Ive done a bunch of searching here on thirdgen and various search engines and found nothing more than basic information on 400 SBC. Sure, i could find every spec on a 283,305 or 350, but what about the nasty 6.6L? Im gettin ready to finally build my own and am having a hard time with the research. so, this is some basic stuff to start off with so it doesnt get double posted:

The 400 SBC started in the late 60's and was equiped in larger cars and later in pickup trucks. Its a stout engine with a stock bore of 4.125" to a stroke of 3.75". it came from the factory with 5.56" rods.

The blocks have syimese cylinder walls ( no gap between cylinders) which helps with strength. The cylinder heads and engine deck also have steam holes ( two between every cylinder) to help with cooling.

The 400 has larger main journals than other small blocks, with 2.65 as compaired to 2.45 on the other engines. This crank is often turned ( journals are ground down) to fit in a 350, creating a 383 stroker, ( which as a 350 with a .30 overbore.)

The 400 rods (5.56) are often changed to 5.7 rods for more torque.

The 400 SBC balancer and flywheel cannot be interchanged with other small blocks, due to the 400 being an externally balanced engine ( other small blocks are internally balanced).

the mains are much broader the those on other small blocks.

Its been suggested when doing a build to get the 2 bolt main block over the 4 bolt, due to the area between the bolts being thinner and causing them to crack. The best bet to to go with a 2 bolt block and have it drilled for aftermarket 4 block main caps.

if theres anything about the information i listed thats incorrect feel free to correct me. i hoping im not the only one to benefit from this information so help me make it right so everyone can benefit.

My questions: How does the 5.56 rod vs the 5.7 rods change the operation of the internals of the engine? i beleive it changes the pistion geometery which makes it spin faster than with stock rods, but im not sure.

Whos got a COMPLETE list of specs on this engine? Im talking years, production numbers, hp ratings, anything you got.

What combos are people running with this engine and what are you getting out of it?

What problems have people run into?

Lets get this thing rolling, i know im not only one looking for this info.

thanks!

 

the longer rod actually slows piston speed down. it also increases dwell time at TDC and BDC allowing for a more powerful combustion during these dwell times from what i've read/been told.

 

and there's nothing wrong with using the 5.56" rods. Longer rods need pistons that move the wrist pin farther up into the ring lands. You can only go up so far.

Factory crankshafts are cast not forged.
Factory heads are low performance.
Factory blocks can only be safely bored .030" over. More than that and you risk cutting into a water jacket because the cylinder walls are so thin.
Installing a non factory head requires drilling out the steam holes in the new head.
A 350 crank can be installed into a 400 block with bearing spacers to make a 377
The engine was prone to overheating because of the thin cylinder walls and the poor 883 casting heads which commonly ran hot and cracked.
This engine is the largest factory SBC produced. It shares the same external dimensions as all the other gen1 small blocks.
The most popular block casting is 509

The last 400 SBC was produced in 1979. Most have been snatched up by racers and engine builders and an original one is getting very hard to find.

GM also produced a 402 BBC. It was a 396 that was bored out .030. Many early 70's pickup trucks got this engine and a 400 badging on the fender causing confusion as to whether it was a SBC or BBC under the hood.

With many aftermarket choices available now, it can be cheaper to buy a new engine block with a better casting that trying to rebuild a 30 year old engine.

 

awesome, if you were to you 5.7 rods, is there a clearence issue? Ive heard the connecting rod bolts will have to be grinded down to make they clear the shirt on the bottom of the block. Also, with a larger rod do you need a special camshaft so the rods dont hit the lobes?

 

Yes, 5.56" rods (stock 400 rods) are not only shorter but they have subtle differences in the rod bolts and their location on the rod (that's why you can't interchange 400 rod bolts with any other factory rod bolts). Once you go up to 5.7" rods or longer you will again have potential issues with the rod bolt heads hitting cam lobes, just like guys who stroke out a 350 to a 383 and keep using their original 5.7" rods.

The cam is in the exact same location in a 400 as it is in a 350.

My experieince is that the shortie rods make the exact same power as longer rods but they wear out the rings and bore faster due to greater side-loading of the piston. I would recommend upgrading the rod bolts in the shortie rods, even for mild engine combos (but I do that to every engine I build regardless of displacement or rod length).

 

Chevy small block 400's could be had from 1970-76 in the B-body cars (like Caprice or Impala) and A/G cars (like Malibu/Chevelle/Monte Carlo) and from1976 to 1980 in pickups.

They get a raw reputation for constantly overheating, like stated above, and it was mostly due to heads and lack of cooling system maintenance which lets the steam holes get plugged.

4 bolt blocks should be overlooked in favor of 2 bolt blocks. I wouldn't bore one out, either. I'd rather have it bored and then sleeved back to standard bore size.

All that aside, I like them and have run them. They provide that ultimate CID advantage to start with. Just like the saying goes between the 305 and 350, so it goes with the 383 and the 400. All things being equal, which means same hardware bolted to the short block and same cam/compression ratio. The 400 will smoke the 383 every time. The math just doesn't lie.

That's my argument in support of the 400 block.

 

Well, I wouldn't run a 400 SBC just for the facts stated above, plus a 350 is way more common and probably alot cheaper to build because there are so many of them running around, and have a huge after market support.

My 81 camaro ran 2 tenths slower in the 1/8th with a 400 than it did with a milder 350, I am not sure why though.

 

Well, I'm running a .040 over 509 casting now. It's not too uncommon to see others run up to a .060 overbore. Same rules apply with any block - not just the 400.....it depends on how much core shift occurred when the engine was produced. Never a bad idea to have the block sonic checked to determine how much of an overbore any block will take - this includes 350's, 283's, 305's, 327's etc.

In almost every case, an aftermarket block will be superior to a factory one. Beefier webs, fatter oil pan rails for clearancing, thicker cylinder walls, splayed mains - well you get the idea. Dart and Motown know the shortcomings of the factory blocks and improved their aftermarket blocks accordingly. If I were building a strip car, I personally would get an aftermarket block to begin with.

Only time I had problems with overheating is when I had a bad water pump, but I suppose it's possible to clog up the steam holes - in which case you have serious cooling system issues anyway if that's happening. All that being said, I've found that these engines are torque monsters. Mine put out 390 HP and 490 ftlbs. of torque at 3450 rpm's on the engine dyno. Try that with a 350 N/A!!

EDIT- As aid above, when using a 5.7 length rod, you'll need to clearance the block a bit. No bolts had to be ground down on my Eagle SIR rods.

 

In the FWIW catagory, the factory 400 was never built for high horsepower, it was intended as a high torque low rpm motor to launch station wagons, large frame cars, and pickup trucks without using high ratio rear gears. (remember, these were the pre-overdrive days) The factory couldn't relocate the wrist pin higher in the cast piston without making the ring lands thinner and sacrificing durability under detonation.
The short rods work at severe angles yielding high side loading on the piston but also gobs of torque at the crank. This also limited the rpm of the engine preventing it from making big horsepower. This is why it was never used in the corvette.
But.
Now, the aftermarket can supply specialty pistons and rods that solve those problems.
400 block engines can now be built that satisfy some niche SBC applications.
For example:
high horsepower and torque at stock SBC rpm.
high horsepower and torque on nasty 87 octane gas.
high torque for lowest weight.
However, one drawback of the engine still exists until today:
It's going to get crappy gas mileage due to high friction loss similar to a BBC...
(which explains why there are so many 383's)

 

430hp and 525ft/lbs with vortec heads.

 

I agree, 430hp at 5200 rpm and 525ft/lbs at 3500 rpm. My 700r4 lasted less than 40 minutes behind my 409 SBC engine! A "built" trany is on the way.

I followed the engine build up in the SA Design book, by Greg Hansen, How to Build Big-Inch Chevy Small Blocks. He had two 400's he built, the 430hp torque monster or the high rev 581hp at 6300 rpm. I picked up the book at Autozone. He gives all the details on how to build the engines.

Here is what we did to our 400sbc:
We picked up a used block and it needed to be bored .040 over because of rust in the cylinder bores, gives us a 409cid. Align hone, turn crank, 5.7 350cid rods with new ARP bolts, no grinding of the block is nessesary, a few rod bolts needed grinding. Stock Vortec heads (casting #906, $50 each off of e-bay) Lunati flat tappet cam, 230/230 at .050, .45" lift. Keith Black D pistions with a 30cc dish. Zero decked the block giving us a 9.2 cr static and 7.7 dynamic cr. Hooker 1 5/8 shorties 3" cat back, Flowmaster 30 with a single dump at the rear of the car. A Quick Fuel 750 carb, Edelbrock EPS Vortec intake. 427hp @ 5,100 and 525ft/lbs @ 3,500.

It will light up the tires rolling along at 30mph, Priceless! No need to rev it up, it has power at any rpm.

 

A few quick questions for the sake of future searchers:
1. Were the rods aftermarket, or stock from a 350 just with special bolts?
2. Did you use a stock 2 bolt block, (no drilling mains)?
3. Was the cam a "small base circle" cam or standard?
4. Would you consider this a daily driver? (for the guys thinking of building one for their "grocery-getter")
5. I don't guess the tranny lasted long enough to get an idea of MPG?

 

I have this same engine in my car. I have all cast internals and a 509 block, 2 bolt. It's bored .060 over (too much but I bought it used and it's working) Cam is a Lunati pn 00010. I don't know how this would run in a auto tranny car, but with the 5 speed it's fine. I would imagine I'm in the 10 mpg range. You need to run premium gas (93 octane or whatever it is). Not really a daily driver by any means unless you have a HUGE fuel budget.

 

you guys have no idea how happy i am about this thread i was just going to do searches to try and find 400 infocause i am getting mine from a 1980 c-10 pick up which i am leaving it in the truck cause its a step side (looks nice ) any one know were i can find susp and body upgrades like how we have spohn and umi i need to find some one that has c/k for the 80's upgrade

 

Thats an sweet setup! Im on my 6th build-up and finally learned from my mistakes. I always started from the engine and worked my way back. After smoking a few trannys and learning aboout rear ends that suck, i decided to start from the back and work forward. If you check my signature ive got all the details. I built everything around this engine so its wont break.

im definately gonna have to get that book tommorow, it sounds like a wealth of information.

How do you know if its a 509 block? I have a casing number on the rear of my block by the top of the bell housing flange ( near the rear of the intake) of 330817. Anyone know how to get info about the materials in the block? ex. nickel content or other metals?

Also from what im hearing is the 5.56 rods will work fine. Can you still get higher rpms out of them? Im looking to build mine to run to around 6200 rpm so i can try and keep up with some of these LS1's.

thanks

 

509 blocks end in 509. You have an 817 block. If it's 2 bolt it's fine. Nickel has better thermal properties. Nothing major to worry about though.

 

No need to go fancy on anything with this motor, the shift point is 5,000 rpm. This is one fun car to drive intown with all that torque!

The 350 rods were used, new ARP bolts and the big ends were reground.
I had a choice between either 2 or 4 bolt, again with max rpms at 5,000 I went with the 2 bolt mains.
The cam was not a small circle base.
This would make a great daily driver. Vacuum at idle is 18"
This replaced a 305 and when it idles you know it isn't a 305 or 350, when you open the throttle you think it's a BBC.
In general torque motors have better gas mileage plus I have overdrive.

 

from what i found from the net , the engine i just bought which is currently in my 1980 c10 stepside is a 1976 impala

http://www.chevytrucks.org/engines/ctechv_400lb.html

and wikipidea says
# 400cid 255-265 bhp Turbo Fire V8 (1970-1976)

i dont know anything else about it yet i am still digging , i want to know everything in this engine so i know what i am going to building off of with so if any one is interested in helping i am open for siuggestions , this sould be a street/strip /weekend toy

 

Update
The rebuilt 700R4 ($3,000) is back in the Trans am with a 2,000 stall converter. We still have to dial in the carb and shift points on the transmission.

Took it for a test drive today. The tires spun all the way through first gear and half of second gear, past 60 mph. (3.23 gears in the rear axle)

My 15 year old was driving, we both had big grins .

 

You really should be shifting around 5500, NOT 5000. You want to shift around 500 rpm AFTER the PEAK....NOt before the peak.

 

Ive been searching and have found 3 400sbc in my area now im tryin to pry one of them from one of the owners hands but no one wants to let go!. My question is would my 305HO heads work on this motor with a flat top 4 valve relief piston or am i going to have to much compression to drive it and enjoy it. i want to use my 305ho heads because i have them and wouldn't need to buy and redo a set of vortecs.

 

With flattops the compression would be too high.

Find a used set of vortecs. I got mine for 200 bucks. Lapped the valves, installed new valve springs and stem seals which all cost less than 100 bucks.

You're also going to have high compression if you run vortecs and flat top pistons.

 

I had a feeling my small ho heads with the large bore of a 400 would be alot for a street motor, but i bet it would be an awsome mud bog motor

 

I would think the heads would not flow well enough for a 400 as compared to what could easily be had with a set of vortecs.

 

They would flow better than stock 400 heads.

 

Okay I have a 400 Siting in the garage right now that I'm itching to build but, is it possible to mate it with a T-56 that I already have in my car. Any solutions??

 

same as doing it with a 350, except the flywheel will need to have the extra counter weight. You can buy a counter weight that sandwiches between the flywheel/flexplate and the crank(havent tried one, but have seen them for sale).
Anyhow, there is no difference externaly,other than the counterweighted flywheel and balancet compared to a 350 or 305. Evrything bolts up the same.

And as far as the "overheating" thing goes, I have never had any more problems with 400's than 350's. Its no big deal at all.