Rocker arm failure?

[Kiefer]

Rebuilt my AMC360, has about 5,000 miles on it now. The pushrod shot through the rocker arm. Anyone else have this problem. Thanks, Keith :razz: :razz: :razz:

[jeepsr4ever]

:shock:

[BREK]

Were you spinning high rpm's with stock valvetrain?

[fifesjeep]

"The pushrod shot through the rocker arm" #-o 8)
Wow.... that is both impressive and yet still disheartening... It actually went through the Rocker?... The only way I can sort of see that it is that the "cup" wasn't installed in the rocker and you were hitting some good Rpms to say the least... Please clue us in with more details.

[jeepsr4ever]

Ha what a great story, thanks for the phone call :?: :?:

[Kiefer]

Normal driving 55mph going down the highway, when all the sudden it sounded like a rod let go. Bad, Bad, Bad knock noise. I had oil pressure, but I shut the engine down really fast. Towed it to the hangar an tore into it. Dropped oil pan first expecting the worst, "DAM'" everything looked great. Had one black sparkplug, took the valve cover off and there it was, the pushrod sticking up through the rocker arm. Talked to Mike on the phone "GREAT" guy and offered to buy another rocker arm since it not his fault, but he insisted to ship another one free. Thanks again, Mike!. <PS> My daily driver is a 1986 CJ-7, AMC-360, 727TF tranny, dana 30 & 44 w/4:58 gears and ARB's front & back, 4-1/2 Rubicon w/1 "body lift running 35x12:5 Goodyear tires . :razz: :razz: :razz: :razz: :razz:

[fifesjeep]

Did you ever find the cause/reason etc?... Or was it simply just a weak rocker?... I've enver heard od such a thing until now... Awesome!

[Kiefer]

Don't no really the reason. Mike told me it sounded like the metal was over harden. The dimple where the pushrod tube seats in the rocker is where it let go and then it split the arm. Keith :lo1l:

[fifesjeep]

I heat treated a small piece of T6 aluminum the other day and for some reason I added an extra 1 in my math an I over treated it... Glad it was a test piece.. but anyway, it definitely made it to where the aluminum is soft/flakey.. a green scotch brite pad would remove material.... Crazy.. long story short... I found my mistake before my actual piece... treated my actual piece and it's BUTTER!

[ironman_gq]

i've seen rocker arms where the rod has worn a hole through the rocker. i've only seen it happen to a few stamped steel rockers though with lots of miles on them

[a440plus6]

i've seen rocker arms where the rod has worn a hole through the rocker. i've only seen it happen to a few stamped steel rockers though with lots of miles on them
I've seen it also on Mopars. I ALWAYS buy new ones when I rebuild a new one. Just cheap insurance imho.

[AMX69PHATTY]

Any chance the rocker was adjusted to tight,
allowed the valve to touch the piston,
and the pushrod to then end up poking thru the rocker ?
Guess there'd also be a bent valve then though.
Or was the rocker binding on the rocker stud ?
What rockers were they ?
The Harland Sharps with the bottom chamfer ?
What rocker studs ? or were they the Bridge type ?

[Wrench Man]

I've never seen an AMC do this but I've seen about 20 chivys do it!

[Kiefer]

The rocker was Mike's .015 gold anodised versions for increased oil pressure. Mike sent me a new rocker(exhaust) but after further completion I found that the rod on the Intake side was bent, the pressure had no where to go in the cylinder. I talked to several guys that run cars and they said! Bad rocker arm and that was normal on the same cylinder to bend a pushrod. I have use'd all of Mike parts, and I mean everything!, small diameter cam bearings, gold push rods, gold rocker arms, Oil pump, ect, ect. I cross drilled my crank and my Oil press stays at around 70-75psi all-day, I have seen it once drop to 60-65psi. But, "MAN!" am I happy with this engine. I've built around a hundred airplane engine's and this is my first attempt at a vehicle. Best Regards, Keith. :?

[Goose]

ummm who's Mike?? (just curious)

[Kiefer]

I have no idea why I keep calling Matt- Mike. :?

[jeepsr4ever]

I would look at the valve spring on your head. Sounds like it hit a piston and is very weak.

[Goose]

wow do you think thats why he keeps calling you mike?? some sort of "Head Injury??" (Sorry sometimes I cant help myself)

[Kiefer]

I installed the new rocker and pushrod and guess what?. Oil pressure at 70psi drops at idle at 65psi. I've had plenty of head inguries, I can remember numbers great it's just name's I have a problem with. Keith (83 toyo truck flip end over end 3 times, me going thru sun roof) 111!!!

[Holeshot]

Not enough oil going to the rocker & WAY too much oil pressure - you should be having 10~15 psi per 1,000 RPM (10~15 psi @ idle, 65 lbs @ 5000 RPM), anything over that is wasting horsepower, heating the oil up, and putting undue pressure on the distributor gears and timing gears.

Again, 65 psi @ idle is WAY TOO MUCH!!!

[jeepsr4ever]

Not enough oil going to the rocker & WAY too much oil pressure - you should be having 10~15 psi per 1,000 RPM (10~15 psi @ idle, 65 lbs @ 5000 RPM), anything over that is wasting horsepower, heating the oil up, and putting undue pressure on the distributor gears and timing gears.

Again, 65 psi @ idle is WAY TOO MUCH!!!

Depending on the viscosity this is not too much cold. 70psi is where the stock spring (in good condition) is rated at. Remember Dave that these pressure are optimum with a cold engine and can/will drop up to 15psi on a rebuild

[ironman_gq]

what kind of pressure increase can be expected with small hole pushrods on a rebuilt engine with fresh bearings and pump

[jeepsr4ever]

Well we had a couple guys get 65psi on start up and 50psi warm with

1. smaller hole cam bearings
2. smaller hole pushrods
3. smaller hole rocker arms


These were rebuilds with new timing covers.

[Holeshot]

Last time I had that kind of pressure the oil filter inflated like a grapefruit!!!

I still say that 50 psi warm @ idle means you are giving away HP, heating the oil, & pushing the distrib gears & timing set more than needed.

[Kiefer]

Hi Holeshot,
I replaced the rocker arm (exhaust) and the pushrod (intake). Fired her up, oil pressure at 70 it will drop to 65 when it's warm. I used Matt's undersized pushrod's, rocker arms, cam bearings, and nickel plate oil pump housing and gears, also I used his hardend cam and distributor gears. It's running perfect. No complaints. Keith :lo1l: :lo1l: :lo1l: