Thread: Tell me about a 400 sb

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I found a 1979 out of a RV with about 80k on it. Are these things any good? Why don't people use them more rather than building 383's.Thinking about getting it for one of my projects, he's not sure on the price yet.

no subsitute for cubic inches

yes they are pretty good------------do use same mounts, accessories, exhaust--------

They can run hot though I never had any problems with the one I had. It came out of a 72 Caprice Classic station wagon with around 100,000 miles on the clock. I dropped it in a 62 1/2 ton and backed it with a 3 speed, all I could afford. When the cam went south I replaced it with an Isky 30-30 from 1964, an Offy 360º intake, a Holley 650 dp and a set of Hedman headers. I had a 3100 # pressure plate built for it and the best clutch disc I could afford. The only problem I had was keeping rear ends together.

I've also heard they can run hot but I don't know much else about them. My brother has it and I've been toying around with putting it in the 82 Z28 this winter as a sleeper disguised a smog dog 305 ,or more likely a motor for the 71 RS. That's if it doesn't need a rebuild.

Originally Posted by 53 Chevy5

I've also heard they can run hot but I don't know much else about them. My brother has it and I've been toying around with putting it in the 82 Z28 this winter as a sleeper disguised a smog dog 305 ,or more likely a motor for the 71 RS. That's if it doesn't need a rebuild.

If you do you must have an externally balanced flywheel/flexplate.

Originally Posted by 53 Chevy5

Are these things any good?

Yes, great motor. I think that part of the overheating legend is using heads other than original 400 heads on the block that lack the extra cooling holes that a 400 came with originally. That and/or maybe using a 350 head gasket instead of the obligatory 400 gasket with steam holes. Unlike any other Gen I SBC, the 400 cylinders are siamezed into the crankcase, so that cooling water does not flow all the way around the cylinders. This leaves some dead ends where the water can be superheated and turn to steam, blowing the head gasket, if the steam is not relieved. Here's a tutorial for drilling steam holes into heads from a 350, for instance.

Chevrolet used a shorter connecting rod in these motors, 5.565" instead of 5.7", so you want to be aware of that when rebuilding. Most fellows will opt for the 5.7" 350 rod when rebuilding, but then you must grind on the rod shank for clearance between the rod and a few of the cam lobes. Companies such as Scat sell rods that are clearanced from the factory, a much better idea than grinding on a stressed part, in my opinion. Look at Scat Pro Stock rods.

Technical Articles at Greg's Engine & Machine

Add up the parts of your stack when building a 400 and pay attention to the compression height of the piston that you use.

Originally Posted by 53 Chevy5

Why don't people use them more rather than building 383's.

Scarcity. Most of them have been found and used by now and are in the possession of a hot rodder or circle track racer somewhere.
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I had a 1986 IROC Camaro and was going to put a bored 400 into it-even got the license plate IROC 406---------However, many other things took up my time and never got it done before lady painting her finger nails t-boned it and totoled it.

The 400 block I added splayed 4 bolt main caps to 3 center webs, had Brodix aluminum heads, roller cam/lifters, Crower rockers etc-sold to a friend for his car-----------

I built several of them for dirt track circle cars-------a few used spacers in the mains and 302 crankshaft-------killed some torque out of turns and added lots of RRRR's for staight away

Thanks for the input, I got two Camaros and trying to sort options out in my head. I would like to order exhaust for the 82 but a little hesitant because I'm pretty sure one of the two cars will get an LS based motor and one is getting a gen 1 motor.

Tech laid out the good for you.

In my opinion, they are great engines. I had two trucks with them, T400s, and 4x4, 3/4 ton work trucks. they ran like draft horses. I never had overheating problems, but they were both stock 400 foundations with torque maker cams, headers, and blueprinted Quadrajet carbs, and HEI ignition. I towed heavy trailers and hauled heavy loads for long miles, and they seldom gave me any trouble; scheduled maintenance and attention to general care was of the utmost importance, though. If I was looking, and could get my hands on a stock 400 long block, I would feel like I found a diamond in the rough.

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I get every 400 core block I run across---------

He would like 650 for it, that seems a bit steep to me. I'm leaning towards buying the vortec I'll have about a hundred bucks into the motor after I junk in the pickup and then do rebuild on that

Anyone recommend the best cam I can go with using a performer intake with manifolds? Using vortec 350

OK, the '82's were a little lighter than their predecessors, curb weight at right around 2900 lbs. Add a 200 lb driver and you're at 3100 lbs. Assuming this is a '96-'02 Vortec motor, the static compression ratio will be 9.4:1, with the best iron production heads that Chevrolet ever mass-produced for a Gen I motor.

Cam will be a factory hydraulic roller that is limited to around a 0.530" valve lift, using a standard 1.5 rocker. More lift than that can cause the roller to disconnect from the dogbone and things get ugly in a hurry. You can use a 1.6 rocker to get more lift, but it is not worth it in my opinion, because of the extra effort that it introduces into the valvetrain. Those components have an extraordinary job to do in the first place, without adding undue stress for a 10-12 horsepower gain. I don't use or recommend extreme energy grind cams for the same reason. If you are not seeking every last horsepower to drive around a competitor in a racing venue, then use a cam that is a little easier on the valvetrain and get some extra mileage from the package. Other thing about the L31 Vortec heads is that they stop gaining flow at about 0.500" valve lift, so there is no reason to go with more. When you reach max flow at a certain lift, then you make more horsepower by extending duration a little, limited by the static compression ratio of the motor.

OK, if you are with me so far, let's move on to the intake manifold. The absolute best intake manifold you could choose for a street motor is a high-rise, dual-plane design (NTFDAY might argue with me about that and he has valid reasons). When Chevrolet designed the Z-28 5-liter motor for introduction into the 1967 model year Camaro, they contracted with the Winters Foundry to cast the all-aluminum intake manifolds for the motor. It was a tall dual-plane design that proved so popular (read effective) that Edelbrock, Holley and Weiand copied and began production on their own part numbers for the aftermarket.

The Edelbrock 7116 or Weiand 8151 would be my choices.
https://www.summitracing.com/parts/edl-7116
https://autoplicity.com/3549338-holl...iand-manifolds

I would avoid using an air gap intake manifold for use on the street. If you want to use them in drag or other kinds of racing, that's OK, but avoid them for street use due to possible drivability problems in coolish weather. The intake manifold needs to stay really good and hot to help atomize the mixture for complete combustion in a street driving venue. Use the Air-Gap if you need another 10 horsepower in a racing venue and are not concerned about drivability.

For an everyday driver, a 600 is all the carburetor you will need. For max horsepower on a 350 with headers and gears, use a 750.

You will want to pay attention to the squish/quench and keep it between 0.035" and 0.045" by juggling head gasket thickness. A thin squish will insure that the motor can operate on pump gas without detonating. If you want to PM me about this, feel free.

For a cam, I'd use a mild grind due to using cast iron manifolds. Headers begin to shine at higher rpm's, so since you will be using logs, I'd use a cam that makes driving pleasurable in the lower ranges, with great throttle response and low end torque.
Here is a suggestion for you, a step-nose cam and lifters from Howards......
CL180315-10 kit, cam and lifters.....
Advertised duration 262/268
0.050" duration 209/215
Valve lift 0.465"/0.470"
Intake lobe centerline 106
Exhaust lobe centerline 114
Lobe separation angle 110
Hydraulic Intensity 53
Power range 1000-4400 rpm's (will work great with a stock 3-speed auto or an overdrive transmission, together with stock converter and gears, although a rear gear in the mid 3's would work really well.) If you think you will need a little less power down low and would rather have increased manifold vacuum for power brakes, have Howards grind the cam on a 112 degree lobe center rather than a 110. 108/116/112.

Call Howards and discuss this cam with them, tell them everything about your driving habits and what you expect from the motor.
http://howardscams.com/
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Originally Posted by techinspector1

OK, if you are with me so far, let's move on to the intake manifold. The absolute best intake manifold you could choose for a street motor is a high-rise, dual-plane design (NTFDAY might argue with me about that and he has valid reasons). When Chevrolet designed the Z-28 5-liter motor for introduction into the 1967 model year Camaro, they contracted with the Winters Foundry to cast the all-aluminum intake manifolds for the motor. It was a tall dual-plane design that proved so popular (read effective) that Edelbrock, Holley and Weiand copied and began production on their own part numbers for the aftermarket.

He's right about that. I prefer an Offy 360º which is s a single plane medium rise manifold with a split plenum. You basically get the best of both worlds for the street. It more or less is a matter of choice or opinion and I have experience with an Offy. Someday if I get ambitious I have a dual 4 Offy 360º setting in the garage that I want to put on the Vette, mainly for looks as IMHO nothing looks better than dual quads unless they're sitting on a blower.

I sounds like you know exactly what I'm looking for, a driver with decent power, not looking for every pony possible.If I would use shorty headers,would I gain much and would that change the receipt for parts? The choices for exhaust on this car come down to 2 1/2 true duels with pressure bends hooking to manifolds. Or shorties with a y pipe going to a single 3 then splits to 2 1/2's to a dual muffler in the rear. At least that's all I can find on the internet, they really limited what you can do under this car, It's pretty tight under there. Right now it has 3:42 gears that can easily be changed because it's a non posi rearend. I'll be getting a different one to swap it with so any gear ratio is possible.It will be getting 4 speed trans also.Thanks a lot for advice on this. I would like to get the exhaust ordered and throw that on the 305 for now and do the engine and trans swap later this winter. My banker has cut my funds until some stuff sells, I sleep with her so I better listen I will need more learning info on the pinch point but I might as well wait till I get the donor motor out and apart.