My 1985 720 4WD project

[ttyR2]

It looks like there are bi-metal and tri-metal bearings now. The bi-metal are aluminum on steel vs. the older coating/babbitt/steel of original. Do you guys have any recommendations on which ones to go with?

[datzenmike]

Tri-metal bearings will handle the most load while aluminum ones are just above half of that. Aluminum bearing have much better 'embeddability' in that debris is forced into the bearing and way from the crank journal surfaces.

 

 Find out what bearing type was used by Nissan and go with it. Probably tri-metal where the clearances and oil film thicknesses were wider and debris was more easily flushed out and embeddability not so important?

 

 

Either will work.

[Stoffregen Motorsports]

Never ever use aluminum bearings. They are not forgiving like tri-metal and can chip or crack. I've even seen them "muddle" which is when the aluminum starts to squirm around.

[ttyR2]

Yep. I ordered tri-metal ones in the appropriate size.

[ttyR2]

Welp cylinderheads.com is out of Z24 reman heads so I'm having to take a chance on a used head from a local auto salvage yard. They guarantee it to be rebuildable (no cracks). With any luck, it might be usable as/is, but I'm not holding my breath.

 

The stack of new parts in the shop keeps getting bigger...hopefully that pile starts shrinking in a week or two.

[ttyR2]

Any recommendations on durable engine paint? Will any of the good ones hold up to SuperClean? Or is that just going to tear up pretty much any paint?

 

Is this the original engine color on Z24's? 

 

I picked up a good used cylinder head. Today's list involves a thorough block cleaning and paint, and prep the head including checking for warpage. I'm still waiting on rings to show up, so I can only go so far for another week or so.

Edited February 24 by ttyR2

[ttyR2]

After getting a quote on rebuilding the head, I went that route and dropped both the good and bad heads off, thinking they could use parts off the bad one say if a valve is bad.

 

I asked them not to surface the head unless it truly needs it. I know most of them do, but no point in taking life off of it if it's not needed. Two weeks out.

 

Radiator went into the shop as well.

[Stoffregen Motorsports]

Dupli-color engine enamel is what I use. It has a high ceramic content and will resist most chemicals. Most engine enamels have a high ceramic content.

 

I will say that prep is most important. Clean the hell out of the block and make sure there are no oils on it before spraying.

[ttyR2]

I pulled the core plugs out of the block, drilled/tapped and pulled the two oil galley plugs, and dropped the block off at the machine shop for a good hot tanking. I'll spend time cleaning all the oil passages and give it a good pressurewash when I get it back.

 

How do you go about cleaning the passage behind the orifice that feeds the timing chain tensioner? It looks like it might be removable, but I don't see replacements available. Just blow a bunch of carb cleaner back through it along with an air nozzle while the oil galley plugs are out?

[datzenmike]

From the longitudinal gallery that you drilled and tapped there are 4 descending smaller feeds to the main bearings on the crankshaft. The tensioner oil feed is drilled into the front one. No way to really get at it. If there is anything in there it will be pushed out by oil pressure into the tensioner and will do no harm there. You can wire brush up the four feeds into the gallery. 

[ttyR2]

So...I win the bozo-of-the-month award. I neglected to notice that the Hastings rings sold at Summit Racing are sold in sets of one (1)! So...another few weeks and I should have the rest of the rings. Still...there's plenty to do in the mean time.

[ttyR2]

Took advantage of a nice morning out. Did a thorough block cleaning, masking, and paint.

 

Pre-bath that the machine shop did for me:

 

As received from the shop post-cleaning. On the stand ready for a good stiff scrub. I bought a set of long engine block brushes off Amazon (Speedway brand), hot soapy water, scrubbed every single oil passage thoroughly, and ran the pressure washer on the water passages aggressively. Likewise, I flushed a bunch of brake cleaner along with an air nozzle on the tensioner oil orifice, and upper-block orifice as well.

 

Masked and tossed the old empty oil cleaner on to keep paint out of places...

 

Duplo "GM Blue" color. It'll work, though not quite authentice. Thee good coats.

 

Tomorrow, after giving the paint a day to cure, I'll be putting the new freeze plugs in, and installing the crank/bearings.

 

I picked up the rebuilt head and the machine shop appears to have done a good job. Long term, the hold up will be the additional piston rings I had to order...they are still a few weeks out.

Edited March 16 by ttyR2

[Thomas Perkins]

Looks great.

[ttyR2]

Lesee...what else got done today. The paint seemed to have dried well after a few hours in the warmth so I put all of the freeze plugs back in, the two oil galley plugs, cleaned and reinstalled the block oil breather screen and baffle, tapped all of the head and crank bolt holes, and tried out the ring-squaring gadget I bought to make checking ring end-gaps easier. It was a good day.

 

I also took a bunch of video including time-lapse. I hope to put some of it up on Youtube soon.

[ttyR2]

Total video editing newbie...but here's my first couple of stabs at it. 

 

[ttyR2]

More progress today. Crank is in, clearances, checked, rear cap sealed. I ran the rear main crank seal flush with the outside of the casting, just a couple millimeters off of the groove worn in the crank. Still need to cut the two push-in seals on the rear cap but waiting until the sealant dries.