Need opinions re: rockers

[GeorgeK]

I have these 9 rockers, early forged style.
Which ones can be used? I am rather naive regarding this, so please let me know your thoughts. Polishable? useable, tossable?

[Tim Walsh]

one question,
why use the forged rockers since porsche redisigned them to be the weak link in the valvetrain?

[GeorgeK]

I wish I knew.
They are technically not for me, but I am curious as to their health. Can these be polished/ re-hardened/machined?
I know they should go in a HIGH-power engine.

[GeorgeK]

Come on, no one wants to give an opinion?

[Shuie]

Are they from anything exotic?

My situation is probably not similar to yours, but I was told by my machinist to just buy new rockers. If you get them resurfaced, make sure the machinist has the correct fixture.

[camgrinder]

My vote is for "tossable".
Most are worn, a few scuffed.
Some early rockers had the radius pad chrome plated. These rockers are not rebuilable at a reasonable cost.

[emcon5]

Sorry for the hijack, but are used rockers worth anything? I replaced mine when I rebuilt my engine, and still have the full set (115K mile) in the garage somewhere.

Tom

[camgrinder]

Hey Tom, I will buy them for $20

[Wayne 962]

Forged = Bad. Porsche designed the later rockers to be "breakable" upon impact to protect the rest of the valvetrain. They found the forged rockers were too strong, and if piston / valve impact occurred, they resulted in bent valves...

Toss the forged ones, and buy new cast ones...

-Wayne

[Henry Schmidt]

Originally posted by Wayne at Pelican Parts
Forged = Bad. Porsche designed the later rockers to be "breakable" upon impact to protect the rest of the valvetrain. They found the forged rockers were too strong, and if piston / valve impact occurred, they resulted in bent valves...

Toss the forged ones, and buy new cast ones...

-Wayne

It is true that Porsche redesigned the later rocker to be breakable but I'm not certain that cost was not a major factor in that equation. Still most if not all early factory racing engines were built with forged rockers. It has been my experience that forged rockers offer better reliability, are lighter and have a slightly better rocker ratio [more valve lift]. Porsche has redesigned their cast rockers for more strength over the years making them ever heavier.
If your concern is survival after valve/ piston impact, perhaps greater valve to piston clearance, ty retainers, Supertec valve springs or a simple rev limiter make better sense.
Racing engines encounter extreme conditions requiring better parts but if the parts are better for racing they are quite often better for every day use.

BTW: If you have valve to piston contact that does not bend the valve you must still replace the valve or risk the probability of the valve breaking during ordinary use.

If you are planning on throwing early forged rockers away please throw them in my direction.

.

[jase007]

A reason why they are cast ...



and another ...



Overrev on a 2.0L race motor we run. Replaced, drove around the paddock, did a leak down and #s were marginal (besides dmage to valves) ... called it a weekend.

Jason

[Henry Schmidt]

With proper valve to piston clearance and SUPERTEC valve springs, there is a good possibilty that you would not have needed breakaway rockers.
BTW: we have seen cast rockers break on over rev with absolutely no valve contact. At first we thought coil bind, but after inspection we determined that the cause was just stress.

[jase007]

BTW: we have seen cast rockers break on over rev with absolutely no valve contact. At first we thought coil bind, but after inspection we determined that the cause was just stress.

So have we. Especially on BIG overrevs. (Telltale tack and reset is out of the driver's reach.)

We had "special" valves in there and some other tricks. Won't get into details as several of our competitors are on this board .

Ever get a measurement on how much force it takes to brake the forged ones versus the cast ones? Just curious.

Jason

[snowman]

I would suggest going to a Porsche machine shop like Ollies and ask them what they think and how much to resurface.

I strongly suspect that they would recommend resurfacing and using what you have.

PS if you don't want to send them to Henry, please send them to me.

[ANTONIO]

I supprt Henry's assesment.,cheers,Antonio.