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400 sbc build

If it runs good now,why waste money and time trying to improve it??...

You might be ahead just by leaving it be,or maybe adding a better intake and carb and cam ,one designed for low rpm use where the 400's have the most torque...

I had a 400 sb from a '78 Suburban in my 77 GMC,it was not the most desireable year with the higher compression,but it made my truck perform better than it did with the '74 454 it had in it that came from a Chevelle,the lower HP emission one rated at only 235 HP and 360 ft lbs of torque...the 400 was lighter,felt more powerful and was a bit better on gas than the big block was...it used a bit of oil ,but I never bothered to do anything about it...

The only things against a 400 sb is they have thin cylinder walls and can crack easy if bored out,and they can overheat easily if you dont have a big enough radiator...I cant say how they compare to newer V8's since I have yet to own anything newer than the late 80's..I'm still stuck in the dark ages as far as they go...
 
I wouldn't buy another motor to build, just build the 400. BUT, if you can get an LS motor for a good price, I'd start there. Got nothin against my 400 or FAST setup, but if I were to build another vehicle (while keeping the blazer) it would need another power plant. An LS motor and matching trans would be it.


Oh yeah, no more two piece rear :)
 
I've had 2 factory block 400's and one aftermarket. A 2 bolt high nickel that I had splayed mains installed(Nelson Racing did the machine work, one factory 4 bolt that I had fully built and blueprinted at Nelson Racing, and also one 482" small block built from a GMPP Olds Rocket Blocket cast in the 90's. All of them have made big torque and HP, totally reliable, and while they run 10-15 degrees hotter, they still run cooler than what modern cars typically operate at. I wouldn't hesitate to build another one if it was idea for my application. I still believe there is no substitute for cubic inches!
 
i thought 400s were bad, until one was in my blazer when i bought it and it had tons of power...i creditted that to the 4.11s in the rear axle, then when i checked the axle it was 3.08s! A stock 400 put me back in my seat with a way high geared rear axle.... I am also building mine and im keeping it under $2k. Will be about 1800 bucks once i finish. 406 with aluminum heads and a torquey cam. Should be pretty fun.

But to answer your question i would definitely invest in it, as long as its a good block. Heads, cam and intake. And if you are building it, as mine as well get it bored to have a better finish on the cylinders. Some guys re-use crank and rods, but im going the route of going to a 6" rod. But many guys use the 5.7s as well. Do your research, because when you get into big cubes in a small block, things get tight, but if done right you will have the power of a big block and it will weigh less and rev higher...my 2 cents...
 
Im just saying, ive driven plenty of trucks with a lower gear ratio and 350s and they had no where near the torque.
 
Won't have the power of a big block. Small block heads suck compared to big block heads plain and simple. A 396 will beat a 400 in power if built similarly. But true there is a weight sacrifice. We are also talking about a vehicle that weighs how many thousand pounds? Buuuut no replacement for displacement when it comes to a similar motor. And anything you can do to a 350 works for a 400. Plus you already have a 400. So I'd say building the 400(as long as it's a good candidate) is your best bet $-performance wise too.

With that said power cost $ so how fast do want to spend :D seriously what's your budget $ wise? Know anything about the motor? How many miles, how tight is it now? Is it box stock? Know what heads are on it currently?

Doing a full rebuild will increase the cost obviously but can yield a better end product. Might be able to do a head/cam/intake swap. Might just swap the cam? That's a 40 year old motor in a vehicle it didn't come in originally I'm guessing? Might have deccent heads on it? Could be rebuilt? :dunno:
 
Thanks for the info, it'll be a dd tho and 2600 rpm will be too much. I was looking for a bolt on head and cam kit quite like the edelbrock 2022. I'm just not sure if there's another brand that'll get me more power and save
Money
 
Also the motor was recently rebuilt, but it was not bored over. And they rebuilt it to stock, I replaced the intake manifold with an edelbrock midrise performer and edelbrock carb. I hv headers I plan to install this week. Rlly I just need low budget, low rpm, high power heads and cam, i just can't decide on wich set
 
slap a set of vortec heads on there and a torquey cam and be done with it then. Heads will be cheaper than aluminum and they do pretty good for what they are, and if you get a cam to match and already have a good intake and headers, i think you would really notice a difference.

Unless you wanna shell out the money for aluminum heads, then i would say vortecs are the best bet.
 
Another vote for Vortec heads, but you'll have to get a different intake.

Martin
 
I think you could get a 400 with the 2.02 or 1.94 heads.

Having casting #'s off the heads would help. Also you know know what your pistons are so you can figure out what compression you have or will have? You want it to run on 87 octane I assume or u mind running premium? Adding the cost of buying another manifold and valve covers depending how you shop and what condition of the vortec heads buying a new set of aftermarket heads might be an option too? There are decent aluminum and steel complete heads out there depending on your budget. profilers are nice and can be had for about a grand assembled
 
454Sub said:
Dont the 400 heads have the larger valves compared to the Vortec castings?
Click to expand...

No 400's ever had 2.02/1.60's from the factory. Most of them had **** heads.

A Vortec with 1.94's will out flow a camel back with 2.02's.

Martin
 
82355 said:
No 400's ever had 2.02/1.60's from the factory. Most of them had **** heads.

A Vortec with 1.94's will out flow a camel back with 2.02's.

Martin
Click to expand...

Aren't there 2 or 3 different "camel back" heads? I know there were smaller humps and larger humps and even some angled plugged factory heads and don't forget the fuelies either.

Don't overlook the fact there are some **** casting truck vortec small block heads that don't flow too well and tend to crack.

But, I think anyone would be better off buying some after market heads rather then dumping a crap ton of money in to 40 year old tech.
 
There are multiple camel backs. None of them are that great. Some are 1.94, some are 2.02, some over the counter ones were 2.05 I believe. Not sure on that. None of them are really that great.

The worst Vortec heads outflow the best camelback. Factory to factory.

Martin
 
cuervo said:
Aren't there 2 or 3 different "camel back" heads? I know there were smaller humps and larger humps and even some angled plugged factory heads and don't forget the fuelies either.

Don't overlook the fact there are some **** casting truck vortec small block heads that don't flow too well and tend to crack.
Click to expand...

there was NEVER a factory angle plug head. Over the counter at gm yes NEVER factory. I have flowed 186s (accessory bolt camel humps) 461 (non accessory bolt camel humps) and both 906 and 041 Vortecs and about another 100 other factory GM heads. Camel humps are a 40 year old design. Once upon a time in a far off land they were a OK head and decent because you couldn't get anything else. Despite the fact Vortecs are lighter and crack if you run the coolant low and get them hot (which camel humps like to do to) and the 906s tend the flow worse on the exhaust than the 041s they are HEAD and SHOULDERS above any other factory casting. I have one set of highly ported Bowties that are close to a factory 041. Bowties to remind you were GM's OVER THE COUNTER performance head in the 80s and 90s. There is a problem that when GM sent the vortec casting to Mexico they started getting much worse and do flow poorer. The fix? Get non Hecto in Mexico heads from the junk yard. I have built a class winning 355 that had nonported 2.02/1.60 vortecs with a 4412 500cfm 2 bbl making 450 dyno proven hp. The is NOT another factory head that would be in that territory without porting and alot of other work. If I was to build a 400 it would have vortecs on it. The rest are good for collector cars and door stops.
 
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