tongva

So in the fsm there is no information on the valves or numbers. i understand that the valve lashes are hydro so they will self adjust. but I would like the numbers of the exhaust and intake valve height. basically im looking for valve lash, the FSM has a spec for balancing shim valve with bucket valve, but no initial valve stem height(valve seat height to be technical) when seated. im doing replacing valve seats as well as valves, and any other info other than that given in the FSM would be much appreciated. HEre an example to get an idea what im talkin about. These numbers are from the pulsar. I would like the 180sx sr numbers:

valve clearance

hot 0.30mm-0.035 cold 0.21-0.28

camshaft clearance

hot 0.20-0.23 cold 0.14-0.17

tongva

nobody got info???

daryl337

Well, I think I am a little confused about what you are asking.

The FSM pretty much gives all information that you will need. There is not a hot/cold clearance limit on a system with HLA's, because as soon as you get oil pressure, your effective clearance becomes nothing.

The SDS actually has shim clearance info. It literally says less than .001" for cold. Are you trying to determine whether or not your valve train geometry is ok? Essentially, they base your "shim size" off of the "guide size" to ensure that the two are even. All of the guides supplied by Nissan are of equal size from the factory, so they use that as a baseline. So to sum it up, they have you install the rocker guide on one of the valves, and then measure the depth difference between the guide, and the other valve. This gives a shim height to use in order to make sure that the two valves are opening at the same time. To accurately determine what shim you need on the HLA set up, you need to essentially use a dial indicator. Unfortunately, this does not really give you a "spec" like you are seeking, but its actually because by effectively keeping 0 lash against the lobe, in an HLA set up the determining factor of your valve timing is strictly going to be your cam lobe profile. In this way on an HLA set up, properly degreeing your cams, and ensuring proper preload on your valve springs are going to be the most important steps.

Here's some info that may be of assistance if you are going through your head:

Valve Length:
Intake- 101.19 - 101.61 mm +/- .2mm
Exhaust - 102.11 - 102.53 mm +/- .2mm

Seat Depth - 6.25 mm +/- .05mm
Interference fit of course. They give a .064 - .096mm range

Duration of cams is given as: 240 degrees.. at what lift the FSM does not give (I believe its an 'advertised' duration, meaning from 0 lift to 0 lift.. not the traditional .050"/1mm)


On a solid follower set up is where you will end up with lash being critically set to allow for expansion of the stem (something that HLA's automatically account for).

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daryl337

I should probably elaborate for the TLDR version.


As long as you do not cut the seat too deep (dont go past 6.3mm deep) and you install new valves within the lengths that I have supplied.... you will have proper height. Your next step is to adjust your valve spring preload by adjusting the spring seat shims.


Hope that helps!

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