Thread: 400 block

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Originally posted by erik erikson
Why not try a 383? Same 3.75 stroke as the 400.

Bore is just as important to torque as stroke. Remember, it's the pressure in the cylinder that makes the power. Pressure is measured in lbs per square inch. A 350 block with a 4 inch bore has 12.57 square inches which means 1 psi of cylinder pressure will create 12.57 lbs of force downwards on the connecting rod. A 400 with a 4.125" bore makes 13.36 lbs force. Take the perpindicular to the crankshaft component of that downward force and multiply it by the effective length of the lever arm created by the stroke at that crankshaft position, and you've got yourself the torque produced by the engine. Obviously, both the size of the piston and the stroke contribute.

Originally posted by 76GMC1500
Bore is just as important to torque as stroke. Remember, it's the pressure in the cylinder that makes the power. Pressure is measured in lbs per square inch. A 350 block with a 4 inch bore has 12.57 square inches which means 1 psi of cylinder pressure will create 12.57 lbs of force downwards on the connecting rod. A 400 with a 4.125" bore makes 13.36 lbs force. Take the perpindicular to the crankshaft component of that downward force and multiply it by the effective length of the lever arm created by the stroke at that crankshaft position, and you've got yourself the torque produced by the engine. Obviously, both the size of the piston and the stroke contribute.

YES,THEY DO.DON'T FORGET THE SHORT 5.565 ROD IN IT. BUT TAKE A LOOK AT THE SMALL AMOUNT OF METAL BETWEEN EACH BORE ON A 400 CYLINDER THEN TAKE A LOOK AT THE METAL BETWEEN THE CYLINDERS ON THE 350 BLOCK.KEEP IN MIND THE SMALL AMOUNT OF METAL BETWEEN THE CYLINDERS ON THE 400 AND YOU HAVE TO SEAL IT UP WITH A GASKET.NOW HOW MUCH PRESSURE DO YOU WANT TO PUT ON THE CYLINDERS OF A 400 BLOCK?

Originally posted by 76GMC1500
Most of the Gen I small block blocks GM is producing nowadays are of a 400 bore (4.125" or greater), some do have 400 mains, and most have siamesed bores, just like the 400. Heck, even the new LS2 and LS7 motors have siamesed bores. There is nothing wrong with cylinders that touch.

BORE SIZE,MAIN SIZE AND SIAMESED CYLINDERS ARE NOT THE POINT.THE POINT IS THE OLD 400 BLOCKS USE LESS METAL IN CERTAIN PLACES.THE 400 WAS A CHEAPLY MADE ENGINE FOR CARS,AND TRUCKS AND WAS NEVER MADE FOR ANY TYPE OF PERFORMANCE APPLICTAION.IF IT WAS DON'T YOU THINK THE ENGINEER'S AT G.M. WOULD HAVE PUT A LONGER ROD THAN A 5.565 IN IT.HOW CAN YOU COMPARE A 30 YEAR OLD ENGINE WITH THE ENGINES OF TODAY?WHEN THESE ENGINES FIRST CAME OUT THEY DID'NT EVEN HAVE H.E.I. A LOT OF THINGS HAVE CHANGED IN 30 + YEARS.IT IS LIKE COMPARING (APPLES TO ORANGES).

No eric,that would be 'apples to lemons'. Who said you can't run a 377 on the street?

GM didn't change the distance between bore centerlines on the new 400's which can be bored to 4.190". That means even less area between the cylinders. Obviously, this isn't a problem.

Originally posted by erik erikson
YES,THEY DO.DON'T FORGET THE SHORT 5.565 ROD IN IT. BUT TAKE A LOOK AT THE SMALL AMOUNT OF METAL BETWEEN EACH BORE ON A 400 CYLINDER THEN TAKE A LOOK AT THE METAL BETWEEN THE CYLINDERS ON THE 350 BLOCK.KEEP IN MIND THE SMALL AMOUNT OF METAL BETWEEN THE CYLINDERS ON THE 400 AND YOU HAVE TO SEAL IT UP WITH A GASKET.NOW HOW MUCH PRESSURE DO YOU WANT TO PUT ON THE CYLINDERS OF A 400 BLOCK?

THERE IS NO DOUBT GM *#@#$! UP ROD SIZE IN THE 400 BLOCK. BIG DEAL THROW EM AWAY JUST LIKE THE HEADS AND THE CAST PISTONS. ENGINE BUILDING AND MODIFYING ISN'T LIMITED TO WHERE RODS CAN'T BE CHANGED. I HAVE A 509 400 BLOCK WITH A 3.875 STROKE AND 6.0 RODS. FELPRO MAKES GREAT HEAD GASKETS THAT SEAL THAT SMALL AMOUNT OF METAL WITH NO PROBLEM.

Originally posted by shevy not heme
No eric,that would be 'apples to lemons'. Who said you can't run a 377 on the street?

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I DIDN'T SAY YOU CAN'T RUN IT, YOU CAN DO WHAT YOU WANT.
HELL YOU CAN RUN A TOP FUEL DRAG ENGINE ON THE STREET FOR A LIL WHILE. (3MIN) AS FOR 377, ITS NOT A TORQUE ENGINE. IT MAKES HP HIGH IN THE RPM RANGE. UNLESS YOU GOT A DEEP GEAR, MANUAL/HIGH STALL, AND LIGHT VEHICLE, A STOUT 383 WILL SPANK THAT @#@.

Originally posted by shevy not heme
No eric,that would be 'apples to lemons'. Who said you can't run a 377 on the street?

YOU CAN IF YOU WANT JUST USE A 4.88 GEAR AND A 4,500 STALL YOU WILL BE FINE.

Originally posted by 76GMC1500
GM didn't change the distance between bore centerlines on the new 400's which can be bored to 4.190". That means even less area between the cylinders. Obviously, this isn't a problem.

HOW CAN YOU COMPARE AN ALUMINUM BLOCK WITH CAST IRON SLEEVES TO A CAST IRON BLOCK?WOW!! THIS IS REALLY A STRETCH.IT IS ABOUT LIKE COMPARING MY DART BLOCK WITH ONE OF MY OLD 283 BLOCKS.AT LEAST THEY ARE BOTH CAST IRON.L.O.L

Hello, folks! I discovered your fine forum while researching what I should ask for my 400 engine, and I liked it so much I joined! Looks like $300 is about top dollar for this rebuildable bad boy around here (complete motor, stock heads and intake, all the tin, still ran great). Any other opinions? It was still running strong when I retired it after 12 years - still blows the tires, ran a 10.0 1/8th. Would have run in the 9's or 8's if it would hook. But has a noisy lifter now (probably worn out cam - TRW with a bit of lift) and burns a little oil. Valve guide seals have been leaking for some time - I expect there will be a good deal of carbon in there, also from the aging Q-jet). A couple of my buddies built the motor for me many years ago!

(Part Two)

Without trying to get into the running argument, I did crack a head a few years ago, and the 400s have just seemed a little hot-running to me (I did put a 4-flu radiator in it, and the 350 heads did have steam holes) and it never liked anything below 92 octane. So I retired it this month in favor of an HT 383 crate motor, which actually makes the ol' 400 look sick. Of course, the Vortec heads and higher intake may have something to do with it! (435 ft-lbs and 340 hp) But I'm just less nervous about it now, and it runs great on 89 octane. I could run 87, but that stuff stinks when it burns.

So, should I hold out for more for the 400? Maybe hang onto it and rebuild it at my leisure with real stuff? It's not eating anything in the garage, and they just aren't growing any more of them... But it would be nice to recoup some of the dough I laid out for that 383!

IMHO price really depends on the part of the country you are in. Near motown here motors seem to be relatively cheap. I recently picked up 2 400's for around 175 each. In other areas i know they go for quite a bit more. Of course around here the motor is the only thing left after the rust gets done the car.

i didnt even read all the posts on this one...i ran 400 blocks with a 600 hp shot of juice...they never lasted long...BUT once i bought the DART Iron Eagle block...all the cylinder walkin, steam hole burnin gaskets, deck distortin went away

DART ROCKS

Thanks, DC! Glad to know you can still find your favorite flavor of mouse motor around Detroit, at least!

Oh, this sleeper is an everyday driver. Just something to get you out of a jam.

There seems to be deals-o-plenty around here. That's why I have 6 blocks setting around (I got a little carried away). Bought a Th350 trans, the guy throws in a 350 engine for an extra 50 bucks. Bought another 350 4 bolt 010 for $105, he includes a set of new TRW pistons that I turn around and sell for $109. I love ebay (no I don't have an ebay problem, really ).

I would think you could get decent $ for it around Birmingham as long as it's Birmingham Alabama and not Birmingham Michigan.