Tom Mogush
Member
I have a 65 Dart GT with the 273 in it, and would like to swap in a 340. will any year 340 work? or are certain years less work/modification needed? what are the common problems with installing the 340? Thanks in advance
273 to 340 swap
- Thread starter Tom Mogush
- Start date
-
I know one problem is motor mounts for the 340. Why chrysler changed lugs on the A engines between 273, 318 and 340,360 doesn't make any sense. You can get mounts from Schumacher but a little pricey. Some guys put a shim in mount to make 273-318 work on 340 & 360..
replicaracer43
Grumpy Old Man
- Joined
- Oct 10, 2008
- Messages
- 6,051
- Reaction score
- 7,867
Externally ballanced 340s will require a ballanced convertor or flex plate also.
67Dart273
Well-Known Member
I think a better word would be "weighted." To me, "balanced" means "neutral."
67Dart273
Well-Known Member
Crackedback and others have posted on this. To be "tech" correct, these are not "motor mounts" they are "engine brackets." The mounts are the separate rubber part. The brackets are the separate pieces that bolt to the engine
OOOOOOOPOPPPSSSS He cracked YOUR PHOTOS ARE GONE!!!
crackedback, engine brackets - Google Search:
replicaracer43
Grumpy Old Man
- Joined
- Oct 10, 2008
- Messages
- 6,051
- Reaction score
- 7,867
Yeah, your probably correct, not the best terminology
BillGrissom
Well-Known Member
Dent oil pan to clear steering, or use 65 pan. Need spacer ring on torque converter snout to fit later crank.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 24,922
- Reaction score
- 12,273
You'll be adding in the neighborhood of 100hp and a lot of low-rpm torque,comparatively. So don't neglect the chassis and brakes. 9inch drums are gonna be a problem, as would a 7.25 rear. And the rest of the chassis will only be good for point and shoot.Think HD everything. Brakes,springs,bars, shocks,U-joints,torque strap,starter,battery,and of course tires. There would be no point to add 100 hp to run skinny rollers back there.
And obviously, the 340 is not gonna like the 273 log-manifolds.And forget the 273 pipes.
Depending on you power level, you may need upgrades to the cooling system, the fuel system,the ignition system, and possibly to the charging system as well.
Go over the body welds, making sure everything is still connected to everything it's supposed to be and especially the frame stubs and front suspension pick-up points.
As far as swaps go, this is a great one; plenty of power in a light-weight pkg; a real giant killer.
And obviously, the 340 is not gonna like the 273 log-manifolds.And forget the 273 pipes.
Depending on you power level, you may need upgrades to the cooling system, the fuel system,the ignition system, and possibly to the charging system as well.
Go over the body welds, making sure everything is still connected to everything it's supposed to be and especially the frame stubs and front suspension pick-up points.
As far as swaps go, this is a great one; plenty of power in a light-weight pkg; a real giant killer.
If you really want to be technical the rubber part is the insulator. You can call the bracket anything you want but it still has to be changed.
67Dart273
Well-Known Member
MayBE, but if you go to the parts store and order an "engine bracket" they likely won't know what you mean, or will try and sell you an engine mount.
And if you ask for an insulator they will REALLY be confused.
belmateo
Well-Known Member
Any year will work as they are externally the same dimensions. What transmission are you mating to it?
BillGrissom
Well-Known Member
While deciding, consider that 340 blocks and parts are quite rare now. There are more after-market parts for a 360, so many go that way. Seems a 340 is more for those wanting the original power engine and also higher rev'ing (especially 340TA w/ mechanical lifters).
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 24,922
- Reaction score
- 12,273
And you can bore the 360 out to 4.04 and call it a 340 stroker, now it's being a 367. It can do Everything the 340 can do. If you build it to the same horsepower, it will get better fuel economy, maybe run on cheaper gas, and need less rear gear, to be a much more fun tractor of an engine/city-friendly combo.
But if you build it up with the same 340 type parts with lots of compression,that little 268/276/114 cam will pull like a diesel tractor, while reving to the moon, and getting thru the the traps quicker and faster than the 340.And she'll probably do it with 1 size smaller rear gear.
But if you bolt it together with 8.0 compression, it will still make more torque than the late 340s with also similar CR ratios.
There's just no losing with a 360, except perception. The 340s got the reputation, the 360s got the rap-utation. Taintso when they are similarly street-built.
But if you have your heart set on a 340, the 68 stick engines were the hottest, the 68 to 72s were the next hottest, and the 73-ups; well some call them slugs. While they 73-up CRs were down, this mostly affected their low-rpm operation. Just crank the timing back in and they were still pretty good performers.Make that; really good, for 73up
None of this is likely to mean much to you, cuz any old 340 you can find today is likely gonna need a rebuild, and then you can pick and choose to build what you want or need. Or perhaps you get lucky, and someone else has already done it for you.
But if a 340 is not written in stone, then a 360Magnum is probably the best thing going these days;or at least it could be with a little forethought.
Physically, they are all pretty much the same. Paint them red and it will take a keen eye to tell them apart.A stroker 318 is a special case. It looks exactly like a 318 on the outside; EXACTLY. Yet they have been bored out to 4.00 and stroked to 4.00, and that makes 402 cubes, or plus 26% displacement. And that is a game-changer. In your GT that's about 7 pounds per cubic inches. SEVEN!
My 68 Barracuda at 3450pounds would need 493 cubes to match that.
So at 402, you can pretty much build it as tame as you want and still be the bully on the block.
If you were to build it up to 1hp per cube, it would make 402 hp, and have the potential to drive your GT to over 120mph, perhaps mid 11s in street trim.
If you built it tame, about the tamest you could make would be .75 hp per cube or 300 hp. 300hp. That's already on par with an early 340, that was pushing .9hp per cube. Ok but; 300 could push your GT to around 110 in the qtr.Still really fast.And that tame engine could make an awesome streeter. Mega-smallblock-torque. You will not be able to put big enough tires into the stock tubs to tame the torque. Nor will the smallest gears tame it. Nor the smallest TC.
But if you went middle of the road, at say .88hp per cube, giving up some of that mega torque which overpowers the chassis, now you have the potential for 350 hp and 116mph in the qtr. It will still have too much torque for the chassis, but it will also have alotta pull on the top. A LOT!.
And it still looks like a 318 on the outside. In fact, you could even put the 2bbl back on, and not even know the difference until well past the speed-limit! Talk about being a giant killer.
Of course I suppose you could do this to a 360, for an extra 6 cubes...... The only easily visible difference would be the right-side engine lugs................yes the teener top-end will bolt right on,lol
But if you build it up with the same 340 type parts with lots of compression,that little 268/276/114 cam will pull like a diesel tractor, while reving to the moon, and getting thru the the traps quicker and faster than the 340.And she'll probably do it with 1 size smaller rear gear.
But if you bolt it together with 8.0 compression, it will still make more torque than the late 340s with also similar CR ratios.
There's just no losing with a 360, except perception. The 340s got the reputation, the 360s got the rap-utation. Taintso when they are similarly street-built.
But if you have your heart set on a 340, the 68 stick engines were the hottest, the 68 to 72s were the next hottest, and the 73-ups; well some call them slugs. While they 73-up CRs were down, this mostly affected their low-rpm operation. Just crank the timing back in and they were still pretty good performers.Make that; really good, for 73up
None of this is likely to mean much to you, cuz any old 340 you can find today is likely gonna need a rebuild, and then you can pick and choose to build what you want or need. Or perhaps you get lucky, and someone else has already done it for you.
But if a 340 is not written in stone, then a 360Magnum is probably the best thing going these days;or at least it could be with a little forethought.
Physically, they are all pretty much the same. Paint them red and it will take a keen eye to tell them apart.A stroker 318 is a special case. It looks exactly like a 318 on the outside; EXACTLY. Yet they have been bored out to 4.00 and stroked to 4.00, and that makes 402 cubes, or plus 26% displacement. And that is a game-changer. In your GT that's about 7 pounds per cubic inches. SEVEN!
My 68 Barracuda at 3450pounds would need 493 cubes to match that.
So at 402, you can pretty much build it as tame as you want and still be the bully on the block.
If you were to build it up to 1hp per cube, it would make 402 hp, and have the potential to drive your GT to over 120mph, perhaps mid 11s in street trim.
If you built it tame, about the tamest you could make would be .75 hp per cube or 300 hp. 300hp. That's already on par with an early 340, that was pushing .9hp per cube. Ok but; 300 could push your GT to around 110 in the qtr.Still really fast.And that tame engine could make an awesome streeter. Mega-smallblock-torque. You will not be able to put big enough tires into the stock tubs to tame the torque. Nor will the smallest gears tame it. Nor the smallest TC.
But if you went middle of the road, at say .88hp per cube, giving up some of that mega torque which overpowers the chassis, now you have the potential for 350 hp and 116mph in the qtr. It will still have too much torque for the chassis, but it will also have alotta pull on the top. A LOT!.
And it still looks like a 318 on the outside. In fact, you could even put the 2bbl back on, and not even know the difference until well past the speed-limit! Talk about being a giant killer.
Of course I suppose you could do this to a 360, for an extra 6 cubes...... The only easily visible difference would be the right-side engine lugs................yes the teener top-end will bolt right on,lol
Last edited:
-
