400

[Irish_Alley]

a friend is selling a 400 out of a tow truck. before i put it in i want to put a cam in her, was originally thinking about building a 383 but due to the new baby cash should be saved for him but if i need to build the 383 i can save for it. but about the 400 what should i be doing to it to give it the power to turn 38s but still be a good road truck? i guess what i want is almost like a 383 but trying to see if it will be cheaper to build this 400 up

[beastie_3]

You can build a 400 to be pretty good, but heat is its enemy with stock heads. It should be a little cheaper because you dont have any clearance issues. Everything is bolt on.

[chevymanrob]

my old 400 was pretty basic....
5.7" rods with small dish pistons ($200 and reasonable compression)
edelbrock RPM heads
comp XE 284 flat hydraulic cam

i know the heads were not cheap, but it made some
SERIOUS torque. like pulled both tires 2" at the track. ran 11.86 at 113. after i drove it 20 miles to the track!!!

with some decent heads like vortecs or maybe a ported 993 or similar you can make good horsepower, loads of torque, and it still be pretty mellow. i think my old engine would have found the weakest link in your axles/ujoints/diffs pretty quick

[muddpuppy01]

just make sure you have steam ports in the heads if you build a 400

[chevymanrob]

i dont believe all the hype about needing steam ports. i did drill them in my heads and the 1st pair of stock head gaskets made it 600 miles. yeah i know, felpro said they would be ok...anyway the 2nd set of better quality race felpros didnt have the steam holes and it worked just fine. car never overheated or did anything quirky.

[Irish_Alley]

can i use my double hump heads on the 400?

[1979C20]

Why not build a 372 or 377? 372 is 400 block with 350 crank and 5.7" rods and a 377 is a 400 block bored 30 over with a 350 crank and 5.7" rods.

[Irish_Alley]

if i go with the 400 i was thinking about just a cam swap and heads that i have laying around. if i keep the 350 then i was thinking maybe the 383 work. knew about putting a 350 crank and rods in a 400 but would that be like building a 383? as in tq numbers

[Grim 82]

I wouldn't spend a bunch of cash to lose cubic inches. Throw a cam and decent heads on the 400 and run it. If you run iron heads you can have them drilled for ~$50, which is cheap insurance.  The right cam and some bolt-ons will get you some good numbers, but bumping up the CR wouldn't hurt if you have to tear into the bottom end of it. Remember to use a 400 adapter plate so you can re-use the flywheel from your 350.

[chevymanrob]

never build an engine smaller unless you're trying for a mega high rpm monster. our heavy trucks need all the torque you can throw at them. and then add more!!! you can drill your stock heads using a head gasket as a template. i drilled my NEW $1100 edelbrock rpm heads.....scary. 1/8" bit iirc, one hole perpendicular to the deck, one at about 30 degrees. if you d/l the edelbrock instructions they give info in detail. and you can get a 400 flexplate for cheap, a flywheel wont be so cheap.
and the double humps will work if you drill them for street use. i actually covered my steam holes withe the REAL felpro gaskets (not the junky stockers) and it was fine.

[Irish_Alley]

i have a 400 flex plate just sitting it only need the rust knocked off