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400 sbc???? (All assembled)

Wow that s sweet!!! Yah i will be only going off road a couple times a summer at the sand dunes here. I wont really drive it much more than that in the summer and the rest will be in the winter which will hopeully help with cooling issues if their are any.
 
TDAWG1 said:
O and NO Cooling Issues what so Ever Make sure it is a Virgin Block though that would be the Best in this MOTOR
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Virgin Block would mean no over bore.
You just said bored to 406 which is I guess 30 over. :dunno::confused:
 
badmix said:
Never been a fan of the 400s. There is a reason hot rodders and racers dont use them and stick with 350s, parts are everywhere.
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:confused:, I thought they were a favorite of desert guys?

As for the overheating issue, Mines got 178k on it and its never had a problem heating up at all. Hell if anything it runs a little cold sometimes. I ran it up summit at hollister during summer 100 or so degrees out in 4wd hi since 4lo was being a PIA and according to the gauge i was right at operating temp once i made it back down from summit i popped the hood because someone wanted to check it out and noticed it was really hot externally but the gauge still said perfect running temp internally :dunno: . I do have to run 91 octane as RFJ said or else its a dog and trys to bog down all the time, but that never really bothered me its like an extra 6-10 bucks a fill up. I dont even DD it anymore so its a non issue. I stuck half a quart or so of octane booster along with a full tank of premium and i managed to pop the entire rear end loose coming out of the gas station :D. Not bad for a v8 comin up on 180k.

I almost wonder if someone swapped in a 350 based on what everyones saying. In the rigs previous life it did some chase truck work for a score racing team over in cupertino so maybe its got a shet ton of cooling upgrades i never noticed.
 
1. The more it's overbored, the worse the overheating issue is. I don't know why exactly, but multiple people have told me this. They say .030 is as big as you want to go before the walls start getting too thin.
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ok, Dueling......if this is the case, then you're new motor is like a disposable lighter.....use it till it's done then throw it out. i wasn't sure, that's why i asked. higher compression will make it run hotter yet. i never had a 400 Chevy but i believe they run hotter by design and nobody EVER talked well about the fuel economy. you still do have fuel economy concerns, no? i'm sure not saying a 400 is a bad motor, just maybe not the best choice for you and your requirements.

i don't know, but saving a few hundred now could cost you more in the long haul. you went from a "cheap" rebuild on your 305 to a 400 sb....what intake would you put on this, that Performer RPM you have? torque and horsepower? depends on lots of things......stock, only marginally more powerful than a stock 350.
 
imiceman44 said:
Virgin Block would mean no over bore.
You just said bored to 406 which is I guess 30 over. :dunno::confused:
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Yes you cant double Bore a 400. If you are going to Bore it at all it needs to be a Virgin Block sorry for misunderstanding. The Walls are to thin and cant handle it Thus Over heating mas Breakage
 
Deuling said:
Wow that s sweet!!! Yah i will be only going off road a couple times a summer at the sand dunes here. I wont really drive it much more than that in the summer and the rest will be in the winter which will hopeully help with cooling issues if their are any.
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He has Driven that Truck on Ultimate Adventure and we Drove from Colorado to Logendale NV to Wheel at Hump N Bump and Drove home in it. So it can be Driven as a DD and as a Wheeler
 
I am going to be putting my edelbrock 1406 on the motor, after i rebuild it and hopefully selling the performer RPM manifold for just a performer. Idk exactly what i will get but, im getting 9mpg highway with my 305, i mean come on if i can get 9 mpg and have twice the power, Now thats something i can llive with, but 9mpg and a clunky motor that cant even squeek the tires? Screw this.
 
sweetk30 said:
run the intake you got. thats what i ran on my 400sbc.
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Really? What were you getting mileage wise? I know its a big motor and definately more than what i need lol, but it would be cool i think.

I just have this image stuck in my mind of rolling up to test hill at the dunes and people laughing at me saying "Look at that little stock blazer" Then let er rip :thumb: Goosebumps lol
 
Merv said:
It's not a bad design. It's the biggest GM can go with the small block. The center holes are touching ie: lack of water passage. If your not sure why things are acting like they are, don't give out uninformed advice. Alot of different engines when taxed like your have a hard time cooling themselves.
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Don't try to make me sound like I don't have a clue. My advice is in fact dead on. :deal:A 400SBC IS a bad design. It's why it wasn't in production for very long. I am pretty sure I remember the issue being, the more it's overbored, the thinner the walls get from one cylinder to the next, and that makes the engine even more prone to hotter temps. What I know for a fact is the way a 400 acts on a day to day basis, compared to a 350, 454, and even big HP Cummins diesels. It's the hardest engine to keep cool that I've ever had, and many other people also suffer from the same issues. A few don't, but if you notice, a lot of them are stock bore engines that were original in the original vehicle. The overbored motors seem to be more problematic.
As far as my 406 being "taxed".... are you kidding me? I wouldn't consider a stock 406 with a cam, a bump in compression, edel intake, and headers a "taxed" engine. I'm not even making 1HP:1CI.:rolleyes:
 
The larger bore in the 400 makes thin sections between 4&6 and 3&5 pistons which is why they tend to overheat. The steam ports were put in to help with this issue, but these "middle" cylinders run hotter than the others.

With the right cooling system, proper fan / shroud, and a smart driver (keep an eye on your gauges), you'll be fine. I personally love my 400 and know of a lot of hot rodders tricking out these engines.

To each his own...
 
I would go with a 350, but that's me.

As for the intake, the Performer RPM will be just fine.

Martin
 
i dont know what others are doing that are having all these cooling issues, mine ran no hotter than 200, and that was in southern calif and lake havasu city az in the summer. i had a good flowing water pump, large radiator with dual electric fans in a shroud, no engine fan.

i do agree that you cant go to big on the overbore as the walls get thin.

the power my 400 made was very good, i broke the rear 12bolt diff twice, i breifly had a 700r4 in it, while i managed 15mpg, i also destroyed the internals 2 times, then i swithed back to a t350 and broke the input shaft in that. my blazer is now apart and waiting for a late model 6.0 iron block with alum heads and a 4l80e.
 
Lol i love how half the guys say, "Dont do it thats stupid" While the other half say "Theirs nothing wrong with that". Lol
 
manchildau65 said:
The larger bore in the 400 makes thin sections between 4&6 and 3&5 pistons which is why they tend to overheat. The steam ports were put in to help with this issue, but these "middle" cylinders run hotter than the others.

With the right cooling system, proper fan / shroud, and a smart driver (keep an eye on your gauges), you'll be fine. I personally love my 400 and know of a lot of hot rodders tricking out these engines.

To each his own...
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So what are you running for a cooling system?

I am running a newish stock 4 core BB radiator, 160* stat, high volume pump, and these fans. http://www.summitracing.com/parts/FLX-292/
 
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