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Rocker Arms - State of the situation


NewZed

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Got curious about rockers arms since people are still ruining camshafts, apparently from poorly reground rockers.  Although camshaft properties might play in to it also.  I pulled up a list of sources from the web.  Looks like they range from cheap "new" ITM rockers ($9.40 each), to expensive new, ZCCJDM CNC-made rockers ($86.67 each).  And a variety of reground options.  I like to have plans in mind for future work and I don't see a way to swap a cam with confidence.  Maybe some discussion will turn something up.

 

 

Cheap ($9.40) - 
 
http://www.rockauto.com/catalog/moreinfo.php?pk=4800036&cc=1209260  You have to get in to Rockauto and choose the model to see the option.  ITM is the only one.
 
 
 
 
Spendy ($86.67) -
 
 
 
Reground -
 
 
http://www.datsunstore.com/rocker-engine-refurbished-p-869.html  (Probably Delta?  Both Seattle-area.)
 
 
 
 
 
DIY reground - 
 
Edited by NewZed
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My comments enlight of recent issues. Bad rockers will ruin your day. Don't assume new is good .

Schnedier cams told me that they can have them done , but Delta did the job well and cheaper then who they contract.

When degreeing my cam and not coming up with exact card specs - Schneider said that te rocker ratios can sometimes not be exact and this throws off the numbers.

Identifying bad rockers is probably done better by using a engine builder familiar with Datsun geometry. My head was done by a local machinist that didn't look for a 'bad rocker' situation when putting together my head. Yes he got the wipe pattern perfect but didn't detect the improperly machined surfaces .

Careful blaming rockers for cam failure. My Schneider cam - which has gotten some bad raps- looks great after 12k miles of hard driving. Too many variables involving to many builders gives too many outcomes.

The cam is being sent to Schneider for an evaluation as we speak.

We have also had issues with lash pads in the forums.

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This might be a good thread for this question.

Putting together a bunch of rockers to send to Delta and I pulled some off of an early e88 . The rockers had a low spot on the surface that rode on the cam lobe. The 'low spot' looked like an intentional groove machined into the center of the rocker face to hold oil?

I have never seen this before. At first I thought I had a bad rocker, then I realized they were a that way.

Any comments- sorry I should have taken a pic

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A low spot on the rocker is from 200,000 miles of running in the same spot. 

 

The Rocker should be 5 RC Softer than the Cam, therefore wearing out instead of the cam. Of course, absence of lubricant, improper lubricant or starving of lubricant will cause accelerated wear.

 

I've seen guys who swear by no cam assembly lube and just dump a quart of oil on the top end before fire-up. Of course, they also developed a 'groove' much like you mention in a relatively short period of time (nowhere near 200,000 miles!)

 

If you look, there are cammed Datsun engines assembled in the late 70's out there with 100,000's of miles on them and no cam issues. I know of at least one where the car broke in half at 245,000 miles, and the owner figures that the vast majority of them were Auto-X miles as he rarely drove it more than 10-miles to the AutoX each weekend for the life of the car, and rarely to work or tours (had another Z for that...) That cam and head had over 100,000 miles on it and looked like new...and it was hard miles.

 

The standard isn't what looks good after 10,000 miles, it's what looks new after 100,000. 

 

At least, that was the standard. Maybe things are devolving...

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Heh, I can't believe I was hand-finishing rockers at that price then. That's a LOT of work!

 

Reground Nissan rockers have been what I use and will continue to use, as they LAST. I've not had good luck with aftermarket parts...even the Atsugi Japan rockers I have showed significantly more wear than the Nissan rockers from the same engine.

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  • 2 weeks later...

More rocker arm stuff.  MSA's seem like they might be Paraut brand.  Which seems to be a more expensive option, maybe of higher quality than the ITM's.  Guessing only by the shiny mark in the pictures, and the price.

 

http://www.redlinemotive.com/store/replacement/wizard.asp?year=1978&make=NI&model=280-Z-001&category=A&part=Rocker+Arm

 

http://www.thezstore.com/page/TZS/PROD/10-2030

 

http://www.elautoparts.com/item.wws?sku=A4040-51981&itempk=86615&mfr=Paraut&weight=0.20

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Looks like they are a low-profile supplier to Nissan, if the attached reference is correct.  There's not a lot out there about them in English.  

 

If a person really wanted to take care with their new camshaft, the Paraut brand might be worth the extra money over ITM.  Nissan used to chrome plate the early rocker arms but changed in 1969.  Attached a Technical Bulletin copy.  Seems like maybe they've always been a little bit problematic.

 

 

Japanese Atsugi page:

 

http://ejje.weblio.jp/content/ATSUGI+MOTOR+PARTS+Co.,Ltd.

post-8864-0-55574500-1412288593_thumb.png

post-8864-0-94338200-1412288614_thumb.png

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  • 4 months later...

So I find myself in the middle of the rocker arm dilemma-what to do? I searched around AGAIN and found a lot of dead ends. The Paraut rockers sounded promising in that it is a Japanese company, but out of stock everywhere.

I stumble on this site

  http://www.rockerarms.com/

and gave them a call. Talked to guy for about 10 minutes and found out they are an older business that moved. They have experience with the Datsun rockers and have a special fixture to make sure their specialized grinders(radius type?) perform parallel on both both surfaces(what I wanted to hear). They charge about 7$ a rocker and do have some spares. They have moved recently so they are not at 100% capacity yet. I'm going to send a set to have as back up since the ones I got from Delta looked a bit sketchy.

Gary(I think that was his name) said they guarantee their work. 

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So I find myself in the middle of the rocker arm dilemma-what to do? I searched around AGAIN and found a lot of dead ends. The Paraut rockers sounded promising in that it is a Japanese company, but out of stock everywhere.

I stumble on this site

  http://www.rockerarms.com/

and gave them a call. Talked to guy for about 10 minutes and found out they are an older business that moved. They have experience with the Datsun rockers and have a special fixture to make sure their specialized grinders(radius type?) perform parallel on both both surfaces(what I wanted to hear). They charge about 7$ a rocker and do have some spares. They have moved recently so they are not at 100% capacity yet. I'm going to send a set to have as back up since the ones I got from Delta looked a bit sketchy.

Gary(I think that was his name) said they guarantee their work. 

 

Nice find. Sounds like a way better option than Delta and corroborates with what I've learned in speaking with Ron Iskenderian. Although if you can find new rockers I'd go with that.

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