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400 vs. 350

Don't be afraid of the 400....Open it up and let it breathe on both ends....Use 5.7" rods in which ever route you choose, 383 or 400....

Since you already have a 350, go the 383 route. You 'saved' $$$$ on the cost of a rebuildable block. I think the cheapest rotating assembly for a 383 I have seen is like $650....You can save for heads by assembling it yourself, and clearancing the block yourself.

For a truck motor I don't think you will really notice the difference between a 383 or 400 from the drivers seat dyno....

http://www.chevyhiperformance.com/techarticles/148_0401_imp/ Just some ideas for you. Note the cam they used is not very computer friendly. That all can be duplicated on a 383 as well with very similar results.

4X4 HIGH mentioned a recipe for a 500 ft lb tq @ 2000rpm's. That would make a GREAT truck/towing motor, and get respectable mileage to boot if geared right....
 
those 400 guys need to quit using 350 parts then, and the tables would turn....Getting that 400 to hook up might be some of their problem too....
 
Hello man whatever you do keep it simple how about a chip in your comp free flowing ex. gear ratio change unless your engine is blowed
 
I had a bone stock 400cid sbc in my 76 K5. Never had a problem with it. The 400 SBC doesn't like high RPM, but when off roading, you're not redlining it anyways, so go for it. Great torque motors. A basicly stock rebuild with a cam for more low end grunt is perfect for a K5. Don't know about the FI, but I'm sure it can be made too work. Might have too have a new chip burnt for it.
 
FI is complicated and expensive to put on higher hp motors. In order to get her to run right you'll be spending well over a grand but will also be able to custom tune it however you want it. The prominator bill makes can be hooked up to a switch which gives you 6 different fuel maps. you have to burn them yourself but you can spend 100 bucks for 2 hours on a dyno and have one map for low end tq, one for hp, one for gas mileage, etc. the holley 670 cfm will support 350 hp with computer tuning. That is what holley told minimull but if you go over to www.thirdgen.org there are guys making 400 hp with a holley 670 on top.

I think a 383 is your best bet.... you could build up a 350 for tq but in the end you would be spending the same as a 383 and wouldn't have the low rpm grunt of a 383. A 350 can make insane numbers down low if you have a deep pocket and know what your doing. there are guys making 450 ft lbs at 2500 with 350's but its going to send you to the welfare line. The jegs engine build challenge had a 350 making 600+ ft lbs at 5500 rpms naturally aspirated. I spent a little over 3k on my 355 and wound up with good low end torque(about 350 ft lbs at 2000 rpm) and peak(around 400 ft lbs) as well as 330 hp and I kept FI.

The 400's are known for overheating and can't be cured unless you throw some heads with better coolant flow on it.
 
I actually run a built 406 small block.

1. THey cost a lot more to build up when you are trying to replace a different engine with the 400. Obviously, one is that you need a block. If you kept your 350 you already have a block which would be no cost. 400 blocks are getting very, very rare. You want a 2bolt, original bore 400. Good luck. :wink1: I got lucky and had a friend that worked for a machine shop that grabbed mine for me. :crazy:

2. My experience with it's cooling... First off, I'm the kind of anal person that is determined to keep an engine at 180-200* while pulling a hill loaded at WOT. I can't stand stuff that can't handle to be worked. I have battled my motor since I installed it and yet still can't keep the temp from climbing under WOT for extended time (like pulling a hill with a trailer). I have a new 4 core BBC radiator, dual 13.5" electric fans, and a high flow water pump. Mine runs 200* all the time and near *220 in 100* ambient temps with the A/C on. :( I finally just said screw it, i've got a TON of cooling power and let it run as warm as it wants because I was tired of fighting the guage.

3. Even after dealing with issue in #2, I still would have taken my 406 even if I had known what cooling issues were ahead. ;) My 406 makes decent power, 200HP and 300ftlbs on the inertia dyno and with my running gear, thats probably around 300HP and 400+ft lbs at the crank. Thats with stock heads, a mild 218*/454" cam, performer intake, hot ignition, 9.2:1 comp., Performer Qjet, and headers with flowmasters.

350's are boring, don't be boring. :D
 
My 406 makes decent power, 200HP and 300ftlbs on the inertia dyno and with my running gear, thats probably around 300HP and 400+ft lbs at the crank.
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More like 330-340hp at the flywheel.... your running 35x16 boggers.... they don't make a heavier 35. Also the gearing won't affect peak hp and tq numbers... it'll just get you there faster by using more rpm at a slower speed.

World sbc makes the ideal 400 sbc block... they expanded the coolant jackets, gave it priority main oiling, and nodular iron 4 bolt mains. It's gonna cost you 2100 (600 more than i paid for my longblock) but you won't be overheating and you'll have one of the baddest blocks in the city.
 
Mad-Dog said:
i apologize for confusing you....
You would do fine just beefing up that 350, start with the exhaust.....full length small tube (1 5/8") hedders, 2.5" duals with a h-pipe or crossover behind the transfer case and flowmaster mufflers.
Work on the air filter system and let that motor breathe (ram air is a good thing) some cool air.
The intake is very restrictive and should be replaced with a Edelbrock unit (very nice)....this would allow to install the Holley TBI unit which outflows the stock unit and really kicks butt.
Stock TBI heads are the worst flowing heads that chevy makes so upgrading to set of World SR Torquers (expensive) are worth 50HP and AFR's (real expensive) are worth nearly 100HP.
Intake runners should be around 180cc and the chamber size can be decreased to 64cc and raise the compression w/o changing the pistons.
Changing the cam to a comp roller with 210/220 @ .050", 266/276 advertised , .500/.510" lift on a 114 dgree lobe center would be the icing on the cake and will push the motor to the 350HP mark easily with the other mods installed.
You would spend a lot less going this route and you don't have to pull the engine........the motor will have more power than you need cause a 350 HP 350 aint nothing to sneeze at....
lemme know what you wanna do and i will put together the part numbers for you....!
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well said.

As for heads get the sr torquers from world. They are built for tq and also make decent hp. If you get the s/r's you won't have to spend 325 bucks on a performance intake manifold like you would with the vortecs.

To give you an idea on price:

Heres what i did...

bought a 10:1 compression 355 longblock with camel hump heads, L-79 cam (soon to be comp cams 4x4), high volume oil pump, and gm's x connecting rods off ebay(did my research on the guy and his motors first) for $1735 delivered. Then i went out and bought a holley 670 cfm tbi for $350, $150 accel inline high pressure fuel pump, $180 holley projection efi manifold, afterburner headers and y pipe $230, k and n filter and chrome xtreme lid $110, a prominator and labtop for $500, $120 2400 stall converter, and soon a comp cam 4x4 cam and world sr torquers will be on that list.

http://www.cardomain.com/ride/805335

By the time i'm done with the heads and cam i will have 4K into the entire thing but it will be worth it. when its all said and done it will be making around 375 hp and 420 ft lbs. More power than I will ever need and something to go big block hunting with.
 
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I can honestly say that I have learned a great deal from your replies and I truly appreciate your input. I think I have ruled out the 400. Just doesn't seem to be as reliable of a platform as a 350. Right now I'm thinking 383 with the s/r torquer heads (depends on price. trying to find that now).

After reading the link posted by Mad-Dog on "stroking any engine" it looks like the 5.7 in rods would be best (cheapest since I've already got them) for torque in a K5. If I were building a Vette and wanted high hp at high RPM then the 6.0 rods would be best. Am I correct on that?

Another decision is on induction. I guess the 670 CFM Holley/Howell unit would be fine, but it seems from what I'm reading that that unit may not feed this engine well enough. What about the Howell MPFI system. I can get it and use my computer/harness for around $1200. According to the guy at Howell, this MPFI system uses the same 670 CFM TBI, but it flows 700 CFM when you get the injectors out of the way.

Dirtwarrior made the point about programming different configurations to run the truck in. I would love to do that but I think that might be a little over my head, and honestly I don't know anyone around here that could help me with it. I have a laptop and I'm decently good with computers. How difficult is this?
 
tiger9297 said:
Dirtwarrior made the point about programming different configurations to run the truck in. I would love to do that but I think that might be a little over my head, and honestly I don't know anyone around here that could help me with it. I have a laptop and I'm decently good with computers. How difficult is this?
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If i had the money and i was building this motor i would get the mpfi from edelbrock AND the prominator. There are a few set backs with the mpfi like not being able to change your own map and being at the mercy of the local shops or edelbrock.(not sure how much but you have to pay if you want a different map then the one the make for you when you get the mpfi). If you really want to customize your own fuel maps then spend some time researching it and see what you think. Don't settle for something less because you think its too much. It seems very complicated when you first start to check it out but it gets simpler and simpler with persistance. since you can make on the fly changes with the prominator you will be able to correct your mistakes with the click of a mouse.

Right now I'm thinking 383 with the s/r torquer heads (depends on price. trying to find that now).
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Good choice. S/R torquers are gonna cost about 130($379.00) each more than vortecs but you get that back when you go to buy an intake manifold and not have to pay 330 bucks like you would with vortecs.

After reading the link posted by Mad-Dog on "stroking any engine" it looks like the 5.7 in rods would be best (cheapest since I've already got them) for torque in a K5. If I were building a Vette and wanted high hp at high RPM then the 6.0 rods would be best. Am I correct on that?
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Flip that theory and your correct. Shorter rods mean high rpm and better hp. Longer rods mean better low end power but less rpm capability.

Another decision is on induction. I guess the 670 CFM Holley/Howell unit would be fine, but it seems from what I'm reading that that unit may not feed this engine well enough. What about the Howell MPFI system. I can get it and use my computer/harness for around $1200. According to the guy at Howell, this MPFI system uses the same 670 CFM TBI, but it flows 700 CFM when you get the injectors out of the way.
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I went with the tbi setup and prominator because i really didn't think i would be spending 1200 (but i had to buy a labtop) on efi. I chose it mostly because of versatility ... you can either spend 1200 on mpfi or 900 on tbi with a custom setup. Its a toss up. If you want the ability to customize your map go with the tbi and prominator. If you don't want to mess with the prominator and labtop go with mpfi. Or you could spend 1200 on the mpfi and then another 300 for a prominator and have the best of both worlds. A holley tbi and holley projection intake manifold is basically a 454 intake manifold and tbi. you shouldn't have a problem feeding the 383 with the 670cfm but it will HAVE to be tuned if you go that route.


Sorry for the long post but when i was trying to figure this stuff out i wish somebody had posted this stuff.
 
Tiger 9297 is correct on the rod length issue.....
you need to flip your theory around, short rod motors like the 400 with it's 3.75" stroke, 5.565" rod and low rod ratio of 1.48:1 does not like to rev but makes great torque.
long rod motors like the 350 with a 3.48" stroke , 5.7" rod and more rpm friendly rod ratio of 1.64:1 makes less torque but is willing to rev higher.

A 383 with a 3.75" stroke, 6.0" rod and 1.6:1 rod ratio is also a willing screamer.
A similar 383 with a 5.7" rod has a lower rod ratio of 1.52:1 which is slightly better than a stock 400 will make great torque but redline at 5500 rpm.

Dart Iron Eagles with their fantastic exhaust port will make more power than the S/R's and cost the same if not less....
 
Mad-Dog said:
Tiger 9297 is correct on the rod length issue.....
you need to flip your theory around, short rod motors like the 400 with it's 3.75" stroke, 5.565" rod and low rod ratio of 1.48:1 does not like to rev but makes great torque.
long rod motors like the 350 with a 3.48" stroke , 5.7" rod and more rpm friendly rod ratio of 1.64:1 makes less torque but is willing to rev higher.

A 383 with a 3.75" stroke, 6.0" rod and 1.6:1 rod ratio is also a willing screamer.
A similar 383 with a 5.7" rod has a lower rod ratio of 1.52:1 which is slightly better than a stock 400 will make great torque but redline at 5500 rpm.

Dart Iron Eagles with their fantastic exhaust port will make more power than the S/R's and cost the same if not less....
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I thought I was correct on the rod lenth/torque issue. Was wondering if I had misread that article you posted. Anyway, that's why I think I will probably stick with the short rods. I want torque and I won't have to buy new rods. Also, thanks for the advice on the heads. I will definitely check the Dart Iron Eagles out.
 
Only problem with darts is the intake runners...I thought they didn't make a head smaller than 200cc... not ideal for tq. they might give you better peak tq but becuase of the intake runners being 200cc the s/r's will out perform them downlow.... not to mention the darts are another 500-600 bucks.
 
Here are links to cylinder-head flow-bench databases that lists the popular SBC heads and their respective flow characteristics.

http://www.carcraft.com/techarticles/116_head_chev/

http://www.chevyhiperformance.com/techarticles/41598/index.html

What is important when determining a cylinder head is material (iron or aluminum), aluminum dissipates heat faster and allows higher C/R's w/o detonation.

Combustion chamber size (small chambers like 64-67cc allow the use of flat-top pistons to achieve healthy compression ratios w/o disturbing the flame front like a domed piston would.

Intake runner volume (180cc is as big as you wanna go with a mild 350)

Valve spring setup and open seat pressure (single spring/damper with no more than 300psi open seat pressure is fine for hydraulic flat tappet cams but always try to follow the cam grinders suggested rates.

Last but not least the exhaust/intake flow ratio at various lift measurements such as .050", .100", .200", .300", .400" will determine whether you want a single-pattern or dual-pattern cam, .500" measurements are futile if the cam has less than .500" valve lift.
Take the exhaust flow at a chosen valve lift of a particular head and divide it by the intake flow at the same lift...this will give you a example figure like .75,
heads that have a poor ratio require a dual-pattern cam to balance the flow relationship between the intake and exhaust at a given rpm......
on the same note motors that require a lot of top-end power or use nitrous will benefit from a dual-pattern cam as it helps the scavenging effect at high rpm's.
There are so many variables involved here i can't begin to make a suggestion to you unless you tell me EVERYTHING about your chosen engine recipe....
LOTS of info required.!
 
They most certainly make a intake runner smaller than 200cc, 165 and the 180's which i have currently

http://www.dartheads.com/chevysh.aspx

In a side by side comparison the Dart's made 30 more ft lbs of torque than the S/R's on the same engine because they have a better exhaust port.
 
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