Charlie69's 86 720 King Cab DD

[Charlie69]

Good info Mike, thank you.  The reason I think the pistons are wrong for this engine is the intake valve reliefs on the top of the piston are smaller than the the exhaust valve reliefs.

Edited September 4, 2019 by Charlie69

[Charlie69]

My brother Garret and I tore the lower end of the Z20 apart this morning.  The only thing we found was a rod cap on backwards.  Checked the ring end gap, piston to cylinder fit, rod & main bearings clearance, and adjusted the valves.  One exhaust valve was real tight, could no get a feeler gauge in between the rocker and the valve stem end.

 

We re assembled the the crank, pistons and rods.

Edited September 7, 2019 by Charlie69

[gene knight]

hopefully that will fix your engine issues and get it in your 720 soon

[TimmyG]

On 8/31/2019 at 8:00 PM, Charlie69 said:

Here is what I found when I opened up my 84 720 Z20 junk yard engine.

 

 

 

 

 

 

 

 

 

 

I noticed a mistake some one made.  The pistons are flat tops which is correct for this mileage plus engine.  When the pistons were fly cut  for valve clearance they cut the intake side of the piston the size of the exhaust valves and cut the exhuast side of the piston for the intake valve size.  This mistake is causing the intake valves to vit the pistons and bind up the engine.  Simple fix will be to pull the pistons and have a shop fly cut the intake side of the pistons to clearance for the intake valves.

 

This might be why the truck ended up at the junk yard.

I can't believe you found this at the U- Pull-It yard LOL. Did you find the truck first day? Hopefully got the pistons sorted out. 

 

I was gonna ask you about the comment you made talking about getting door lock cylinders keyed to match ignition. How can I do this?

[Charlie69]

I had the locksmith that I use order a new set of door locks keyed alike for $80.  I ordered a new ignition cylinder with key off the internet a long time ago.  I actually ordered 3 of these ignition cylinders with keys.  I will take one of these ignition cylinders to the locksmith and if the new door lock cylinder key goes into the lock OK then the locksmith can key the ignition cylinder to match the door locks.

 

When dealing with the new aftermarket lock cylinders  some times the keys do not fit the door and the ignition cylinder.

 

I am going to try to get a glove box and a gas door locks keyed the same as the new door lock cylinders also.  My goal is to have one key fit the ignition, doors, glove box and the fuel door locks.

 

My brother and I went through the crank, rods, and pistons, on Saturday morning. everything checked out.  we found 1 rod cap on backwards and corrected this on re assembly.  We also set the valve clearance on the head to cold settings.  I need to get all the parts cleaned and painted ready for re installation. I repainted the block already in the pictures above. 

 

One problem with the engine I believe was the timing gears and timing chain set not timed properly.  It also might have a Z24 chain which is longer than the Z20 chain.

 

I will most likely have all the parts cleaned and ready to install by next Saturday.  I will try to get the timing chain and gears set up this week.  If I find the chain is to long I will order one next weekend with the KYB shocks for this truck. 

 

It is time to have my tires re balanced and rotated so new shocks will not hurt.  Every bushing and the tie rods, center link, idler arm, and the ball joints were replaced about 6 months a go.  This truck rides and handles great except the shocks are starting to bounce a little.

[TimmyG]

2 hours ago, Charlie69 said:

I had the locksmith that I use order a new set of door locks keyed alike for $80.  I ordered a new ignition cylinder with key off the internet a long time ago.  I actually ordered 3 of these ignition cylinders with keys.  I will take one of these ignition cylinders to the locksmith and if the new door lock cylinder key goes into the lock OK then the locksmith can key the ignition cylinder to match the door locks.

 

When dealing with the new aftermarket lock cylinders  some times the keys do not fit the door and the ignition cylinder.

 

Sorry, I'm confused. You ordered 3 ignition cylinders? Just to have spares? 

 

And I don't exactly follow what you mean with the aftermarket door locks and ignition.

 

I understand you want 1 key to fit all... are you saying you ordered the new door lock cylinders with key, and would like to have your locksmith change your ignition cylinder to match?

 

If I wanted a spare key made for my door locks, could I get the number off the door cylinder and just take that number to a locksmith? 

[TimmyG]

Also, I'm looking forward to you getting this z20 figured out 😎

[Charlie69]

Yes I bought 3 Ignition cylinder locks with keys so I would have spares.

 

Aftremarket locks are not Nissan Dealer OEM.  Dealer locks for the 720 are discontinued.  The primer doors that I had on my 720 were from one of the 1980 720s I had.  These are my backup set of OEM locks incase I can no longer buy aftermarket new locks. These 80 door locks are litely used as the truck was broke down and parked in 1987. The reason I purchased new locks is my 85 720 doors I installed on my 86 720 were damaged by someone hammering in a screw driver.

 

I will be ordering 1 more set of door locks for my 84 720 because when I purchased the truck the locks were missing.

 

Yes I want my locksmith to key the ignition switch to match the new door locks.

 

Yes the key code is usually on the passenger door lock.

[Charlie69]

The door locks the locksmith ordered in were wrong.  So I will go through my stash of locks and pick out the correct ones and have them keyed to match the the new ignition key and cylinder.

[wayno]

What is different about the locking mechanisms except for the arms, I have removed the arms and put them on other locks and they worked fine, I was even considering seeing if the 720 lock cylinder would except my 521 arm and then putting it in my 521 work truck, but I have had way more 521 doors apart than 720 doors.

[Charlie69]

The shape of the new locks were different to the point that the lock cylinders would not go into the doors with out modifying the hole on the door.

Edited September 10, 2019 by Charlie69

[Charlie69]

My brother Garret and I assembled the head, timing chain & cover, oil pump, valve cover, and he welded up and installed the oil pan.  The Z20 turns over great.

 

One thing I did notice was the chian tensioner side guide was not adjusted in against the chain to take up chain slack.

 

 

 

[wayno]

So the valves don't hit the pistons now, was the cam timed/installed wrong?

[ol' 320]

Charlie: You always seem to have endless energy for your projects;) Progress is good!

 

[Charlie69]

The cam gear appeared to be set on #1 position instead of #2.  As you are facing the front of the engine the timing chain guide with the adjustment slot in it was set all the way to the left.  This allowed extra slack in the chain allowing the hydraulic adjuster to come out of the the block and get bound up in the chain.

 

This engine was never run and it did not look like it had caused any valve, head, or piston damage.

Edited September 22, 2019 by Charlie69

[wayno]

This is good to hear, you can move on with the build now.

[TimmyG]

2 minutes ago, Charlie69 said:

The cam gear appered to be set on #1 position instead of #2.  As you are facing the front of the engine the timing chain guide with the adjustment slot in it was set all the way to the left.  Thisa allowed extra slack in the chain allowing the hydraulic adjuster to come out of the the block and get bound up in the chain.

 

This engine was never run and it did not look like it had caused any valve, head, or piston damage.

Glad to see you got it sorted out and probably without having to buy parts. 

[Charlie69]

I purchased an overhaul gasket and seal kit.  There are also other parts I have purchased for the swap.  Fluids, mounts, plugs, wires, cap and rotor, just basic stuff.

Edited September 16, 2019 by Charlie69

[gene knight]

looks good

[Charlie69]

If all goes right this weekend the Z20 and low mileage transmission will be going into my 86 720 king cab.

[Charlie69]

Z20 install did not happen, parts order not here yet.

[datzenmike]

 

Pistons are in properly if the notch is towards the front. I don't know about the valve relief cuts but at TDC on the exhaust stroke the exhaust valve is nearly closed and the intake just beginning to open so there's lots of clearance between the valves and the piston.

 

 

 

 

This is not the Mileage head so your compression should be reasonable. The Mileage head is a W-04 casting and has small quench areas on them. If you were to use the W04 head your compression would be 9 to 1 and likely ping like hell. The Mileage engine uses a knock sensor in the block and an ignition retard feature.

 

 

 

[Charlie69]

Mike I was going to use the Z24 distributor in this Z20 because the wiring on the Z20 distributor does not match my 86 wiring.  Do you see any problem with me running the Z24 distributor?

[datzenmike]

No... it should work fine.

[gene knight]

do they have the same internal parts as in counterweights and spring tensions and what about the part on bottom of shaft/ plastic bushing?