appearance of a 340 vs. 360

-
trudysduster

trudysduster

FABO Gold Member
FABO Gold Member
Joined
Aug 24, 2009
Messages
5,033
Reaction score
224
Location
Corinth, Ky.
question guys: It has been a long time since I have had a 340. bout 30 years I guess. I know you all can answer this in no time so here goes. If you are standing in front of a Mopar, any Mopar looking down at a 340 engine or looking at a 360, what is the difference in appearance if any. without checking the numbers can you tell the difference in the two just by looking at them. And if you were going to build an engine from scratch, nothing radical, just bore it .030 over, cam, x-heads, intake and carb to match.......... would you do a 340 or a 360. I have heard a 360 would give you more if using the same components. My sons car has a 360 in it now and I have 2-340's down in the garage sitting. One is a 69 and the other is a 70. I was gonna go with the 69 and put the 4 speed behind it for him. what are your thoughts on this.thanks,Bill
 
The balancer is the only real outward drifference in appearance that I know of... the 360 is externally balanced.. so the balancer looks different than the one on the 340...

As for which is better is to build from scratch, I will wait for those with more knowledge to chime in about that...
 
the old saying there is no replacement for displacement is a good one.

Unless you just want to be able to say "this thing has a 340" (wich i never say anyway,i always claim that its a 318 out of some old van)
 
To me if it only depends on what you want. If he has a 69 or 70 car you then would have a period correct engine just a little added something, if you going to race it or run it hard I would not risk a 340 for that. Kinda just your choice unless a little added HP is something you want for same money.
 
The pan rails are wider. 360 will be cast on the side and stamped on the front drivers side of the block
 
dano said:
The pan rails are wider. 360 will be cast on the side and stamped on the front drivers side of the block
Click to expand...
No, the pan rails aren't any wider(rail to rail). Just the rear main cap is different where the end pan seals against it.

All components being equal, the 360 will give you more torque & HP at less RPM too. 20 more cubes!
Looking at both side by side, 340/360, most people couldn't tell the difference & even the experts would have to looks close at the differences(block markings, balancer etc).
 
And since that is under the car, no one will see that tip off.
The oil pan itself is a bit wider at the crank seal area than the other ones, the embossed displacement on the drivers side of the block, the stamping on the block, under the drivers cylinder head, but I think super vision is needed or an eye ball within inch's. and the balancer, which is also hard to see. I personally don't car what the displacement is. You call it a 340, fine, it could be anything and I don't care a bit.

If your going to use a 360 in place of a 340, 99% of all people will never notice.
 
Also need to note, that the 1973 340 was externally balanced, same as the 360.
The 340 external harmonic balancer will have the phrase "FOR 340 CAST CRANK" , cast into the front side.
Some very late 1972's & all 73 340's had cast cranks.
It looks like Chrysler used the cast 318 crank in these engines to save a few bucks before they went to the 360 for 1974 A-Body.
 
I'd build a 360 without a second thought if I did it again. Other than to be able to say you have a 340 there's no real good reason for it. It might impress the folks who know the reputation of the 340 but don't know what the potential of the 360 with the same build would be. Assuming the 360 had been available during the horsepower era I don't think too many people would have gave the 340 any consideration.
 
I have had both the 360 & 340 in my race car.
Both built simular, the exception being Iron heads on the 340 & Alum. on the 360.
Compression ratio was comparable, the 360 had more cam than the 340, both solid.
The bottom line, not much difference in ET's
The 360 ran a best of 7.02 with a best 60ft of 1.46.
The 340 ran a best of 6.96 with a best 60ft of 1.48.
 
Dont the good 340s have 4 bolt main caps? and they are a bigger bore too. 2.02 valves.?
 
As said before, none of the production block 340s had 4-bolt mains. But both your '69 and '70 340s will have forged cranks vs. the cast crank in a 360.
Also both of your 340s will have 2.02" dia. intake valves, but you can also build 360 heads with 2.02 (or larger) valves.
The 340 T/A blocks had a higher nickel content and filled oil pan rails for a bit more bottom-end strength.
I love the 340 engine but I'm building a 360 for my '69 Dart because it came from the prior owner with a crate 360 in it.
 
pro-tech said:
Dont the good 340s have 4 bolt main caps? and they are a bigger bore too. 2.02 valves.?
Click to expand...

The TA block, that was used in the TA Callenger's & AAR Cuda's had the oil pan rails filled soilid to provide enough metal to add 4-bolt mains to it.
 
...the 360 will build a little more torque but the 340 may rev a little quicker
the argument will never end.....but only a 340 is a 340!
Guess i'm showing my age.
 
Isn't there is a difference in weight as well? The 340 weighing 525 and the 360 weighing around 575.
 
Originally Posted by pro-tech
Dont the good 340s have 4 bolt main caps? and they are a bigger bore too. 2.02 valves.?
Click to expand...

Bigger bores do help. Basic physics tells us this. A 340 bore would have 1.01% more down force with the same pressure exerted in the combustion chamber. Proportionately 1.01% more power with all else being equal. But it's not.
Bore your 360 to a 340 bore. It's only .040 and you'll have the best of both worlds. A 340 bore with a quarter inch longer stroke. It's like a 340 stroker for free. Only a 366 and not a 416. We won't tell anyone.
 
mikedevore said:
Also need to note, that the 1973 340 was externally balanced, same as the 360..
Click to expand...

I don't think you meant this, but this could be construed as "same balance." Both engines were externally balanced, but "not the same balance." A 340 external, and 360 external balancer are not interchangeable.
 
I have a 340 in my car and it has a chrome 273 air cleaner on it and 99% of guys that say they know Mopars can't tell them apart.
 
The only weight difference I can think of is the crank being larger in the main area a d may e the cylinder sleaves being a tad bit heavier be ause there not the same bore but could be the same outside diameter. In other words, same sleave used just not bored out as much.

Other than that, perhaps the weights are taken off of stock engines that are fully dressed. This could show a large difference. Add an A/C compressor and there is a good chunk of weight.

As noted above, the old "X" block was a pan rail filled block capable of a 4 bolt main. I do not remember or thick it was a stock item in the Challengers and Cudas in 1970. The only way the engines came stock were simple 2 bolt mains, IIRC.
 
Another thing on the weight of the cranks...yes 360 had larger main bearing, but the cast crank is less dense then a forged crank...and there fore probably weight less.....one of the reason for the externally balancing of the crank.
 
You must log in or register to reply here.
-

Back
Top