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chevy 400 buildup

8K views 15 replies 8 participants last post by  BruceBanner 
#1 ·
Newbee to the forum and to the chevy 400 small block, please bear with me.

I am going to build a 400 small block to go in my 72 chevelle and would like the forums expert opinions and guidance concerning how I have planned to build the 400, recommended brand of engine parts and links as to where to buy the parts that I need.

I am starting out with a cleaned and checked bare chevy 400 block, I will need to buy all other parts including a crank, this car with be driven on the street and taken down the ¼ mile track every chance I get, I would like it to be very fast with a lot of low end torque, and run on pump gas, keep it at about 9.5 to 1

My build plan goes like this:

*Have the block bore to 4.155” and decked to 9.008”
Stock 400 crank 3.75” stroke (need to find one)
Stock 350 rods 5.75”
*Have the crank and rods balanced
TRW forged –16cc dished pistons
Cromemoly piston rings
Trick Flow 195cc heads 72cc chambers
Cam ?224 at .050?
Edelbrock Performer duel plane manifold
Edelbrock 750cfm carb
1 ¾” headers

Trans is a turbo350, when it dies I will replace it with a TCI turbo350.
The rear is a 10 bolt and has 2.92 gears, not sure what I will do with it.

Thanks in advance for any guidance!
 
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#2 ·
you have a well balanced, good all around combo there, you could save a few bucks on some hyper-eutectic pistons and put as much valve lift as you can (1.6 rockers?) stick with the 224 type cam (power brakes) (go with a 2500 convertor).Have new rod bolts installed and the rods reconned, you probably will be better off buying an aftermkt cast crank, they can be had for less than $160. Go with around a 3.55 rear gear and you will have a dependable,impressive street performer.
 
#3 ·
First. Welcome to Hotrodders.
Your setup sounds pretty good. If your running higher rpm's or your powerband will be set for more upper rpm's, you may want a single plane intake, but the Edelbrock is a great all round one.
I have a PAW catalog from 2002, so prices are still real close and I found a great Racing kit for 400. It has a crank, Rods, Bearings, gaskets, cam n lifters, rings, Forged pistons(TRW), oil pump, timming chain. Pretty much everything for a short block. They have an .083 dish piston that with 72cc heads will give ya 9.2-1 comp or a flat top that will give ya 10-1 which is still good.
All for 950-1000 bucks. Not a bad deal. You need to see what buying individual parts would be to see if its a good deal 4 ya.
Anyway. Hope that helped. HG
 
#4 ·
I'm no expert on 400's but I do know they use a 5.56 rod not the 350 5.7's. If you want to use the long rod then be sure to get the correct pistons. I should think you could get to low 13 to very high 12's with good traction and 200c heads from AFR. Good luck.
 
#5 ·
Thanks for the response they are helpful, builds a little confidence in what I am doing, I will be looking into the 1.6 rocker arms and hyper-eutectic pistons (always good to save a few buck).
I will also take a closer look at the single plane intake, from what I have read so far they are for higher RPM motors and don’t do well on the street but I guess it is all in the setup, I am not sure I am after the right setup to handle a single plane intake.
Getting my hands on a PAW catalog in my next goal, I do have a Summit catalog it has a lot of components in it but seem to skimp on the 400.
I have been check out a few racing kits and they do seem to be the way to go if they are already balanced, I can put all the individual part together for about 900 bucks, but a proven kit is very appealing.
On the 350 rods, yes they are longer, they vastly improve the rod angle and there are several over advantages to putting the longer rod in the 400 way too much to go into right now. I do have question on using the 350 rods, it my understanding that I must grind a few of the rods bolt to clear the cam and the block near the oil pan, can anyone tell me what the clearance tolerance is for grinding the bolts off ?????

Thanks again,

Bill
 
#6 ·
Hey 406.
Pm me or ask on here for any PAW pricing ya need. I have the book handy, so its no problemo!
As for the bolts. You shouldnt have to take much off. I heard the bigger the cam, the more, but not sure. HG
 
#10 ·
i just finished my 400 buildup. heres my list....

the rods will most likely not clear the block, especially if your using late model rods, so have them machined just to be on the safe side, i didnt , they hit, and i wasted my whole weekend tearing it back apart to fix it.. i used the stock crank with 350 rods&ARP bolts... had it put over.020 and decked .010, with flattop hyperutecnic pistons, this is about 9.8:1 compression, perfect for pumpgas... i reused the stock heads(3 angle job) and went with the summit cam kit. specs: 214/224 @.050" .442/.465

my feelings: fantastic street motor, massive torque to move my boat ('71 caprice) and a Very quick revving motor... definetly a solid motor to drive and drag everyday...
 
#11 ·
my motor man told me he shaved then and i had .100 clearance between cam and rods... and yes, the bigger the cam, the more clearance needed, how much lift is on your cam? if not too much more than mine,youll be PLENTY safe with a little machining....if the man machining knows what hes doing, hell know exactly how much to take off, give him the block and other parts first so he cam assemble one and clay it for clearance.
 
#12 ·
Thanks WsXs3 that’s the information that I am after, I will probably be grinding the rods myself and just need the required clearance.
I am wondering if there is aftermarket rods already machined for this type of application so they don’t hit the block, which brings up a question, where the rods hit the block should I grind the block or the rods to achieve the required clearance??????

The cam I am considering is 224deg, at .50 lift.

Sound like you have an awesome ride, I can’t wait to start enjoying mine.
 
#13 ·
I am planning to buy a full engine kit from PAW for the chevy 406 small block, to including a forged crank, forged pistons, and forged rods, the rotating assemble is advertised as being balanced.

My Question is is it possible for the the crank to be sent to me already balanced, considering the fact that it is a 400 small block and is internally balanced?????

My machinist is telling me I will need to have the rotating assemble balance after I get it, if this is true why would PAW sell them advertised as balanced???? I’m confused!!!

Any help on this issue will be greatly appreciated!!
 
#14 ·
The assembly can be balanced by PAW, but unless they sell the flywheel and Balancer they used to balance with the assembly it will not be dead on. It will be better than oem, but not perfect. I actually ran one of their balanced kits about 10 years ago. It worked very well, and I sold it to a circle tracker after I finished with it. I think it made it 1.5 seasons before he overrevved it one too many times.

Chris
 
#15 ·
Hey 406,I just finished a 408 small block,flat tops,stock crank and rods,ported heads,3 angle valve job,234,244,488,510 cam,and about 10to1,have not had any problems with pump gas(yet),this moves my monza real nice.There is a thread somewhere in here called building a 400 smallblock that might give you more info.
 
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