Rocker Arm Failed. What now?

#21

leggwork wrote:

[quote]Steve D wrote:

[quote]Actually, the rule permitted billet arms, but those widely (albeit expensively) available are not the same size and shape as stock.

Steve D.[/quote]

so if they’re not the same size and shape as stock, how did the old rule allow them?
bruce[/quote]

Bruce -

My point is that your statement that the “old rule never allowed billet rocker arms” is a misstatement. Billet was legal. Billet arms (or those of any other material) that differed in size and shape were not.

Steve D.

#22

IndyJim wrote:

[quote]So along this same logic are forged pistons legal?

Same, size, compression? Weight isn’t specified in any documentation I can find?
[/quote]

9.3.1.2.2. All pistons, including aftermarket replacements, shall be factory replacement spec
and match factory dome, dish, valve relief depth, ring groove placement, weight and
wrist pin height; compression shall meet factory replacement specifications. The
maximum allowable overbore is limited to the largest available factory replacement
piston, not to exceed .020 inch.

We have some lovely parting gifts… :stuck_out_tongue: Weight may not be specified, but it is readily discernable. I would suggest going just a little lighter than the lightest factory one you have in your collection. :wink:

Steve D.

#23

But again using the same logic if is the same in all other aspects the rule as written does not prohibit a forged piston, same as the billet arms.

#24

IndyJim wrote:

Agreed, but does a forged piston of the same weight offer any advantage? I thought forged pistins could be lighter at the same strength, hence the advantage?

The piston rule and the old rocker rule are as different as can be. The rocker rule only specified size and shape, IIRC.

Steve D.

#25

Night and day different. I’ve heard improved or more consistent sealing.

#26

ok, I had in mind the commercially available ones.
bruce

Steve D wrote:

[quote]leggwork wrote:

[quote]Steve D wrote:

[quote]Actually, the rule permitted billet arms, but those widely (albeit expensively) available are not the same size and shape as stock.

Steve D.[/quote]

so if they’re not the same size and shape as stock, how did the old rule allow them?
bruce[/quote]

Bruce -

My point is that your statement that the “old rule never allowed billet rocker arms” is a misstatement. Billet was legal. Billet arms (or those of any other material) that differed in size and shape were not.

Steve D.[/quote]

#27

IndyJim wrote:

With all my engine troubles I had lots of interesting conversations with smart folks. I was told that the biggest advantage of forged pistons is that forged steel is harder (because of the “work” done on the steel during the forging process, for you metallurgists out there). The stronger steel means that the rings don’t deform the grooves as readily. Grooves that keep their shape better more accurately position the rings, and that results in engines maintaining good compression numbers longer into their service life. So it’s not so much a performance advantage as a longevity advantage. At least that was their take.

#28

Ranger wrote:

[quote]
With all my engine troubles I had lots of interesting conversations with smart folks.[/quote]

And then Ranger comes here to make himself feel smarter.:blink: :wink:

Steve D.

#29

Steve D wrote:

[quote]Ranger wrote:

It doesn’t take a rocket scientist to ask questions and repeat what they said.

Steve, we’re your friends here. If you’re pissed, go kick your dog and yell at your children or something.

#30

Ranger wrote:

[quote]Steve D wrote:

[quote]Ranger wrote:

It doesn’t take a rocket scientist to ask questions and repeat what they said.

Steve, we’re your friends here. If you’re pissed, go kick your dog and yell at your children or something.[/quote]

Not pissed at all. Sorry if I gave that impression. Just s little self-deprecating humor gone awry. My apologies.

Steve D.

#31

That price almost certainly means that the head incorporated used rocker arms. And they could be the old design, new design, or a mix. A set of new rocker arms would be about half of what you paid for the reman head.

#32

Rocker arms are problematic if not adjusted correctly or not blueprinted. I have seen blueprinted stock rocker arms last years when kept under 7000rpm. So, blueprint your rockers to the original BMW specs and if you don’t shift down too soon, you should never have problems. Chuck

#33

Ranger, didn’t you mean to say: ‘It doesn’t take a Rocker scientist?’

#34

Back to the fix, please.
How can I determine if this valve, under the broken rocker is seized or moving properly? I’d like to determine this before installing the new arm and, then, breaking it due to a stuck valve.
I thought of turning the engine by hand through a full cycle to see if the new rocker/valve combo moves ok. Any other suggestions?
Thanks.

#35

Short of pulling the head and removing the springs on that valve there’s no good way of making sure that the valve moves freely. So I’d say that you have two choices. Replace that rocker and see what happens, or pull the head, disassemble it and check everything, and reassemble with all new rockers if no other problems are found.

#36

Jon, we’ve done lots of rocker arms at the track. Never seen a problem after the replacement with the corresponding valve. Call me and I can give you some removal tips.

My motto, try the cheap fix first and spend money only when you have to.

Robert 770-886-2500

#37

Agreed on cheap fix first. I’ll give you a call; I hope to replace the rocker this weekend. Thanks.

#38

FWIW, why can’t you check to see if the valve is seating (should be if moving freely if spring pressure adequate to seat valve). You can do this by checking compression or adding air to the cylinder and see if any audible leaks are present. A compression guage setup with a removable guage allows you to connect a air hose to the hose that connects to the spark plug hole. Use low pressure - 20 psi. You will hear a leak.

You can also compress valve manually by pressing on stem to see if it moves freely.

My 2c. Agree with Robert - have actually witnessed RP assisting in several valve replacements at track with good results.

Ed

#39

From the MA forum, I think someone else may have broken one too from the reports. For a part that no one has had any trouble with these sure do break a lot. So much that the guy that makes the rules (to be accurate head of the rules consortium) carries extras…

#40

IndyJim wrote:

From the MA forum, I think someone else may have broken one too from the reports. For a part that no one has had any trouble with these sure do break a lot. So much that the guy that makes the rules (to be accurate head of the rules consortium) carries extras…[/quote]

There was two broken ones at this event. Both replaced and back running with no issues.