Small block 400 build up...anyone running that setup?

[68 C-10 KID]

Originally Posted by Irishpilot

Hey all, I finally found a great donor truck ('75) that had a 400 small block in good condition. This engine is going in my '71 C-10, so I'm looking to get some decent power out of it. I've torn it apart and will have a machine shop look at the crank and block tomorrow. My questions are:

Is anyone running a non-stock 400 sb and what power/mods are you getting?

Are the stock heads worth porting (I'm thinking no at this point)

I'm looking for 400+ ft/lb of torque and upper 300's for hp and wondering if the following parts would get me there:
edlebrock performance intake w/750cfm carb
aftermarket heads (still undecided on which ones, any thoughts?)
Comp 282XR cam w/1.6 RRs
Long tube headers
Rebuild to 406ci with a rebuild kit

I'm really excited to build this engine as it's my first step to restoring the family truck! Thanks in advance for any/all thoughts!

Looks like your off to a good start.
For your machine work ask the shop to put deck plugs in. Strengthens the bores. I also recommend going to a 6" rod instead of the stock 5.5" It gives the pistons better rod angularity. (less cylinder wear) Being a 406 you are going to need intake runner volume around 220cc for all around performance.
If you do a lot of street Driving I recommend Drilling the steam holes unless they come drilled all ready.
I also recommend a 3000 stall speed. The 2500 or stock is going to be to tight and can knock the thrust out of your crank.
These are the # of my 406 @ 35 deg of timing. It also gets a cool 9.5 MPG.

[bigsnookmaster]

My 406 is a two bolt with splayed 4 bolt mains, I plugged the steam holes in the block and zero decked it.I run thermal coated SRP flat top pistons, 5.7 rods,coated combustion chambers,Comp cams X-treme mechanical roller,Jesel shaft rockers,Edelbrock Victor jr.heads, Bowtie intake,Chuck Gulledge Holley reworked to 830cfm.I also run a crank scraper,windage tray,and lifter valley baffle. I haven't got the truck finished but it seems to make sick power on test runs in front of the shop.I'm guessing 560h.p. or so. My last 406 also had the steam holes plugged,with no problems whatsoever. I had sprayed probably 15 bottles of NOS at a 150 shotat the strip,drove it to Tennessee 3 times,and it was my only driver.It never failed.These are the only small blocks I'll ever own,unless we go 427 or 434 in the future.

[Eddie H.]

I have a 400SB that I built about 15 years ago, still running in my 69 GMC. Since these engines were pretty strong in stock form, I built it to be a daily driver, not a race engine. All I did was clean up the bores with a .020 overbore, put in dished pistons and ported the stock heads. I used a Crane 260 cam and topped it off with an edlebrock performer intake and 1406 Carb.
Its a great engine with loads of torque, runs fine on 87 octane, never had any overheating problems, and still gets decent mileage (12-14 hwy) when I can keep my foot out of it.
I'd highly recommend this engine.

[WIDESIDE72]

Originally Posted by Irishpilot

!

It seems as if all the mags are in favor of the vortech heads, but my question is are the ports designed for efficiency or for power? I'm pretty sure the stock iron vortechs are for efficiency but I think GM sells ported versions, which I need to find out more about.

Keep the suggestions coming!

Efficiency= power. Vortec heads ae hard to beat for the money. You can buy better flowing heads, but at the power levels you are talking about,it is not worth it to spend twice as much money on something exotic. I transplanted a Vortec 350 into a 93 3/4 ton 4x4 using a hybrid intake for the TBI, installed a LT4 cam. Even though it is a heavier truck than my stock 97 xcab, it out pulls it. I admit the 4.10 gears and NV4500 vs 3.42 and 4L60 is not a fair comparison. I also built a 383 with a set of Brodi Track ones. I wish I would have gone Vortec on it too, as someone decked the Brodix heads until they had 54cc chambers, and now I don't know if I will have valve clearance for the big mechanical roller cam I want to stab in.

[big_al_71]

Originally Posted by stllookn

Now I know two guys that have done this...I thought the technique was dead...KUDOS to you!

big AL...beautiful motor!!!!!

I have a small block 400 in my Longhorn with a mild cam and Edelbrock dual-plane. It ran warm so I changed the thermostat...LOL! The local short track guys run them all night long, WFO, with no steam holes in the heads.

Thank you!!!!!

[grayw0lf]

What do you anticipate for the compression ratio w/ the Vortec heads? Those larger 400sbc bores w/ the small 64cc iron heads will likely require you to run 93 octane to keep out knock w/ stock pistons.

Anyone have an any experience with this?

[68 C-10 KID]

Originally Posted by grayw0lf

What do you anticipate for the compression ratio w/ the Vortec heads? Those larger 400sbc bores w/ the small 64cc iron heads will likely require you to run 93 octane to keep out knock w/ stock pistons.

Anyone have an any experience with this?

With a flat top and a 64cc head with a .030 bore and a .038 gasket or what ever thick ness they are you will be at a cool 11.6- 1
The v- tec head combo is slick. runs hard.

[MrBeast]

If you build a 400 small block, this has been my experince...

DON'T EVEN DAYDREAM OF PULLING ANYTHING WITH IT!!!

I had a 78 Blazer, rebuilt the 400, 4 bolt main, ran great, had good power. was bored +.030,

Went against the machinists advice, hooked it up to a trailer to tow a 65 impala about 45 miles. By the time got home I needed a new engine. It got way too hot and cooked its self. Started smoking and using all kinds of oil.

[grayw0lf]

Originally Posted by MrBeast

If you build a 400 small block, this has been my experince...

DON'T EVEN DAYDREAM OF PULLING ANYTHING WITH IT!!!

I had a 78 Blazer, rebuilt the 400, 4 bolt main, ran great, had good power. was bored +.030,

Went against the machinists advice, hooked it up to a trailer to tow a 65 impala about 45 miles. By the time got home I needed a new engine. It got way too hot and cooked its self. Started smoking and using all kinds of oil.

Sounds like you have an overheating issue, not a problem with the engine. The 400 is known to put out a bunch of heat, so if you use it in a heavy duty capacity, I'd recommend a 4 row radiator.

Your final gear ratio & tire size have a lot to do with towing capacity. If you have 3.08 gears & 35" tires, don't plan on towing much. You'll end up lugging the engine & may end up w/ some preignition.

[grayw0lf]

Originally Posted by 68 C-10 KID

With a flat top and a 64cc head with a .030 bore and a .038 gasket or what ever thick ness they are you will be at a cool 11.6- 1
The v- tec head combo is slick. runs hard.

What's the minimum octane rating? Would 93 octane even cut it?

[68 C-10 KID]

Originally Posted by grayw0lf

Sounds like you have an overheating issue, not a problem with the engine. The 400 is known to put out a bunch of heat, so if you use it in a heavy duty capacity, I'd recommend a 4 row radiator.

Your final gear ratio & tire size have a lot to do with towing capacity. If you have 3.08 gears & 35" tires, don't plan on towing much. You'll end up lugging the engine & may end up w/ some preignition.

Thats ODD I haul my 3800 pound truck down the track all day long.
A 400 needs a good pump clean radiator and make sure you purge all the AIR out. AIR = steam in a water system.

[68 C-10 KID]

Originally Posted by grayw0lf

What's the minimum octane rating? Would 93 octane even cut it?

Yes you can run 93 with those. I recommend keeping timing down around 33 total for the street, then for all out HP shouldn't need more than 37 deg.

[grayw0lf]

Steam trapped in the system can definately give you a fun time. I've found it helpful to put a small hole in the thermostat just in case.

[gmcnulty]

Ive built several stock cranks will work fine with spot on machine work. If you ran a fast but streetable use aftermarket all heads (pro comps on ebay for 699.00 and hydraulic cam around 240 duration and low 500 lift with performer rpm or victor jr 1 3/4 headers and 10 - 10.8 to 1 compresion. Iused a voodoo lunati cam on last engine with these heads and dyno'd at 436 hp and 458 ft lbs with 750 carb

[MrBeast]

Originally Posted by grayw0lf

Sounds like you have an overheating issue, not a problem with the engine. The 400 is known to put out a bunch of heat, so if you use it in a heavy duty capacity, I'd recommend a 4 row radiator.

Your final gear ratio & tire size have a lot to do with towing capacity. If you have 3.08 gears & 35" tires, don't plan on towing much. You'll end up lugging the engine & may end up w/ some preignition.

I had a 4 row big block radiator, and a dual flex-a-lite electric fan, I was running 3.73 gears and a TH400 with a NP203 with 33x10.50 BF Goodrich mud terrains. I also had a 160 Deg Thermostat.

The load was a 65 Impala that weighed about 4500 lbs, and the trailer was probably another 1200 lbs.

It was a warm day, I pulled the trailer from Prey Mt to Bozeman, Mt over the Bozeman Pass, it was about 85 degrees outside. I never had an overheating problem before I towed the trailer. The engine ran good and made great power.

[ChevyC102007]

Throw my 2 cents in:

400 SB 2-bolt main block bored .030 over

S.C.A.T Crank, Stock Stroke

Melling M-55 Standard volume/Standard Pressure oil pump w/pickup

5.7 rods with ARP Waveloc rod bolts. Full Floating

ARP Main bolts

Speed Pro Flat Top Hyperutectic pistons with teflon coated skirts

350 Truck heads (76 cc chambers if I am thinking right having the steam holes drilled and new springs and oil seals put in)

Right now Im looking for a oil pan that will work with the crossmember in my 71 and the Melling pickup and trying to figure out whats up with my cam bearings.