VCCA Home Forums TECHNICAL - 1945 AND NEWER 1971-1979 400 cid with standard transmission

I think this is the place where I can get the answer. Did Chev ever use standard transmissions behind the 400 sb. If so what are they in? What type of clutch and bell housing Etc?

Len

The 400 engine was a high torque-low horsepower regualr fuel "large economy" engine when introduced in 1970.Was never meant to be a "high performance" engine.The 1970 I had was fairly fast (Impala car).In 1971 the engine was detuned and additional emission controls added.Performance suffered.My 1971 Caprice felt more lake a poor running 350.These engines used 2 barrel carbs. until 1974.Then a 4 barrel was added.Pepped up the higher RPM range a little.
The 396-which was then a 402 was used as a higher performance engine-called a big block 400-cost more to produce but was a better engine.The SB 400 had some weak points.The engine was out to the limit.Cylinders were siamesed-connected between-and had poorer cooling.Cracked heads and distorted cylinder walls were often resulted if worked too hard.For normal passenger car use I thought they were a good engine.---Why were they never used behind a stick?Probably because sticks were becoming less popular then-they wanted a cheap to produce engine to put behind an automatic for a little more torque-and in the smaller cars-Chevells etc-they used the big block for the sticks - which were better performers.

I had a 400 SB in a 1976 4x4 1/2 ton Surburban (automatic)that was rated as a 5/8 ton just to beat the new ruleing that anything 1/2 ton or lower in rating MUST be set up (cat-converter) for burning unleaded gasoline only! I had to completely overhaul the engine after 72,000 miles many pulling a 10,000 trailer, because a replacement 400 CI engine was not available. It would get so hot under the hood with the transmission and engine oil coolers mounted in front of the radiator and A/C condenser that the plastic wire connectors and Nylon Vacuum connectors on the engine would melt and deform pulling the grade between Clines Corner and Santa Fe. I should have gone to a 454 instead of overhauling the 400, The 400 used more gasoline than my brother's 76 2 wheel drive Surburban with a 454. He drove the 454 250,000 miles without even pulling the pan or the valve covers.

It was available in light trucks from 1976-80.The trailer hauling-hot weather use would give just the results that you found.In regular passenger car service it worked fine -except some complained of a little oil consumption.Never was a very economical engine-but what was in those years.I had new wagons as demos. in those years with that engine.14 or 15 MPG on the highway was tops-little less with the "air" on.

My records have a 350 Impala with 3 speed on the column until January of 1972. 400 did not have manual in the resources and references I have.

Hope that helps.

Steve

My records have a 350 Impala with 3 speed on the column until January of 1972. 400 did not have manual in the resources and references I have.

Hope that helps.

Steve

The reason that the 400 small blocks never used a manual transmission was that the crankshaft in the engine had such a long stroke compared to the size of the block that it required an externally balanced crankshaft. All of the balancing was done on the harmonic balancer and the automatic transmission flywheel. These 2 items are not shared with any of the other small block engines. The engine was used in some four wheel drive pickups and some full size vans (all were equipped with automatic transmissions). A few after market manual transmission flywheels were produced for the speed equipment industry, but the engine really preformed better if the shorter stroke 350 crankshaft was used in the larger bore 400 block.

to say that chevrolet never produced a 400 small block with a manual transmission would not be the truth in fact i have a chevrolet 400 small block manual flywheel hanging on my garage wall,i pulled the original untouched motor out of a 1975 chevy 1ton dually stake bed truck the flywheel is also marked gm on it i hope this can shed some light on this controversy.

My 1977 truck parts book lists NO clutch or trans. parts for a 1975-77 S.B. 400.Lists only a automatic transmission flex plate also-no std. trans. flywheel.Engine code section also lists no transmission options-just the automatic.Perhaps they didn't know they made one?

Many parts numbers and catalogs don't tell the complete story of what a "shade tree" can put together and make work, they are just what the Chevrolet decision makers believe is the correct way to go, and what they market. Many parts not listed for a 235 will bolt to a 261 or a 216, like ways a 350 to a 400 a 283 to a 265 etc. I have seen some 400 SB engines used where a 350 originally was used (4 wheel drive trucks manual shift) and they "worked"

The engine will "work" but they will vibrate very badly unless the special "out of balance" 400 flywheel is used-and Chevrolet never produced one.They were only available as aftermarket.

By "worked" I didn't mean they worked well. I had one in a 4x4 Surburban with a Hydramatic OD and 4 bbl carb, it was a gas hog deluxe but had about the same power as a 350 TBI.