Valve adjustment help!

[OneMaybe2]

Ok, I haven't done a valve adjustment since I bought the car which was roughly 9 months ago. I purchased it from someone who had been working on it and it was in pretty good shape. Today I go to adjust the valves and when I lift the valve cover, I notice the Pivot lock nuts are much bigger than any manual said they should be. I haven't been able to find an L28et that looks similar to mine with the cover off. Maybe I'm not looking at it right but I thought I would ask before I started loosening the nuts. Also there aren't two nuts like the manual says, just that one lock nut.

I also tried to get the feeler gauges through just to see If there was any clearance. and I couldn't get even the 0.0015" feeler through with the cam lobe pointing straight up. Is there something I'm missing?

(another note: The lock nut on there is bigger than 22mm, which was the biggest wrench I had on hand)

[Captain_Zeros]

Interesting. Some googling tells me some late model 280zxs had hydraulic lifters, maybe this is that?

[Captain_Zeros]

Looks like a confirm. This is a snipped out of the 1983 280zx factory manual, it looks like at the very least '83 zx turbos had hydraulic lifters that look like what you've got, and I found at least one google hit for somebody who swapped them out for solid lifters using a timesert threaded insert that fit the large hydraulic lifter hole on the outside and a junkyard earlier z solid adjustable lifter on the inside threads.

Beware of capslock: http://www.cardomain.com/ride/3839420/1981-nissan-280zx/page-6/

I also found another forum mentioning that they've seen P90 heads with hydraulic lifters and P90A heads with solid lifters, so sometimes it can be a bit of a crapshoot of what lifters a given head might have circa 1983.

What this means for practical purposes, is that your valves are (or should be) self adjusting with oil pressure. If the lifters stick in the up position, however, they can cause valve float just like too-tight solid lifters and will need servicing.

Edited June 17, 2013 by Captain_Zeros

[OneMaybe2]

Yep that looks to be the case! Thanks for the quick response. looks like I may have to get mine serviced :/

[Simon Doherty]

No sure if this is still relevant, but....I have a 1982 280zx non turbo. I did a valve adjustment and that's what mine looked like. Datsun has a special tool for adjusting these valves, and it makes life much easier.

[EuroDat]

Check the side of the head between 1 and 2 spark plugs. It should read P90A. These heads with hydraulic lifters came out in Feb 1983 on the turbo zx's.

Parts for the lifters are very hard to find these days. If they are working good, they are very quiet and very little valve train noise. I have heard of (never seen it) an adapter for them to convert then to normal adjustable lifters.

Chas

Here is another thread dealing with a P90A. He had trouble and his conclusion to change tomechanical lifters is purly based on his set up and different to your situation.

http://www.classiczcars.com/forums/engine-drivetrain-s30/20617-p90a-hydraulic-cam-problems-still.html

Edited July 23, 2014 by EuroDat