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440 vs 440 TNT


Guest bkazmer

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Guest bkazmer

how does one tell a 440 from a 440 TNT? I don't think the air cleaner decal is a real reliable way.

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how does one tell a 440 from a 440 TNT? I don't think the air cleaner decal is a real reliable way.

If there is an "HP" stamped on the pad on the engine where it says, "440" it will be a TNT, I believe.

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  • 5 months later...

As for what "TNT" stands for, you can find a road test of a '66 Chrysler 300 440/365 "TNT" 2-dr hardtop in the magazine article archives of www.wildaboutcarsonline.com .

Considering this was when the 256/260 "4bbl" cam was the hot cam for Chrysler (new for 1966) 440 and carry-over 383 engines, this was the cam that was in the normal 350 horsepower 440 V-8. Adding dual exhausts and "twin snorkles" on the air cleaner is where the extra 15 horsepower came from (the normal 440 had a single exhaust system). First use of "twin snorkles", rather than the (hidden) open element air cleaners on 4bbl V-8s. Normal exhaust manifolds, too, as "the good ones" didn't happen until 1967 and later.

"HP" block stampings came later, more like 1968. There is some "allure" to that stamping, but from what I've seen, it might have been used on 4bbl V-8s rather than 2bbl V-8s. Some claim that only certain night shift production runs had the HP stamp, too. It, like the "figure 8" coolant passage holes in the top of the cylinder deck are supposed to make things "more special" for some, it seems. In reality, there's NO difference in the machining of the block with an HP stamp from a non-HP stamped block. Possibly it might have been machined to a little closer tolerances, though? Or with a higher-nickel content cast iron?

As for the figure 8 coolant holes . . . consider that the matching holes in the deck surface of the cylinder head are NOT that big . . . that when the head gasket lays on top of the block's deck, the gasket seals the excess hole area and provides the normal flow restrictor hole in the head gasket. This, ineffect, nullifies the larger holes in the block's deck surface when everything is assembled. The ONE possible exception might be on the 440 "motorhome" cylinder head, which is a unique item from any other B/RB cylinder head. Normal B/RB intake ports and such, LA-block style open chamber, but a separate exhaust port for each cylinder (location is raised from normal location on the side of the head). AND, if I recall, a special spart plug just for that application! Circa 1972, typically.

Back to camshafts . . . the 1958 Plymouth Sport Fury came with a 350 cid 2x4bbl B-family V-8. It used a 252/252 degree camshaft. Prior to 1967, the cam was used in the other 383 2bbl V-8s. 340 horsepower 413s used a 256/260 cam, with the 360 horsepower versions using a 260/268 cam. Valve lifts were, .390", .425", and .431", respectively (in some cases, intake and exhaust lift were different, so what I've mentioned are approximations of the average of the two lifts). What came to be known as the "HP" cam didn't happen until the 440/375 engines of 1967 and the 383/335 "Road Runner" engine of 1968.

Check out that road test!

Enjoy!

NTX5467

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TNT and words like Magnum for the Dodge series and Commando for Plymouth were just marketing names..there was nothing special with the 1966 introduction 440 per the factory engine book..as stated above, that was introduced in '67 and the GTX was the one that walked the dog..with the similar packaging introduced in 68 for the 383's ie: 335 pony version

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The HP or high performance motor had certain heavy duty parts not found in the basic 440. The HP engine was the 4 barrel dual exhaust motor used in New Yorkers, full size station wagons and Imperials as well as high perf Road Runners Chargers and GTXs.

Out of curiousity I would be interested in just what parts were different (heavy duty) between these engines other than intake and exhaust manifolds. I have never seen a two barrel 440. However I have seen some differences in the exhaust manifolds. But what about interior parts?

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Another place to verify these "special parts" would be the Chrysler parts book for the particular model year. Everything I've seen indicates the '66 440/350 and 440/365 had NO special parts in them . . . all "normal production stuff". No special bearings, no windage tray, no 1.75" exhaust valves, no special exhaust manifolds, no roller timing chains, no special or different material piston rings, no special carburetors . . . just an additional snorkle on the air cleaner and dual exhausts to get more air into and out of the engine.

In 1965 and prior, most 4bbl engines had an air cleaner which was open around the bottom, with a "gap" between the outer housing and the baseplate of the air cleaner, where the element was retained. 1968 and later Road Runner 383/335 V-8s had that too, with the same air filter element as the "snorkle" air cleaners used. Mixing the Road Runner base plate with the top piece of any normal 4bbl air cleaner has the same result . . . provided the air cleaner's inner hole is the same size as the Road Runners ("Holley" size rather than the smaller hole of the 1967 and earlier "Carter" AFB size").

1967 was a transition year, with the 440/375 having the hotter 268/284 degree camshaft, higher lift and 1.75" exhaust valves. The 1968 Road Runner 383/335 engine had the same camshaft and 1.75" exhaust valves were standardized on all 383 & 440 V-8s. In CAR use, NO 2bbl 440s--period! ONLY 2bbl Chrysler Raised Block intake manifold would have been on the 1960(?) raised-deck block 383 . . . a one model year item only.

It IS possible that if you read the Plymouth/Dodge/Chrysler Police brochures from 1966, it'll probably talk about "HD" this and "HD" that, but some of that might have been overstated as the point of reference for this "HD" equipment was that even the normal production stuff was "HD" in nature, compared to how GM might have done things back then. So, unless it's got something to do with higher-output alternators, the largest-available-in-production (for that car) brakes, high-speed tires, etc., HD cooling, the claim of "HD" might be questioned . . . at this late date.

The OTHER definitive thing would be to look in the Dealer Order Guide and Trim Selector for 1966. IF there's anything unique about the engines in there, it'll be listed specifically.

In later model years, as noted in the particular model year Dealer Order Guide, Chrysler's 383/400/440 High-Perf V-8s did have some specialized and upgraded parts in them . . . right up to the end of production. From 1968 onward, there were the crankcast windage trays, the 1.75" exhaust valves, the noted camshafts driven by roller timing chains, upper compression piston rings were chrome-moly in material spec, Tri-Metal crankshaft bearings might be used, high-flow exhaust manifolds, and some other things which would aid high-rpm durability and longevity in "severe use" situations . . . read "High Speed Police Pursuit", rather than 1/4 mile drag racing.

In the parts book, there was a special section for "Police and Fleet". LAPD and others had some specific things they needed on their cars AND Chrysler was most willing to build it that way for them.

BUT, for the 1966 model year "the guts" of a 350 horsepower 440 and a 365 horsepower 440 were the same. It was "the outer dress" that was different and resulted in the 15 horsepower increase.

As a side note . . . every notice how the engine names were so militaristic or gun-related? Commando. Magnum. And the model names can be an article into itself!

Regards,

NTX5467

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It's a long time ago but I seem to recall the TNT or heavy duty engines began in 1968 or 69. I also don't remember exactly what parts were different from the standard.

I do recall the heavy duty engines were optional in performance models like Road Runner, Charger and GTX. But the same basic engine was standard in Town and Country station wagons and Imperials with 4 barrel carbs and dual exhaust.

This was useful to know if you were scrounging the junk yards for hot rod motors in the seventies and eighties. You could pay big $$$$$ bucks for a Road Runner motor, or get basically the same thing out of an old Imperial or New Yorker station wagon.

Later..............................

From the Alpar web site:

"The 440 engine was introduced in 1966, the same year the 426 engine was replaced by the same-displacement, legendary 426 Hemi "elephant engine." It was used not only for performance, but also for luxury yachts such as the Imperial.

The high performance 440 was introduced in the 1967 GTX and R/T models (see Super Commando photo below). In 1968 the 383 Road Runner and Super Bee models were introduced, starting the biggest performance surge since the early 1960s. In 1969, the first 440-6 barrel engine package was produced with special rods, crankshaft, timing chain, camshaft, valve springs and intake system. This package was continued in 1970 and 1971.

It is worth noting that early 1969 440s had the same connecting rods and crankshaft as in 1968, but heavier connecting rods were introduced around three months into 1969 model-year production; to offset the added weight, a new crankshaft and rebalanced vibration damper and flywheel were used. Mixing and matching these parts results in nasty vibration problems."

The high performance engine was called "TNT" when installed in Chryslers, "Super Commando" in Plymouths, and "Magnum" in Dodges, all the same engine.

There was a heavy duty 440 that had the heavy duty internal parts but not the 6 barrel carburetor package. It was standard in Imperials and Town and Country (New Yorker) station wagons and optional in other models. Basically the 6 barrel motor with a single 4 barrel and dual exhausts.

Edited by Rusty_OToole (see edit history)
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I have deleted a few argumentative posts. Let's please try to keep it factual and civil. I don't have a clue about the answer to the original question, but if anyone has anything else to offer, please remember to try to keep it polite. Thanks.

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