engine swap

1980-1986 Datsun 720 forums. All 720-specific topics and discussion can be found here.
buzzsaw
Posts: 5
Joined: Wed Dec 31, 1969 5:00 pm
Car: '82 datsun king cab, 89 camaro RS, 96 honda accord, 05 maxima

Postby buzzsaw » Wed Dec 31, 1969 5:00 pm

I have a 720 king cab 2wd that has set up for a while due to a blown head gasket.  Since there is no such thing as obtaining a replacement engine from a junk yard I am thinking about swaping for some other engine.  Has anyone done such a swap? If so what would you recommend?  It would have to be a fairly simple swap.  I don't have the shop for a major fabrication.  Any thoughts?


regularjj55
Posts: 11
Joined: Wed Dec 31, 1969 5:00 pm

Postby regularjj55 » Wed Dec 31, 1969 5:00 pm

The best advice I can give you is to use a z22 engine from another 81 or 82 720. Anything else and its going to be too much work, its already a tight fit getting the engine and tranny in there at once. The wiring is also a b**** to take out and put back in and thats with the original s***, i cant imagine what kind of nightmare youd have replacing the entire undercarrage engine and electrical without extensive prior experience.

That said, even if you did that the Datsun body is notorous for rust and doesnt take damage really well in accidents so rebuilding anything with it would be a waste of time.

My dad and I have gone through 3 datsuns over the years. The first 81 he bought back in 1982, it ran all the way until about 1994 when we bought an '82 as a parts truck and used it to replace much of the engine, transmission, and rusted body parts. Then in about '99 we used the old block from the parts truck and rebuilt the engine entirely and put it in the 81. Almost everything from the 81's and 82's is interchangable, little to nothing from 80 and 83-86 is interchangable (to my knowledge). Anyway, that newly rebuilt '81 got totaled by some ***hole with no insurance after only 10,000 miles, so we picked up a freebe '82 that woulda gone to the junkyard otherwise and put the engine in there.

Lots of those old datsuns are pretty decrepid just sitting in peoples driveways until they finally submit to laziness and send them to the junkyard. Both the 82's we just saw them sitting in our neighborhood and made the owner an offer, the first one was 500$ second one was free - so I think youre best bet is definetly to find another parts truck that still has the working parts you need.

regularjj55
Posts: 11
Joined: Wed Dec 31, 1969 5:00 pm

Postby regularjj55 » Wed Dec 31, 1969 5:00 pm

er you might also be able to find another head from a junkyard and get it rebuilt, or have that head repaired - if all you did was blow a chunk of metal outta the head you can have a welder fill it in then file it back down to the proper dimensions

buzzsaw
Posts: 5
Joined: Wed Dec 31, 1969 5:00 pm
Car: '82 datsun king cab, 89 camaro RS, 96 honda accord, 05 maxima

Postby buzzsaw » Wed Dec 31, 1969 5:00 pm

Thanks for the response.  The local junk yards just hang up when I mention  the age of the vehicle I'm looking for parts for.  I've checked with the local parts store and they sell a reman. for the old truck but as you pointed out there isn't enough value in the thing to make it worth the price.  I was hoping to find something from a later model which could be slipped in without too much trouble. Looks like a lost cause.  Thanks again for the insight.

User avatar
IMH
Posts: 352
Joined: Wed Dec 31, 1969 5:00 pm

Postby IMH » Wed Dec 31, 1969 5:00 pm

Did you 'blow a chunk of metal outta the head' as [user=3186]regularjj55[/user] suggested or just blow the head gasket?  If you just blew the gasket, pull the head, and have it resurfaced, and replace the gasket.  Not that hard.  If you did damage the head, then I'd agree.  Not enough value in a 720 to warrant the cost and welded aluminum heads don't really give me that warm/fuzzy feeling. :)

regularjj55
Posts: 11
Joined: Wed Dec 31, 1969 5:00 pm

Postby regularjj55 » Wed Dec 31, 1969 5:00 pm

s*** i hate to see a z22 ditched just cause of a head, if you werent in NC id definetly make an offer on your truck.

last welded head i fixed made it about 30,000 miles, and i drove that thing to death. If yo know a welder who can fill that in for like 50$ you can do the rest of the work yourself and at least get something outta that truck before you scrap it.


buzzsaw
Posts: 5
Joined: Wed Dec 31, 1969 5:00 pm
Car: '82 datsun king cab, 89 camaro RS, 96 honda accord, 05 maxima

Postby buzzsaw » Wed Dec 31, 1969 5:00 pm

Thanks for the responses.  I haven't had the head off yet so I really can't say that it is or is not damaged.  I didn't notice that the coolant had gotten low and it overheated and shortly after that even though it still ran well I started getting steam out of the exhaust which says at least blown head gasket if not more.  It was still running fine at that time but I parked it aiming to get back to it later.  Boy is it later.  I have now retired and have time to mess with it so I am ready to pull the head.  I requested info about swaps since that seemed the path of least resistance.  I've pulled heads and Ive swaped engines and if it is a straight swap out the latter is easier or at least it used to be before computers and while the earth was still cooling.:D Since the body panels are still in pretty good shape I thought I would try to still get a little more use out of the old girl.  She probably has 300,000 on the clock.  For some reason the speedo still works but the odo quit several years ago.


Return to “Datsun 720”