What would you do to a junkyard engine?

[CHSW]

Bought me a nice little 87 300zx and proceeded to rip the engine a new... orifice. 300 mi later we have jumped a tooth on the crank and its time to put the junkyard engine in. I have about a dozen to chose from so I figure I will pick the lowest miles engine and go from there. Plan A is to just do a timing belt and slap it in. I always hate plan A. Plan B consists of a low mileage doner out of a 87 - 93 maxima or some other similar VG30E choices. I figure a upper and lower gasket kit, oil pump, water pump, and timing belt kit. Last 3.0 I played with was a Yamaha 3.0 in a SHO and I did the 3 cam sensors at the same time. I have found no reference to cam sensor replacement being necessary but if it is, then it is. I figure new clutch and pressure plate while I am in there, weather it is plan A or B I follow through with. I plan to pull the engine next week from the junk yard, so this week will be ordering parts. Any recommended sourcing? Rock auto seems to beat everyone on everything short of the gasket sets on ebay. Thanks for your time and consideration. Not my first eastern car but it dam sure makes me prefer the load of room under the old Town Car or Nova Custom. Almost felt like it would hang with the nova...till she blew

Either way I go I am debating yanking the heads and doing a head gasket as well as the other gaskets. If I do this I can almost guarantee a rering and bearings... along with heads in the shop to be cleaned and tweaked... both of which I am trying to avoid. Cars just being assembled to be a fun little highway car with good mileage when I can stay out of it.

Thanks for your advice and time.

[evildky]

It's a case by case issue. If the engine has "low miles" the plugs look good, oil doesn't smell burnt, no crud in the coolant, the timing belt looks good, no noise from the timing belt bearings I'd just put a belt on it and go.

[Pitts]

If the cams are on mark and the crank only jumped by 1 tooth, you should be safe still. On my Z, the left cam had jumped 3 or 4 teeth and she still ran with no valves hitting. Idle was a little rough and so was my low/mid end. But once I hit 4k rpm, she pulled hard. Before going through an engine swap, I'd suggest pulling the timing and cams to do a compression test to verify you have a good seal (no leaks) from the valves. Saves a lot of time. You can do a compression test with the cams in (but valve covers off), but its a bit of a hassle and takes longer.

[CHSW]

Hmm thanks for the advice. She was still running when I parked her, but the next morning when I cranked her up she was missing on 4+5 (pulled plug wires and while still sparking there was no change in engine sound) I reved her up to about 3 grand and then she just shut down and will not crank, even on carb cleaner. I just figured I had jumped another tooth. The existing engine has 215k so if a comp check clears the block I might just go that route. I really do not like yanking cams unless necessary but I should be able to just loosen the rocker nuts and compression test without pulling the cams. Thanks for the advice, now to fix the ac in the garage.

[evildky]

You only remove the spark plugs and wire the throttle open for a compression test (also pull fuel pump fuse and disconnect coil). You don't touch the cams or valve train for a compression test.

[Desert Rat]

VG33 supercharged from a 2002-2004 Frontier or Xterra...That I'd love to see in a Z31....gonna need a hood bump though

[CHSW]

You only remove the spark plugs and wire the throttle open for a compression test (also pull fuel pump fuse and disconnect coil). You don't touch the cams or valve train for a compression test.

If my belt has sliped as I think it has wouldn't a comp test give false readings if the valves are partly open?

[G-E]

If the belt jumped, fix it before you do anything else... don't start testing/checking things until everything that's wrong is set correctly, unless you like chasing phantoms

[evildky]

If the belt jumped, fix it before you do anything else... don't start testing/checking things until everything that's wrong is set correctly, unless you like chasing phantoms

this

[Pitts]

The reason I said pulling the cams would be easier (or as the OP said, at least loosening everything so the rocker arms aren't being pushed down) is because all the valves would be closed. Then all he has to do is start running a test. It's ideal to remove the timing belt for this job. Doing this test first will let him know his engine condition. Then he could always install a new (or the old) belt and go from there. Both a compression test as well as a leak-down test will tell him how healthy his engine is.

[CHSW]

Plan to do this this weekend, soon as I have the time. Car is to clean to scrap but I am told the hatchback and t-tops are worth more then I paid for the car. Lots of variables to consider but I think I will fix it. Glad someone understood what I ment about loosening the rockers.

[evildky]

The reason I said pulling the cams would be easier (or as the OP said, at least loosening everything so the rocker arms aren't being pushed down) is because all the valves would be closed. Then all he has to do is start running a test. It's ideal to remove the timing belt for this job. Doing this test first will let him know his engine condition. Then he could always install a new (or the old) belt and go from there. Both a compression test as well as a leak-down test will tell him how healthy his engine is.

That would work if running a leakdown test,in order to do a compression test you need the valves opening and closing as normal. Even in a leakdown test I'd roll the cam till the cylinder I was testing was closed.