[killerformula]

OK, in the opinion of everybody here, what is the better street motor, a 383 or a 400? Take into account the strength of the motor, availability of parts, reliability and power.

I'm torn, I have a 388 and i guess its nice to have the availability of 350 parts and the better cooling at virtually no sacrifice in power.

What do yall think?

K

[coldknock]

I guess all that matters is which block you happen have on hand. 400s tend to unshroud the valves a little more than 383s for a few extra hp, not to mention the extra cubes. 383s don't have the cooling issues though. A toss up I guess. What's layin' on the floor is what get's built as far as I'm concerned.

[lluciano77]

Originally posted by killerformula
OK, in the opinion of everybody here, what is the better street motor, a 383 or a 400? Take into account the strength of the motor, availability of parts, reliability and power.

I'm torn, I have a 388 and i guess its nice to have the availability of 350 parts and the better cooling at virtually no sacrifice in power.

What do yall think?

K

With all of my posts written on the subject you already know what I think.

Originally posted by coldknock
I guess all that matters is which block you happen have on hand. 400s tend to unshroud the valves a little more than 383s for a few extra hp, not to mention the extra cubes. 383s don't have the cooling issues though. A toss up I guess. What's layin' on the floor is what get's built as far as I'm concerned.

If you use the Fel-Pro gasket #1014, there are no cooling issues with a 400.

[coldknock]

That's what I used. I still had to get a better radiator and fan. Probably because I went from 325hp to 450 or so. More hp=more heat.

[lluciano77]

I'm up in the 450 hp range. I have never even come close to coolinig problems. I would always recommend a new radiator, or at least apretty new one. They are only around $100 bucks for a 4-core.

[Centerline]

I'll take either the 383 or the 400 but make mine MOPAR, thank you very much.

Centerline
http://www.hotrodsandhemis.com

[Steve karch]

I went with a 400 because a buddy of mine gave me a core for free. Turns of the core was no good. I would have built a 383 if I couldn't find a 400 block. It was either a 383 or 400 but definitely not a 350. I like the extra displacement of the 400. My engine dynoed at 425hp/470 lbft torque. With a 160 t-stat, on an average summer day in the high 70's low 80's it runs 170-180 degrees, 190 in traffic. I have a 3 core rad. My 350 on the other hand ran 200-210 in traffic and on the highway on a hot day 205 with the same cooling system. It all boils (pun intended) down on the machine work and clearances. If I had to do it over again I'd stick with the 400.

[willys36@aol.com]

Settle the conflict and get a 354 hemi!

[M&M CUSTOM]

There's NO replacement for displacement.

[406chevelle]

Years ago I built or was involved in building several SBC�s (305s, 327s, 350s, 383s, 400) only one of them was a 400 which was the last and best, the 400 was built after researching and putting aside the bad reputation it had.
Now 20 years later I am back to building another SBC, I did my research and choose to build another 400, more bang for the buck.

The issues the 400 have are basic and very easy to over come (keep in mind the 383 also has it�s unique issues). 1) It is a SBC with a 4.125 bore so you are limited to how far you can bore it out, 2) It is a bigger displacement motor and creates more HP and heat, it will need a bigger radiator, 3) The design of the block (so we can have more cubic inches) requires steam holes, so use the correct head gasket with steam holes and drill the steam holes in the heads.
Take care of these issues and a 406 will run just as well as a 383, but when you stomp the gas pedal you will feel the extra cubic inches the 406 has.

400 Pro�s
No if and or buts there is NO replacement for displacement:
350, .30 over, 3.75 stroke = 383 CI.
400, .30 over, 3.75 stroke = 406 CI.

It cost about the same to build a 406 or 383.

You can put a slightly bigger cam (more HP and Torque) in the 400 and maintain a good idle.

400 Con�s
The 400 blocks are getting hard to come by, but they are out there.

Weak main webbing, this is not a problem unless you are building a wild racing motor.

DISCLAIMER: I am no expert my statements are based on my personal research and experiences, I have NO problem with some one giving constructive criticism, I don�t mind learning even if I�m wrong, so lets hear it.
Both the 383 and 406 are awesome motors and almost anyone is going to be happy with ether one, if you have a 350 block sitting in your garage build a 383, if you have a 400 block build a 406, it�s that simple.

406chevelle

[firestone]

I would have to say 400 for the reasons that have already been stated. As long as you dont bore them too far, and you have a good fan and radiator, there shoulden't be any cooling issues. Like stated before, with a 400, the bigger bore allows the heads to flow better plus you get more cubic inches. As far as strength of the block goes, I know of people running 2 bolt 400s (splayed mains though) in IMCAs, and from what I have seen the blocks hold up pretty well, and those motors are reving to 7500-8000 RPM.

Adam

[killerformula]

That's basically what I was going to put in the poll but forgot. Basically its just an availability of parts. If you have the parts to build a 383 its probably not worth it to go hunting down a 400 block. For me its nice to have the safety of the 388. I was lucky to get a really nice 350 block (heavy casting four bolt). Definately though, my next small block will be a 406 or a step further to a stroker. That's another point that hasn't been brought up, stroking. The 383 is at its potential limit, whereas the 400 can be stroked all the way to 434 or further.

So there u have it, build whatever parts are in your garage!

K

[Robinson Robin]

As far as I'm conserned the only reason to build a 383 instead of a 400 is if you just can't find a 400 block. But I hope people keep building 383's it leaves me 400 cores for me

[Jmark]

anyone in the Phoenix areal looking for a good 400 2 bolt block let me know. Have the crank, rods and pistons and heads too. Block had been rebuilt but the cam went bad. Metal in the oil took out all the bearings and scored the crank badly. Block is .030 over and still usuable at that spec. Machine shop said it was .001 over where they like to have them, but for a mild or stock engine, it would be fine. Heads are ok, pistons are ok, rods are ok. Crank is questionable, but could be turned again I suppose.

[Sandflea427SS]

I have 3 350 blocks and my machinist can get me the stroker cranks for $175. So I'll say 383 383 383......
When I get a good 400 block I'll say....406 406 406!