[Roger Bettoni (Roger)]

Okay, - don't laugh all you hardened mechanic types out there, but what's the difference between the 2v and 4v motors? I always read posts on Mopar sites extolling the virtues of the 4v, yet to someone like me, who can change the oil, filter, brake shoes and a few other minor jobs, this is all double-dutch (sorry for the analogy Hans)

[Phil Raynor (Philth)]

It's my understanding that 2v means two barrel carb, and 4v means 4 barrel carb, i.e. standard and high performance.

[Christer (Christer)]

I guess the ´v´ comes from the word venturi. It is a short tube that is used in carburators to create under-pressure . I will not try to describe the look in words, because it is best done with a drawing. Hope this helps!
(My guess is that each of the carburator throats have two venturi shaped tubes, one small and one big.)(This topic has been covered here earlier, I think)

[Dave-R (Roppa440)]

An 'americanism' for venturi is 'barrel'. So a 4 venturi carb (4v) is often called a "4 barrel" (4bbl).

I am not sure without looking it up but there may have been other differences between the 2v and 4v versions of the same engine such as cam or compression.

[Roger Bettoni (Roger)]

Simple when explained - thanks guys. I initially thought it may have had something to do with the crank shaft - either four or two bolt mains or something like that... but obviously it's just the carby / inlet manifold type.

[Donald Luke (Oerm2133)]

The 383 cu. in. engine was built from approx. 1962 through 1971. The primary difference between the 2v (or 2 bbl(barrel)) and 4v versions were few but important. The 2v version was usually considered the low performance version and had pistons with a lower deck height to yield a lower compression ratio. The camshaft profile was also milder. The noticeable difference, of course, was the intake manifold and carburetor. Sometime during 1971, the crankshaft for the 2v version was changed to a cast one versus the forged unit that had been used previously. In 1972, the 383 got an overbore and became the 400. The 383 4v version came in two versions, heavy duty for station wagons and big cars like Chrysler and big Dodge and Plymouth sedans and the high performance version called the Magnum, etc. Again, the difference was the higher deck on the pistons to yield a higher compression ratio and the slightly hotter camshaft profile. The engine blocks were essentially the same and interchangeable from year to year, the crankshaft the same, the connecting rods the same, and the cylinder heads the same within a model year. This is probably more than anyone wanted to know.

[Joel Bennett (Joel)]

Production of the 383 began in 1959. The 383 started off as an RB, (Raised Block). It had a bore of 4.03", dual-quads and put out 345hp @5000rpm and 420ft lbs @3600rpm.

In 1960 the the most powerful 383 that year came with the famous 300J heads and inline dual quads, which produced 343hp @5000rpm, but this engine is very rare. The 2bbl that year had a compression ratio of 10.0:1 and put out 305hp @4600rpm and 410lbs @2400rpm.

In 1963 There were three high performance versions. THe first had a single 4bbl with 10.0:1 and had 330hp @4800rpm and 425ft lbs. @2800rpm. The second most powerful version had 10.10:1 a single 4bbl carb and put 360hp @4800 and had 470ft lbs @3200rpm. The top-of-the-line 383 for 1963 came equiped with dual quads, but had a lower compression ratio, 9.60:1, but it put out 390hp @4800rpm and 485ft bls @3600. The 2bbl 383 that year put out 305hp. 1963 was the 383's penical and nothing but lower power outputs were to follow.

In 1964 the power output was lowered so as not embarrass the hp ratings of the larger engines. A only 1 4bbl 383 was offered. This engine had 10.0:1 compression and had 330hp @4600rpm and 425ft lbs @2800. THe performance remained through '65.

In 1966 the 383's performace dropped a bit. The 383 in '66 had 325hp @4800rpm and 425ft lbs @2800rpm and 10.0:1 compression. The output remaind through '67.

In 1968 the 383 got a boost in power, however the 2bbl's power dimminshed. The Super Commando 303 had 330hp @5000 and 425ft lbs. @3200rpm, 10.0:1 compression, an unsilenced air cleaner and dual exhaust. Also in '68 a special edition 383 was developed exclusively for the RoadRunner and the Coronet SuperBee. This 383's power was bumped up by adding high performance parts designed for the 440 in the GTX and the Coronet R/T, introduced in '67. The new parts included redesigned heads, larger exhaust valaves, (1.60" to 1.74"), recontoured ports, and heavy duty valve springs and rocker arms. This 383 also used high performance cam from the 440 was also used. A new dual-plane intake manifold was used, with a Carter AVS 4bbl carb on top. THe air cleaner was also unsilenced and the engine was also given dual exhaust. The power rating for the engine was deliberatey under rated, kinda like the Hemi was. This awsome 383 had a supposedly power rating of 335hp @5200rpm and 425ft lbs @3400. The engine stayed the same for '69.

In 1970 there were three versions of the 383 and all three had their compression ratios dropped. The 2bbl dropped to 8.7:1 so it could run on regular gas, but its horsepower ratiing stayed the same at 290hp. The two high performance versions had their compression dropped to 9.5:1, but their h.p. and torque ratings stayed the same. The 335h.p. 383 also switched to a Holley 4bbl Carburetor in '70. In '71 the high-performance 383 was detuned. Both the 2bbl and the 4bbl 383's compression ratios were dropped to 8.5:1 to be able to run on regular gas. The 2bbl had 270hp @4400 and 375ft lbs @2800rpm. The 4bbl had 300hp @4800rpm and 410ft lbs @3400rpm.

In 1971 Chrysler stopped prodcution of the 383 and began the production of the 400 in '72, to take the 383's place, which it did poorly.

[Phil Raynor (Philth)]

Good info, but have to disagree with the 400 comment at the end. It didn't take the 383's place poorly, it just did the best it could with the specs the engineers gave it. If the 400 had been made to the same specifiactions as the 383 in the sixties, then it would have likely trounced all over it. Fact is, government emission regulations, and the drive for better fuel economy, were the only factors that saw the 400/440, etc producing less HP than previous engines. This is obvious even with the 383, as it's clear to see the comp ratio dropping as the engine rolls over into the 70's! This is a HUGE factor for engine/car makers - if the engine can't make the grade, then the vehicle doesn't get the stamp of approval, the car/engine is not made, and the company looses money. Still happens to this very day (I work in the industry). Anyway, the 400 development went on to give us the acclaimed '452' heads, so I ain't complainin'!!

[Dave-R (Roppa440)]

Good stuff. Thank you Joel.

Just to add to what Phil has said;
The 400 is also the strongest V8 block Chrysler made. It is the perfect basis for a street/strip or race engine. It will take a 440 or stroker crank and because of it's bigger stock bore it will give you more cubic inches than a RB block only it will be stronger, lighter, and physically smaller if room is tight (i.e. fitting into an A-body).

(Message edited by roppa440 on May 08, 2003)

[Joel Bennett (Joel)]

Don't thank me, thank Anthony Young. I get a lot of my info from his book "Mighty Mopars". I knew that Chrysler made the best 400, but I really never read much about people using them. Most people go for the 383's, 413's, 440's and Hemi's. However, I do remember reading one article in the library during lunch, when I was still in high school, about a guy who drop a 400 into his Challenger, I think it was a '71. Does anyone remember that article by any chance?

From what Anthony Young wrote, the 400 has a bore of 4.34, while the migthy Hemi has a bore of 4.25, that's a .9 difference. Considering, like Dave pointed out earlier, that's a stock bore, the 400 should have some great potential, aside from its original factory state of course.

Originally, I wanted to drop a 400 into my Challenger, but for some reason, I changed my mind.

Phil, could you enlighten me about the 452 heads? Forgive me, but I've never heard or remember anything about those heads.

[Douglas Little (Dlittle)]

Thanks for the very usefull information on the 383 Joel. I have a 65 Newport that runs good that we plan to use in a Challenger. I would like to know if this 2v, 383 engine has a 10:1 compression and what might be its hp. Also will this year bolt in the 73 engine compartment or will special mounts have to be made. Any help would be appreciated.

[Dave-R (Roppa440)]

Joel. It is VERY common pratice to use the 400 incher in drag cars. But usually with a 440 or stroker crank. The 452 heads are the good ones. They are very like the older 906 heads only these versions have hardned valve seats for unleaded fuel. They flow well for stock heads and respond very well to porting.
The only reason I use 906 heads is because they were original to my 1970 engine and I wanted to be able to say to people that they are stock heads.

[Joel Bennett (Joel)]

Well Doug, I checked Anthony Young's "Mighty Mopars" and the only thing that he mentions about the '65 383 2v's, (2bbl), performance was that it was no different from '64's poweratings. 1964 was the year that the 383's power took a dip, so as not hurt the image of the larger displacement engines. From 1960-1963, the 2v 383 put out 305hp @4600rpm and 410ft lbs @2400. In 1968 the power output was 290hp @4400rpm. Nothing is said about the 383 2v's performance between '64-'67, but from the little info that Anthony Young gave about the 2v, I'd say that your engine has between 290hp and 305hp. The compression for the 2v 383 at the start in '60 was 10.0:1 and in 1970 it was lowered to 8.7:1. My brother had a '68 and he said his had something between 9:1 and 10:1. I'm pretty sure its safe to say that your 383 has a higher compression than 8.7:1. I know that the 318's produced between the years 1967 and 1969, have a compression of 9.2:1. I wouldn't expect your 1965 383 to have a compression ratio any less than that, regardless if its a 2v or not. I know I didn't answer your question to the exact letter, but I hope what I wrote helps you in some amount. I recommend looking at a repair manual for 1965. I know for sure that the manual will satisfy questions for sure, because my repair manual clearly states what my compression, horsepower, and torque ratings are, for my year.

So I guess even you have to draw a line in the sand sooner or later when it comes to saying how far you can go before your car is no longer original.