340 actual horsepower

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Crackedback is correct..340 - 350 is closer to the true hp of that build.
..those magazine guys 'gotta make a living so printing what we want to
believe sells magazines...and we've all seen some amazing numbers on
318 and 383's with just a carb and cam change.
 
My 340 pulled 298 at the rear wheels at 6000 rpm. And it is stock. Even less than stock as I run about a point under the OE compression rating. 9.5:1 today vs. 10.5:1 factory
 
the 68 340's were the powerful ones, it's HP was definitely more than what Chrysler announced but same goes for Ford and GM, it was an insurance thing. As stated earlier somewhere between 340 and 350 was what it should have been.


I heard that 0 decking and 750 dual pumper carb and that gave you quite a wallop.
 
C130 Chief said:
I doubt these factors are still current, as not too many people currently run 340's in NHRA Stock Eliminator classes, but here's a few factors from back in the day:
1970 340-6 Bbl. 325 hp E Stock
1971 340-4 Bbl. 320 hp D,E,F,G Stock (w/Thermoquad)
1968-70 340-4 Bbl. 295 hp F,G Stock (w/AVS)
1972-73 340-4 Bbl. 275 hp G,H,I,J Stock

In most cases (except the 440-6 cars for some reason), the NHRA factored Mopar engines at a higher output than their advertised output. Horsepower numbers before 1972 were pretty much advertising propaganda, and seldom reflected actual output. Beginning in 1972 the SAE "net" ratings were mandated for all cars sold in the US, which were supposed to reflect output "as installed".
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I bought a brand new 1970 AAR with the 4-speed, 340 -6bbl, rated at 290, I think. And from the way it ran, that isn't even close. Casualty of divorce with about 40k miles on the clock. It was hard on clutches and u-joints, but it would really, really run. Black on black on black. This isn't my car, but it looked precisely like it. The 6-bbls as I understand were installed after production of the car itself, at Hamtramck.
 
I rebuilt my 1970 340 engine to fairly stock specs. It is .030 bored over and has a Lunati Vodoo 703 cam along with roller rockers and 9.5 CR. Besides those mods, it has the factory intake, exhaust manifolds and Carter AVS. My break-in dyno run on the engine yielded 312 hp and 324 ft-lbs of torque. I was hoping for higher hp numbers but this engine is going into a restoration car and won't be thrashed at the track.
 
ir3333 said:
seems about right with just a cam change.
300 hp is plenty in an A body
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the 6-bbl had other mods, Edelbrock manifolds, cam. Aftermarket parts the Ramchargers had managed to assign Mopar numbers to. The 6-bbl motor was unique. Call it 300 hp with the center 2-bbl. It really kicked when you brought in the extra 4 bbls.
 
6 packs had the same EXACT camshaft and head (as far as ports go) as any other 1970 model 340.

They never ran like a car with 300+ hp. The trap MPH just doesn't work out against cars weight. If you got one that ran close to 100 mph in pure stock form you got lucky.

FJR, that's a solid run for what you have. Bigger carb, headers and it would be in the 325-335 range. That cam is a LOT bigger than the factory stick that some of these guys think will allow a stock OEM 340 make 325hp.. yeah sure it does!

Reality is they didn't
 
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[QUOTE="The 6-bbls as I understand were installed after production of the car itself, at Hamtramck. [/QUOTE]

The engine final assemblies were done at the Windsor plant, sixpaks & all. The completed engines were then shipped by rail to the Hamtramck plant for installation in the cars.
 
Alaskan_TA said:
[QUOTE="The 6-bbls as I understand were installed after production of the car itself, at Hamtramck.
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The engine final assemblies were done at the Windsor plant, sixpaks & all. The completed engines were then shipped by rail to the Hamtramck plant for installation in the cars.[/QUOTE]
I never had opportunity to break the engine open; perhaps I just got a 'good one'. But it ran like a scalded cat. And particularly in 'stoplight to stoplight' performance. Perhaps this was more involved with the lighter block of the 340 compared to bigger blocks, and being less weight on the front wheels. But it launched extremely well, hooked up quickly, and in almost all cases I was hooked up and gone before the bigger blocks of any manufacturer could get connected to the pavement and able to put their superior power to use. I never ran the car against the clock. I was finishing college and was working as well as in school, so I had not time nor money to run it against an absolute measure. But it was Edelbrock induction manifold, and it was quite easy to tell when the outboard 2-bbls engaged. You wanted to hook up before you let the outer carbs come into play. And in 40k miles, it went through two full clutch assemblies and a set of U-joints. As stated, maybe I just had a good one. And from the reading I have done, I have been led to believe that the Hamtramck plant was involved in more than simple installation of the engines. All the data I have is hearsay, I cannot verify the absolute process of the 'build' of the car. But it was extremely high performance. And I will tell you this for fact-- the window sticker on the car said '340-4bbl' as did the 11x17 inch printout available to the dealer. Which tells me that at some point somebody thought the car had a 340-4bbl in it. THAT is fact. There was no money premium on the 6-pack motor-- it would appear that whoever generated the paperwork was ignorant of the fact.
 
The engines have a final assembly date stamped on the front along with the W engine assembly plant code for Windsor, so I would love to see scans of that paperwork when you have time?
 
Alaskan_TA said:
The engines have a final assembly date stamped on the front along with the W engine assembly plant code for Windsor, so I would love to see scans of that paperwork when you have time?
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geez, guy, that was over 45 years ago. I had seen one AAR in New Orleans on a showroom, where I was in Tulane, in perhaps late May or very early June of 70. I knew the AAR was a 6-pack, and therefore ignored the paperwork at the dealership. My grandfather was buying the car for a graduation present, and I actually first got a plain 383 4-bbl Cuda from a dealership in Atlanta. It had a dust cover instead of a thermostat, and overheated before I got out of sight of the dealership. I refused the car, and we returned to Gadsden. My grandfather was a silent partner in the Mopar dealership there. My AAR was listed as being on the 'factory lot', was shipped by rail to Birmingham and by truck to Gadsden (Bama). And it was rolled, brand new, off the truck. There has been an awful of of water over the bridge and under the dam since then, but that is a long and not altogether happy story. My wife hated the car, and that was the reason I sold it. I have nothing left but fond memories. I wish I could oblige you. But I assure you, my grandfather would not have bought the car for me had it said 'rocket ship' on the factory printout in possession of the dealer. I knew what it was, and just said 'that one will do'. I came into possession of it in probably late June of 70, perhaps early July. And it had a problem-- the Hurst pistol grip shifter was lacking the cross-bolt mount at the bottom, and the shifter came out in my hand going from 2nd to 3rd up an expressway on-ramp. And, as I mentioned, it ate clutches. I suspect the clutch disk was undersized, likely the standard 340 disk. When I really stuck my foot in it, I could smell burning clutch disk.
 
70aarcuda said:
Ok..thanks...
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I turned into an engineer, got into Autocross and raced Triumph Spitfire and MG Midget. Never had the bucks for the big iron (divorce and two kids are expensive). I was better on twisty tracks than drag, anyway. And while the old Kawasaki powered Formula 440s are gone from them now, the Malibu Gran Prix tracks were a wonderful outlet for that 'need for speed'.
 
ir3333 said:
Crackedback is correct..340 - 350 is closer to the true hp of that build.
..those magazine guys 'gotta make a living so printing what we want to
believe sells magazines...and we've all seen some amazing numbers on
318 and 383's with just a carb and cam change.
Click to expand...

It's not the cam that make the power it's the heads. Build a 10:1, 750 air gap and headers 360 with ported eddy heads and start with a stock 2bbl 360 cam probably would surprise ya at the power it would make. But then install the roller cam that should be run and you'll see probably 150-200 hp bump.

Stock 340 has the goods from the factory to make good power just the cam and exhaust holding it back. Even look at the 380 hp magnum create engine stock long block and just cam/carb/intake and headers been dyno over 400 hp.

Same reason the new hemis and LS engine come alive with cam change race head flow numbers.

318 is way under headed from a power stand point but there's more than enough flow to double the stock power numbers.

Same reason a cam/intake/exhaust don't really work on a /6 there really not much extra flow in the stock heads to be capitalize on.
 
273 said:
It's not the cam that make the power it's the heads. Build a 10:1, 750 air gap and headers 360 with ported eddy heads and start with a stock 2bbl 360 cam probably would surprise ya at the power it would make. But then install the roller cam that should be run and you'll see probably 150-200 hp bump.

Stock 340 has the goods from the factory to make good power just the cam and exhaust holding it back. Even look at the 380 hp magnum create engine stock long block and just cam/carb/intake and headers been dyno over 400 hp.

Same reason the new hemis and LS engine come alive with cam change race head flow numbers.

318 is way under headed from a power stand point but there's more than enough flow to double the stock power numbers.

Same reason a cam/intake/exhaust don't really work on a /6 there really not much extra flow in the stock heads to be capitalize on.
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I mentioned that I am an engineer. Breathing-- air-- is the name of the game. You can bolt on fuel supply, but not air. But right this moment, I an 66, have been diabetic for 55 of those years, and am sitting in a wheelchair with no legs, mid-thigh. My racing days are over. I can't even turn wrenches, any more.
 
SoulSurvivor said:
So have I. I knew the article was a little older so that's why I 'added' to the build a bit. I will say that the 800CFM carburetor comes in handy at the top end of the 1/4 mile. My 340 is gobbling all the fuel she'll take and the end of the track. And the TQ Converter makes a world of difference when launching the car which I'm getting better at. Dyno sheets are nice but they don't tell the whole story and its hit and miss with the operator. The only good thing about dyno'ing an engine is that you catch something potentially bad before you put it in the car and you are breaking in the engine at the same time. Thank you for the compliment.
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Had a 69 Dart gt sport back in the day. With headers, comp cam and high rise intake I was running an 850 duel line double pump and it drank it right down. Even for a short time ran a 1150 Holley 3 barrel
 
Here is a factory 340 run.

70 340 6 4.jpg
 
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