Lash pads

[ryderfmjones21]

I know for sure the valve springs and valves were changed but I think the original retainers were used. When i picked up the car i was given the old valves and springs but no retainers. Maybe they guy before me lost some lash pads and just ordered the wrong ones and didn't notice..
Ill have to look into it some more. I've been in the bottom end pretty much did all that myself. Those numbers z-196 are correct. Hopefully Ill be able to use some pads from dean otherwise im screwed.This realm of the auto world is black magic to me. Ill have to give you a shout when I try to start making carb adjustments.

[ryderfmjones21]

Some of the valves have what looks like shorter pad. cyl 123 exhaust have a tall pad but cyl 4 has a shorter one. Unless they compress in there then there. I haven't looked at it today. To frustrated!

[ryderfmjones21]

taking a look at the other pads. cyl 4 exhaust is tall while intake is short cyl 3 intake is short exhaust tall cyl 2 intake short exhaust tall cyl 1 both tall. each exhaust pad is only 14 mm and appears to have alot of slop in the seat. Also each tall pad has slits cut paralell with the ears like the L series where the sorter intake ones do not. that are smooth on top with the exception of cyl 1 which both are tall and 14mm wide. Each short intake pad is 15mm. ill drop some picture i pulled a rocker from cyl 2 and the lash pad appears to be a roadster one

[ryderfmjones21]

Cylinder 2 lash pad and rocker

[ryderfmjones21]

From the intake side

[JT68]

No one makes .25" lash pads for roadster retainers. .165 is going to move cam wipe way to the rear compared to .25. Really suggest you do this correctly before more serious destruction occurs. Unless it bent a valve when this happened (no telling what exactly transpired when it came apart), you dodged a bullet. Consider it a gentle wake-up call that things are not happy in the valve train department. So I don't think you are screwed. Kinda lucky the failure wasn't worse (assuming no additional destruction) when that valve got out of control.

There is no problem with running L lashpads in retainers designed for them. L-series pads in U-20 retainers is a fail. Add to Sins of the PO thread.

We do have Isky retainers for U20 valves using L-pads. But to use them, the whole valvetrain needs to be checked out. Most specifically cam wipe and installed height.

I think Stan also had some U20 retainers sleeved to accept Lpads. That is probably the least expensive fix, but you still need the entire valvetrain checked out and corrected before it fails in a bigger way.

That's good news about the bottom end. because of the lashpad thickness, I have to think the pad choice was known and deliberate. We'll chaulk it up to the PO.

[ryderfmjones21]

I’m getting the cam out so I can examine the rest of the top end now.
Why would to taller ones be on the intake and exhaust on cylinder one? That’s the weird part that makes me think it wasn’t done on purpose.
I’ll pm you my number and we can chat about it when you’re free.

[david premo]

Looks like the tip of the rockets have been modified and is most likely the cause for the extra thick lash pads. I have never seen any like that, looks like someone ground down the tip that contacts the lash pad.

[JT68]

Right, or just badly reground rockers. There are some really bad reground rockers out there. The more material removed from the rockers, the bigger the problem, especially with giant lift cams. (Greatly reduced base circle)

I bet the adjusters were up high again trying to compensate for lack of base circle on the cam, ground rockers, or maybe over-ground valve tips. Could be either (or a combination of all three) That will cause all the wear on the front of the rocker as shown. Bit of a mess.

Maybe Dave could help you get it fixed up Ryder?

[JT68]

I’m getting the cam out so I can examine the rest of the top end now.
Why would to taller ones be on the intake and exhaust on cylinder one? That’s the weird part that makes me think it wasn’t done on purpose.
I’ll pm you my number and we can chat about it when you’re free.

Right, sounds like there are significant differences cylinder-cylinder. Different (used vs.new vs re-machined valves?) possibly new seats in some locations,but not others? Deeply seated valves vs. not-so-deep? All these variables play into it.

J

[Gregs672000]

Ugh, yes it's a mess. JT and others have far more expertise in these areas than I. There are reasons as to why you would find "some" variance in lash cap thickness but as JT said, wide variances there suggest compensation for other things being funky... and without disassembly it will be difficult to know what it is... overly cut or recessed valve seats, different length valve stems, very recut cam base circle...
That's one issue. The other is that the Z196 cam is not likely a good cam selection for the street. For Spider to run it effectively, he has changed cam timing (will need an adjustable cam gear at the least and be comfortable with what you're doing, and we have no idea what shape the timing chains are in) and geared his car to be in the power band more quickly, runs 50mm carbs with 43mm ventures, etc.
I have no idea what you want from your car, but my humble suggestion is to at least pull the head and have it inspected by someone who is experienced with Nissan overhead cam engines. You'll need to locate a good used A cam for regrind, or a B or C cam, as well as new or properly reground rocker arms. Then once it's assembled you'll have to do some trial and error to find the correct lash pad thickness which can only be done by installing each one, putting whats called "bluing" on each rocker arm pad where the cam rides, adjusting the valve lash, spinning the cam by hand, removing the rocker arm and noting where the cam wipes the bluing off on the rocker arm pad... need to be very close to equal wipe from each end of the pad. The cam and rocker wear in together, and once the pattern is on the rocker, changing that without regrinding a fresh surface properly it will wear the cam quickly. Ugh, unless you have an experienced friend who does cylinder heads and you want to develop some knowledge, I don't see this as being something to do on your own... just too many variables.
Try to not be discouraged. You have some valuable parts in the intake and carb set up. The head may be salvageable but I do believe you will need a rebuild, cam and rockers. I think the PO cobbled together some parts with very limited knowledge or long term care. Sorry man...
There is a good looking U20 head on the site right now with proper B cam etc and likely would bolt right on and solve your problems (those known anyway)... that may be the way to go. Otherwise, again we're happy to provide guidance and to help you understand things and what questions to ask. I have no idea what your budget is, but I've always been on a budget with my car, 33 years and counting.

[Gregs672000]

BTW, I was looking over your pics and noted an open vacuum port on one of the intake runners in the manifold. If you had a vacuum advance line running from that to your distributor it is wrong... exact opposite of what needs to happen. The distributor is set up to adjust timing from a port BEFORE the throttle plate, not after. With the throttle plate closed, the vacuum in the intake manifold is very high. There's no load on the engine (like at idle), but the timing is being maximally vaccum advanced, not what you want. As you open the throttle plates the vaccum drops in the intake manifold.

Under normal circumstances when folks run this carb/manifold set up the vacuum advance is disconnected and you just operate soley on the mechanical advance built into the distributor. If your carbs are set up for vacuum advance with a port before the throttle plates, you can use that (some sidedraft carbs came prepped that way).

[ryderfmjones21]

Regarding the vac port. I have one of Brian’s 123 ignitions in the car so there’s no vacuum advance but there is a manifold sensor.
Regarding my head.
Well at this point I’m about to pull the head and measure it to get shims. Then hopefully later this week I’ll take it to a shop to get the seats lengths and spring rates checked. I am having trouble finding someone locally here in cave creek Az.
My budget is low I’m only 19! Currently I’m going way over budget into the car I’m probably okay with paying 1200 bucks but that’s to low to have someone build it. Plus I have a time set for the end of April and don’t want anyone hanging on to it for months.... I’d have to assemble it on my own.

I’ve already ordered some new rockers and am going to order a b cam. That’s all I’ll do until I make sure the valves in the head are okay.

Where is this head on the site you mentioned?

[ryderfmjones21]

You guys wouldn’t believe it but I traded a 800 vw bug for this it was primer grey and I had to paint but she’s coming along aside from the disaster the head is I’m still feelin motivated to get her done. I better work quick as we all know this motivation doesn’t last very long

[notoptoy]

Wow, that looks great, keep up the great work and motivation!