 

[Shorthorse]

Got a little time this afternoon to mess with the car. I pulled the rocker assembly and turned the oil pump with a drill. While doing this, I turned the crank to try to find the oil passage. Not a drop of oil came up to either head. I accidentally had the sender unit out and oil did spray out there as soon as I hit the drill. I am positive I never lost pressure on the gauge when the motor was last run.

What was the condition of the rocker shaft and individual rocker bushings? Especially on the discolored ones as opposed to the ones that don't appear to have gotten hot.

 

[Garys1969RR]

Yep, that is what I did. My son kept the drill going and I slowly turned the crank. I turned the crank around at least 3 revolutions. So the #4 bearing controls all the oil to the heads?

Oil is fed to the bottom hole of the #4 cam bearing which has 3 holes in it. Also the #4 cam journal has a passage drilled thru it, but not straight thru. So when the holes line up as the cam rotates, oil goes thru the bottom hole, thru the cam journal, and into the block passage that leads up to the rocker arm shaft # 4 pedestal. Same thing on the other side. You can always spin the oil pump while cranking the engine with the starter, with the rocker shafts OFF, and you should get oil flowing to the #4 shaft pedestal. If no oil flows, then the cam bearing is most likely not installed properly.

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So yes, the #4 cam bearing supplies all oil flowing to the rocker shafts.

 

[747mopar]

Oil is fed to the bottom hole of the #4 cam bearing which has 3 holes in it. Also the #4 cam journal has a passage drilled thru it, but not straight thru. So when the holes line up as the cam rotates, oil goes thru the bottom hole, thru the cam journal, and into the block passage that leads up to the rocker arm shaft # 4 pedestal. Same thing on the other side. You can always spin the oil pump while cranking the engine with the starter, with the rocker shafts OFF, and you should get oil flowing to the #4 shaft pedestal. If no oil flows, then the cam bearing is most likely not installed properly.

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So yes, the #4 cam bearing supplies all oil flowing to the rocker shafts.

Agreed, Just look at the pic I posted and you'll see the passage but it doesn't illustrate the L shaped hole drilled threw the actual camshaft. So either your cam bearing is installed incorrectly, the cam isn't drilled (very unlikely) or something is plugged up but if your not getting oil to either side it all points back to that cam bearing. Either your builder doesn't know Mopars or it spun.

 

[hunt2elk]

So what would cause the #4 cam bearing to spin if that's what happened? This motor ran great for 475 miles, so whatever malfunctioned had to have happened recently. Even now, there is still oil sitting on the tops of the heads. On the passenger side it is more of a black thick paste though.

 

[Garys1969RR]

I think if you put #1 cyl at TDC on the firing stroke, one of your cam oil passages will be perfectly lined up to deliver oil to one of the rocker shafts. I know it was on my 451 build. Then I had a hard time getting the other one lined up. I really would try this method once before proceeding any further.

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The motor will run for a little while with no oil to the head. I dont know how long. I suppose you could also stick a long steel rod down the oil feed hole (with the cam out) and see if it protrudes thru the cam bearing hole. Should be able to see it with a flashlite.

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If you have dried oil paste on the cyl head, you are not getting fresh oil up there. You should have plenty of fresh liquid oil sitting on the head under the valve covers.