350 vs 383 vs 400

[HotRodPC]

I'll take your word for it. Gimme one of yours that don't overheat then and I'll make some ponies out of it, and whole lotta torque with that long stroke. For a small block anyway.

 

[Guardian]

I'll see if I can find that right casting number block and let you know.

 

[Mark L]

Build a 406 out of your 400, motor makes good power, and you will be using block and crank you already own. You just need new pistons which I would change anyway. As far as heads there are a lot of options out there but I would be looking at some of the after market heads out there. Just my .02

 

[Christian Nelson]

Bah, if it over heats a tish, drill a couple holes in the thermostat, or get a cooler running one, just don't go too far, or you run it too cold. I've had more experience with the 350, I've seen a few 400 small blocks, and they really snort. A bit of heat, you can deal with it.

I've heard stuff about the married cylinders too, but people run 'em, and don't seem to have issues.

I dunno. My rusty old truck I need to fix before I can drive it has a 400, so I suppose I will find out some day (when I have time/$$ to deal with the issues I have with it)..

LOL.. Time and money, hurry up and fix your truck now while you still have both!

 

[Guardian]

Hey HotRod, that casting number is 511. I have one short block but it won't work for the street, it was a playtoy and has a bunch of run time on it.

 

[HotRodPC]

Hey HotRod, that casting number is 511. I have one short block but it won't work for the street, it was a playtoy and has a bunch of run time on it.

That's a 70-73 SB400 4 bolt main. Those are believed to be the ones more prone to cracking. What do you mean by can't be used for street cuz it had alot of runtime on it? Do you mean the bore is wore out? Was it standard? Can it be bored .020 or .030 over and used 1 more time? The amount of time on a motor doesn't matter to me as long as it can be made a fresh bore again.

 

[Guardian]

Nah, it is .040 over now; but I had put 14 nights on it before I get racing. It has 14.5 cr and has been used to test heads with for the past couple of years. I still help out some budddies that race so it has about 300 dyno hours on it.

It normally runs 200 to 210 on the temps, I don't consider that hot but some do. The engine in my daily runs about the same and has performed well for the past year. All of the engines I have now use aluminum heads partly because I have them already and partly because I like the flow characteristics of them.

If you want I will see if I can find another block for you but this one has been run hard for a while and I really don't want to get rid if it in case we decide to try something new again. I know a guy with a 406 for sale, just a short block. I find the information on it and get it posted.

 

[Driver4r]

Ok , im gonna add my 2cents worth to this topic. A 350 is better because it has water jackets between the cylinders(a 400 does not(you can cut them out, but its to dangerous to do it(if you mess up, your block is fudged for life))). A 400 is a nice block for stroking. But if your gonna build a stroker, then use a iron eagle dart block. They are a block made to clear the large throw of a stroker crank. If you run your 400, then just be carefull. If its an original block then you wont be able to find one that matches that truck. Where as, if you run a 350, you can make it a 350/355/383/etc.....You could also destroke it. Either way, the 350 will run alot cooler than the 400.

 

[Mishri]

Thanks, I still haven't even popped the hood since I last checked in. I've been busy. It is still the original block and for now we'll keep it as is for now and I"ll focus on things that are broken. My dad said he's never had any heat issues with it, and he drove that thing all the time in phoenix 120 degree heat in traffic.

for now i'll work on the speedometer, fuel gauge, making sure the new choke is working properly and replacing the wood bed with new wood... after that getting the doors closing and sealing properly will be my next goal. then body repairs.

 

[Guardian]

Sounds like a good plan.

 

[bucket]

Ok , im gonna add my 2cents worth to this topic. A 350 is better because it has water jackets between the cylinders(a 400 does not(you can cut them out, but its to dangerous to do it(if you mess up, your block is fudged for life))). A 400 is a nice block for stroking. But if your gonna build a stroker, then use a iron eagle dart block. They are a block made to clear the large throw of a stroker crank. If you run your 400, then just be carefull. If its an original block then you wont be able to find one that matches that truck. Where as, if you run a 350, you can make it a 350/355/383/etc.....You could also destroke it. Either way, the 350 will run alot cooler than the 400.

I'm guessing these are all things you have heard, rather than personal experience?

Guys used to race built 400's all the time, before the 383 became so popular. The biggest reason the 383 is so common now is cost and availability. My grandpa had a '70 wagon with a 400, it didn't run hot. I had a '77 K5 with a 400, it ran no hotter than any 350 I've had. A friend had a 400 in an '83 T/A with a stock radiator, it never went past 200*.

There's so much false info that gets tossed around about the 400. Usually its "my brother said that his buddy had an uncle who heard from his cousin Bob that 400's overheat". Talk to any fella that has actually ran a 400 and they will tell you it wasn't a bad motor other than being thirsty for fuel.

 

[HotRodPC]

Have a mild cam with some compression in a 400 sitting in LA rush hour traffic, with a 4 core radiator and electric fans blowing full force and a 160 thermostat and then tell me they don't run hot. 240 is running hot and not a damn thing you could do about it. My 350 with the same setup, could get close to 220 at times but usually around 210. The 400, everyday was 240 at some point. IN stock form, they may be OK. Also always had to let them cool between races too. 383 is a common build because 350 blocks can be had easily.400 blocks are rare these days.

 

[bucket]

How much compression? Stock Iron heads?

 

[HotRodPC]

How much compression? Stock Iron heads?

Probably 10 or 11-1, but I'll assure you with the cam, the dynamic was only about 8.75-9 and running 93 octane leaded back then with double hump aka Fuellie heads and steam holes drilled gasket ported.

 

[Guardian]

To hell with it!! Convert it to alcohol.