The Stovebolt Site Forums The Shop Area The HiPo Shop 383 or 400

If price was the same which one?

If the 383 was a Mopar and the 400 was a Pontiac, I'd pick the Pontiac.

(This response will probably ire the Forum Meisters)

Bill, since Ferris wasn’t very clear on what he was looking for your answer is perfectly acceptable.

If referring to Chevy engines the 383 is a proven performance engine with a great longevity record.

A small block 400 is a step too far. Even with "steam hole" heads, they had chronic overheating problems and the rod/stroke ratio was way wrong for good torque. Other than a few applications in big station wagons, motorhomes, and trailer towing pickups, it was a solution looking for a problem. Anything a 400 could do, a big block could do better, be it a 396, a 427, or a 454. 383 was never a factory engine size- - - -the hotrodders invented that one.
Jerry

We raced in the 410 class with our sprint car and picked up some pointers on the sb400. First was block selection, forget the one with three freeze plugs---thin decks and heat problems. The block with the two freeze plugs and boss for the third one is acceptable but still not the best. The block that has two and looks like any other sbc is the one to use. Also 6" rods for good geometry and Mallory metal in counter weights for internal balance. All told an expensive engine to build but would run at the front of the pack. Sprint cars run no fan and small radiator so heat was controlled with alcohol fuel. Richer the mixture the more heat carried out the exhaust plus driver could kill mag at end of straight a way for instinct cylinder cooling. On ANY car the exhaust gets rid of 85% of the heat and radiator 15%.

Seeing this is a dedicated gm site, my assumption was it would be understood I was referencing gm engines................

I agree Jerry a BB will outperform the 400 in almost all areas. I have read extensively about both engines and the problems associated with both. The 400 with cooling issues and steam venting is concerning, but it seems those issues have been ironed out after a couple decades?

Price for the two engines were within 75 dollars of each other and the 400 lays down better numbers. I have always known to stay away of all 400s, but when put together correctly they seems to be a screamer???

The other issue with the 400 is that good rebuildable cores are getting hard to find. As Coilover said they raced them, a lot of them, and just finding a good clean block is hard. The 383 combination is a proven build, literally thousands have been built, it's also a great motor for building torque. Torque gets you away from the traffic light, horse power gets you to the next one faster.

This place in NE does their own blocks. Does not matter if it is 350 383 or 400. No seasoned cores.

The 383 is 434/450
The 400 is 505/450

Both run similar rpm's. I questioned them about steam passages, rpm range etc. HP and TQ curves are similar, just more with the 400.

The bottom line is that unless you're building an all-out race engine that's going to be worn out or blown up in less than 1K miles, a well-built 302 will smoke both of them with the right gear ratio.
Jerry

Very true. Looking for bang for buck. Hard to put a motor together with all bells and whistles for less than what some of these large assemblers are doing it for. For example: To buy a sniper FI system is 1500. Add it to an engine build and its 1K. Buy a serpentine belt system for a engine and your at 1500 once you get all pulleys etc. Add it onto an engine build and its 800. The list goes on and on.

383 and 400 are not the same kind of engine: a 400 is a torquey engine, originally designed for the heavy cars of the mid '70s, no performance aspect to it; the 383 is a "hot rodder invention" for performance. So, what do you want? A low-end torque engine for cruising? The 400 is great, although they are getting to find and a regular 350 will do the job just fine. If you want to race, burn rubber, and such, build a 383.

Since a 383 is just a 350 with a 400 crankshaft, why is there less torque with the same stroke? 13 more cubic inches and 1/8" more bore size doesn't make that much difference in the torque the crankshaft sees, unless a lot of other modifications are done. I can probably build a 383 that will out-torque a 400 by paying some attention to the connecting rod length and cam profile. That's particularly true if a custom crankshaft with internal balancing is used to build the 383.
Jerry

The TV show Engine Masters uses a Chevy 383 as their primary SBC test mule. Hundreds of pulls with all sorts of aftermarket stuff bolted on and absolutely zero problems. If I was building again and didn’t have an engine lined up I would be saving up for a built 383.

Here's a bit of trivia, since this is the HiPo forum where oddball stuff gets discussed at times. When I bought my crankshaft grinder from King's Crankshaft over in North Carolina, he showed me his "cheater" crankshaft- - - - -it's made from a solid billet of steel that weighs around 250 pounds or so and gets whittled out on a CNC mill. The finished product weighs around 38 pounds, instead of the standard 55 pound 350 crank. The first two cylinders at the front have a standard 350 3.48" stroke. The other three cylinder pairs have a 4" stroke. Since the cylinder volume and/or stroke length is usually measured at the #1 cylinder on a tech inspection, most of the time the extra displacement doesn't get discovered without a full engine disassembly. Like Smokey Yunick used to say- - - -"It ain't cheatin' if ya don't get caught!"
LOL!
Jerry

Made good money in the early '80 at GM dealer on small block 400. They didn't seem to like being run 1 qrt low on oil under load, wipe out some rod bearings. I think part of the issue is more heat transfer to the oil than other small blocks. Replace many blown up 400 with "Target Master 350" due to they were cheaper than a short block to partial engine 400. Since the 400 is externally balanced, would replace crank damper & knock the balance weight off the flex plate.

I was originally going to build a 383 for my 51, but after reading about block clearancing required (and maybe some filler around bottom of bores) I decided to go with a 400. It is from a running 87 Monte Carlo, 87K miles, so it should just require a standard rebuild. Some good alum heads, EFI and a RV cam, it should make a good engine for the truck to pull a trailer. Probably going with a 5 speed manual and a 12 bolt or 9 inch rear. I am nowhere near actually getting the truck running though. my .02

Is weight a factor in your build, for some reason? Aluminum heads will transfer some of the power you're making to the radiator instead of the rear axle, sucking up that thermal energy and blowing it away with the fan instead of using it to shove the pistons down the cylinder bores. Doing race car stuff on a street engine usually doesn't have very good results.
Jerry

Weight reduction is not a huge factor, I am assuming the availability of new alum heads is better than cast. With an overdrive trans, it will not be pulling high revs, so I want the power band down low. Has to run on 87 octane, so no high compression, hate detonation ( I have that issue with a 10.5 CR 350)

So with low end torque as the goal, what heads would you go with? They cannot be Vortec as I have a vintage alum square bore intake for the EFI. Plus they have to have steam holes.

KevinW, since you have hi jacked the thread please start a new thread with your questions about your 400. Thank you.

Did a search strictly on reliability 383 vs 400. While a few people have 400s lasting a long time a vast majority are self destruction at the 80k mark. No warning, no reason, just a rapid overhead and done????

A 4 1/8" bore size in an engine block that began life as 3 3/4" in the 1955 265 engine is just pushing the envelope a little too far. AMC did the same thing in the early 1970's with displacements from 290 to 401 in the same block. MOPAR went from 273 to 360 in the same block with similar results. Ford- - - -221 to 351. I turned a 426 hemi into a 547 cubic inch truck pull engine by filling the cooling passages with epoxy, boring all the way through the cylinder walls in places, and installing flanged sleeves. It lasted for 2 1/2 pulls before breaking the crankshaft into 3 pieces. Putting big cubic inches in little engine blocks doesn't make good nonsense, no matter who is doing it.
Jerry

My vote goes' to the 383, I built one for low RPM torque 'cuz I was gonna' swap it into my fiberglass Chevrolet, automatic, 3.08:1 rear end. I decided to leave the car stock but I'm keeping the stroker in case I have to pull the 283 out of my LCF and I'll have an engine ready to go.

Excellent info and opinion from people. With additional info I have found I am off the 400 and back to the 383. Hell I might even just go a 350, but I doubt it.

A 350 is no slouch. It's tried and true, will run all day and give you years of service. I think what is missing here is your end goal for the truck, if you want a tire frying beast then a built 383 is the right choice. If on the other hand you want a dependable daily driver that will start every time and bring home a load of lumber with no struggle then look at at the 350... Just for the record, I would keep the 283, great strong running engine with plenty of power and can be built to run with the Big Dog's. I have seen 283's that can eat Big Blocks for lunch. Just my $0.02 worth.

Just does not return performance for the money spent. I am going to hang onto it. Maybe engine I buy will go into another build and I will rebuild this 283 eventually.

I'm going the other direction- - - -small bore, super short stroke, around 250 cubic inches, and enough valve springs and other go fast goodies to run all day at 8K+ RPM. Then it will go into a fiberglass body roadster that will weigh around 1500 pounds.
Jerry

You have the knowhow and spare parts to play with combinations all day and night. Chuck a turbo on that 250 and see it shine.

While there are a few bad reviews, the overwhelming amount of reviews are very positive.

I was on the fence between a 400 and 383. Now that I have come to my senses I am on the fence between a 350 and a 383.

I think they are 90 days out. Here is some real money about to be spent!!!

If you are going to keep the 3.73 rear end I would go with the 350 only due to the shorter stroke.

78buckshot,

Good point. My ultimate plan is to go with a OD transmission. Probably sooner than later, but still uncertain.

Bang for the buck?
Buy an entire big block car for the engine, and leave it alone

Well I plunged in with both feet. I have gone back and forth on so many things, crunched numbers every which way to Sunday and tried to factor my time into the equation as well. I searched local bone yards for used stuff, looked into the LS swap at bone yards and clist, buying things individually etc etc etc.

Long story short the cost of buying a turn key is less than buying everything individually, almost the same as buying used stuff, and refreshing. Less if you buy a wrecked or used rig (LS or no LS), but then there is the headache of R+R, computers, etc.

I ended up going in deep with a traditional SB engine and 5 speed trans package. I am planning on keeping the 283 4speed together and selling as a pair or keeping with the truck if I ever sell it.

Cost was up there, I didn't need it, but I am having a ball with this restoration. There was a 10% discount for some promo I didn't know about. I do think it is going to solve many headaches before they present themselves. Should be getting here for Christmas!!!!

Here is the package. Pics shown are for a auto. I am very excited for this to start going back together this winter.