While I have the cylinder head removed, what should I do while I’m in here?

[kcpope]

Had zero compression on the rearmost cylinder. Could hear air escaping through the exhaust port. Removed the cylinder head to will be taking it to the machine should for a valve job.

While I’ve got the engine open like this, is there anything that would be prudent to do or check?

Also the machine shop asked me to deliver the cylinder head with the cam installed. Is that typical?

Here’s a couple pics of what I’m seeing…

Edited May 8 by kcpope

[Zed Head]

Timing chain, gears, and guides, and cylinder wall finish/wear are two easy ones.

If the machinist knows Datsuns he'll want to check the rocker arm wipe patterns after the valve job, and cam lobe quality, so he'd want the full assembly.  That's a good thing..  Maybe he wants to give you a "ready-to-install" head instead of a bare one.  If he's not installng new seats it might be worth having it done.  That looks like a "soft seat" head, 75 or 76.

[kcpope]

Timing chain and cam sprocket are new, ITM brand. I checked for stretch following the FSM method and it’s perfect, believe it or not.

Yes, it’s a 76 head I believe, with those soft brass seats 🫤 I’ll see what the shop says. Here’s a pic of the cylinder walls. They all pretty much look the same.

Running my finger nail up the wall, I feel no ridge, so I think that’s a good thing.

Is there any point to removing the carbon on the piston tops? Only problem is I can’t rotate the engine without risking losing my timing chain in the pan. So hopefully this isn’t necessary.

 

 

[Zed Head]

This book is worth buying even if you're not doing a full rebuild.  $18.08 on Amazon. 

How to Rebuild Your Nissan/Datsun OHC Engine: Covers L-Series Engines 4-Cylinder 1968-1978, 6-Cylinder 1970-1984 Paperback – April 10, 2002

[dutchzcarguy]

Here for comparison, a cyl. that has run for 119000km, it still has the cross "scratchings for the oil.. this is good.. Your cylinder has "polished" spots.. this is not good, it will use a lot of oil.. As the wall is much to slick.

If you want a good engine it needs a oversize piston and new cyl. walls

[dutchzcarguy]

Btw, your engineblock looks like it has a cooling problem at the rear end.. If a datsun 6 cyl.block has a problem with cooling it is at the back i read somewhere.. so clean it out, before assembling.. There are topics about that subject on here.

[kcpope]

Welp, a little oil consumption never hurt anyone😉. The budget is gone, so it’ll have to do. At least it’ll have a fresh cylinder head.

ill work on cleaning out the water passages at the rear.

[dutchzcarguy]

On 5/9/2024 at 2:28 AM, kcpope said:

Is there any point to removing the carbon on the piston tops? Only problem is I can’t rotate the engine without risking losing my timing chain in the pan. So hopefully this isn’t necessary.

If you put a piece of wood or something in the chain loop, You can easely rotate the engine. Lots of people use chemical stuff to get rid of the carbon, you can do this now easy as the engine is open. At least clean the cylinders and the top of those pistons.

[Captain Obvious]

16 hours ago, dutchzcarguy said:

If you put a piece of wood or something in the chain loop, You can easely rotate the engine.

Pics or it didn't happen.   

[kcpope]

1 hour ago, Captain Obvious said:

Pics or it didn't happen.   

I was skeptical too, because everything I read said to tightly wedge the timing chain holder in place, thus making rotating the engine over impossible.

however, I think I found a method that works. See pic below. It keeps the timing chain tight, while allowing my wooden timing chain wedge to stay semi tight and keep the tensioner in place. It seems to be working so far. I’ve cleaned up 3 of the 6 pistons.

maybe this is only working for me because my chain tensioner is already in the bottom of the oil pan 😅

 

[dutchzcarguy]

8 hours ago, Captain Obvious said:

Pics or it didn't happen.

Oh well.. then it didn't happen! 🤣  I've done it before, yes you need, during the turning, of the engine keep the chain on tension but that seemed OBVIOUS to me..😐

[dutchzcarguy]

To ad..  I would take the front off of the engine anyway as there are also a few seals that better be renewed when you do the head..  With the front of it's even more easy to do the piston cleaning.