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Awesome budget 400 sbc block builds

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400 gmc
14K views 23 replies 11 participants last post by  6426yy 
#1 ·
I've my next build up in the air all I know is I'm starting with a small block 400 whats a good idea for goin kinda budget but get good power for the time I will have to put in?
 
#6 ·
cheap 400 I built for a friend. 1978 monte carlo, 20 plus miles to the gallon when right foot is restrained and 14.1 1/4 mile times with 2.73 gears and white wall radials.turbo 350 with shift kit,stock converter.
Bone stock short block rebuilt with cast pistons and static balanced,stock heads.Mild 430 lift flat tappet hydraylic cam,street master manifold, 625 carter carb,1 5/8 primary headers,2 1/2 " dual exhaust not mandrel bent. no where near 400 HP,but a tonne of torque. tire melter
 
#10 ·
Why in the world would you take a 400 and put a 3" stroke crank in it if you want a lot of torque????? Abosolutely makes no sense and Vinniekg2 ???? the guy said he's on some kind of budget and you're filling his head full of Bill Mitchell block $$$$$. Do some reading Uni and stop dreaming.
 
#13 ·
I would jus like a few pointers on 400 builds,I'm not goin to diss anybody's knowledge a lot of people have done a lot of things and I enjoy discussing those times had ,that's how I learn all my knowledge since I started building sbc's and so fare been successful, thanks everybody
 
#14 ·
if all you are looking for is a 400hp sbc 400 then dont bother with forged internals. if you can find a complete 400 (good luck!), tear it down get what ever machine work needs to be done to the rods, crank, and block done. buy a set of 18cc dished pistons, a mildly price set of 200cc runner/ 72cc combustion chamber steel heads (should put you around 9.4:1). get a hyd f/t cam with somewhere around 220-232° duration at .050, dual plane intake, 50-60k volt cheap HEI distributor, 750 vacuum sec carb, $250.00 set of headman headers, 2.5" exhaust and some decent mufflers. it will want atleast a 3.73 gear in a truck if not a 4.10 and it will probably want around a 2800-3000 stall.

bam! simple 400-430hp (easily) 440-460tq (again easily) motor that will be rather easy on the pocket.
 
#16 ·
One of our friends has a '78 GMC "short bed" weighing in at 4,100 and change (with him in it), running 12.20s all week on 93. His goal was a mid 12 second pickup. He has Chevy aluminum heads (late '80s Corvette) mildly ported, Comp solid flat tappet (XS274S), 6" rods and SRP pistons. Performer RPM and Hooker... He's VERY happy, and the thing is a beast. It runs well in traffic and gets ABOUT 13-14 MPG on the "open road". 406 CID.

A nice pair of iron heads would actually make more power. This combo seems to have plenty of low-end for driving, and is severely "traction impaired".

I disagree on using stock 400 connecting rods. 5.7 rods are too cheap to ignore, and MUCH better. 6" rods are better, yet. Many pistons available either way. I DO agree, no need for a forged crankshaft as long as you have a genuine Chevrolet nodular casting. We've seen many iissues with the cheap import "cast" cranks (regardless of brand). This is the single small block application we recommend a "high volume" oil pump, due to the size of the main journals (we don't use the HV pump in "race" engines, just street).

FWIW

Jim
 
#21 ·
377 = smaller engine ,so less torque at a higher RPM.Its all simple math,,,start with what you want,add in what you have and see what it will take to get you to where you want to go.EG: If I have 400 rwhp in a 1970 Nova,set up with 4.11 gears,matching transmission to engine,the car hooks well( assuming drag race) has traction bars that are tune able, the car weighs 3500 pounds or less with driver and fuel,ready to go,he has slicks,this car will go 12.0s.

to figure out what your car will do,add or subtract 1/10 for every 10 hp up or down.If you use a (Winderupper} you will need gearing to accommodate the different powerband.for every 100 pounds difference add or subtract 1/10th.If your car is not as good at hooking as the nova,expect slower times.If you do not use slicks,expect 13s.If you dont need slicks expect slower,much slower.Add 3/10ths for exhaust system on small blocks.This is not an accurate guide but it will give you an idea where you might be or where you might get to with some tuning.
 
#22 ·
what could i expect from a 400sbc bored +.030 with flat top pistons. stock heads and stock rods stock crank maybe a mild cam for a 79 chevy 4x4. running 3.73 gears with 25 inch tires. i have 4.11 gears for rear and 4.10 for front but an a tight budget and never put gears in diffs. so im not real confident on installing them. any thought would be appreciated.
 
#23 ·
I ment to say 35 inch tires. I was reading earlier about the small block 400, which i do have a compllete one. has been rebuilt once, but the kid who had it spun #3 rod bearing. plans are to rebuild it again at put it in a 79 chevy silverado 1/2 ton 4x4. any suggestions on more horsepower and torque for this engine.
 
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