Resurfacing rocker arms twice?
 

I have a set of rocker arms from a 2.0l. When I took it apart I saw that the rocker arms most likely have been resurfaced before, is it possible do it again?

http://img503.imageshack.us/img503/9397/car014wp8.jpg

http://img521.imageshack.us/img521/4848/car012tb9.jpg

Early 2,0 rockers have silver-solder on the rubbing face I believe. This would need to be removed and built up and then the rocker face resurfaced.

Also you may have the short 18x48 rocker shafts with the small pinch bolt vs. the later type, this is simple enough to measure.

John,

Those early steel rockers are hard-chrome faced and shouldn't be re-ground.

Steve is correct
The contact surface is hard chrome. I believe it can be replaced with a more modern process call thin-dense Chrome.

Here is a place to have your forged early rocker (both solid and adjustable) rebuilt.
The cost to recondition each arm is $45 USD and Mike Reed at "Electronic Chrome and Grind" is the preferred source for reconditioning these very rare racing parts, "Webcam" uses his services exclusively!
You can reach Mike at (562) 946-6671, they are located in Southern California at
9132 Dice Road, Santa Fe Springs, CA 90670
Website http://www.ecgrinding.com

These early rockers are well worth restoring. They are without doubt stronger and they also have a slightly better rocker ratio. 1.5:1 vs 1.45:1 if memory serves me.

Thank's for all the info...

I measured and they have the shorter rocker shafts. Can these rockers be used with the longer (later) shafts and would that be a benefit?

Steve said these rockers shouldn't be re-ground, can they then be used as they are with new cams?

Henry, the cost of recondition the is $ 45 USD each... what would I have to pay for a set of reconditioned later style rocker arms?

Sigmund,

You can buy a used set of cast-iron rockers, contact Tom1394Racing (Tom Butler)- he sold me the set I used. Ollies reconditioned them and rebushed, they are ready to go.

The trouble with the short shafts is I believe they use the smaller diameter pinch bolt.

http://forums.pelicanparts.com/uploa...1171291328.jpg

http://forums.pelicanparts.com/911-engine-rebuilding-forum/343519-rocker-shaft-pinch-bolts.html?highlight=inbus

John

Do you have an e-mail address for Ollie's?

This set on Ebay looks like a reinforced Carrera set (stronger than earlier styles) and Ed can ship them to Walt @ competition Engineering to get them properly rebuilt.

http://cgi.ebay.com/ebaymotors/Porsche-911-Rocker-Arms-Shafts_W0QQcmdZViewItemQQcategoryZ33624QQihZ005QQi temZ150260299079QQrdZ1QQsspagenameZWDVW

Walt at Competition Engineering is a great choice for all Porsche machine work.

www.competitioneng.com

Email: compeng@gte.net

$23 and change shipping for the above rockers/shafts. Hmmm. Reminds me. Sellers don't pay Ebay the amounts collected for shipping.

Sherwood

Hello P-car engine/rocker pad experts,

I found this thread after looking at the condition of my rocker pads (surface that rides on the cam).

Car: 89 3.2, rockers resurfaced at 72k miles, now 98k. Cam reground to 964 at 72k miles by cgrinder. Cam surfaces look fine. Oil BP 20-50. Rockers resurfaced at a place near San Jose CA. , I was told, it is "farmed" out. Some of the rocker pads look fine, about 1/2 of them.

Walt viewed these pictures and said it looks like surface not hard enough. I agree this is the most likley cause. I'm not second guessing Walt just wanting some more ideas and comments. I found this situation while taking all the rocker shafts out and checking sealing leaks and installing new rsr seals. This is on another thread called rocker shaft fretting. I just wanted to get more opinions that surface hardness is the issue and what to do from here. Since I have the engine out of the car I might as well resolve this if it won't last another ~ 20k miles.


The picture editing I did sort of makes things look bad, you can feel the pattern with your fingernail.

Thanks very much for additional comments.

http://forums.pelicanparts.com/uploa...1273414825.jpg



http://forums.pelicanparts.com/uploa...1273414856.jpg

Update - I found a wear pattern.
Cylinders 1,2 and 3 both intake and exhaust rocker pads have this type of wear pattern.

Cylinders 4,5 and 6 exhaust look very good, almost no visiable wear marks, 6 intake has a mild form of the "pitting" problem.

Does this mean - lubrication issue on the drivers side bank? I have the updated oil line restrictors installend and using Brad Penn 20-50.

Those rockers are forged and if you jump time, they dont break but brake everything below them.
ruce

I'm not real good at interpretation.... I take that to mean the the condition of the pads will eventually or soon mess up the cam. If you mean something else please relay it.

Here is another theory - you may recall I was one of the people who have rebuilt their engine and installed a cam 180 out and ran it for maybe 40 mins. that way. This means one side didn't heat up. A bit far fetched.

I'm thinking now of checking the tube oreintation and pulling the spray tube/etc. and checking for any blockage.

Another person just posted that some are not really in favor of the oil line restriction mod.

I think Bruce is talking about the rocker arms at the top of the page. Those are for an early car and are forged. Your rockers are cast, as all 3.2, 3.0, 2.7, 2.4, 2.2 engines have. (Unless someone retro-fitted the early forged rockers for a race motor build.)

here are a few threads to kill time :rolleyes:

I am in the "No Restrictor" camp.

http://forums.pelicanparts.com/911-engine-rebuilding-forum/446489-oil-restricrors-revisit.html

http://forums.pelicanparts.com/911-engine-rebuilding-forum/310463-cam-oil-line-restrictor-adapter.html

http://forums.pelicanparts.com/911-engine-rebuilding-forum/259165-anyone-used-oil-restrictors.html

http://forums.pelicanparts.com/911-engine-rebuilding-forum/107641-cam-tower-restrictors-good-break.html

http://forums.pelicanparts.com/911-engine-rebuilding-forum/151035-cam-oil-line-restrictors-p-ssing-me-off-they-keep-splitting-sealing-washers.html

After more thinking and reading posts regarding the root cause, this is where am at on the most likely root cause.

1 - One cam geometry is messed up causing the wear. I think this is low probability with cgrinder and I saw one rocker on the other bank with a similar issue. It was intake #6, last inline for oil.

2 - Rocker Pad Soft - this is a low probability considering the hard thickness is 0.030" and typical grinding takes off very little and it didn't happen spread across both banks.

3 - Inadequate Lubrication - I think this is the most likely cause:

a - what changed (installed oil line restrictors)
b - left bank has a "clog" in the spray bar or feeding lines/fittings
c - is it the fault of the oil? I don't think so using BP 20-50 and I live in a moderate climate
d - right bank last worse oil feed is #6 intake rocker so lubrication is likely not quite enough on the right bank either

4 - long shot - when I rebuilt I ran one bank cold (cam 180 out) and or I forgot to put asm. lube on the cam faces, 25k miles ago.

My plan at this point is to pull the spray tube on left cam tower and clean out all the lines and drill out my restrictors to 1/2 way between current and original stock. Get the rockers re ground, install everything and give it a try. Maybe inspect after 5 k miles.

"2 - Rocker Pad Soft - this is a low probability considering the hard thickness is 0.030" and typical grinding takes off very little and it didn't happen spread across both banks."

Where did you get this info? Hardness layers aren't typically this thick - more like a few thousandths.

This is a high pressure area and a high pressure break-in lube is usually called for at first start. How's the matching cam lobe? Factory cam or rewelded?

However, if this was the only rocker, perhaps excessive material was removed or, as you suspect, there might be other causes of this.

Sherwood

see notes above

My error. It seems 0.030" (~8mm) is on the upper end of for case hardened materials. However, would still like to confirm that's the depth for rocker arms.

Thanks,
Sherwood

When I get home tonight I will have to sacrifice a good rocker and put one to the test and post what I find here. I will take one down until I loose it.

cgarr,
Very kind of you to sacrifice a rocker and provide solid general info. for the group but may not be completely necessary on my account. Cgrinder mentioned that typically not much is ground off to resurface a rocker but I don't recall he mentioned an amount, I'm guessing 0.005" or less. On some thread there must be the hardness depth on a stock cam lobe, this has been discussed on threads here and there is an adequate amount to cut out a 964 profile with increased lift. That's my reasoning to guess the thickness is well over a few mills. Thanks much for doing an experiment.
-h