89formula422

I am thinking of building a 377, a 350 block with a 400 crank using the standard bore.It will save me in machining cost.I will be putting it in a street/stripcar.Any suggestions or comments would be greatly appreciated.

QwkTrip

iTrader: (22)

The typical term for a 400 crank in a 350 block is a '383 stroker.' A 377 stroker actually implies a different setup with the 350 crank in a 400 block.

89formula422

nope, im afraid you can do it that way to.What makes it a 383 is boring it 30 over, it adds the extra 5 cubes.Just like boring a stock 350 30 over makes it a 355.

89formula422

A 377 can be a 400 with a 350 crank, but it can also can be a 350 with a 400 crank using the stock bore making it a 377.What makes it a 383 is putting a 400 crank in a 350 that has been bored 30 over giving it the extra 5 cubes.Trust me I know what im talking about.

87RS402

If you know as much as you'd lead us to believe, then you know that if you plan on using a stock 350 block with out machining it your wasting your money. If you don't machine the block you are starting with a foundation that is out of round, has no crosshatch for oil control, has uneven gasket surfaces, has clearances that are far enough out of spec that I wouldn't trust it to run longer than a month,...(or should I keep going?)

Oh, and 383-377=6. 6 extra cubes not 5.

QwkTrip

iTrader: (22)

I just wanted to make sure you were talking about the right motor. '383' shouldn't be taken literally. It's a designation for a type of stroker motor just as '377' is a designation for a different type of stroker motor. You go to a machine shop and tell them you want a '377' and guess what you'll get..... a destroked 400. You want a stroked '383' then you ask for a 383. The bore is understood and will be taken to whatever dimension necessary.

Keith5

When he said 377 I knew what he was talking about. Especially since he freakin said what he was going to do.

Blocks don't always need to be bored. To get the crosshatch you hone. Uneven gasket surfaces? I doubt it. Besides what made you think he wasn't going to check clearances? How do you know he doesn't have a brand new block? And what's with the calculations? Most people know that engine displacments aren't perfect. You think a 350 is really 350 cubic inches? Or a 305 is a perfect 305 cubic inches?

You stupid smartasses.
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1989 Pontiac Firebird Formula LO3/700R4
-180 degree stat, Hooker Cat-Back, Wonder Bar
Waiting for install: Open element 14x3, 95 vette LT1 cam
**Coming Sometime**
4th gen seats, 3.42/torsen(posi), Edlebrock Performer TBI intake, headers, y-pipe and cat, afpr
http://www.geocities.com/krt80/

[This message has been edited by Keith5 (edited August 07, 2001).]

89formula422

Keith your reply was greaty appreciated man.

87RS402

1. Your correct, blocks don't always need to be bored. Since he is only thinking of building the engine he probably doesn't have the block already so he doesn't even know the condition of the bore. So how do you know it it's fine?
2. Just hone? Go for it, make it that much farther out of spec. Don't be suprised if you the pistons rock in the bore or if you hear alot of piston slap.
3. Uneven gasket surfaces? Every time I've sent a block to the shop I've had them true up the deck, and every time they have had to take off .002 to .004 to get the surface flat. Blocks warp, happens to every block the first time it's assembled and run.
4.He said he was going to use stock bore to save money, that tells me he is trying to use a stock block, why worry about cost when you just paid several hundred dollars if not thousands for a high performance block?
5. The only thing stupid about being a smartass is sitting on something so intelligent. If my butt is as smart as you say just think of what my mind is capable of and you'll notice I make sense.

Bottom line is you can build it cheap or right. You might get lucky and not have to bore the block. The only way to tell is get out the mic's and see.

QwkTrip

iTrader: (22)

Why did you explode on me? All I did was offer up some useful information.

I know this one wasn't directed at me but 87RS402 has a valid point....

It's all right there is black and white. It is implied he is saving cost by incorporating a used block and is not going to machine it. It's NEVER cheaper to buy a new block so the only conclusion is that he's using a used block.

Secondly, if he knew what he was doing then he wouldn't be posting this question, now would he? No insult intended. Just a simple observation.

89formula422

I was just wondering what kind of power this combo made, i had people tell me it would make good top end power, and i wasnt trying to say i was doing this cheap, i was saying it would save me in the machining cost. I was just thinking of running something a little different than a 383,I was just considering my options.

87RS402

Don't worry. I knew it was pointed at me.

Kieth, He asked for comments or suggestions. That's what I gave him. If you don't like what I have to say than post a rebuttal not a personal attack.

We've all been in a position that we had to conserve money. I know from experience that the last place to get cheap is the shortblock. I've made my mistakes, the latest one is going to cost me at least $2000. That was from trying the very same thing he's talking about and the block I was trying it on only had 12,000 miles on it since it was bored .030 over at a quality machine shop.

sbrice18fan

There is an excellent article called "Street Fighter 377" in the January 2001 issue of Chevy High Performance.

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1990 RS Camaro 305 TBI
700R4 Tranny
3" cat back system with flowmaster mufler
Edelbrock strut brace tower and rear panhard bar
Spohn subframe conectors and lower control arms
all polyurithene bushing under the car
March underdrive pully
K&N filter
Hypertech chip
Aluminum driveshaft
3.42 posi rearend
Killer sound system
Many new mods to come

Grim Reaper

On the issue of the 377 destroked 400; remember that it is also a .030 overbore too. With a standard bore, the destroked 400 is actually a 372.

sbrice18fan

a 377 is a big-bore, short-stroke version small block using a .030-inch oversize 4.155 inch bore and a 350ci engine crank (3.48-inch stroke. Basically a higher winding engine that can take advantage of the shorter stroke to reduce piston speed. I never hear of anybody using this engine, but I have thought about it myself (something different). Anyway good luck with your engine build-up.

------------------
1990 RS Camaro 305 TBI
700R4 Tranny
3" cat back system with flowmaster mufler
Edelbrock strut brace tower and rear panhard bar
Spohn subframe conectors and lower control arms
all polyurithene bushing under the car
March underdrive pully
K&N filter
Hypertech chip
Aluminum driveshaft
3.42 posi rearend
Killer sound system
Many new mods to come

five7kid

iTrader: (14)

Some day we'll all learn to read and do simple math. A 4 x 3.75 V8 displaces 376.99 cubic inches, close enough to call it a 377 for me, but not the "standard" 377, as said above.

Everything that has to be done to make a 383 would apply to you except for the cylinder boring. However, have you ever seen 4.00" bore, 3.75" stroke pistons? I don't think I ever have, because of the reasons given - strokers are typically made from used blocks, which typically need a clean-up rebore. Getting pistons other than "off the shelf" will probably cost you more than getting a standard 383 kit and having your block bored .030" over.

Even if you find 4.00" pistons for a decent price, you'll still have to have the pistons pressed onto the rods, you'll still need to clearance the pan rails, you'll still need externally balanced flexplate & balancer, etc. The power difference would be the ratio of hp/cubes - assuming 1 hp/cubic inch, you'll have 6 hp less with this style 377 than a 383 would have.

FWIW, GM Performance Parts has what they call the HT 383, which they recommend for trucks that tow. It has 4.00" bore, 3.8" stroke - do the math, that's 382.017 cubic inches, and they still call it a 383.

Can we all just get along now?

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Edelbrock 1901 Q-Jet, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

[This message has been edited by five7kid (edited August 08, 2001).]

Tas

well I didn't read all the flames us there so.... anyway. You can get new GM block to make your 377 stroker, the only thing you will be missing from the 383 version is all the extra compression you get when the walls are .030 over. So keep that in mind. Scat has cheap stroker cranks. Cast steel. They are inbetween cast iron and forged steel.

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-Tas
'89 Formula WS-6

305, TBI, auto, 14x3 chrome flat based open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

To be installed eventually far far far into the future: Yours if the price is right and I don't have to ship :
Hooker 1-5/8" 50 state legal headers, Dynomax 3" I pipe (PN 44063 and 43248), Catco 3" cat, and injector spacer.

Super GRK_Taz World
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Mark W. Winning

My 400 is in the shop right now, getting .30 over'd and a steel 350 crank. What the hell, its fun to be different.

As for uses, apparently this combo is real popular in off shore boat racing. I do not know the details of why yet, but I will find out.



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1992 Pontiac Firebird 350/Six Speed
1987 Toyota Pickup 383/500+ HP

AJ_92RS

Just curious how a shorter stroke reduces piston speed? I thought 6000rpm was 6000rpm. I didn't know that a shorter stroke made the piston move slower. I knew it makes the piston travel less distance but not at a slower rate. HUH? Never thought of it that way. It would make sense though. If it travels less distance in the same amount of time, that would mean a slower rate of speed.

Guess you learn something new everyday!!!

Thanks,
AJ

dhirocz

iTrader: (2)

Glenn is right. A 350 is a 355 with a .030 overbore, a 377 with a 3.75 stroke and a std. bore, a 383 with a .030 bore, a 388 with a .060 bore, these are stroker motors. A 400 is a 372 with a 3.48 stroke and a std. bore, and a 377 with a .030 bore, these are destroked motors made to rev higher with a larger bore for more top end. The list of combos goes on and on. You can make a 350 into something like a 412. There are just about any strokes available. If you say 'gimme a 383 stroker, or a 377 stroker, I'm sure you'll get a stroked 350, unless you specify a destroked 400.

Lemme finish now that I jumped into a **** throwing contest...rev's and bore contribute to horsepower, when you stroke a motor you add torque, since torque is made by cylinder fill. When the valve is open the cylinder travels further down the bore than a 350 and pulls more air and fuel in with it. That increases torque dramatically. Same principle applies for TC and SC engines... more cylinder fill.

As far as always needing to bore a block goes, I believe that is BS. You often should, but don't always need to. It depends on several factors. How many miles on the engine. How hard it's been used. Piston and ring type. Being more specific; engine wear, distortion due to overheating, bad casting, scratches, it all depends on how far out of round the cylinders are. If one is out of spec, bore all to match as a good practice. I'm building a 377 stroker, and will not bore a perfectly good 41k mile 1998 350 roller block just to call my engine a 383. The thing has perfectly sized bores. Why overbore? I just hone the bores. Boreing and engine really doesn't make sense unless it needs it. Wastes time and money.

Now that's I'm about done preaching my $.02, it would probably help as well as **** off to say that you guys shouldn't start fighting over this ****. Sometimes people are wrong and sometimes you aren't clear. In this case, it looks like you guys just aren't clear. Have fun

BTW AJ...I think what he means is when a crank turns at 6000 RPM it's turning at 6000 RPM. But a 350 with a 5.7" rod and a 350 with a 6" rod both have the same displacement, but different rod/length ratios. Ideally a 6" rod would be best for a 350 since 1.7:1 is best...anyway, the piston speed is different even though the crank is turning at the same speed due to the difference in rod length and how tall this piston is. This changes the piston speed. A shorter rod pulls the piston away from TDC faster...rod length does play a role in the powerband.

whew!

89ProchargedROC

i know of a pretty built 377 DESTROKER

Brodix Track 1 heads
Victor Jr intake
longtubes
4.10
TH400 with 3500stall(footbrake) 5200stall(transbrake)
1050 Dominator Carb

Car went 10.30s all day on motor

went through the traps at 6400rpm

any questions?

QwkTrip

iTrader: (22)

.... and then it drove up on the trailer for the trip home

Guest

Looks like I missed the flame war... Looks like everyone has calmed down.

Anyways, about machining just to straighten things out from both sides. I dont care how good the machine is that the rebuilder/engine shop uses, but taking .002 off the deck is nothing. The difference in setup between the factory and just getting it lined up on the machine at the shop can easily eat .002. Thats why there are lots of people that will check the surface with a straightedge and if it checks ok they will refuse to cut it just because they dont want to take any material off of the block. Machining the deck is generally not necessary most of the time. Honing is also ok depending on the shape of the engine itself. Some come a little tight from the factory and havent yet worn in. I have a 350 block sitting in my garage right now thats been honed to take off the glaze and add some crosshatch back into the block, and added a whopping .001 to the bore size. Its plenty adequate for just about anything I wanna use it for. Some are so worn out and shiny or oversized even with factory crosshatch you wonder if the factory goofed really bad. For many people and many applications taking the block in and having everything done to it top to bottom isnt always necessary and should be determined only on a case by case basis, no blanket wrapping of absolutes in either way should be used. Some blocks wear worse than others and some just havent been taken care of... theres no way to know up front and you should always request that things be checked first and then you can decide for yourself what you want to do from there.


And this post is precisely why I hate people referring to their engines by displacement. The original post was dead on, listed displacement, block, bore, and stroke. Then someone saw cubes and thought they knew it all from there. If you go to a racetrack(like a roundy round), a 355 can be practically anything, its sorta meaningless. Thats why to me 377 and 383 should be used as reference, but to call it a 350 .030 over with a 400 crank or 3.75" stroke makes a bunch more sense, then I know exactly what it is. If I said I have a 306 in my car (and I do, I checked the sizes myself) would you even have the slightest clue what it was? Kinda hard to determine without all of the necessary information.

Rodger

Here's the specs MorTec has listed.

377 = 4.155" x 3.48" (5.7" or 6.00" rod) 400 block and a 350 crank with "spacer" main bearings

383 = 4.030" x 3.76" (5.565" or 5.7" or 6.0" rod) 350 block and a 400 crank, main bearing crank journals cut to 350 size

AJ_92RS

dhirocz, I already explained the concept to myself. You kept mentioned rod length, but you forgot that we were talking about the stroke. Thanks though.

Another point is that increasing stroke also helps torque for the same reason that using a longer wrench (whenever possible) eases the removal/installation of a bolt or nut. When you increase stroke, the center of the rod journals is moving farther from the center of the main jounals. This has the same effect as a longer wrench. It increases the leverage that the con rod has on the crank, increasing the effectivness of the downforce of the piston. Therefore increasing torque, or twisting. Afterall, that's what torque is, twisting force.

AJ

Keith5

I guess it does, but a longer stroke increases the torque, and improves emissions because more fuel is burnt for longer, and more completely.

dhirocz

iTrader: (2)

oops, didn't stay on topic to well. I shoulda make it easy. Rod length changes piston speed. easy. my bad.

Looks like I'm building 2 different motors! Wonder how this 377 will work...the 350 comes first!

89ProchargedROC

nope, not a trailor queen. Car had 10.5:1 compression and a solid roller cam which is becoming "not rare" anymore in a street car and pulled 10" of vacuum at idle. Driven to the track and driven home.

any other questions?

Keith5

How does rod length change piston speed?

AJ_92RS

It doesn't. Going with a different stroke does. If you increase stroke from 3.48" to 3.75", the piston has to travel .27" farther in one revolution. To do that it must increase the speed of it's lateral motion.

Increasing rod length only decreases the angle of which the piston is pushing on the crank. This only reduces the amount of movement that the rod has to pivot at the wrist pin. By reducing movement, it reduces friction, and you will see a slight increase in power because of the reduced frictional lose. Same concept as a roller cam. Frictional loses reduce power, so the more you can eliminate, the better. I suppose that it increases leverage also, but not as much increasing the stroke.

But what I don't understand is why someone thinks that a longer stroke or rod increases the allowed time for the fuel to burn. The only thing that does that is lower RPM. Higher RPM decreases time for the fuel to burn. That's why you advance the timing at upper RPM. To compensate for the reduction in allowed burn time.

Obviously RPM is Revolutions Per Minute. Increasing stroke only increases the distance that the piston has to move in that given time. It doesn't change the amount of time that the piston moves.

Example; At 6000 RPM, the piston is starting at TDC, goes to BDC, then back to TDC 100 times per second. No matter what the stroke or rod length, it's still gonna take it that long. At 9000 RPM, the piston does that 150 times. At 3000 rpm it only does it 50 times. That is what changes the time that the fuel has to burn, not the amount of distance traveled. 100 mph is 100 mph, no matter how far you are going.

Now do you see how increasing the stroke increases the speed of the piston?

AJ

Guest

It does. It would take more effort than I feel like expending at the moment (I hate dentists) but you already know it affects angularity. Exaggerate the rod length, like 100 feet and .1 inch and see what sorta piston speeds you get along the way. I have a program that calculates piston speed based on stroke and rod length, and its different. Thats why you hear people who say longer rods allow the piston to 'dwell' at TDC longer, they do... its all about piston speed.

A small excerpt (and I hope it posts right)

Crank Angle (degrees) Leverage Arm (in) Rod Length (in) Bore (in) Piston Depth (in)
0 3 10.2 4 0.0000
10 3 10.2 4 0.0589

0 3 7.2 4 0.0000
10 3 7.2 4 0.0644

As you can see the depth is different, so assuming the crank angle is changing at the same rate (same rpm) the velocity of the piston (ft/sec, or whatever units you like) wont be the same obviously.

QwkTrip

iTrader: (22)

Yes it does. It’s a classic slider mechanism. The longer the arm (rod) the quicker the piston snaps from top to bottom and vice versa. By increasing the arm length you change the dynamics of the slider mechanism such that the piston dwells at the top and bottom of the stroke for a longer period of time then with a shorter rod. This causes the piston to travel faster from top to bottom in order to complete a full cycle in a specific amount of time.

The point of reducing friction is a good put but it does much more then that. The increase in power from a long rod motor relative to a short rod motor is primarily due to the dwell time at the top and bottom of the stroke. This gives more time for the cylinder pressure to build resulting in more power. It also gives you more time (opportunity) to maximize cylinder pressure during the angle of crank rotation where the motor makes most it’s power. In addition, a longer rod causes the maximum stress in the rod to decrease. This allows for lighter rods and/or higher rpms.

See above. It’s a fact of mechanical systems.

Your example is flawed because you are concentrating on cycles per unit time. It tells you nothing about what is happening BETWEEN the cycles. In order to determine that you have to solve for the equation of motion of the piston. You’ll find that as the rod length increases the piston will dwell longer at each extreme and snap back faster.

BadSS

Average piston speed is the same regardless of rod length. Piston speed will vary at different point with different rod lengths,, but the average is the same.

Since no one really knows me, instead of me explaining it and my experiences with different engine combinations and taking up way to much space here - you can check out this link that pretty much sums up my persective on rod length and rod to stroke ratios. #2005. Also check out the charts comparing rod lengths so you can see for yourself the differences.

http://www.iskycams.com/techtips.html

AJ_92RS

I am fully aware of all the valid points that you guys made. However, those times of dwell which you are reffering to are sooo minute that they aren't even worth the but a few (3-4) HP on a 1000+ engine.

I guess if you are a prostock drag car builder, then yea, it could possibly make a .001-.002 second difference. But for the reason of explaining it to a guy that doesn't understand the concept at all, then my explaination is perfectly relative to the situation.

Plus, changing rod length has nowhere near the same effect on piston speed as changing the stroke. The dwell time of the piston on either TDC or BDC may change but .0001 of a second, if that much. That's it. 6000 RPM equates to 1 revolution per hundredth of a second (.01). Even if the dwell time was as high as half that (which is not physically possible because half that is equal to each ,either the up or down motion of the piston), then that would still only be .005 seconds (before subtracting the dwell time). We can't even wink that fast.

I'm not saying that you are wrong, but your trying to explain trigonometry and calculus to someone that asked a question about simple physics and geometry.

EDIT: BadSS, I just read that Isky story and I have to agree 100%. I had wrote it earlier, but then erased it due to response length. But here it is anyway.

My thought was if you increase dwell time, then the piston is at rest for a longer period of time. Cylinder fill is caused from the piston moving down, and the space that it once filled is then filled by air/fuel. So if you increase rod length, you increase the time that the piston does not move, then you are decreasing the amount of time that the cylinder has to be filled. And you are also decreasing exhaust time. That would have the same effects as a shorter duration cam. Granted it would increase air velocity, but that would then (seems logical anyway) increase low RPM torque, not upper RPM HP.

Seems to make sense that it's another reason that a longer stroke helps torque, while a shorter stroke helps upper RPM.

AJ

BTW, Thank you, BadSS, for that link.

[This message has been edited by AJ_92RS (edited August 16, 2001).]

berts

well then, a 383 or a 377 or some thing but it will kick butt! te he....anyways there is no replacement for displacement! but dude think about this" Gm has a crate motor with all the specs. just take a look at it and check out the parts list. and you can figure out what you may need. now this is a 385 because of the heads "vortec" if I'm not mistaken http://www.gmgoodwrench.com/crate_en...all_fast.shtml or this after market place w/ a large mark up http://www.paceparts.com/ht383_crate_engine.htm good luck

Guest

I never said anything about minimal or not, I was saying there is a difference... so now you can say there is a minor difference rather than none at all, which is an incorrect statement.

The guys who build race engines for a living shoot for certain bore/stroke/rod length ratios, and oddly enough I see the same numbers everywhere. Cam timing is another thing to optimize along with everything else. Otherwise cam timing is as much of a waste of time as anything else, a couple degrees wont make any significant difference if you want to get down to it. Parts have to be matched properly or you are wasting your time.

QwkTrip

iTrader: (22)

It's obvious that you still don't understand. Your explanation wasn't simplified, it was flat out wrong. I did explain the easy stuff. You CAN understand this if you want... don't sell yourself short. Your ability to visualize what's happening shows you are pretty smart. You simply need a more thorough explanation sitting in front of you. You should probably hook up with BadSS on this because you're not receptive to what I have to say. Good luck.

[This message has been edited by QwkTrip (edited August 16, 2001).]

BadSS

This is about as through an explanation as someone will get from me over the internet – especially when there are books available by David Vizard, Bill Jenkins, and the late Smokey Yunick one can read. Compared to a shorter rod, a longer rod causes the piston to dwell longer in the vicinity of TDC, but it also causes it to dwell less in the vicinity of BDC. Compared to a shorter rod, the longer rod accelerates slower from TDC, but accelerates faster from BDC. No reason to believe or not believe me,, look at the chart comparing piston travel per 5 degrees of rotation at the ISKY link and you will see. The differences are proportional and the average piston speed (regardless of rod size with a given stroke) at a given RPM will be the same. So to say a longer rod increases piston velocity is only “half right”,, and to say there is no difference is incorrect as well,, unless you are looking only at average piston velocity.

Big money race teams have explored different rod to stroke ratios and they develop that rod to stroke more so around the type induction systems they HAVE to run or CAN run. The slight differences in instantaneous piston velocity different ratios give you can give one a slight edge (needed to be a leader in restricted class racing) when the rod to stroke ratios and induction systems are better matched. If you’re saddled with a particular induction system, and have gotten all the “easy” power from cubes, head flow, and compression or if you want to “tweak” an RPM band,, then changes in rod to stroke ratios and cam timing to compliment the rod to stroke ratio can make a very positive impact in the “package/combination” you design.

So, sure there are advantages in varying rod lengths. So I’m not saying one should not consider a modified rod to stroke ratio. It’s just most people have trouble getting a “basic” combination truly optimized and dialed in with the “stock” rod to stroke ratios. I can’t tell you the times folks have brought me a car and simple carb tuning and ignition curve changes yielded half a second drop,, or the heat range on the plugs are off,, or they over cam the thing,, or they have it choked for air,, or the exhaust is not right for the engine,, and it makes no difference what the rod ratio or the instantaneous piston velocity is,, follow me?

PETE

iTrader: (1)

blah!bla!blah!while we are in never,never land could someone build me a real screamer
a 4.155in. overbored 400 block with a large journal 3.27 crank(no need for bearing spacers)with 6.125in. rods i'll pay with petter pan paper if you want.grow up guys this is a discussion not an argument we are all on the same side here at least he isn't asking questions on how his 302 ford could become a 347.

Guest

I dont see any problem with this post until yours. Grow up? Why dont you?

BJK85Z28

Okay, well, I'm really kind of dumb so I'm confused... but all I'm wondering is what are the power differences between the 377 and the 383? Sorry if this question has already been answered in this topic, but I try to stay away from flame wars.

89ProchargedROC

There isn't a big hp diff between a 377 and 383 STROKER. They have the same stroke (3.75) and same block (350) but they have a diff bore size (stock bore compared to .030 over bore)

There IS a difference between a 377 DE-STROKER and a 383 STROKER

The main diff is that a 377 will make more higher rpm horsepower because this motor has a 400 block and a short stroke to rev higher and make more higher rpm horsepower

A 383 is a better torquer motor because of the INCREASED stroke in the 350 block.

if you want a mainly a strip car build a 377

if you want a better all around street strip car make a 383