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First ever build sbc400

2223 Views 24 Replies 14 Participants Last post by  85Sierra
Well im going to build my first motor for my car under the supervision of my dad who has been building for years...

Its a 1973 400 that i picked up for cheap and is stock as far as i know of. what i want to do is keep it as practical and realiable as possible. this is what i have so far

Heads: Stock with a port and polish 1.94/ 1.50's (maybe step up to 2.02/1.60's depending on what machine shop says)

I want to keep the CR around 9.5:1 but im wondering how i go about that.

Pistons: not sure on what brand yet but im looking for some affordable Flat tops

Carb: I have a rebuilt 750cfm Q-jet works great

Intake: i have a brand new edelbrock performer rpm

Exhaust: Flowtech headers, into turbo's through duals

and for the cam i was thinking of a

Comp Cams Xtreme Energy Xe262h, says it operates from 1300-5600rpm and has .462/.469 lift (just wondering if this cam is to small or what? suggestions?)

is there anything im missing or vital i should look into? suggestions?

help is greatly appreciated as this is my first build
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I'm curious as to what your block casting and head casting numbers are.

I have a 400 SBC that I'm going to start building and am also interested in everyone's opinion.

Thanks and good luck.

1967 Camaro
Turbo 350 Tranny
3000 Stall
3.73 gears
You appear to be on the brink between "practical and reliable" and racing.

It looks solid so far. The XE262 or the XE268 are good cams for low end. The 400 is not a high-winder. Also, your static compression should work well with them.

You didn't say what vehicle you're going to put this in.
85Sierra said:
and for the cam i was thinking of a

Comp Cams Xtreme Energy Xe262h, says it operates from 1300-5600rpm and has .462/.469 lift (just wondering if this cam is to small or what? suggestions?)

is there anything im missing or vital i should look into? suggestions?

help is greatly appreciated as this is my first build
Weight of car, trans., converter stall if auto., rear gears, etc. would be taken into consideration & needed for cam choice.
As far as what pistons to use to achieve around 9.5:1....need to know combustion chamber size. can find that out with head casting #
SB 400

One other thing I would do first is make sure to have the block acid vatted and make sure it is spotless,and also to make sure that there is no cracks before you start. $120 and most machine shops vat it, new freeze plugs & cam bearings. The best money you can spend before you start your re-build. I'm sure your Dad knows. Good Luck!
Dirt Track Thunder offers speed pro hyper flat tops for the 400 at a good price. The combo you have outlined should be a pure tire shredding torque monster, 400`s aren`t revvers as already been mentioned. If you plan to use the stock rods, I`d have new rod bolts installed as insurance, or I would go with a set of 5.7 350 rods over the 5.565 stockers. also make sure you have the correct balancer and flywheel or flexplate, this is important, since the 400 is externally balanced and all other small blocks are internally balanced, if you were to run say a 350`s balancer on your 400, you`ll be talking about the crank in the past tense.
Depending on the cc of the combustion chamber, you are going to need either dished or 4-valve relief flat tops. Two-valve flat tops would put you around 10:1 with a 76cc head. Also you want around .040 quench as I have learned to keep you out of detanation and get peak performance. Your stock rods at 5.565" length would be fine but be sure to have them checked and put new ARP bolts in them. The stock bolts are the weak point of stock 400 rods. Also unless you got the Performer RPM with the spread bore pattern, you will need an adapter to mate that Quadrajet to that manifold. I would get the Performer or the Weiand Action-Plus since it looks like you are going after torque. I would also go one step bigger on the cam (268xe). The rpm ranges companies list for cams are for 350's and the extra cubes will allow for a bigger camshaft. Also make sure your heads have the steam holes necessary for street operation on the 400. Make sure you have an adequate cooling system as the 400's do put out more heat. Machine work will be your most expensive part of your build. Don't skimp on the machine work as it will cost you more in the long run. Good luck
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first engine

It sounds to me like you have done some good research on setting up your engine. I think that is the ideal cam choice. Its gutsy but not radical. About the only problem I see is in your intake choice, having opted for a standard Performer, were the choice mine. The RPM starts working at 1500 rpm, where the Performer starts out in the basement, and you probably will never if ever see over 6500 rpm out of your engine.

As a general rule, when you start getting over 230 degrees duration at .050", in engines from 350-400 CID, you are starting to get into the rpm cams vs torquers.

In my estimation, its always better to err if you make one, on going with a smaller cam, since you can always over wind it for rpm and still make power, but if you have too big a cam, theres nothing you can do to regain bottom end but to replace it.

The choice of cam you have made, is a practical choice and a good all around cam for most any type of vehicle. Go with it.

The only other thing I would recommend is not to polish the intake ports, but to leave them with a florentine finish. The reason being that polished ports on intake seem to have an adverse effect on keeping your fuel/ air mixture suspended. It all has to do with laminar air flow, and not being an engineer, I wont try to explain that.
However, on the exhaust side, polishing will not only aid in flow of the exhaust but will also help in preventing buildups of deposits in the passages, as it reduces area for them to collect onto and bond with.
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As a first build I would approach it from this angle:
The bottom end build for reliability and the top half for the desired power.
Heads/Cam/and intake make the power. 400 heads are not worth fooling with for the cost of putting large valves and screw in studs and plates. Look for a good set of aftermarke large chamber heads, this will be money well spent.

Cam selection looks fine, if you roller rockers look for a split set and run 1.6's on the intake and 1.5 on the exhaust. this is the best bang for the buck.

Intake look into a an air gap type Edelbrock intake. Professional products has a good intake of this style.

i have a 406 that i've been using in a 3/4 ton van.i just made some changes to it while freshenning it up.i had used the 400 rods to begin with and they are not a good choice.go with the 6" rods if you have to buy rods and pistons yet.or at least the 5.7 can get a set of 9.4-1 speed pro hypereutectic coated pistons on ebay at racers outlet for 160.00 and a set of 5.7 or 6" eagle or scat 5140 rods good to 500 h.p. for another 189.00.your piston and head combustion chamber size combination will determine your c.r..400's will take almost as big a cam as you want but the one you mentioned along with 1.6 rockers and about 200 cc intake runner on the heads you choose along with 2.02-2.08 - 1.60 valves.400's love air and they make all your power down low where it spends most of its life on the streets lite to lite.they make more than 400 lb. ft. of torque right off the bottom and up thru 5500 can also get a cast steel crank from eagle or scat for 189.00 also good to 500 h.p. so as someone else said build a good bottom end.i mentioned the 9.4 pistons because of the price of gas but if you can afford it you can use 11-1 no problem with a good long duration bleeds offthe extra pressure during overlap.
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The 6" rods will require a small base circle cam and other clearancing issues with the rod bolts. I had Comp Cam custom make me a hydraulic-roller in a small base circle design since I am running 6" rods and the machinist still had to clearance the rods to clear the camshaft. With 170cc heads, my 408 has extremely great torque but I will be going to 200cc heads since I run mostly around 5800rpm through mud pits and these heads will benefit me more. Also check this article out:
if you go to chevy high performance magazine on line and look up the tech article "the impersonator 1 & 2",impersonating a big block,you'll get some go reading.
It makes my day to come home from work and see all the comments and suggestions its much appreciated and my dad is actually giving the computer a chance now

ok the vehicle is a 1981 El camino, th350 stock converter and it has the boaty 273 posi. Now i know most ppl will say to ditch the gear and get some lower ones but i was wondering if the torque of the 400 will overcome the gear loss. my current 305 (cam,intake,exhaust) manage to beat out my brothers '81 el camino 283 (cam,intake,carb,heads) with 4.11's but he let it auto shift and i have the ratchet but anywayssss... where was i

So i should stay away from polishing my intake ports?
Buy some ARP bolts for the rods

Now when i take the block to the machine shop i need to get it hot tanked, inspected, get new cam bearings? and frost plugs?
i may need get it bored i was thinking 30 over

now for the cam some ppl are saying its good some say i could step up.. help me here

im really appreciating this help and im really enjoying all the new stuff learning

i cant remember the head casting numbers but they are stock so im assuming there 76cc
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400 sbc

I still think you should stay with your origional choice of cam.
You are really going to like your motor. I'd keep the stock valve sizes so as to retain the hardened seat on the exhaust. For street usr cast or hyperutectic flat top pistons will be just fine.
this is strictly for the street and maybe like 1 day for the summer drags?

some other random questions are where can i find good deals on parts up here in Canada?

should i use a high volume oil pump?

pistons, i seen 30 over that will give me 10:1.1 for like $22 a piece now i know this is cheap but for my intentions will they be suitable?

Another important one is should i upgrade my ignition? like go full out msg or will my stock one be ok?

much appreciated and i will keep ya updated on progress
Cheap? Cheap is Powerhouse racing. Home of the 383 stroker!

Some time back I ordered a set of their 11:1 "claimer style" pistons for a .060" 350 for under $100.

Well they didn't tell me they came with full floater pins or balanced, all at 706 grams each. Now that's what I call service!

I mean they have "stock" rebuild kits for 350's priced at $153 with new pistions and cam...complete. They will even allow you to swap pistons and cam in your kit to match desires! :cool:
I would use a stock oil pump and a stock HEI distributor. I would get an advance kit and experiment with springs to get centrifugal advance all in by 2500 to 3000 RPM. I would try 32 degrees total. I would also use vacuum advance with an adjustible cannister. Adjust till it starts to ping at part throttle then back off to just before it starts to ping.
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