I've been told numerous times to stay away from the 400 small blocks...they say that they crack really easy and get really hot...whats the deal?...i've been wanting one for some time and now i hear this?

 

Those old wives tales aren't gonna die until the old hot rodders die off. If you build it properly, it's a fine choice. The 2-bolt-main blocks are actually stronger than the rare 4-bolt blocks, so don't waste extra money for a weaker block. Standard-bore 400 blocks can still be found for a couple hundred dollars.

 

Since 1986, I've built and ran 9 different 400 small block engines in various incarnations. Only ONE of those gave me any problems whatsoever, and that was one that had rod start knocking 15 miles after startup and break in. None of them gave me cooling problems, but I always took the extra precaution of installing a heavy duty radiator in whatever vehicle the 400 was in.
They are awesome engines built and used correctly.
That's one reason I have 2 400 shortblocks out in my garage, I guess. I fell in love with them a long time ago and can't pass them up if I find one for sale.

 

ya i can get my hands on a few...i just really wont be able to build it up a whole lot right away...can they take a decent amount of rpms? say 6500?

 

I guess I can't tell TXBowTie40 my source, or there won't be any left for me :-) 6500 rpm should be okay, with ARP main bolts or studs and a very light align-hone.

 

the only problem with them is the siamesed bores present a thermodynamic nightmare---uneven cooling around the cylinder walls which would reduce ring seal.. not a problem on a street motor though... other than that they are fine,, anything you hear about overheating is old wives tales or someone forgot to drill steam holes in the heads.. more cubes=more power

 

what would be a cheap way to spruce up a stock 400 to get some good horse and torque out of it..different cam? pistons? what kind of intake and carb?

 

Those things are good, but the thing the 400s need more than anything is better flowing heads. The vortec heads are all done at 5000 rpm on a 400, and anything else GM installed is done by 4500.

 

what does it take to get those steam holes drilled?..would some old camel hump heads work? or would that be a waste of time

 

yeah but your compression will be sky high,, we ran some on a 406 with flat tops and shaved 202 fuelie heads and we guessed the compression was around 12.5:1 it would only run on 100 octane and we ran it on 94 once and burned a hole in the piston.. I would use the camel humps IF they have the 2.02 intake valves.. you just have to drill the steam holes, I have never drilled them myself but from what I have read its not overly precise they just have to be drilled at a certain angle, you should be able to find some info online somewhere..

oh and by the way the old camel humps worked well.. very well that 406 was more like a 454.

 

scratch that idea!

 

are there any other decent heads besides the vortecs?...at swap meet's ive found some sportsmans for under 500 easy for a pair assembled...how are those?

 

I've run a few 400's on sportsmans. they work great, far superior head to anything chevy ever bolted on a smallblock, including overthe counter slantplug 292"turbo's". better metal, thicker deck, thicker evrywhere, nice big ports, screw in studs... yes there are much better performing aftermarket heads, but if you can get good sportsmans for 500 bucks its a good deal!

I've been very happy with all the 400's I have built. and drilling the "steam" holes is really easy. Just be sure to run a good water pump (cast impeller or stamped impeller with a flowcooler type disk, and a good radiator.
Keep in mind that a medium sized $180.00 aluminum radiator will outcool a larger 4 row copper/brass type. If your current cooling system is marginal for a 305 or 350 then a 400 may push it a bit over the top, but so would anything else 50-100 cubes bigger.

 

The siamesed bores actually stabilize the whole thing. Another old wives tale.

If you have any cooling issues, it'll be more likely on a street engine than a race engine.

I've only had one 400 SBC, a '70 Impala, it had a little over 200k miles on the stock bore when I traded it within the extended family. It overheated once - when the lower radiator hose burst. It was abandoned on the streets of Topeka in the mid-90's.

FWIW, the winner of the Denver Pinks All Out was a '68 Camaro with a fairly mild 400.

 

Read this article.....

http://www.chevyhiperformance.com/te...que/index.html

The wives tales are true to an extent. Most of the 400's built by Chevrolet went into trucks built in the 70's. Ask anyone from that era. Trucks weren't the trailer queens you see today. Trucks were worked and beat down like no other. People abused the hell out of them and didn't maintain them at all. Any motor would overheat if you never changed the coolant or even bothered to check your coolant level. Once overheating took place, cracking was the next in sequence of bad things. About 3 of the seven 406 blocks I have had magnafluxed failed. Make sure you have the block magged before you do any work!! If it checks out, your good. The motor will work as well as any other SBC build as far as reliability goes.

 

five7 -The siamesed bores actually stabilize the whole thing. Another old wives tale.



It's not an old wive's tale its a scientific fact. I'd like to know where you heard that.

"When a block with siamesed bores is at operating temperature, the cylinder bores are not perfectly round and they never will be. To keep a cylinder round there must be an equal amount of metal all around the cylinder. The siamesed block violates both of these physical laws. The metal where the cylinders are joined together expands at a different rate than the material in other portions of the cylinder, and completely dividing the coolant cavity around the cylinders into two seperate cavities produces additional temparature variations in a system thats not all that good to begin with. As a result, the bores in a siamesed cylinder block won't be truly round at operating temperature, and cylinder-pressure leakage will always be a bigger problem in such a block." - "POWER SECRETS- Smokey Yunick pg 17"

 

Now..is it necessary to have that kind of bottom end to MAKE that power?....can you still make that power with a "close" to stock bottom end...possibly different pistons?...is all the power coming from OTHER than the bottom end?...of course i know it really comes from the heads and cam but..i was just wondering if you could get by without having that bottom end that they used...and would sportsman heads be better than those???

 

I have ran a 400 small block for better than 5 years in my daily driver. i have one of the rare 4-bolt main blocks. i have put it through alot and it holds up well. what i was told about the 4-bolt motors is to stay away from high rpm's thats there weak spot but they will stand a beter beating from a super charger or turbo's or nos... (though most of thost like high rpm's so im not sure the point ) any way mine was a street motor so thats just hear say. As for over heating i have never had a problem, this motor makes loads of torque just stock but any thing over about 3500 rpm's it falls on its face. a cam and heads seem to fix that though. as for rpm's i know several guys that build and race 400's thay say keep it under 5500. they will go higher but your asking for problems. all and all though im happy with mine

 

The problem with the 4-bolt main blocks is cracking in the main caps. The main bearing journals are larger on the 400 and the 4 bolt caps are thinner in the area between the inner and outer bolts.

 

As cast..No.
Ported.....Probably

The vortec and sportsman II flow numbers are very similar. With as cast heads, the advantage to the vortec would be the smaller, higher velocity intake port (170cc vs 200cc). This would help the vortec produce the brutal torque numbers shown in the magazine build up, while the sportsman II would sacrifice some low end torque beacuse of the lower port velocity.

If ported, the sportsmans probably have a little more in them beacuse of the larger runners and valves.

If you keep your lift under .460 (.480 in some cases) its pretty hard to beat the vortecs for raw cheap horsepower.

Link to flow data if you care to look

http://users.erols.com/srweiss/tablehdc.htm#Chevy

 

I've had some great success with four bolt main blocks by running main studs instead of bolts. You can relieve a good portion of the pressure by going this route. Here's pretty much the run down I use.

1) Get the block magged.
2) Clean out the water jackets with muratic acid (swimming pool acid). I do this one side at a time, getting each deck flat on the engine stand and with a 50/50 solution acid to water, let it sit about an hour. Drain and flush with water and baking soda. This cleans out the rust and acid etches the surface for...
3) Hardblok the water jackets about 1/2 way or what is called in the Hardblok directions as a "street fill". This stabilizes the core for better ring seal. I have never overheated. I use Edelbrock water pumps exclusively...and a cored and cleaned radiator.
4) Use the proper size drill and by hand, clean out the steam ports.
5) Install Moroso Deck plugs as per the instructions leaving about a 1/16" of an inch above the surface so when you deck the surface, it will cut the plug perfectly flat. I open up the plug from its original 3/8" to 1/2" to allow a little more water flow. Don't qoute me on the dimensions. Anyway, open them up a little more. Then go get the machine work done...decking, boring, line honing, etc...

http://store.summitracing.com/partde...part=MOR-37800
6) Install head studs on at least the head bolt holes closest to the steam holes. This area is most prone to cracking and studs are safe insurance. Then go get the machine work done...decking, boring, line honing, etc...
7) I like a 6" rod and an internally balanced crank for many reasons. Eagle makes a good forged. Scat makes a good cast. Don't use the 5.565" rod. At least use a 5.7" length.
8) Steam hole drill the heads. I've used G1 Trickflows, Vortecs and AFRs, all with great success.
9) My latest passion is running a large journal 327 crank with Comp Cam main spacers, Scat 6.25" rods, off the shelf forged pistons originally for a 406 with a 6" rod (same compression height) and AFR Eliminators. It's the closest thing to a two stroke that a car engine gets. It revs super quick. It's just a blast to drive.

 

Smokey was a pretty smart cookie, but there isn't a block out there that has an equal amount of metal all around the cylinder.

Siamesed cylinders are more stable than divided cylinders.

 

I still don't believe that old wives tale about big-port heads losing low end torque or throttle response compared to a small-port head. I changed from a 601 cylinder head (160-ish cc's) to a World Sportsman II (200-ish cc's) and the throttle response and low speed power were almost exactly the same - the SP2 was actually slightly better IMO. Same cam, carb, intake, etc. The drivebility did not change at all with the 200cc ports - but got a MASSIVE improvement from about 3500 rpm and up. And that was on a 350.

400 small blocks LOVE big-port heads. I'd say to go for a MINIMUM of a 195cc intake port. Something more along the lines of a 210cc intake would work even better on any high compression 400 (something between 9.5:1 and 11:1)

The bore/stroke of the 400 is almost identical to the 396/402 BBC. Those engines had heads with port sizes between 260-320cc in stock form. They were great! Even the most mild factory 396 had 260cc intake ports (the oval port heads).

 

But in the case of as cast vortecs against as cast sportsman II's you are not gaining any flow to speak of by having a larger intake port. The only advantage that the sportsman II's have is on the exhaust side at the higher lifts.

Vortec ...........Sportsman II

.200 142/104 .200 132/103
.300 191/135 .300 188/132
.400 227/141 .400 225/151
.500 238/148 .500 241/165
.600 229/149 .600 243/163

Here is a comparison of intake port velocity between the two.
vortec.....sportsmanII
.200 116 .200 104
.300 114 .300 99
.400 130 .400 103
.500 137 .500 110
.600 131 .600 111

More intake port velocity means better filling of the cylinders and better power at lower rpm levels

I dont want to try to come off like im an expert, beacuse im not. The flow data and intake port data came out of a book I read a while researching both heads a while back.

Im not trying to knock sportsman II heads, beacuse they are good heads and have been for a long time. with good port work, the sportsman II's can make some serious power

But on the build in question, In my mind the proof is in the pudding. 428hp at 5100 rpm and 525ftlb tq at 3500 rpm speaks for itself, and IMO would last a long time on a stock bottom end.

 

yes out of the box sportsman's vs Vortech's are on even ground performance wise, but the advantage of the sportsmans is the better overall quality, durability and future potential of the heads.

 

Sportsmans are old tech, and compared to anything except old production chevy smog heads, they suck. I'd start with a 195-200 cc head on a 400 going into a third gen.

 

The guy was wanting to know if sportsmans he was finding at swap meets for under 500 bucks were an okay choice for a 400. Obviously a new set of AFR's or the like would give far superior performance, but I take it that he is wanting to maximise the his performance per dollar ratio and probably has a budget that wouldnt allow more high end heads.
I say that you'd probably expect to have to spend about twice that for better heads than sportsmans.
I have not used vortech's personally but are they not a typical late model thin casting? and they will limit the spectrum of manifolds you can use too.

 

Here's my recipe for the 400 I am finishing up to drop into my 82 Z. It is a 75 2 bolt main block that was bored .030", decked to square it up, magnufluxed, hot tanked, new bearings, brass freeze plugs, etc. The short block consists of the stock cast crank that has been polished and checked for straitness and the mains are held in place with Milodon studs with a windage tray and a Moroso 6qt pan. The stock 5.565" rods have been reconditioned, resized and new ARP bolts installed.
The heads are a pair of Dart Pro 1 Aluminum 200cc with 64cc. I have Comp Beehive springs and hardware on them. with ARP head bolts holding them in place. The cam is a Trick Flow retro hydraulic roller with .563"/.574" lift with Comp Magnum Roller rockers. The intake is an air gap unit with a Holley 770 Avenger vac/sec carb. Before taking it apart for the rebuild this thing just flat out screamed and should be even better now. Red line will be about 6200rpm and shooting for about 475+ hp and 525lb of torque. You go with the 400 and you will not want anything less, jmo.

 

Vortecs > Sportsmans

 

okay, in what way? and I'm not looking to drag out a head comparison argument, so I'll shuttup after this, but I am curious what criteria you are basing that opinion on?
Myself, I dont like late model GM cast iron heads bacause of the metal quality and thickness(or lack there of). But I certianly do acknoweledge the low rpm benefits of the higher velocity intake port.
I believe the iron eagles and new RHS heads are better than the SportsmanII's, but they are harder to find in "used" swapmeet form.

 

The reason the sportsmans are showing up: 1) you can get a new, bare pair of Darts, RHS, or the last of the Pro Toplines for under $600 including shipping, transfer your valves and springs, and find another 20-40 horses (2) the sportsmans' guides are getting worn out and need a trip to the machine shop. (3) You can get a new, bare pair of aluminum heads for under $750 delivered, transfer your parts, make more power, and save 50 pounds, then recoup half the cost by selling the sportsmans (4) the economy is bad; I'll sell my worst heads. Noone's gonna let good heads go if they have a pair of not as good heads they can let go instead.
If you're gonna spend money on speed parts, spend more for better heads now, and save the future costs of gaskets and better heads.

 

+1.....BTW, all the LS motors, and the 502BB have siamesed bores and

they make pretty reliable horsepower. Just food for thought.