I have a 400 block, and I am going to build a 434. I found a forged rotating assembly from bowtie performance for $1549.
I have a few questions before I buy it though.
-A 434 is a stoked 406 correct? If so I would need to bore the motor out .030 over?
-Will this kit fit in my block without any other mods to the block such as clearancing?
-What kind of rings should I run? Should I go with the total seal gapless rings?
-What heads, camshaft, and intake manifold(carbureted) should I run?
I am looking to make the motor some what streetable, but I want to try and get big hp numbers out of it. Any help would be appreciated. Thanks.

 

Well, first off, if you were wise, i would go to a motown or dart block to start. Better foundation to build that big cubic inchs on. Lets say 195 AFR's and a roller cam around 230@.050 with around .600 lift. A victor jr intake with a holley 950 will suit your needs good for about 580 hp. Total seal rings should do you good. No need to bore the motor any more over. You will need to clearence if i remember correctly, maybe someone can back me up.

 

A 434 is 4.155" bore (.030" over 400 block) and 4.000" stroke (.250" more than a stock 400). It will work fine in a stock block. I'd recommend considering a set of splayed main caps though.

As far as clearancing, that depends entirely on what the rods are. If they're I-beams, be prepared to punch holes in the block, and use a half-fill of Hard-blok. Even with the right rods, which would be H-beams with cap screws not any nut-and-bolt rod, you'll likely need a small-base-circle cam.

It's amazing how this subject always gets replies from people who have never even seen a 400 block, let alone built one of these motors. They'll always tell you to go spend lots of money on the block. Watch, there'll be more like that I'm sure.

Last one I had anything to do with was a STOCK 509 BLOCK. It had Eagle ESP rods & crank, Edelbrock PerfRPM heads, and a XR282HR cam. IIRC the cam in that one ended up being the off-the-shelf version, which JUST BARELY fit in that particular block. Sometimes yo uget lucky, but it's best not to bet on it.

A big motor needs FLOW. 195 cc intake runners are probably not enough. 230° of cam is just about entry-level, as I found out with the one I mentioned. It wasn't enough. The heads definitely weren't enough. The guy had it in a Blazer with some real nice headers, and an Accel ProRam on top with a 1100 CFM 4-barrel throttle body; those were enough. But that manifold won't come close to going in one of these cars, it would even have trouble fitting under a 4" cowl I do believe. It's about the same size and height as a Vic Jr., maybe a Super Vic.

If I was going to do this for myself on an unlimited budget, I'd probably go with Brodix 11X or Dart Pro1 220s; and a solid roller, around 240-245° intake @ .050". Probably the matching single-plane intake and a Race Demon carb. It sure as hell wouldn't have a "drop-base" air cleaner. And I don't know what I'd do for a hood.

 

buy a dart block to start with

and for the record i did see a 400 block once.

 

Thanks for the help so far. The rods with the kit are h beam rods so they should be alright. I was planning on using Brodix Track1 heads. I already have a Victor Jr. manifold and a 750 Edelbrock carb would that work alright and would it fit under my SS hood. I really need more specific help on finding the right cam because that is what I know the least about.

 

I'd suggest a solid roller with intake duration in the range of 245° - 250°, and .600" - .650" of lift. You want to keep the valve above .400" of lift as much of its open time as possible with those heads. With a cam like that, aim for a compression ratio of aroun 12.5:1.

You need a performance carb to get the full benefit of this, instead of a Carter. A 750 is too small for a motor intended to make serious HP besides.

I have no clue whether that would fit under whatever hood that is.... I'd guess not, at least not with a non-restrictive air cleaner.