So this is semi-hypothetical at the moment as I don't have the money to get started on it, but I hope to this fall.


My plan has always been to stroke my 350 into a 383 (it currently has Brodix IK200 heads, Lunati 268 Cam, Performer RPM intake). It runs good, but I want more power, and I'm still running the stock cast dished pistons.

So then I decided I want a roller cam for the 383, and preferably a one piece rear main seal, so I would be starting with a new block. But my plan was to reuse the Brodix heads, Quadrajet carb, and possibly intake to keep the costs down.

Which got me thinking, if I'm doing that, why not just pick up a cheap 400 block, have all the machine work done just like I would on the 383, and just drop a 406 rotating assembly in it. The price should be almost the same right? And I get an extra 23 cubes.

There are a couple bare 400 blocks and a couple old short blocks on my local craigslist for a couple hundred dollars. Any reason I shouldn't pick one up and drop it off at a machine shop and then just assemble the short block and swap my Heads/Intake/Carb over and have a ton more power to play with?

 

Go for it. But aren't those 400 blocks finicky?

 

Why you shouldn't?
You hate torque.
You love your rear tires.
You're scared of breaking other things transmission/rear diff/half shafts.
You don't have money to replace broken items above.
You cave to peer pressure to easily.
You're not familiar with the ins and outs of a 400.
You want better MPG.
You don't have the money to upgrade your cooling system.
just to name a few

 

Ok fairly comprehensive answer. Next question, is there any good reason I shouldn't just go 632?

 

I had your exact dilemma almost 5 years ago now I bought a cheap 400 and let me tell you I love every second of it. However...
- blocks are becoming more expensive because they are "rare" call b/s
-make sure it's virgin or re-ring these blocks are prone to core shift, and bad egg shaped cylinder wear due to the small rod configuration so they only get one good shot a a rebuild and they cannot be bored over .60 and some will tell you even that is too much.
- rod/pistons/crank are a little more pricy than 350 and must be properly balanced.
- stock cam are trash and most have the 882 heads which are boat anchors so plan to ditch those right off the bat

 

You will want to look for the 2-bolt version of the 400 Chevy Small Block for it is stronger than the 4-bolt version believe it or not. If you can find a std bore block and have it bored .030" oversize and add a set of ARP Main studs to strengthen up the mainline. Take a look at a set of AFR 195cc CNC ported heads to make 550hp with the proper size hyd roller camshaft.

 

If you go that route, go with 5.7 or 6.0 rods.

I built a 383 with 6 inch rods and it liked to rev, but probably won't last as lon due to the short piston skirt.

 

Ok sounds good. So all my accessories/transmission/timing gear/oil pan, etc... will all bolt up just fine to the 400 block from my 350?


If so, this seems like the way to go. Should only cost me a couple hundred extra dollars for 20+ extra cubes. Seems worth it to me. Better than building the 383 and possibly wishing I had a bit more power.

 

Good advice so far.....I went 406 years ago, and also learned the hard way. The power is something everybody wants, and once you get it,...be prepared to upgrade pretty much everything behind it.

I've been through three transmissions, upgraded fuel system, cooling system, tires for traction....but wouldn't change a thing if I had to do it over. If you go mild at first,...you can grow with it as funds allow later.

Definitely go for it!

 

I would go with a 6" rod and yes all of your front accessories will be a direct bolt up from the 350 block to the 400 block. Keep in mind that the 400 Chevy will use an external harmonic balancer and flywheel so you will not be able to use them from your 350.

 

Thanks for all the input!


One other thought: the 400 can't accept a roller cam (at least not without an expensive retrofit) while the 383 could. With that in mind, if I built a 383 with a roller cam setup and a 400 with a FT cam setup with both motors using the same compression ratio, heads, intake, etc... would they be pretty dang close in power level?

 

Don't go cheap on parts like rocker arms (ask me why).

Why not do a retro roller? It costs more, but piece of mind, reliability and no substantial break in except for the rings was worth it to me - plus you usually get a better power curve out of most retro rollers with equal duration/lift.

On the external balancer - if you have to buy a rotating assembly anyway, you can get on that is internally balanced.

I say do it and do it right -parts like heads/balancers/intake can be reused if you are smart with your build plan. I suspect after driving a torque-monster 400/406, a 383 may be slightly disappointing.

 

do the roller cam, with out it you are left looking for oil that has the correct amounts of zinc, or finding a good zinc additive and did I wipe a lobe is always in the back of your mind whenever a problem appears.

the 383 would take more cam to make the same power as the 400 and would probably do it at a little higher RPM. Hell you could always pick up the 400 and put it under a work bench for future use and build the 383.

 

Morel makes an entry level Retro Fit Hyd Roller Lifter that will be a direct fit for the 400 block and they go for around $400 so the price is not too bad for what you get. Depending on what you are running for a head you could go with a cam spec of duration @ .050 236/244 .575/.575 lift on a 110 LSA to make some good power with a carb set up.

 

400 hands down

 

where did you get that "406" V-Flag deca? I looked for one, but settled for a "400"!

 

Below is a post I madea couple years ago, after building a 406 for my Camaro--might give you some ideas on final cost--good news is you have a good pair of heads already:

I recently built a 406 for my Camaro, making about 460HP...I already had the block and heads (but did have machine costs, as you will note)...The heads were DART Iron Eagle 200CC intake runners, 64cc chambers...

I ended up a little shy of $2600--you can expect an extra $300 or so for a "509" block, and heads will be a huge debate on here...You can probably expect to spend at least $1200 on a good set of heads--but you will also save some cash on the headwork noted below, and if you work with the head manufacturer to set them up for your chose cam, you will save some additonal cash that I had to spend on valvesprings, etc (in the "cam-kit" price below.

All in, I bet you could build a roller cam, 450-460 HP motor (like below) for about $4K

406 build
Machine work:
Block: cook and Magnaflux $60.00
Block: Bore and hone $110.00
bearings/freezeplugs $93.03
Heads: disassemble and clean $40.00
Heads: comp valve job $85.00
Heads: setup spring pressure and assemble $50.00
Balance assembly $125.00
Drill steam holes $0.00
Resurface flywheel $25.00
Comp Cams 7609 pushrods $90.42
Machine work total $678.45
Parts:
Cam Kit: K12-432-8 $983.27
cam kit discount ($49.16)
Roller rockers--CCA-17004-16 $165.95
Rods--Scat--SCA-25700 $283.97
Pistons--SLP-H615CP30 $168.39
Harmonic balancer PFS-80001 $60.00
water pump-SUM-311006 $67.95
Timing tab SPE-4237 $4.95
Head bolts NAL-12495499 $33.97
oil pan bolts SUM-G1570HS $4.95
Timing cover bolts SUM-G1574HS $2.95
Head gaskets-FEL-1014 $77.50
oil pump MEL-M155 $31.95
oil pump screen assembly MEL-55-S1 $7.95
oil pump pushrod MOR-22070 $14.95
Parts total: $1,859.54
Total: $2,537.99

One note--I think I had to exchange the oil pump for a different pump--price was the same, but do not go by the part number listed above

 

Very helpful, thanks.


I'm assuming you already had the crankshaft since it wasn't listed in the parts?

 

Used the stock crank that came in the block

 

If you are going to build for power look at a Dart SHP block. You are able to go 400ci to 440ci with one of them . Its "All new" not used or rebuilt and you will be starting with a platform you can trust and depend on.

Funny thing about power, it can break itself just as easily as it can a axle or any other component and in today's wold where "new" is fairly affordable VS rebuilding its almost a no brainier .