Lash pads

[2ManyZs]

Well, I happened to look in the drawer and there is another book also, How to Rebuild Your Nissan/Datsun OHC engine by Tom Monroe.

It also goes into detail on how to check you contact patch on the rocker pad, basically what you want is the contact patch to be centered on the pad. You can check it with layout dye, or even a black magic marker. You need to cover the pad of the rocker with this, doing one rocker at a time, and assemble the valves, lash pads, etc with a good cam lube, and rotate the cam 360 degrees with the while the rocker pivot is threaded all the way in and the jam nut is up as far as it will go. Then you will be able to remove the rocker arm and check the contact patch.

Thicker lash pads will move the contact patch toward the rocker tip, and thinner moves it towards the pivot.

BTW, some of the aftermarket cam manufactures may be able to supply the lash pads, as well as Nissan Motorsports. The are available in thicknesses from 3.85-8.5mm (.150-.330 inch) in .010 increments... So you can see, this can be a very involved process.... One which I haven't done either, I'm learning it while I read it myself....:cross-eye

[Zedrally]

Yes Sir, that's the one that the name escaped me!

The procedure may look daunting, but it does work and after you have done the first one the next becomes easier, oh, and I did it with the head out of the car.

Actually the hardest part was finding a permanent maker that I could use on the arms.

[2ManyZs]

Is this normal?

Can you define normal Mike?

Guess some people might try it while the head is still on the engine in the car, especially those who don't have an engine hoist or stand........

[Zedrally]

Normal is what "normal" people do, not things that "experts" like yourself do!!!!

ROFL ROFL ROFL

[Brett240]

i was thinking of doing it while the engine was running.

[2ManyZs]

Here's the pic... The top pic shows what you don't want to happen. The top pic would need a thicker lash pad to correct....

As far as doing it while the engine is running? You doing one of those Zedrally type porting jobs?

[Zedrally]

Why not polish & port it at the same time?

Just get some sand and follow the instructions in the P&P Thread!

Don't forget to add oil to thicken up the mix, metal shavings to replace the metal that accidentally flies off and glass beads so the lot rolls out of the exhaust!

ROFL ROFL ROFL

[Brett240]

thanks for that!

yeah i heard that using no pistons rings decreases sliding friction too! ROFL

[RB30-ZED]

Hi Brett, if you have a set of narrow feeler gauges, you can slip one in between the rocker tip and the lash pad to calculate the extra thickness over the stock item.

This is a help if you have to order parts.

But a better way is to go to tack it to, Stewart Wilkins Motorsport:

Fax: 02)4577 4299 Ph: 02)4577 2400

Email:swrallying@ozemail.com.au

and have him do it, saves running around exchanging pads.

Nice car, from what i can see , ill have to come up and have a closer look one day. Are you in the Sydney zed club?

Steven

[sjcurtis]

Hey guys can I tell you some stories about lash pads. I used to think I new it all , had a good 510 with webbers and an oversize L20b bought a great cam billet profiled to works numbers with yes you guessed it lead lobe internal oiling. well got the head fully serviced new valves and springs in. got home had all the right gear set the cam in used the original lash pads that I had. Everything went together sweet it all looked great even the wipe on the rocker pad was looking good. Absolute hero, WRONG, I drove off from Townsville to Melbourne the next day 3200kms (roughly)

For the first 500KMS car was a legend sat on 140KMs for two hrs at a time between towns. The second half of the trip the performance started degrading with minor increase in rattle. I new I had a problem at glen Inis so I limped down the New England highway to Singleton then through the putty road to Penrith. by this stage I was not getting anything like normal 80KM max. went to a mate called BARRY at DATSPEED.

Pulled the rocker cover all looked good except all the cam lobes had troughs in them so next to no lift at the valve the hardened rocker pads run through the trough. This was caused by not centring the contact point correctly and effecting a lobe over run basically destroying the hardened surface. I had a cheaper regrind cam fitted and lash correctly set up, oil flush and webbers retuned. A very expensive exercise.

For my 2c please get it professionally set up.

Cheers

Steve:classic: :classic:

[Ed]

Speaking of valve stem height. Would anyone have the factory specs on this. I want to have the seats redone on my head and the shop was asking what the correct valve stem height is.

[Brett240]

hi steven ,

yeah i might have to get stuart to have a proper look, ive got it pretty close but this engine revs to 7000 often so i want it perfect. yeah im in the sydney z club are you?