Hi All,

Does anyone know the factory rocker valve guide "Lash Pad" thickness for a completely stock E31 head?

I have a few factory part numbers but not sure what thickness is the correct one. I've heard .118" & .120"

13218-21000

13218-Y7000

The numbers above might be the same part, but if anyone can help identify the correct thickness and part number, that would really help.

 

Thanks.

I've got some original 13218-21000's sitting around in my parts bin. I'll Mic them a bit later. I'm in insomniac mode right now. ( Memory is saying .115" to .117" stock.... but I don't trust my memory 100% any more. )

Bear in mind that even if head is " completely " stock, once the valves and seats have been ground or replaced, you have to check the lash wipe pattern.

 

Edited March 15, 20169 yr by Chickenman

Thanks Chickenman, looking forward to the info. You're right about the wipe pattern. I am only changing out the rockers and pads out, but I don't know if the valves have been replaced or ground prior to my ownership. I'm only doing this to quiet down the ticking sounds which I believe are the rockers contacting the pads.

Edited March 15, 20169 yr by oemz

1 hour ago, oemz said:

 I'm only doing this to quiet down the ticking sounds which I believe are the rockers contacting the pads.

Ticking is normal, to a certain extent.  

Only jumping in to save you some money, before you order parts.  If your lash is correct now, it will be the same after you swap out parts.  It's the lash that allows the ticking.  

Memory's apparently pretty good. Used lash pads with some visible wear. Minimum ( worst ) = .1165".  Best lash pad = .118"  The stock lash pads are really, really tough. I'd say the .118" pad is bang on and the .1165" pad has about .0005" wear. Can't feel any wear with the fingernail test on the .118" lash pad. A barely perceptible edge on the .1165" lash pad.

Edit: Looked through my library. Frank Honsowetz ( How to Modify your Nissan & Datsun OHC Engine ) says stock Lash Pads are .118". That's good enough for me and confirms my measurement of used Lash Pads.

Edited March 16, 20169 yr by Chickenman

Stock Lash pads have a recess on the bottom. If they are flat they are aftermarket.  Only exception I have ever come across were some early  .115" Datsun lash pads which I believe only came in a 1968 L-16's and earlier L-13's/L-14's.  These were also flat on the bottom. No recess.

Thank you Zedhead. I think i'm going to check and adjust my valves to see if they are off spec first before I purchase anything.

The link below is what lead me to the idea of changing out the rockers and pads with new ones would help quieting it down a bit.

http://forums.hybridz.org/topic/106910-loud-tickingknocking-noise/

Thanks Chickeman. Great info and very helpful. I'll definitely check them before I do my adjustments.

 

^  Most often it's the rocker arm that causes the issue. You will get a discernible wear line right at maximum lift on the rocker pad. Drag a finger nail over the line and if you can feel anything at all, either replace the rocker or get them resurfaced.

Edit: Just checked the link that you supplied above.  In post #12 you can clearly see the wear line in the rocker ( Red Arrow ) that was causing the ticking. That's got a fairly deep dip as you can plainly see it in the photo. No need to drag a fingernail across that. It's toast.

The thing that tricks people with worn rockers, is that the the feeler gauge will very seldom line up exactly on the center line of the dip. So the Cam Lobe contact point will be to one side or the other of the dip when you make your measurement with your feeler gauge. The dip can easily be an extra .005" deep. You can set your lash to specs a hundred times... but the " Tick " will still be there....

Edited March 16, 20169 yr by Chickenman

^ Of course if you do resurface the rockers, guess what that changes? Yep.. the effective Lash pad thickness. You have to check the wipe pattern all over again.

That's why a lot of engine builders prefer either brand new Nissan rocker arms ( if you can find them ) or a good used set of genuine Nissan  rocker arms. Beware of new " aftermarket " rocker arms. There are horror stories all over the place regarding them. Quality is very " iffy" and you never know what you are getting.

Thanks for all the help. I ended up changing out the rocker arms and lash pads with genuine Nissan parts and no more ticking whatsoever.

I adjusted the valves to spec, checked the wipe pattern and it was all good. 

PS..I checked all the new rockers and lash pads before installation and only one rocker would not slide into the lash pad groove. I returned that one and ordered another and it fit like the rest. Just a heads up in case any one end up in purchasing new ones to check. 

 

 

 

 

 

 

Edited March 20, 20169 yr by oemz

Good stuff

23 hours ago, oemz said:

Thanks for all the help. I ended up changing out the rocker arms and lash pads with genuine Nissan parts and no more ticking whatsoever.

Did you adjust the valve lash before and found that they were still noisy?  You didn't really show a reason to replace parts.  Just good to know.