Well I have built a 302,305,327, half a dozen 350's and a 383 so I guess I'm due. Where can I find a good block to start with, preferably a four bolt main? How do AFR heads perform on these
motors? How are people getting these huge displacement small blocks. This is really not going to be a budget build, I will spend the money where it needs to be spent. My objectives are 500hp
500ft lbs. and streetability. How do you keep these motors cool?
Are forged bottom end parts a must or will cast steel cranks take the abuse. I know it's a whole lot more than the motor, but 11 second street cars are cool especially when they are N/A. Help me out guys, I want to scare the hell out of our fourth generation buddies

 

Find a factory 2 bolt block and have it machined for splayed 4 bolt nodular iron caps. The factory 4 bolt blocks are actually weaker in the main web area. Although i have a 2 bolt block with arp studs and it holds up to 546 (nitrous assisted) horsepower on a regular basis, where as how i see stock 400s with 4 bolt caps cracked in the main web area. i'm getting my splayed caps when i start my turbo project.

 

Finding a good block is problematic (unless you want to fork over megabucks for an aftermarket casting). I just keep my ear to the ground and when I look at a block I ALWAYS tell the guy it's gotta be no more than 30 over and has to pass a magnaflux test (that I pay for myself- pass or fail).

Keeping cool is no big deal- make sure the heads and head gaskets are drilled for the unique 400 block's 6 "steam holes" per side). They are CRITICAL to low RPM, low speed cooling. Otherwise, just remember that you've got 50 more CI than a 350 and that means it's going to need that much more cooling system capacity, even if properly set up in every other way.

Bottom end is strong- forged crank not required unless you're going for extended high RPM use. Stock 2 bolt main blocks are actually stronger than 4 bolt mains in these castings. 4 bolts tend to get cracks in the main webbing. A 2 bolt block converted over to an aftermarket 4-bolt spayed main type cap would be the best way to go but again, totally unnecessary unless you're building for high RPMs.

I build my street 400s rotating assembly with nothing more than a good set of rod bolts. I use ARP WaveLoc and nothing else in the rods, other than typical hogh performance rod prep. Yeah, even with shortie-style 5.56" 400 rods. They're tough little buggers, but I wouldn't use them for high RPMs either. I'd use 5.7 or 6.0" rods if high RPMs are your goal, with pistons to match, of course.

 

Damon,

Do you know of some good lower compression forged pistons(9:1) that I can run with 5.7" rods in a 400 engine? I am building a high-performance street/strip engine that I will want to spray with nitrous sometimes, but am having a hell of a time finding pistons for a 5.7" rod in a 400. I want to be able to run higher RPM's sometimes for those days when I am feeling spirited. I have a set of pink rods out of a 350 that I wanted to use but can't find pistons. Do you think that hypereutectic pistons could stand about a 100 hp shot of nitrous every now and again and still stay reliable? Because I did find some hypereutectics that I like.

You sound like you know a lot about 400's. If I have questions in the future would you be willing to help me out? Thanks a lot.

 

I was thinking of using the DART M block with ductile caps. 6 inch rods, flat top pistons, roller cam. Dart claims the block can handle a 4.00 stroke and 4.185 bore, sounds like fun. The only company I have seen that makes a small block 4.00 crank is Callies. I was thinking about Childs and Albert rods they claim they are good for 650 Hp. I haven't even seen pistons for a 4.00 stroke and 4.185 bore though. I want to try AFR heads, but the Edelbrock Victor Junior heads look nice as do the Canfield heads, still undecided. Any cam suggestions? Remember this motor will be driven on the street with 4.11 gears and 500hp and 500ft lbs is my goal.

 

bes 217-

i'm running 5.7 inch rods in my 406, forged SRPs. 72 cc heads = 9.0:1 comp. High silicon aluminum for small blower/nitrous.

 

Where do you get these pistons and how much did you pay for them?

 

Jeg's p/n 867-139625, $514.99 + shipping. They are floaters with double spiro lox (4 per piston).

 

I am currently using KB Hypereutectic pistons most of my engines. I've hit them with nitrous (150HP shot typical- have done over 200HP) and I'm now using them in my blower motor. They're certainly strong enough to hold up (but not if you encounter significant detonation) and they're available in a LOT of different dish sizes. Plus they're cheap.

I am not RECOMMENDING a hypereutectic piston for nitrous or boost, but it can be done. I'm just being weird, which is kinda normal for me.

Just remember that forged vs. cast vs. hypereutectic isn't going to make much difference if you run in detonation for very long. They'll ALL fail- it'll just take a little longer to kill a forged piston.

 

Look for casting number 509 block... theyre the factory 2 bolt, and also high-nickel content block. I would definatley recommend splayed main caps and studs... both of which would make a VERY stout block!

 

I have called around the junkyards and no one has these blocks. I found the splayed caps fromm Milodon for $200.00 and called about align boring the block, cylinder wall boring, spray tanking, cam bearings, sonic testing, squaring and decking, plus the cost of the block itself (if I can even find one) could add up to quite a bit. If I can't find one in the next week or so I will just order the DART M block, it may cost more but I know its new and its stronger than a production block.

 

How much does one of those blocks run? I know that the World Motown block can be had for fairly reasonable prices (cheaper than Summit/Jegs), just wondering.

 

About $2000 give or take 1-200 depending on where you get it.

 

any advantages of the Dart block over the Motown? i was thinking maybe changing blocks instead of putting splayed caps in mine. I've seen the Motown available for around 1500, but you still have to have it finished honed.

 

The Motown also looks good, coming in at $1,900 for billet splayed caps and a max bore of 4.185. The DART block for the same price uses steel non splayed caps. The Motown Lite heads also seem like a natural for one of these engines, 2.08/1.60 220cc
intake port. Defineatley something to think about, although I'm almost dead set on AFR's.

 

https://www.thirdgen.org/techbb2/sho...9&goto=newpost
this is the build up of my 406. it runs 7.8's right now with no suspension mods or tuning. Hope to his 7.4's in the spring.

 

Wow it sounds like you had one hell of a time with that project.
I know they can be a bear sometimes, but it's worth it in the end.
Thanks for the info, mine will probably have a Holley DP too.

 

To answer your AFR question, Chevy Hiperformance put a set of 180 AFR on the motor they dubbed the Impersonator making the numbers you want. The 190 or even the 195 would be a better choice for you, though. This is the link to the basic motor with Vortecs. Pick up the latest CHP and it details the AFR installation.

http://www.chevyhiperformance.com/te.../148_0306_406/

One cool thing about 400's is the availability of pistons. Pretty much every major manufacturer has a set with multiple dish configurations for the 5.7" rod length. You won't need a turbo to make a very streetable 500 tq/500 hp motor. I would forgo the turbo for now and put money into the chassis to put the power down. That is going to be a tougher task than the 500/500 goal. Like the renowned Joe Sherman says "Big torque is useless if you can't put it down". Use the Spohn Performance link on the top of each webpage to gain more information on chassis mods. Good people with a lot of helpful information.

 

I got my Dart block from www.flatlanderracing.com They have Dart little M blocks for $1909 with steel caps or $1669 with Ductile Caps, and they have free shipping on Dart blocks.

 

My uncle is selling a 400, .30 bore, freshly machined. Comes with a crank, pistons already connected to rods. Double roller (or soemting cant remember at moment ). Camshaft, no lifters. Also is selling Vortec heads. 550 bucks for the 400, another 550 for the heads.

Forgot to add...I think the 400 comes with harmonic balancer. If interested e-mail: red_83_Z28@yahoo.com