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400 Small Block: How To Build A Torque Monster For $2,500!- Hands On

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Unfortunately, all this put us in a crunch to completely disassemble the engine to clean it (and another set of cam bearings), fix any other damage, and reassemble it so we could test again all within a rapidly closing deadline. There was no joy in Mudville.

Drilling for Steam
All 400 small-block Chevy engines use siamesed cylinder walls, creating pockets in the cooling jackets that require venting. These holes allow steam and air bubbles to vent vertically out of the block and into the heads. Unfortunately, neither the stock Vortec nor the Bow heads come with these steam holes. That means you need to perform this step. We used a stock 400 head gasket to mark the position of the holes, but note that holes closest to the intake side must be drilled at a 45-degree angle to contact the water jacket. The exhaust side holes can be drilled straight in. It's best to do this using a drill press, but since we didn't have one, we managed with a handheld drill motor.

Compression Lessons
When we began this project, it appeared that the static compression would be ideal at around 9.5:1 with the Vortec 64cc heads and a 22cc dish in the piston. This was assuming a roughly 0.020-inch deck height. So imagine our shock when we checked the deck height after reassembling the 400 to find the best cylinder was 0.062 inch down in the hole and No. Eight was buried a stupefying 0.074 inch below the deck. This created literally an 8.5:1 ratio in the "good" cylinder and a measly 8.39:1 in the worst. We also discovered that no one makes a thin steel shim head gasket for a 400, so we couldn't use a thin head gasket. We considered running a steel-shim 350 head gasket, but the gasket would protrude into the bore and cause serious detonation problems.

We did some further calcs, and with a 0.030-inch overbore, a zero deck height, and a smaller, 15cc dish custom piston and 0.040-inch gasket, we'd have a much stouter 10.46:1 compression, which is a full two points better than we have now. In all our years of assembling small-block Chevys, we've never seen a small-block with such miserable deck heights.

Power Day
After much chasing around to hot-tank the block again and install new cam bearings, we carefully reassembled the 400, this time with the new nitrided Comp Thumpr cam (actually, the Mutha' Thumpr) and the Comp break-in oil. We also reinstalled the lighter, 80-pound seat pressure Vortec springs, and the break-in, thankfully, went according to plan by using Comp Cams' new oil and break-in additive. This allowed us to get back to the original effort, which was to see how much power this beast could make. The power was not as impressive as it could have been because of the poor deck height and therefore the low compression, but the small Vortec heads still produced some decent torque. The power curve numbers reveal that this initial effort produced 448 lb-ft of torque at 3,800 rpm with a marginal 376 peak horsepower at 5,000 rpm. All this required 40 degrees of initial timing to achieve. While disappointed, we swapped directly to the Bow Tie Vortec iron heads to see how those larger, 225cc-intake-port heads would fare on our 400ci engine.

The results were less than spectacular, mainly because of our dramatic compression handicap. The bigger heads demanded even more timing, with 44 degrees to achieve best power. With timing and jetting maximized, the 400 managed to produce 458 lb-ft of torque at a still low 4,000 rpm, while kicking up the peak horsepower to just 401 at 5,400 rpm. As is typically the case with larger-port heads, we traded some low- and mid-rpm torque in exchange for much more horsepower farther up the rpm chart. Comparing power numbers, you can see that at 3,600 rpm is where the big-port heads began making more torque over the smaller Vortecs, carrying that power all the way up through 5,400 rpm at peak horsepower.

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68 comments
Michael Guirey
Michael Guirey

Hey Ford people...................Way to go Chevy ! # 1

Justin Patch
Justin Patch

I agree the torque numbers will never be outstanding, but our argument was about HP. Saying you could not get a 302 over 400hp with out power adders was just not correct.

Zachary Morris Fick
Zachary Morris Fick

If you guys are getting 450hp out of a iron an head ford 302 mine must be making 500hp.. which it's not it makes maybe 350hp.. it has Ed Curtis worked AFR 165 heads, F cam, 10:1 static, ported air gap 4bbl intake, and a Holley 650 w/ a 1" open spacer..

Robert Paul Holmstrom
Robert Paul Holmstrom

Crib stock rules...my 451 hp 302 had stock rods and crank...when we had it on the dyno, we went through 90 gallons of gas...pump gas, iron heads, went 11.13 at 121mph in a nearly stock 1990 Mustang the first time down the track...

Robert Paul Holmstrom
Robert Paul Holmstrom

In October of 1992, SuperFord did an article on one I built that made 451 hp that was a 302 on pump gas with iron heads.

Robert Paul Holmstrom
Robert Paul Holmstrom

With 302 cubes, don't expect 500 lb-ft without a blower or adder. Back in October of 1992, I built a pump gas Ford 302 with Iron Heads that made 451 HP at 7000 rpm, 368 lb-ft of torque and went 11.13 at 121 mph in a nearly stock 1990 notchback Mustang, the first pass down the track...we got thrown out by tech, given we only had a single hoop. Had a blow proff bell housing, c-clip eliminators, a drive shaft loop, 410 gear, and slicks...SuperFord did an article on the engine and called the article "Poor Man's Boss 302". After the ink, I built several copies after.

Peter Lehmann
Peter Lehmann

+1 Rob, it's all about torque and let's keep in mind this after all, is a no frills budget build that was salvaged junk.,. I doubt a 302 would even come close to those TQ numbers :)

Carl Stjernqvist
Carl Stjernqvist

Really, is this still news in 2014? Do it with some other makes, we see Chevs EVERYDAY!

Cam Beaton
Cam Beaton

You could do it with a Windsor, but you would need two of them.

Justin Patch
Justin Patch

Many a 302 has bested 400 HP with iron heads and no super charger or turbo. Who does your porting? Find someone else...

Donald Burley
Donald Burley

Still like the small block 400 over the big block 400

Jordan Nutt
Jordan Nutt

I read long time ago in Chevy high performance mag that the most power and torque they could get out of a vorteq headed small block was 500 lbs and 400 hp

Rickey Driskill
Rickey Driskill

@ Zachary . A Ford 302 will make 400up with iron heads. I have had one. 10to 1 compression. Nice beefy cam and with 2.02 1.60 valves in the heads. It will make it all day.

John Denker
John Denker

Alexander SkiourisPut this in the ranger

Zachary Morris Fick
Zachary Morris Fick

I'm not going to argue ... a Ford 302 won't make 400hp with iron heads with out boost..

Jesse DeGaro
Jesse DeGaro

Well that 400hp Ford did make that number as I bought the shortblock from Matt King who wrote the article and built the motor. He still has the cam and the heads that went with it and won't part with them. ;) I do agree not everything you read is true but some stuff is.

Kug Mag
Kug Mag

Two bolt, Vortex heads, and with all the accessories it makes that power all day long!!! With a little more aggressive top end will make close to if not 600 hp and torque and still be under $3,800 I'm loving this build...

Carroll Smith
Carroll Smith

why do these build ups go down the track ,minus 120 horsepower?,and are these numbers corrected air? 60 degrees zero humidity?AND NO MOPAR EVER SAW HEADERS like that except on a "RAIL" LOL

John Hinant
John Hinant

When you are done with it send it to me

Zachary Morris Fick
Zachary Morris Fick

Lol ya 400hp with an electric water pump and no accessories mounted just like the stock 87 Mustang 5.0 that made 400hp when it was closer to a 250hp motor..

Steven Bechler
Steven Bechler

Meanwhile a 50's Chrysler small block, will give you 650+ ft lbs!!!

Ken Howell
Ken Howell

Why does anyone use a chevrolet as that is french for crappy equipment.

Matt Derosia
Matt Derosia

think people search the globe for these blocks,

Matt Derosia
Matt Derosia

dream on 400,s got much more low end grunt than a 327 or a 350 why do you y

Jeff McMillan
Jeff McMillan

Why do people build 400 motors when there are much better and more reliable ones out there. My 327 could take this without breathing hard;)

Mark Glowacki
Mark Glowacki

Come on. It is tuff over here just to find a 400 let alone one that isn't cracked from freezing or way too expensive. We don't have any mines near me I can scavenge for one either. All the junkyards crushed everything when scrap was high back around 2008. I was hopin for the best with this article until I saw it was for a 400.

Lee Henderson
Lee Henderson

A 335series Ford 400 would DEMOLISH this thing with a budget build :D

Gunnar Larsson
Gunnar Larsson

I run with the same values on the camshaft the same pistons, 64cc combustion chambers 462 camel hump heads. but I've also run single turbo intercooler and 750 blowthru carburetor 6psi boost 32 degrees locked ignition. work well might be something for you to try on the car craft. I have tried with GTECH 0-60 4.2 sec engine sits in a 1964 impala

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