Greyson

Hi, I've got a 1981 280zx. It was running fine, yet one morning I woke up and it was knocking. I've not driven it since, except to start it occasionally and then i didn't run it long enough to get to running temperature. I've had 3 people now tell me that the knock is more than likely the connecting rod and that I need to rebuild the engine from the bottom up to fix it.

However... I was working on it this morning in my driveway and this guy driving by stops and asks me if I need an engine for it. What luck right? Well here's the issue. The engine is out of a '76 260 with twin carbs and automatic. Mine has manual fuel injection and a standard transmission.

The question is will that engine work in my car? Keep this in mind, I'm not a mechanic, not even a backyard mechanic. But I can read and I have the service manual right here for my car. (It's written in both Japanese and English and it's printing date is 1981 so I'm assuming it came from the manufacturer)

I think it would be much easier to swap a motor than rebuild it, but I honestly don't know if that engine will work in my car. The guy with the engine says it will work but he's also trying to make a sale so I'm asking you, the Z community here for some advice. Please help me guys.

naviathan

Yes a 260 engine will swap in just fine. The oddity here is you say you have manual injection? That wasn't standard in a ZX. Are you sure it's no electronic injection? Now, although the 260 engine will bolt up just fine there are some discrepencies you want to look at first. The 260 didn't make quite as much power as the 280ZX engine so it will lack a bit there. The head on it also does not have the injector cutouts in the ports for the fuel injection, so you either have to swap in your old head or change over to carbs. Honestly I think you should rebuild what you have. It's not difficult to do. That said, first pull your valve cover and make sure you don't just have a lash pad that came off and is causing the rocker to tap on the tappet. Then drop your pan and check the rod bearings for play. Your FSM will have all the specs you need, but I don't think it would just start knocking out of the blue. These are tough engines that last 300-400,000 miles.

lww

I think he meant he has a 5-speed and it's fuel injected where the 260 is an automatic transmission with carbs.

If you were going to do the swap and keep your fuel injection (this will be the least technical swap - requires no change in the electronics), you'd have to pull the intake/exhaust manifolds and the heads off both engines.

Disconnect the tranny's, slide them back to pull the shaft out of the crank then cherry pick the blocks out of the cars. I would probably remove the fan, water pump and radiator to give a little more room.

Drop the 260 blocks back into your car, re-install your head, intake and exhaust manifolds. Then re-install your tranny.

Sounds easy doesn't it?

Greyson

Thanks for that quick response.

I'm pretty sure it's manual fuel injection. As soon as my phone is finished charging I'll go take a few pics of it. The reason I said it was, is that's what a mechanic told me.

As for power, I'm not concerned, I just want it to run again. It's been off the road for almost 2 months now. The guy only wants $150 for the engine and transmission. Apparently he had built a 260 for his kid and gave it to him for his 16th birthday. The kid ran it off into a ditch and bent the frame. So dad took the toy away from him, pulled the motor and trans out of it and it's been sittin there for a couple months cluttering up his garage.

I have taken off the valve cover and looked in there. There was sludge all over the furthest back lobe of the cam. And that's about where I was placing the noise when I last had it running. One thing I didn't understand was the holes in the cam itself. It appears the the oil runs through the cam and squirts out those holes. And that back one is probably sludged up to hell. Would that be enough to cause it to knock? As for the valves/springs and all the other stuff I have no idea what it is under the valve cover. Nothing appears loose or broken or missing.

As for changing things over, I was going to just leave the carbs on it and get rid of that fuel injection crap altogether. I simply don't know anything about fuel injection, so I figure leaving the carbs on it would simply make things easier. I was just going to unbolt that engine from the automatic trans, pull mine and drop that one in there as is, bolt it all up and pray like hell.

I would junk the car but it only has 110k miles on it. The body only has rust on the right front fender. The interior is perfect except on the seats where the fabric is worn out. Oh and 2 cracks in the dash. And I just put struts, rotors, wheel bearings, tires, and brakes all the way around it less than 6 months ago. I got the car last Jan. (2005) from my uncle who got it from his father in-law. The car was garage kept until I got it. And prior to my uncle the car was only driven on the highway for out of state trips. My uncle on the other hand dogged the hell out of it telling me it'd do 80 in second gear without straining. That I never tried myself. Hell I never even went over the speed limit. I babied the damn car and now it's leaving me high and dry. Ah sorry for the spammage but I'm just at a complete loss with this car. I've never had to or wanted to work on a car before. (Normally I would have junked it and gotten something else but this time around my cash is low and as I said I just put a bunch of money into it within 6 months.)

EDIT: The engine I would be buying is sitting out of the car in a garage already. And yes I did say manual fuel injection. Just going on what I was told, and yes it does have a 5-speed. Errm I think that's it.

lww

Your mechanic doesn't know these cars. Datsun/Nissan NEVER had 'manual' fuel injection. It's ALWAYS been 'electronic' fuel injection.

Absolutely, YES!

That's a hell of a lot more work and you'd have to adapt the 260 engine electronics to the 280ZX. Not an easy task for a beginner. Also, that crappy fuel injection is about 1,000,000% better than the crappy carbs that went on the '73 240Z and the '74 260Z.

Again, your mechanic doesn't know what he's talking about. No 'manual' fuel injection was ever installed in a Z car from the factory.

jfairladyz

and just to add my 2 cents...make sure the engine you're buying is atleast in better shape then yours is. Otherwise you might be coming up on a huge $150.00 paper weight thats just going to put you in the hole even further.

On another note, if you want to pay me I can come up and do the swap for you. I'll be moving back to VA this week. PM me if you're interested. I can do it either way for you; Fuel Injection or carbs...your choice.

duowing

Well the thing with his cam, couldn't that essentially be cleaned up, rather than having to swap engines over?

jfairladyz

possibly...but it all depends on if there was any damage done. Of course swapping engines is a most extreme option. But it all depends on whats actually wrong with the engine.

skittle

my opinion keep the engine rebuild it so you can keep every thing where it belongs electronics and all. now if the guy had a turbo engine that would be a whole different story..

Greyson

Hey thanks for all the advice

I had a friend of a friend who's a mechanic look at it, he dropped the oil pan was up under it for about 15 minutes and said I had a busted pin in a connecting rod or something. He also said I'd have to take it all apart to fix it.

So, I went and looked at the other engine. It's not stock. From the outside I couldn't see all that much, except those strange little carburators and a 3" header. Guy said the motor had been rebuilt about 30k miles before it was taken out of the car. And that work at a Nissan dealership. He told me a lot more about the engine. A whole lot more. It seems to have had a bit of work dont to it. Guess thats how and or why the car was wrecked. Pfft yeah. It turned freely with a wrench at the crank so it wasn't locked up. The motor was extremely clean, and it was kept in a nice dry garage. End result, I'm picking it up soon. That engine from outward appearances is in better shape than mine. Much cleaner except for a light layer of dust on the breather.

Now I have to figure out how to put it all together. All the parts are there, the engine and trans of course, trans mounts, driveshaft, radiator. I think everything I need to convert it to automatic if I want. Now I just have to figure out which intake, fuel injection or carbs. From what I gather from reading the thread, it would be simpler to use the fuel injection system.

Now I'm assuming that my intake will bolt right on up to this thing, because if not I won't have much choice and have to make the carbs work. And I'm hoping the same for the trans, I don't really want to lose my 5-speed. Even though I curse it everytime I sit in traffic.

Someone told me that 240, 260, 280 means the liters of the engine like 2.4L, 2.6L, 2.8L... is this true? And if so does that matter as far as the parts all working with each other? IE the 260 block and 280 intake? As for the exaust manifold I already figure I'll be shopping for a 3" exhaust to fit the header. It's old enough not to need emissions anyway.

Oh yeah, here's the odd thing. My car still runs fine. Idles normally. The only problem is the overly loud knocking. Even after I put the valve cover back on this afternoon. Shouldn't it have died or something? The only problem it ever had was overheating a little last summer when it was 95+ degrees. And it didn't knock until one morning this past spring (about 2 months ago) when I started it. The night before it didn't. It was running perfectly normal. It still does for that matter except the knock. I've just been afraid that if I drove it, I'd tear it up to the point where rebuilding it wouldn't even be an option.

jfairladyz pm me man, how much would I be looking at?

Sorry but I thought of another question. My car no longer has to have emissions. Can I take that catalytic converter off? Or does it have to stay on there for inspections? (Virginia)

Again thanks for the input.

WildmaN

If you have to have the catylitic convertor there. Do what I did, gut it out, and stick it back on there. I passed emissions here with flying colors, with a gutted cat. But it is your call, I mainly did it also, because my cat was shot to sh#t. And I didn't want to buy another one, if I didn't have to. Also my Z sounds better with the cat gutted. A little rougher, kind of roadster sound. Which I think really rocks. Anyway as for your engine, if it is bad internally, I wouldn't run it too much. It could do more damage, if you want to rebuild it later. It will be less to mess with, if you run it the least as possible. Just my 2 cents, and good luck to you, whatever you decide. We are all here to help you out man. And keep us updated.

SHADY280

if your cam is damaged, i can sell you a stocker with no damage for cheap, i got 4 of them just sitting.

jfairladyz

A gutted cat actually impedes power compared to a properly working cat. Of course gutted is better then blocked up. But the chamber a gutted cat creates causes problems with the exhaust flow. It creates a stagnation in the flow. Be better off putting a straight pipe in its place, or if the cat needs to be there you can put a pipe through the cat so that the exhaust can still flow straight through.

Greyson I'll PM you soon. Let me figure it out and I'll get at you. I'm not looking to make anything off of you. Maybe a few bucks. Basically just looking to cover the cost of coming up to where you are. What city are you in??? It just says Northern Virginia.

Greyson

Here's an Update:

I've moved the car to a friends garage and started pulling the engine myself. I have a few manuals and so far they're sufficient. I also have a friend of a friend who's a mechanic checking up on my progress and he gave me his cell number just in case I totally screw something up.

I've also decided to leave the carbs and manual transmission on that engine. The only parts that I've noticed I'll need so far are a fuel pressure regulator (I have an electric fuel pump and the older engine has a mechanical one) and a shifter. The reason I'm going to go with the carbs is I can eliminate a lot of crap in the car. Well not eliminate, I'm going to bypass the electronic stuff and just leave it there until I get the original engine rebuilt. That and I'm hoping that by not changing a lot of stuff on the new engine I won't have to keep tweaking it to get it running right. This way I can have an entire assembled engine once I do get it rebuilt and just drop it in. The reason I'm going with the automatic is that will give me a chance to have my 5-speed rebuilt. Which it does need, the synchronizer gear in it was going bad anyway. It was starting to grind going into 2nd. Did I mention I have the trans cooler, crossmembers, a couple driveshafts and I think everything else I need to changover except the shifter itself? Umm yeah oh and I guess I have to remove the clutch pedal.

You guys know where I can find an automatic shifter for a Z? I called a couple junkyards around here and one of the guys laughed when I said 280zx, apparently they have a tendency to rust out and get crushed in junkyards.

But long story short, so far so good. Luckily the old engine didn't leak anything so it's fairly clean except for road grime. Which brings up another question. Can I powerwash the old engine when I get it out? And the engine compartment without worrying about the water damaging the car? It's just dirt, dust and road grime, no oil or anything. Yeah guys I'm a complete noob when it comes to repairing vehicles. Most I've done is change the oil, brakes, plugs... you know the idiot proof things.

I took a break today, but plan on having this finished hopefully by the end of the week working on it in the evenings. I'll keep you updated.

EatmyDust

well atleast you have to wory about out runing any fuel injection z with your new carb setup. all those electronics and stuff might have made the car a little too responsive for you . I could also understand why somone would want to get less miles for the gallon too .

Electronic engine controls are not a bad thing to have. I would probably brake the engine down and have the block bored and put some over sized pistons in. simple and efective. yeas a little work, but still effective.