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Discussion Starter #1
The 400 came out in 72 and has a rep. as a smoged down polution engine.
Looking at the specs of both engines can get confusing because of the way they measured power in those days, the change of gross vs net ect....

Question: What was the better performing engine, was 72 400 magnum b body faster then a 71 383 magnum? which engine is more robust?
 

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My experience would go for the '71 383 in a RR.
 

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The 400 is essentially just an over bored 383. Bump up the compression on the 400 and choose the right camshaft and you've got a good performance engine. For the 400 in my '71, I had the heads surfaced just enough to clean up the gasket surface, use the steel shim head gasket, and chose a cam close to the specs for a 383 Magnum. It ran a best of 14.48 with a 3.23 rear and 275/60-15 tires. That time is on par with a stock '71 440 car.
 

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Yes, the 400 can be quite a good engine with pistons that raise the compression to 9:1 or higher. In stock form, the 383 is the more powerful engine.
 

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The production 400" engine had lower compression (8.2-1), milder cam (260-268-38), and a cast iron crankshaft as compared to the 383".
 

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The 1972 400 was a cleaner 'smog' engine and could be fitted with an EGR valve and/or air pump if needed. The 383 was pre-smog, but had strong torque output.
My neighbor had a 1965 Newport with a 383 2-bbl that could really move out for a big car.
I believe that the 1977 400 with LeanBurn was able to pass emission certification without a catalytic converter that year only.
Allpar article with links to other B-engine related articles here:
The Mopar (Chrysler, Dodge, Plymouth) B series V8 engines: 350, 361, 383, and 400
 
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Discussion Starter #8
The numbers I found for cop cars are .......383/4 1971 15.6 400/4 1972 15.3 ............for 1/4 mile times.
 

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The 400 is a smoger engine which was a punched out 383. It had the largest surface area of the piston surface of any Chrysler engine and was noted for being a gas hog.
 

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I thought the first year 400 had steel cranks, could be mistaken on that, but a 383 steel crank drops right in.

68RT, yes, in stock form.

Quarter mile times from year to year have lots of variables, from weight, gear ratios, compression of engines, so really hard to make a positive comparison.
 

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Discussion Starter #12
I think if your going to do a engine rebuild with some hp parts like intake and heads the 400 might be a better performer.
 

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The production 400" engine had lower compression (8.2-1), milder cam (260-268-38), and a cast iron crankshaft as compared to the 383".
Yes and no.

I believe the 1972-74 400-4V Magnum used the 440 Magnum cam whereas the 1975-78 400's all used the '2 barrel' stick, regardless ofr induction and exhaust.
 

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The 1972 400 was a cleaner 'smog' engine and could be fitted with an EGR valve and/or air pump if needed. The 383 was pre-smog, but had strong torque output.
My neighbor had a 1965 Newport with a 383 2-bbl that could really move out for a big car.
I believe that the 1977 400 with LeanBurn was able to pass emission certification without a catalytic converter that year only.
Allpar article with links to other B-engine related articles here:
The Mopar (Chrysler, Dodge, Plymouth) B series V8 engines: 350, 361, 383, and 400
1976 400-4V ELB was non catalyst, no smog pump nor even EGR whereas the 1975-76 400-4V 'Magnum' were still non cat (but dual exhaust) and, did need the pump, etc. to pass Federal emissions.............none of the above 400's were offered in Calif.
 
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[QUOTE..My neighbor had a 1965 Newport with a 383 2-bbl that could really move out for a big car..[/QUOTE]

The 383 2bbl was dad's favorite engine. Every "C" and some "B" body company car were ordered with that engine. He would burn Gulftane in it and pull a travel trailer across country. Never ping going thru the mountains or overheat in the desert. That engine was a torque monster in the big cars and a sleeper in a Satellite!
 

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One advantage with the 400 is, the bore is larger than a 440 so the only thing preventing a larger intake valve volume is the exhaust valve itself. That means a 2.14 inch valve over a 2.08 is easily possible, and there might even be some Indy Heads that have 2.25s that would fit without an issue.
 

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The 383s started out as better performing motors;but the 400 has more potential. I crossed the pair for my 69 RoadRunner, I used the Forged 383 crank, and shaved closed chamber heads, Cam was .495 lift and 292 deg duration.
 

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Here's a question for the guys here. Were aftermarket engine pieces built to a closer tolerance (balanced) than the factory pieces? Here's the reasons for my question.
My uncle had a 68 Town and Country with the 383 2bbl. Never mentioned it being sluggish or anything. We borrowed the car to pull our travel trailer and the thing "threw a rod", dad says, half way up north. I was a kid then but it was knocking. It was only three yrs old. After the engine rebuild uncle couldn't believe it was the same car. The car was noticably quicker after the rebuild.
Second scenario was back around 66 a Chrysler employee neighbor had the identical car we had. Engine, options, axle etc. Their vehicle was noticably faster. Some new vehicles just felt "tighter" and ran better with everything else being the same.
 

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Chrysler engines were well balanced right from the factory. However, when the big blocks were rebuilt, there were many mistakes that could be made. Crankshafts, pistons, rods, harmonic balancers, and torque converters [or flywheels] could be interchanged with bad results. Even some of the machine shops made mistakes if they weren't Mopar people.
 

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A 68 T&C is a heavy car to start with. Add a trailer and a load of stuff and the 383 is working pretty hard. Lean carb? Timing? [points could have been off]. Low on oil? Poor gas? [Use hightest for towing] The 383 was a tough engine.
 
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