Rocker arm breakage?

[Daily02]

Has anyone here experienced a rocker arm failure? When I was looking for an '02 I ran across some, or is this something that only commonly occurs on race or well worn motors? 

I was just wondering if the Ireland Engineering collars would be overkill for street, Autocross, canyon with a near stock motor.

 

Regards

 

Dono

[tzei]

On a race engines - yes.

 

If you spend lot of time beyond 7300-7500 rpm (ish) then the risk is elevated.

02 era r/arms are better quality than newer "E21 era" onwards style.

[Mike Self]

Yeah, a friend just had that happen to his stock and relatively low mileage (125k +/-) '73.  Fortunately he shut it down before further damage occurred.  

 

And it happened to my '69 many years ago, but it was caused by a defective valve (from the factory--all 4 were) whose seating surface wore away, allowing the valve to pull up into the intake port and break the rocker.  

 

mike

[d.hitchcock]

Data point: Broke a rocker in the M20 of my old e30. It was high mileage and autocrossed heavily with an elevated 7k redline.

If you're getting a project car, then you would likely want to have the head freshened up anyway, no?

[Senna27]

I've never had a rocker arm break, but I decided to replace them when I had my head refreshed at 185,000 miles. New parts included HD valve springs, HD rockers, rocker locks and a '292 cam. 

 

 

 

[TobyB]

Rockers seem to only break when the valves float.

 

On a stock engine with good springs, this seems to happen at somewhere

over 7k on a long overrun, or on the rev limiter.

EVEN with the newer Febi rockers, WITH voids in ugly places.

 

Yes, if the valves are badly out of lash, or the cam is badly worn, then

they can probably float and break at lower revs.  But it'd be pretty noisy at that point.

 

I've measured a bunch of original springs- there may be ones that sink (shorten) but 

I've found exactly zero- and I've used 'old, original' springs with an auxiliary spring

on several race heads.

 

Given the rash of (historical) problems with HD rockers, I have yet to use them.

However, I limit whatever's in the car at 7600, and don't let it sit on the limiter there

(except for once, when I discovered the abovementioned voids)

With a cam that (barely) fits into the stock journals.

 

Yes, you can go nuts.  But it's not worth it unless you're going significantly over

stock revs, and way more cam ramp than a 292 (which is pretty close to stock, in ramp rates)

 

And I've never had any engine damage from driving it back on 3.  I even finished one race

that way, as I needed the points for a finish.  So, 5 or 6 laps at Spokane's maybe 10 miles?

 

t

has only broken 3 or 4.

 

[Daily02]

Great information. It sounds like a valve float issue. I'm not planning on revving above the rexommended 6200rpm (I bet it will run out of power by then anyway).

The former owner had the head replaced not long before I acquired it. So hopefully the springs were replaced. 

I have the IE collars, but the side load springs would need to be removed to install them. I wonder how hard this would be with the head on the car? The collars seemed like cheap insurance.

 

Regards

 

Dono

 

 

[Brandon]

I went through several broken OE rockers on my track car and finally replaced them with Ireland’s billet aluminum rockers with the collars on the rocker shafts, solved the problem.  I’ve heard of rockers breaking on stock engines though I’ve never seen it myself.

 

 

 

Edited November 30, 2022 by Brandon

[jgerock]

On my 69, I replaced all the rocker arms and both shafts with febi parts.  I removed the rough parting casting edges from the new rockers using a Dremel tool.  Assembly hardware was sourced in kit form from Walloth Nesch.  

[BarneyT]

    My son Kane just broke one on his car, my original car…first time in 45 years to have a rocker fail… the 38/38 was pouring gas out of one jet i think it fluid locked the cylinder and broke the arm every thing else seems good, half way there waiting on new rocker arm.

Edited November 30, 2022 by BarneyT