Rebuilding a 400

[72jimmycst]

any ideas on the most cost effective rebuild, Friend at NAPA says he can get me about 300 to 320hp for around 1100$. needs to be bored over and heads rebuilt. Thoughts?

 

[neverendingproject]

for heads, the best bang for your buck is vortec heads. with 2.02 and 1.6 valves, they have seen 450 horse power.

 

[Hogback Fabrication]

Vortec heads (the popular L31 style) have 1.94"/1.5" valves, but they are cheap and offer great performance (that's what I have on mine). Remember that if you put aftermarket heads on it, you will probably have to drill steam holes in them. I doubt NAPA actually sells a rebuilt 400 that puts out 300hp, and remember that you get what you pay for in a motor. Any of the major chains generally cut a lot of corners to sell a "rebuilt" motor for cheap (though 1100 is on the high end of the chain rebuilt motors).

 

[neverendingproject]

I meant machine them to 2.02 and1.6 there is also a guy in parts for sale section with a 400 sbc

 

[Hogback Fabrication]

I thought about doing that when I did my motor, and the machine shop I dealt with said they had tried that a few years back and the head actually flowed worse by going to bigger valves (because it threw off the awesome flow characteristics that were matched to the stock valves).

 

[rjfguitar]

$1100 For a complete rebuild sounds almost too cheap to be true. I spent $975 JUST in machining my short block hardparts, and I did the assembly.

 

[72jimmycst]

Yeah, I know it sounds on the cheap side, but the mananger and my Dad are shooting buddies.

 

[blazin_blazer]

what he said

i started to go to 2.02 1.60 in my L-31's i talked to chevy's r&d team to get some pointers as to camshaft and anyother special stuff i may need....they told me they bigger valves would ruin my heads and these people spent $$$$$$ to research and develop these heads...they actually stated that the L-31 heads are the best flowing cast head chevy has ever made they said out of the box they out flow the bowtie heads and the wildest ported and polished camel humps still wouldn't touch them..they said the only heads they make in cast iron that will outflow them is a bowtie thst has a stage 2 port job,a stage 1 still flowed less than the L-31's

but they also stated you can close that gap with a little port and polish on the vortecs...i ordered the heads planning on using my old rockers...uh uh..they have to have specia; self aligning rocker and a special intake which i knew and bought with the heads..i wound up buying the magnum roller rockers and the special intake gasket that torques to 10 whole ft lbs. and it requires special bolts for intake also here is what they are:u may want to check with advanced auto parts as they had them for $199.99(i bought 2 more sets from them and an edelbrock intake for the vortec heads)

http://www.sdpc2000.com/catalog/312...tec-SB-Chevrolet-Cylinder-Heads-Assembled.htm

the intake i used is:

http://www.sdpc2000.com/catalog/737/products/1801/SB-Chevy-Vortec-High-Rise-Intake-Manifold.htm

you will also need these bolts, gaskets and rocker....i used magnum 1.52 roller self alighning cost $212 from jegs but here is gm's:

http://www.sdpc2000.com/catalog/523...-Roller-GM-Performance-Parts-Rocker-Arms-.htm


bolts 8 needed:
http://www.sdpc2000.com/catalog/744/products/2604/Vortec-Intake-Bolt.htm

intake gasket:
http://www.sdpc2000.com/catalog/564/products/768/SB-Chevy-Vortec-Intake-Gaskets.htm

i think that is all you need to convert to the vortec heads


i put all my stuff together on this :

http://www.sdpc2000.com/catalog/514...hevrolet-Balanced-Blueprinted-Short-Block.htm

and used this:
http://www.sdpc2000.com/catalog/992...draulic-Marine-Camshaft-Kit-2000-4500-RPM.htm

i used a pete jackson noisey timing gears and msd ignition parts from distributor to the control box with built in rev limiter and moroso tin with 7 qt oil pan and a high pressure oil pump NOT HIGH VOLUME!! and other pieces from gm performance and i love it most people believe i have a big block i've had to pop the hood for several non believers


i'm in the process of building another 1 about the same, same short block but i'm going to use the aluminum vortec fast burn heads(they will accept either center bolt or perimeter bolt valve covers and also the old style intake or the vortec style intake)and im going to use the gm performance hot cam basically these links will be what i have when i'm thru:

http://www.sdpc2000.com/catalog/514...hevrolet-Balanced-Blueprinted-Short-Block.htm

http://www.sdpc2000.com/catalog/3129/products/144/Fast-Burn-SB-Chevrolet-Aluminum-Cylinder-Head.htm

http://www.sdpc2000.com/catalog/992...am-SB-Chevrolet-GM-Hydraulic-Camshaft-Kit.htm

http://www.sdpc2000.com/catalog/265...m-Jet-Fuel-Injection-Kit-Less-Electronics.htm

http://www.sdpc2000.com/catalog/975/products/677/Heavy-Duty-SB-Chevy-Pushrod-Kit.htm

http://www.sdpc2000.com/catalog/1037/products/1582/SB-Street-Performance-Mechanical-Fuel-Pump.htm

http://www.sdpc2000.com/catalog/3523/products/8228/SB-Chevy-725-GM-Fluidamper-Balancer.htm

..and a few other odd and ends..but now we are approaching $7000,but i want to be able to say i built it or i would go with:

http://www.sdpc2000.com/catalog/120...M-Performance-Parts-Crate-Engine-Assembly.htm
thats $4900

or

http://www.sdpc2000.com/catalog/120...ll-Block-Crate-Engine-with-Aluminum-Heads.htm
thats $4800+1500 for the ramair and more fore ignition

which i still may..the last one needs intake and distributor...i leaning toward it and getting the ram jet setup for it and an full on msd ignition system..but like i said i like to say i built it i kinda will have if i put on the ram jet and controler and ignitionbut then we are around $8000 but i'm worth it :-))


i may just come off the wallet a little more and go for:

http://www.sdpc2000.com/catalog/120...M-Performance-Parts-Crate-Engine-Assembly.htm

this 1 has 550 ft lbs of torque and its ready to drop in
or

http://www.sdpc2000.com/catalog/120...sembled-GM-Performance-Parts-Crate-Engine.htm

this1 has 567 ft lbs of torque and is also ready to go