Swapping '69 273 with '84 318 Into My 1969 Dart

[CudaRay]

Hello,

I recently picked up a '69 Dart that was running and driving, keyword was. The radiator blew, and the engine ended up seizing from the heat. So, now I'm looking at buying a smog 318 local to me, it needs head gaskets, but should be good aside from that. It is off a D-150, so I will be reusing the oil pan and pickup tube from my 273 as the humps are in different locations between the two.

My main questions are,
-What kind of work am I looking at with this being an electronic ignition engine, where my car was a factory points unit? Can/should I use the ignition out of the 273 instead of this electronic ignition?

-Assuming I swap the performance 318 intake on my 273 now, use the 4bbl Edelbrock carb I also have on it, and de-smog the engine (the intake helps in this regard, as I won't have to plug EGR ports on the stock intake) should I at least be looking at similar performance if not better than that '69 273?

I still need to get the thing jacked up and find out if I have a 727 or 904, I've heard that the input shafts are different, and the 318 I am getting is currently mated to a 904. Any information or advice is greatly appreciated as a first-time engine swapper.


Thanks in advance for the help, everyone!

-edit-

I forgot to add that the 904, which is mated to this 318 I am getting, comes with it. I wonder if it would just be better to use the whole drivetrain, as that 904 has been rebuilt within the last year. I haven't found information on driveshaft length issues doing this, but I would imagine it wouldn't be any change, even with the new drivetrain being out of a D-150.

 

[junkyardhero]

i'd used the electronic ignition. it's fairly straight forward to modify the wiring for it. however, i'd suggest recurving the distributor for better/optimized performance-- it'll have a smog tune on it.

it'll be similar in performance, the compression ratios aren't that far apart. however, check that the heads don't have smog ports. if so you'll need to plug those.

reuse your flex plate and all that-- it'll bolt directly to the 318

the later 318 has a different front cover with the timing marks on the driver's side to correspond with a balancer that is marked differently and a waterpump that exits on the passenger side (instead of the driver's side in 69). naturally the radiator lower hose is placed on the passenger side.

so you'll need to take into consideration how you want to tackle this-- probably the easiest is to re use your front cover and such and just remark the 318 balancer.

but if you need a new radiator, this would be an perfect opportunity to upgrade everything...

 

[CudaRay]

i'd used the electronic ignition. it's fairly straight forward to modify the wiring for it. however, i'd suggest recurving the distributor for better/optimized performance-- it'll have a smog tune on it.

it'll be similar in performance, the compression ratios aren't that far apart. however, check that the heads don't have smog ports. if so you'll need to plug those.

reuse your flex plate and all that-- it'll bolt directly to the 318

the later 318 has a different front cover with the timing marks on the driver's side to correspond with a balancer that is marked differently and a waterpump that exits on the passenger side (instead of the driver's side in 69). naturally the radiator lower hose is placed on the passenger side.

so you'll need to take into consideration how you want to tackle this-- probably the easiest is to re use your front cover and such and just remark the 318 balancer.

but if you need a new radiator, this would be an perfect opportunity to upgrade everything...

Thank you for the information! This reassures me quite a bit on the situation. I have a new aluminum rad on the way. So, and I'm sorry if this is common knowledge, is the front cover swap done just to reuse the old water pump from the 273? I assume the rest of the accessories are unaffected by the front cover swap or bolt right up? I would imagine it's not too much work with both engines out either way, and I will probably have a lot of my questions answered when I pick up that 318 tomorrow and get a look at the differences between the two.

edit- I will be doing the head gaskets on the new engine, so I will be able to check for those ports, what would you suggest using to plug them if they are present?

 

[CudaRay]

Thank you for the information! This reassures me quite a bit on the situation. I have a new aluminum rad on the way. So, and I'm sorry if this is common knowledge, is the front cover swap done just to reuse the old water pump from the 273? I assume the rest of the accessories are unaffected by the front cover swap or bolt right up? I would imagine it's not too much work with both engines out either way, and I will probably have a lot of my questions answered when I pick up that 318 tomorrow and get a look at the differences between the two.

edit- I will be doing the head gaskets on the new engine, so I will be able to check for those ports, what would you suggest using to plug them if they are present?

To add to this, do we know if my 273 heads would be an upgrade over those 318 smog heads? I won't have the casting number for a day or two, but I doubt they are the 920s. This is just a cruiser/street car, it won't really get revved out much.

I guess this also depends on them not being damaged from the engine overheating. I will try and just get them off and inspected this weekend.

-edit-
I originally ordered a rad with the lower hose inlet on the driver side, but I have now ordered one with the hose on the passenger side (aftermarket aluminum slant 6 car rad). The dimensions are still the same or larger than the stock rad, and it's larger/more tubes, so I imagine that one will do just fine. The upper is further to the passenger side, rather than center, but I imagine I can source a longer upper hose for it.

 

[tonysrt]

To block the exhaust ports I used allen screws, just make sure they are short enough so they don't protrude. I did it about 30 years ago so don't remember what thread size, but it did work out well for me.

 

[RedFish]

I don't recall which early exhaust manifolds collide with the later smog heads. Owners have cracked manifolds while others grinded away castings as needed. Watch for it. Good luck

 

[4spdragtop]

As JYH eluded to both the wp and ALL the pulleys from one engine should be used.
You will end up in a clusterfu*k with mismatched pulleys if you dont.
Good luck.

 

[Oldmanmopar]

To block the exhaust ports I used allen screws, just make sure they are short enough so they don't protrude. I did it about 30 years ago so don't remember what thread size, but it did work out well for me.

1/4 20 - 3/16 long run a tap in and install the set screws flush

 

[CRUZE 418]

You do realize that there is 3/4" difference between the 2 water pumps? Along with they have different inlet sides from the radiator? Then the timing and balancer issues.

 

[CudaRay]

You do realize that there is 3/4" difference between the 2 water pumps? Along with they have different inlet sides from the radiator? Then the timing and balancer issues.

I didn't know about the size difference, but assuming the new radiator had the lower inlet on the passenger side, could I not just keep the 318 water pump installed and not worry about the rest?

 

[CRUZE 418]

There is usually a clearance issue, fan to radiator. The cast iron pump is 3/4" shorter than the aluminum one. The timing cover is the same except for the timing marks and harmonic balancer. Plus will your pulleys line up. You have sorta planted your garden. Someone else will chime in here, I would have stayed on the 273 side, and radiator. Now your in-between the two. Plus, new aluminum radiators, depending on the brand, have a history of everything not fitting very well.

 

[junkyardhero]

I didn't know about the size difference, but assuming the new radiator had the lower inlet on the passenger side, could I not just keep the 318 water pump installed and not worry about the rest?

yes, it will all fit but you won't be able to see the timing marks.

 

[junkyardhero]

To add to this, do we know if my 273 heads would be an upgrade over those 318 smog heads? I won't have the casting number for a day or two, but I doubt they are the 920s. This is just a cruiser/street car, it won't really get revved out much.

I guess this also depends on them not being damaged from the engine overheating. I will try and just get them off and inspected this weekend.

-edit-
I originally ordered a rad with the lower hose inlet on the driver side, but I have now ordered one with the hose on the passenger side (aftermarket aluminum slant 6 car rad). The dimensions are still the same or larger than the stock rad, and it's larger/more tubes, so I imagine that one will do just fine. The upper is further to the passenger side, rather than center, but I imagine I can source a longer upper hose for it.

the 273 heads are *probably* not an upgrade, if anything they *may* be comparable. though if they've been overheated or otherwise beat, then that's a nonstarter.

the slant six radiator will be wrong-- while the outlet is on the passenger side, it's at the wrong angle. get the correct radiator for the application.

 

[CRUZE 418]

You can see the timing marks, it just a little difficult. Mark with a sharpee where your timing will be. My '69 has a newer timing cover on it with a cast iron pump. You can time it.

 

[CudaRay]

the 273 heads are *probably* not an upgrade, if anything they *may* be comparable. though if they've been overheated or otherwise beat, then that's a nonstarter.

the slant six radiator will be wrong-- while the outlet is on the passenger side, it's at the wrong angle. get the correct radiator for the application.

Got it, I canceled that slant six rad and will plan on reusing the pump from the 273.

 

[CudaRay]

There is usually a clearance issue, fan to radiator. The cast iron pump is 3/4" shorter than the aluminum one. The timing cover is the same except for the timing marks and harmonic balancer. Plus will your pulleys line up. You have sorta planted your garden. Someone else will chime in here, I would have stayed on the 273 side, and radiator. Now your in-between the two. Plus, new aluminum radiators, depending on the brand, have a history of everything not fitting very well.

I did some research on the rad, I should be fine on fitment, but I will definitely need to drill a mounting hole or two.

I am a little confused with what you said about staying on the 273 side. Do you mean you would just use the 273 pump to use with the correct radiator and mark timing? I could be reading what you said wrong, but it sounds like you're suggestion is to reuse the 273 pump and mark timing on that 273 cover.

Like I said, I am very new to this. The most involved work I have done in the past is front-end on a B-Body and dropping a trans on a Cummins.

 

[CudaRay]

I don't recall which early exhaust manifolds collide with the later smog heads. Owners have cracked manifolds while others grinded away castings as needed. Watch for it. Good luck

Would you happen to know if a set of headers in place of those smog manifolds would potentially have the same issue? Either way, I guess I will find out soon. Thanks for the heads up!

 

[AJ/FormS]

Maybe the 273 just ended up with swollen pistons? After they cooled, MAYBE, she's all right. I say this because it's happened to me on a few occasions.
If the 273 still turns over, I would oil up the rings, and do a compression test before I took the heads off.

 

[CudaRay]

Maybe the 273 just ended up with swollen pistons? After they cooled, MAYBE, she's all right. I say this because it's happened to me on a few occasions.
If the 273 still turns over, I would oil up the rings, and do a compression test before I took the heads off.

That could've been true, as it turned over for a second after I got more coolant in it at the time of overheating. I know you're not supposed to do that, but at the time I figured if it's dead, it's dead. It had some wild knock just before it shut off.

I'll definitely be taking a look at the engine when it comes out, but as it sits it will not turn over now.

 

[AJ/FormS]

Just so you know:
Even if your smog-318 was a true 8/1 engine, with 020 steel shim headgaskets,
After you install 028s, the Scr will drop to about 7.8, and the engine will lose about 4 to 5psi cranking cylinder pressure.

At your elevation of 1300 ft, that is from a predicted 133psi to 128psi
at that pressure, your performance loss would be quite noticable in an A to B comparison.
IIRC your 69 273 was a 9/1 engine, it should have been making about 156psi.
Yur lo-compression 318 engine is thus predicted to be about 6% less powerful from idle to about 3000/3500rpm.

Just saying; If yur ok with that, great. Just don't be putting a cam in there with a later-closing intake, cuz that will reduce the pressure even more.

 

[junkyardhero]

Would you happen to know if a set of headers in place of those smog manifolds would potentially have the same issue? Either way, I guess I will find out soon. Thanks for the heads up!

they'll still need to be sealed up.

 

[CudaRay]

Just so you know:
Even if your smog-318 was a true 8/1 engine, with 020 steel shim headgaskets,
After you install 028s, the Scr will drop to about 7.8, and the engine will lose about 4 to 5psi cranking cylinder pressure.

At your elevation of 1300 ft, that is from a predicted 133psi to 128psi
at that pressure, your performance loss would be quite noticable in an A to B comparison.
IIRC your 69 273 was a 9/1 engine, it should have been making about 156psi.
Yur lo-compression 318 engine is thus predicted to be about 6% less powerful from idle to about 3000/3500rpm.

Just saying; If yur ok with that, great. Just don't be putting a cam in there with a later-closing intake, cuz that will reduce the pressure even more.

I guess I'm hoping with the dual-plane intake, 4bbl, headers, and mopar orange ignition module it will at least be equivalent to what the 273 was.

It was running lean when I was driving it, so I may not even notice the difference if the 318 is tuned well. I have no further performance mods in mind after those, it'll just be cosmetics.

The gaskets I got were fel-pro, and I want to say they are 039. I couldn't justify 4x the price for a $500 engine, haha.

-edit-
The calculations I just made with compression show a compression ratio of 8.5:1, which isn't bad. The stock gaskets seem to have been .069, so I imagine that could make a difference? I could be doing something very wrong though, as I've never messed with compression ratios.

 

[Illahe]

Hello,

I recently picked up a '69 Dart that was running and driving, keyword was. The radiator blew, and the engine ended up seizing from the heat. So, now I'm looking at buying a smog 318 local to me, it needs head gaskets, but should be good aside from that. It is off a D-150, so I will be reusing the oil pan and pickup tube from my 273 as the humps are in different locations between the two.

My main questions are,
-What kind of work am I looking at with this being an electronic ignition engine, where my car was a factory points unit? Can/should I use the ignition out of the 273 instead of this electronic ignition?

-Assuming I swap the performance 318 intake on my 273 now, use the 4bbl Edelbrock carb I also have on it, and de-smog the engine (the intake helps in this regard, as I won't have to plug EGR ports on the stock intake) should I at least be looking at similar performance if not better than that '69 273?

I still need to get the thing jacked up and find out if I have a 727 or 904, I've heard that the input shafts are different, and the 318 I am getting is currently mated to a 904. Any information or advice is greatly appreciated as a first-time engine swapper.


Thanks in advance for the help, everyone!

-edit-

I forgot to add that the 904, which is mated to this 318 I am getting, comes with it. I wonder if it would just be better to use the whole drivetrain, as that 904 has been rebuilt within the last year. I haven't found information on driveshaft length issues doing this, but I would imagine it wouldn't be any change, even with the new drivetrain being out of a D-150.

your torque converter register will be too small for the 318. Perhaps someone manufactures a bushing or you may have a lathe to spin one up.

 

[Illahe]

I guess I'm hoping with the dual-plane intake, 4bbl, headers, and mopar orange ignition module it will at least be equivalent to what the 273 was.

It was running lean when I was driving it, so I may not even notice the difference if the 318 is tuned well. I have no further performance mods in mind after those, it'll just be cosmetics.

The gaskets I got were fel-pro, and I want to say they are 039. I couldn't justify 4x the price for a $500 engine, haha.

-edit-
The calculations I just made with compression show a compression ratio of 8.5:1, which isn't bad. The stock gaskets seem to have been .069, so I imagine that could make a difference? I could be doing something very wrong though, as I've never messed with compression ratios.

View attachment 1716471355

The Enginetech gasket kit has head gaskets with a smaller fire ring for 318. I recall 4.08n vs 4.125 or 4.140. In your application the felpro gaskets will drop the compression 1/4 point or more.

See: Enginetech ENGCR318-29

You could advance the cam 4* while your making the swap as well.

 

[CudaRay]

your torque converter register will be too small for the 318. Perhaps someone manufactures a bushing or you may have a lathe to spin one up.

The engine came with a fresh rebuilt 904, so I guess I will just use that and pull my '69 904 attached to the old 273.