ok this motor out of 77 ( unknown if original)

Block N42 Unkown milage or Vintage, lots of other mods to car!

head N47 (later model, No spray bar)(recently refreshed)

Original problem was smoking bad after teenager snuck it out for a joy ride!

compression results before tear down (engine was NOT warm, been out awhile)(rubber press in gauge, approx 5 comp stroke each)_

#1 #2 #3 #4 #5 #6

148 148 145 145 148 148

(after 3 Squicks of motor oil)

160 155 159 162 159 170

Tops of all pinston pretty Gunked up, 5 & 6 worse hard oily grease build up!

No crap in oil pan, sump screen clean

Clutch pressure plat flywheel trash, Rivets thru and groves!

Havent pulled lower end bearings yet, but there was no noise or signs of problems when motor was pulled!

The inside of cylinder walls had NO Ring RIDGE at top of cylinders, no gougesor deep scratches, almost looked like it still had hone marks???? Sorta but shinnier!!

all spark plug ports had alittle standing oil on outside by threads, no valve cover leaks, 5 & 6 plugs oily/fouled, rest burning clean.

cylinder bore unknown at this time(no dial mike to check (YET!!)

head looked clean , cam not grooved, sharp edges (ouch!!) valve side 5 & 6 had build up on the valves and a COOPERn look around the ouside edges of the combustion chambers.

Whats everones best EDUCATED guess!! Trying to put this back at Sons EXPENSE!!! And of course he's on a limited budget! I'm Not fessin up another Dime!

This is the motor out of my 77 he trashed, needs to go in his 240 which he just ran out of oil and Knocking like a Bitch , barely will run or start!

I know this is why animals " EAT THEIR YOUNG"!!

Collapsed oil control rings.

Those probably were the original hone marks. Datsun blocks are TOUGH. I'd suggest you slap some rings in it and clean the pistons. Hone with the old style ball hone that you get from the auto parts store. New valve stem seals (since you have it apart anyway), could do a valve job if you want, and slap it back together. Throw some bottom end bearings in it and call it a day. It's not hard to do and the parts won't cost very much at all. Even the valve job isn't that bad if you bring the head to the machine shop disassembled.

Get a flywheel from Mat_M, he's got a few, and have that machined, throw it in with a stock clutch kit, your kids out of trouble for ~$500.

yep, i'd say replace the rings and re-hone the cylinders along with cleaning up the head and valves.

Ok so I dont feel as stupid now! you guys are right on the money with what Ive been thinking, $^!# been 30 years since I tore one down this far for a rebuild, and that was a small block chevy.

couple more questions, would there be a reason I cant have the flywheel turned, seen alot of rotors and drums in worse shape?

Where and what brand for rings and bearings ?

The flywheel can be resurfaced if it is not trashed too bad. Any name brand parts will do fine.

OK ! pulled the pistons, here's #6 which seemed to be the worst of all. Which ring is which , from top down. the only thing I noticed was the bottom set doesnt stick out near as much as the top 2 rings, bearings didnt look bad at all (from what I can remeber they are supposed to look like), crank rod mounting surfaces are clean, slick un scarred.

When honing the cylinders is there a magic speed, low or high, or time spent in each cylinder , dont want to **** this up!

The bottom one is the oil ring and it does appear to be collapsed. The top ring is the one that sits flat against the cylinder wall and the second ring is the tapered one that mounts with the tapered surface downward. I forget the actual names but I learned from once installing them wrong in a L16.

can you expond on the TAPPER, dont see anything that would make me say HEY ITS TAPPERD, and looking at these ( could be stock I dont see any MARKINGS), going to order new $^!# today!

The second ring is kind of trapezoid shaped when you view it from the side. The larger part goes toward te bottom.

I just finished rebuilding my engine and had to go through 3 sets of rings from different manufacturers before I found one with an acceptable end gap. Each one had a different shape (cross section of the ring). You need to assemble the rings per the instructions from the ring manufacturer. Just take your time and go slow. I reread the instructions several times to make sure I wasn't getting something upside down. Tunes were turned off for this step