billla

The more CID we stuff into a GEN I block, the more complex the build gets. Don't underestimate the cost of complexity. Big strokes, long rods, etc. all can get very interesting in the details like cam clearance, tight ring packs, etc. The reason I like a 383 build is that there are no surprises and any builder can be successful.

Aftermarket blocks like the SHP are fantastic, but consider that by the time you get all the internals up to the same quality level, you're likely knocking on high 4 figures...whereas a pretty wicked cast-crank 383 can be built darn cheap. Used roller-cam block, cast, balanced rotating ***'y and decent heads and you're easily at 1.2 HP/CID+. I can't see chasing a used GEN I block, even a 400, when Vortec roller cam blocks, shortblocks and even longblocks are so cheap.

I noted the comment regarding Eagle; my personal experience has been that Eagle cast cranks are junk. I don't say that lightly, but after returning one multiple times for unacceptable journal taper I gave up. Scat is always right, right out of the box.

As always, do the math on the entire build and do a budget - or a couple of budgets for comparision - before making any firm decisions.

billla

By the time you clean, press ARP bolts into and resize a stock rod you've spent more than a NEW set of Scat stroker-clearanced rods.

Clearancing for stock rods vs. stroker-stroker clearanced rods is also a fair bit more work - the Scat rods only require a light touch, stock rods you need to really get into it.

billla

An engine you can afford in the framerails, running and well-tuned is way better than the one you can't sitting on the engine stand for years.

BB72

True, I do remember clearancing the rod bolts AFTER balancing.

Crepitus

That does bring up an important piont;
will the Eagle rod (SIR) clear a std base cam? This will be a small lobe but the rod looks awfull pointy on the shoulder

billla

On a 3.75 stroke, almost certainly. On a 3.875 stroke, almost certainly not. But of course, we need to check

cv67

personally trust a stock rod more than a SIR

When you go to a 396ci sbc its time to spend the money on much better parts especially if youre hammering on it. Costs can jump dramatically
A good machinist will refuse to do a 396 or larger stroke sb without anything less than premium parts.

scottyp99

This here's the best 383 article I have ever read. Lots of info.


http://www.carcraft.com/techarticles...y/viewall.html


Keep the shiny side up!
Scott

commander_47

The 400 block has gone by the wayside for a reason. It is inherently weak and building one is a dicey proposition unless you are VERY well versed in what you are doing.

SPECS:

1970-1973

4-bolt main block

2-bbl Rochester carb

4.125 inch bore

3.75 inch stroke

5.65 inch rods, approx. 795 grams each

2.65 inch rod journals

265 horsepower (gross)

400 ft/lbs of torque (gross)

Externally balanced (requires special harmonic balancer and flywheel/flexplate)

1973-1980

2-bolt block

2 and 4 bbl carbs

175 hp(net)

300 ft/lbs torque (net)

The 400 was choked to death with restrictive intakes, bad heads, and weak camshafts, not to mention single 2 inch exhaust systems.

It ended up spending a lot of time in trucks and larger cars where low end torque was needed.

The engine runs hot normally due to the “siamesed” cylinders. The two middle ones on each side are very hot. Exhaust size is restricted and you have to be very careful overboring since the thinner the cylinders the more hot it runs.

You MUST put in a bigger radiator.

Head gaskets tend to blow here, and if you want to pep it up a little, you can't. To really boost performance you have to get new heads, and these have to be specially made.; You are still restricted due to the small exhaust ports and a limited combustion chamber.

On the other hand, the tried and true robust 350 can be easily adapted to 383, and made to push 500 hp with NO problem whatsoever. Parts are cheaper and more plentiful, and there aren't a dozen or so things you have to concern yourself about to make it perform fantastically.

Why do you think these blocks are scarce? It's NOT because they are popular.

Better a built 350 or a Big block to begin with. Forget the 400.

cv67

Holy smokes had no idea. Think my H beams dont weigh that much

billla

None of these are correct.

Most significantly in error is the concept that a standard head won't fit and must be "specially made" - ANY GEN I head will fit by drilling the steam holes.

There's nothing wrong with a 400 block as the basis for a performance build - it's done all the time

lars

I've done (4) 407 (400) builds in the last 2 years. On the dyno, with various head and cam combinations, these engines have put out between 475 to 535 horsepower and 450 to 530 ft/lbs of torque, and they're a complete riot to drive in a street car.

I have never:

• Drilled a steam hole
• Blown a head gasket
• Used a larger radiator
• Used a "special" head

Just simple, precise build-ups using stock-block 2-bolt 400s with stock cranks and good heads. Cost is no different than building a good 350 or 383, and the rev limit is based on your valvetrain selection - not the block or crank. An easy, cost-effective way to make a ton of torque and frightening horsepower.

Lars

Crepitus

This thread has concentrated on 400 problums and pitfalls. The biggest of prob is GM didnt make very many. All of them are about 40 years old.

cv67

and finding one that isnt fulll of bad threads, cracks lousy machine work worn out lifter bores etc is like finding a needle in a haystack. I looked at many many "good" blocks over the yrs only to find they had some issue to them. If you dont know what to look for youll buy a lot of junk blocks without realizing it.

If I had a few bux Id build this 400 just cause I like the effect of the larger bore/unshrouding, big believer in that.
Just wont happen. So it sits.

scottyp99

Finding SBC 400 blocks in perfect condition is as easy as falling in love, thanks to DART. You can get one of their SHP 400 blocks for less than 1500 bucks. Not a bad deal, considering what it would take in machine work to get a stock 400 block up to snuff, assuming you can find a good one, and the bennies built into the SHP block, such as provisions for using stock roller lifters, (save a buncha money right there!) priority main oiling, blind head bolt holes, etc. Check out this article Car Craft did on it:

http://www.carcraft.com/techarticles...y/viewall.html


Keep the shiny side up!
Scott

tricktom1

Lots of good info here, don't over think it. 400 blocks are harder to find and the cast cranks will hold up to street car power unless u r building something extreme that's not practical on the street anyways.

Little Mouse

See if this makes common sense to you it does to me.

" Rods, like everything else, have a finite life expectancy. This life expectancy may be perhaps 10 million cycles at a paticular load level. The problem is, that unless you have been traveling with the rods since they left the factory you have no idea how close they are to this 10 million mark, Are they at 50,000 cycles or are they at 19,999.500 cycles ? There is no way to tell where your set of rods are in this life cycle time line and as such you may be at the brink of a failure. To make matters worse we can't even predict for sure how many cycles they are even good for ! No one knows for sure. Obviously the more stress placed on the rod the more critical these numbers become. If you look at most aftermarket rods, there cross sections arn't really much larger then a stock rod, but due to there better material 4340 and a life cycle clock starting at zero they would be the way to go. Money spent here will go a long way torward preventing faliure because when a rod breaks, its pretty messy "

IMO, its not just that a new rod is closer to the price of resizing and new bolts its the important fact that the rod is new has not had 100,000 of cycles where its already been pushed hard on and then been tried to be pulled apart by the piston and pin. Then theres the fact the new rod is higher strength metal along with comming with bigger 7/16 bolts then the factory ever used.

Aflac

I have a 400 on the floor of my garage that is eventually going to go into my 77.. it has some slight pitting in #1 but if it needs it, it will get sleeved and put together.. gonna be a long rod version when its all said and done...

cv67

To me "seasoned" parts means old and worn out not desireable yet youll see ads throwing that word around like youre supposed to run outside naked in a hurry to get it before the next guy

I'm Batman

A block that's in good shape after a lot of heating and cooling cycles might well be better than a new block. When BMW turned the old 75hp M10 4-cylinder into an 1,100hp turbocharged F1 engine in the late 70s, they could have used new blocks, as the engine was still in production. Instead, they scoured Europe looking for 2002s in junkyards to use as engine donors. The "seasoned" blocks were simply more stable and durable. That said...

WANT!