Help with my 400 build

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Steve
Truck Year
1978
Truck Model
c20 scotsdale
Engine Size
hopped up L31 waiting for a hot 400
Hello, ive been restoring a 78 c20 and have already purchased and have a few questions about purchasing my forged rotating assembley and what my engine may possibly put out

I have a 2 bold main 400, first im getting a forged 400 crank or maybe a slightly larger crank if it doesnt cause clearance issues 6" forged rods and most likely .20 over forged pistons, i probably will boost this one day but if i dont would want to know if hyperuetetnic pistons could handle this engine n/a i may rev to 7200

This is my engine build so far

Vortec sbc heads off a 93 z71 i will probably port the heads


valvetrain

8- Int Valves 1.94 X 4.91
Swirl-Polished
Hardened Tip Stainless Steel Valves
0.34375 in. Undercut Stems
Increased Flow

http://www.jegs.com/i/Edelbrock/350/9779/10002/-1

8- Exh Valves 1.55 X 4.93
Swirl-Polished
Hardened Tip Stainless Steel Valves
0.34375 in. Undercut Stems
Increased Flow

http://www.jegs.com/i/Edelbrock/350/9773/10002/-1

Valvesprings
Outside Diameter: 1.265"
Inside Diameter: 0.880"
Coil Bind: 1.160"
Complete Kit: Includes Retainers And Locks
Springs Made of Highest Quality Spring Wire
Springs Precision Wound To Close Tolerances
Includes Superior Quality Steel Retainers
Includes 7 deg. Heat-Treated Valve Stem Locks
Retainers and Locks Black Oxide Coated


http://www.jegs.com/i/Edelbrock/350/5794/10002/-1


cam

Operating Range1500-6500 RPMDuration Advertised296° Intake/300° ExhaustDuration @ .050''234° Intake/238° ExhaustLift @ Valve.539'' Intake/.548'' ExhaustLift @ Cam.359'' Intake/.365'' ExhaustLobe Separation Angle112°Intake Centerline107°Intake Timing @ .050"Open 10° BTDC
Close 44° ABDCExhaust Timing @ .050"Open 56° BBDC
Close 2° ATDC


Intake Valve Lift (in.)0.539 Exhaust Valve Lift (in.)0.548 Int. Duration @ .050 in. (Deg)234 Exh. Duration @ .050 in. (Deg)238 Int. Duration Advertised (Deg)296 Exh. Duration Advertised (Deg)300 RPM Range3000-9000 Engine Make/SizeChevy Small Block (262-400) Lifter TypeHydraulic Roller UsageStreet/Performance

Both specs from my cam on the jegs ssite


http://www.jegs.com/i/Edelbrock/350/22015/10002/-1


Premium '50' Series Roller Rocker Arms
Small Block Chevy
1.5 Ratio
3/8" Stud
16/Pkg
Features:
4130 chrome moly trunion
Made from 2024 aluminum (stronger than 6061)
Bearings Made in USA
The latest advancement in aluminum rocker arm design
Lifetime warranty
CNC-machined, lightweight CAD design for quality & ratio accuracy
Additional clearance: Clears 1.625" O.D. valve spring
Rigidity to withstand aggressive spring pressures and high valve lifts

http://www.jegs.com/webapp/wcs/stor...002&langId=-1&productId=1250566&storeId=10001

I have a 700r4 built for 700hp ready to go in too
1800-2100 Stall Converter Included i probably will buy a 3800.. i need a flexplate too
Remanufactured Heavy Duty Pump Assembly
Heavy duty HIGH ENERGY Z pack clutch set
Heavy Duty Wide Band
New sun shell "Heavy Duty" THE BEAST
13 Vane Pump Rotor Kit
Hardened pump rings
New Sprag
Complete new bushing kit
Corvette Competition Servo
Master rebuild kit
Heavy Duty 5 Pinion Planetary
High volume filter
2 Stage Transgo Full Race Shift Kit
500 boost valve
Available in Lockup or Non Lockup ( PLEASE SPECIFY) or will be built Lockup
Up to 700 HP

i may run e85 on it or 91 im still undecided and pretty set on my rotating assembley options i said previosly the pistons will also be 9.5.1 most likely that is what i was recomended by 2 machinists i know let me know some of your opinions.

if i boost it will be nitrous exress or a d1sc procharger or weiland roots

i have a weiland speed warrior intake mani and a new 600 cfm edelbrock i am going to build up also and headman longtubes with a 3 inch collector.

im gunna buy a msd ignition kit

I just want to hear some of your guyss opinions on this and possibly what you would reccomend, thank you
 

kleedus

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I hate 400 motors I would not waste my money on one

I have had a handful of them built different ways and I have never been happy with any of them

I put one that was bored 30 over with a mild cam in a 85 3/4 ton truck and I wished I never would of got rid of the 350 that was in it. the stock 350 seemed to have more power than the 400 did.


I have one in my 79 Camaro now that is suppose to be a 400 horse motor. I hate it I am trading it for a goodwrench 350

I don't know what it is about them but I have never had one that I liked.
 

hirschdalechevy

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What do you want to do with your truck , daily driver , street cruzer from town to town with good power or week end drag machine.

First off vortec heads are great but they are only good for up to .500 lift cam's with out modd's . They work well for a good street machine but for any real power you need after market aluminum heads , (afr's are my fav.). Also aluminum heads will let you get away with more compression on pump gas.

IMO. If you are twisting high rpm's or using any power adder's , nos , turbo , supercharger etc... I would not run hyper. piston's.

Also , do you have a good machine shop? Shop's tell you what you want to hear so unless you are putting your own motor together you will not know what the real compression is , you are just going off what they tell you. You need to know where the piston is in the deck exactly to do the math of all your part's to know what your real compression is , what the part's say on the box doesn't mean anything.

Becareful with cam choice , you need to know your actual compression ,gear ratio , curb wieght , tire size , etc... before picking a cam.

9.5 to 1 is on the edge with the cam you are looking at (IMO) for a heavy truck unless you have plans for low gears and high stall.

It's all about clyinder pressure , to much cam = low cylinder pressure = pig on the bottom end.

I would not be afraid of 400's , a small block is a small block , cubes are cubes , more cubes = more torque , you can make any motor mean.

400's need good cooling because they have saimise cylinder walls and any heads you run will need steam holes drilled in them.

Anyway do your homework , find someone you trust for machine work and have fun.
 
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...
 
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hopped up L31 waiting for a hot 400
Thanks for the quick replies I did not expect any when i checked when i woke up. I just typed a full reply and my computer died and its gone so ill try and make it exactly how i just typed it.

My goal for this truck is mainly to have it as a weekend warrior and break 12s and 11s in it if i can on my trans, and dd it on ocasions it used to be planned as my dd but im buying a mpg car also to go around to work in.

Now I have already purchased every part i put up and am only waiting on my roller rockers to arrive then am buying everything else and sending it out to a local shop L&R to be machined and assembled. I had plans for someone else to assemble it and they were the ones saying they dont reccomend over 9.5.1 with my cam and e85 if that will be a question. For cooling I am buying a higherflowing alluminum radiator I have the steamholes drilled and the waterjackets on the block are slightly bored out. Im deffinantly avoiding the hyper pistons then i dont know why id go cheap on this build at all knowing what ive already put in and what i want in the future id but F ucking myself with those hypers. Ill deffinantly talk with L&R

I trust going with my 400 since i already have the cooling issues worked out and wont be beatinng on it every single day even if i did i would trust it with what i have now that is why i spent the $$$ i feel with the 6 inch rods and .20 over pistons the cubes will deffinantly show over a 383 or smaller..

My gears will be either 3.73 or 4.10s and my stall is reccomended 3800 i will have 16x10s all around

Im not exactly sure what i should expect on power but am hoping 400 to the wheels before any power adders and will sit on the truck for a while with that and then add some power in the near future.. The whole point of this thread was block and comments and opinions on my engine i guess i said what i have i said im getting a fully forged rotating assembley with .20 over flat tops 6 inch rods and forged crank and have the top end i have stated. let me know what you guys think about my build
 
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hopped up L31 waiting for a hot 400
I also must say if I had waited a week on my shopping spree I would have gotten a vortec 454 or ls7 but i know ill be satisfied with my good ol 400
 

rich weyand

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You're in L.A., and L&R is doing the build?

Don't worry about it. They've got a great rep. They do builds for Foose.

Listen to what they tell you, and don't be afraid to change this or that.
 
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hopped up L31 waiting for a hot 400
You're in L.A., and L&R is doing the build?

Don't worry about it. They've got a great rep. They do builds for Foose.

Listen to what they tell you, and don't be afraid to change this or that.

Yes I highly trust L&R on this Im a rookie cnc machinest with no engine work under my belt so im letting them handle it my brothers the only person I know whos had a problem there but it was on a honda not a v8 what they are known for building, they offered a warrenty and to fix their mistake so I respect that shop and plan to do business with them. Thanks for making me more confident in sending my build to them lol i have heard nothing but great things about them!
 

bucket

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A '93 truck wouldn't have vortec heads either, just regular old swirl port heads that do not like high rpm at all.
 

350runner

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X2 mine give up right around 4k rpm
 
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hopped up L31 waiting for a hot 400
I have heads off a l31 vortec
 
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hopped up L31 waiting for a hot 400
The engine I got them from had a vortec box and a l31 casting number so I dont see why your trying to say its not a vortec i made sure the engine was an l31 before pulling the heads. they are not a normal gm casting like the heads i had on my 400 they are a center bolt pattern on the valve covers. Im not gunna give up on an engine you didnt put money in. My weiland vortec 6700rpm manifold fits them too so i guess im crazy:whymewhyme: but your right I think i was wrong on the year i pulled them 2 months ago on a half off day at my local yard.
 
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red

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If you can ,step up to a good set of heads . I like the Air Flow Research heads. For power adders You will be happier with the Pro Charger and air to air cooler. If its not too late, polish your piston tops and combustion chambers . Build it for boost you will love it.
 

68post

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The vortec heads will be fine for a torquey 400, but not enough airflow for a high HP 400 build - especially with power adders. Build it now and enjoy the torque, then when you want high HP change the heads and spin it higher.

You may find that the vortecs are enough if your cam tops out below 5,500. There's not a ton to gain in airflow when vortecs are ported. 195/200cc heads would be an absolute minimum for the cubic inches you're building when approaching 6,000 & up !

AFR 210's would suit a high rpm 400 very well !!

$.02
 

Green79Scottsdale

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The Vortecs and that cam are not going to get along, IMO. The cam has no low end torque, where the Vortecs excel. Then when the cam is going to really come alive, probably around 4500-5000 RPM, the Vortecs are gonna start falling on there face. I think either a different cam or heads would be better.
 

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