Rocker Geometry Woes

[Diseazd]

You need to get a number of size lash pads. When I geometry a Stage III cam, I have a .150, a .160, a .170, and a .180 lash pad. With a stock cam, you'd probaly need a .120, .130 and maybe a.140 (not sure about the stock sizes). Go through each rocker, center the wipe pattern. I use an old egg carton (12 holes) .....I number 1 through 12 and write in magic marker the lash pad size for each rocker. Put that rocker in that hole too, then you know things are where they should be when you put it together. Remember to set proper valve lash when you geomery the rockers. If you have a good engine builder, the valve stem height will be spot on. My last engine was ten .160 pads and two .150's.

[HuD 91gt]

I feel like I should put together a set of multiple thicknesses, and send it around the datsun community. A deposit will be made and won't be returned until the unit is back in my hands.

Not having any experience with lash pads, can they be damaged easily?

[Diseazd]

Nope...

[siteunseen]

I've been thinking grinding off the stock cam would require thicker lash pads?  Sounds bass ackwards now.  The guy doing my geometry kept saying John Williams, R.I.P, got the last .150s they could find.  Schneider guy says he'll send the ones I need with my cam component kit.  The same cam kit MSA sales comes with .175"s.  

[LeonV]

I had a really good and long conversation with Ron Iskenderian a few months ago regarding a damaged cam. The takeaways from the conversation were:

- If your used rockers are smooth, reuse them.

- If old rockers are not good, buy new. Brand doesn't matter as much as them being manufactured the same as the originals (sintered pads).

- Resurfacing rockers correctly takes proper fixturing (this is not trivial) and Ron's guess is that it cannot be done for less than $8-10/rocker. I'm curious as to what Delta's fixture looks like.

 

My experience with Delta was less than stellar. Six out of twelve rockers were not even ground parallel. That's 50%! When you installed the lash pad and rocker, and raised the pivot to set valve lash, this could be seen with the naked eye. In other words, if you had a really thin feeler gauge you'd get different values for valve lash depending on what part of the rocker pad you checked.

 

For all those getting their rockers resurfaced by Delta, I strongly urge you to check to be sure the lash pad and cam surfaces are ground parallel. You can check it visually by doing what is underlined above.

[siteunseen]

What did you do about the 6 that were bad?  Did you send 6 more for proper coordination or buy new?  I may have that same situation.

[LeonV]

What did you do about the 6 that were bad?  Did you send 6 more for proper coordination or buy new?  I may have that same situation.

 

At the time, I took the advice of an experienced L-series builder and sanded some used rocker arms I had. That didn't turn out so well as my cam ended up getting wiped. I have a thread on it on HybridZ.

 

After that debacle, I bought new rockers. Lesson learned...

[siteunseen]

That's something I've read before where they are talking about sanding them yourself.  $36 plus shipping from the North West was only $50.  I would spend that on sanding paper and beer, plus running my heater to keep warm.  Anyways I'm hoping for the best out of the resurfaced pads but maybe will have to learn a hard lesson in a year or so of running the cam.

 

$125 regrind with a component kit of $250 plus the $50 and the unknown set up price, $1,000 at least down the drain if the rockers don't have the "lanolin wipes".

[madkaw]

I'm getting ready to pull the trigger on Kameari rockers. I have also found out the harder way the importance of valve train geometry and the rockers are the heart of that equation. 

My machinist didn't like the Delta resurface job at all. And knowing that my supposedly new Nissan rockers weren't right out of the box, he didn't trust these resurfaced ones either. I told him that we need to check these, but that's time I have to pay him.  I told him Kameari rockers were 600$(chromoly), and he thought that wasn't unreasonable considering their importance.  It's a hard pill to swallow

[grannyknot]

Good old Kameari, they are shameless. $460 for a steel head gasket, $1500 for a aluminum oil pan that sold for $500 in NA

[Zed Head]

Could spend more - http://www.zccjdm.com/catalog.php/azcarbum/pd2120660

[Patcon]

Zed Head

I looked at that link and went well $725 is more but not terrible, then I realized that was for the L4 and that the L6 price was $1040. So it is substantially more but for really great rockers maybe, but from my first glance it is interesting to me that the profile of the new arm is so much different from the original. I am making some assumptions but I would think the original factory rockers would have been fairly heavily engineered since they are pretty crucial and have a lot of stress on them. The thickened section on the original near the pivot side of the pad suggests that is where the maximum bending stress is in the rocker, so it was made deeper to resist that bending or out right failure. So can the redesigned rocker arm survive with out that extra metal? How? Better metal? Harder? Just curious...

Charles