[Nskeeter99]

My 305 finally died, I wont to go with a 400. I have used the search button on here before ya ll flame the hell out of me. From what i have read about 200 hp is all you going to get form a stock set up. So is there a set of hp heads for the 400, and if not do they respond to port and polish? My main question is what all vehicles can i look for this in and what numbers beside 6.6 on the emissions tag? I do know the 2 bolt is the better one.

My plans are simple
comp cam extreme 4x4 268
vortec heads. (with steam holes )
edelbrock air gap intake.

 

[trkklr77]

any sbc head will bolt on you just need to drill the steam hole.


a stock 350 is only 185 hp.

everything like to breathe better.

2 bolt is not the good one, a 2bolt is fine, a 4bolt would be stronger if you were going for 400+hp.

trucks and vans are the only places you will find them.

 

[TEX]

4-bolt 400's were never offered in trucks or vans AFAIK. '70 & '71 full-size cars are where you'll find them (most if not all are 2-barrel carbs too IIRC).

 

[Red Chevy]

From what I have read that if u are after the most strength from a stock block u should go with the 2-bolt and have a machine shop convert it to 4-bolt. My buddy is building one now and that is what he had done in Shreveport. Something about the 2-bolt having more material in the casting even after u drill for the 4-bolt, than what the stock 4-bolt has.

 

[77k5]

any sbc head will bolt on you just need to drill the steam hole.


a stock 350 is only 185 hp.

everything like to breathe better.

2 bolt is not the good one, a 2bolt is fine, a 4bolt would be stronger if you were going for 400+hp.

trucks and vans are the only places you will find them.

4 bolt 400's are notorious for cracking their main bearing caps, that's why people generally prefer the 2 bolt 400's. Just another thing on the list of things GM mis-designed on the 400.

If you want to build a 400 your plan sounds good.

 

[Da10er24]

From what I have read that if u are after the most strength from a stock block u should go with the 2-bolt and have a machine shop convert it to 4-bolt. My buddy is building one now and that is what he had done in Shreveport. Something about the 2-bolt having more material in the casting even after u drill for the 4-bolt, than what the stock 4-bolt has.

A guy I know did the same thing and has been running about 390 horses for over a year without a problem..

 

[Nskeeter99]

I dint think i would see them in to many trucks, I was thinking cars. just dint know which models are years.

 

[abig84]

trucks and vans are the only places you will find them.

heres what mine came out of
CSA 1976 400 LT4 U 175 4 A/Bel Air/Kingswd

great engine. i had 305s and 350s before those engines dont even compare. i had a suburban with 38 inch tires and 373 gears and i could tow a car and i wouldnt even know it was there untill i went to stop of course

i even have the factory 2 barrel and i think its only a 2 bolt main too

you can check out this link
http://www.nastyz28.com/gm-chevy-codes/chevy-engine-codes-suffix-3.php

go about to mid page and youll see a bunch of 400s and what they came in

 

[cj8scrambld]

Yes, it is the 2 bolts that are converted to splayed 4 bolt mains that are ideal. BUT, the 2 bolt will be fine for up to about 500hp IIRC....and I think keeping it less than 6000rpms most of the time. For a torquey truck engine with mod. revs a 2 bolt is fine......and as mentioned stronger than a OEM 4 bolt << due to cracking the webs.

The Vortec headed 400 (**steam holes**) built with low rpm TQ in mind can be a very strong runner. A 400 naturally helps to unshroud the intake valve vs. a 350 (for example) simply by having a larger bore. The large bore and longer stroke just loves to make TQ.

 

[jenks21]

The harmonic balancer is usually different than the 350's and 305's Most 400's are externally balanced and 350's are usually internally balanced. The difference is that the 350's are smooth all the way around, and the 400's would have a notch missing on the back side for about 1/2 the distance around. I have one I would sell but IL is a long ways from Louisiana.

70's chevy impalas and caprices are a good place to look especially the wagons........if you can find them. Demo derby guys like those cars.

later, jenks

 

[BeefCakeScout]

IIRC 400's also have an extra freeze plug. spotters guide stuff

 

[b454rat]

2 bolt mains have 2 plugs, 4 bolt has 3 plugs.

400s are friggin awesome motors. I had a handful, and loved them all. If I had the money and a place to store them, I would snag every one I find.

If you want a killer street/truck engine, follow this recipe, I plan on doing this to both my 400s.

.30 block, KB pistons, IIRC part # 128, with 64cc heads aboot 9.8.
Vortec heads, bigger springs, stock is less than .480 lift.
Comp Cams Xtreme Energy 268 cam
Performer or RPM style intake
At least a 750 carb
1 5/8" headers, 2 1/2" exhaust.

Been looking into this build, and with this stuff the motor will make about 425 horse and 450 ft/lb of torque. All on pump gas.

As far as 2 or 4 bolt, inless your building a race motor, either will be fine. Just whatever you do, get a NEW balancer, and get the whole rotating assembly balanced.

 

[77k5]

I made the choice to use the much better 350 block with a 400 crank rather than trying to deal with the problematic 400 block.

Sure, I guess I lose 20 cubic inches but I enjoy the fact that my motor doesn't overheat every time you look at it (and there will be lots of people that love 400's that will argue this point to death but they are MUCH more prone to overheating than any other SBC)

IMO, GM engineers did not design the 400 correctly and that's why GM did not use it for very long.

 

[b454rat]

I hear that all the time bout 400s overheating. Alot of it is do to owners not maintaining them, or boring them more than .30 over. I've had alot of these, and only 1 ever had any problems, and that was only getting warm. It never got too far over 200, but it would sitting in traffic. Could have been cause the truck was black, but unlikely. BUt the motor was .40 over, had new rad and pump, so no that wasn't the problem. I know alot of guys who run these, and they never have problems. Buddy had a 434 that made 750 horse, that didn't overheat.......

 

[TEX]

I've got a .040 over 400 & VERY limited cooling capacity, and haven't had an issue yet with my 11-year-old build

Oh, and NASCAR 358's are actually destroked .030 over 400's

 

[abig84]

(and there will be lots of people that love 400's that will argue this point to death but they are MUCH more prone to overheating than any other SBC)

IMO, GM engineers did not design the 400 correctly and that's why GM did not use it for very long.

..... aw the heck with it. you know what im going to say.. i had my 400 for years and never over heated it and its great blah blah blah :flipoff2:

 

[Nskeeter99]

I'm assuming when you say 2 bolts have 2 plugs and 4 bolts have 3 plugs your referring to freeze plugs? flame if need be but what in the hell does iirc mean?

 

[BeefCakeScout]

I've seen the overheating problem with 400's before. and they do tend to run just a tad hotter than other smallblocks. but thats normal for any block with siamesed cylinders. my uncle ran his 406 for YEARS without overheating PROBLEMS. make sure the block is clean when you start and practice routine maintenance

 

[bigchevytruckdriver]

my uncle is a machinist and he swears by 350 ci block due to overheating issues but says if you must run a 400 run an electric fan in addition to a flex or clutch fan and maintain the cooling system meticulously flush yearly and definite 50/50 antifreeze water mix

 

[abig84]

I'm assuming when you say 2 bolts have 2 plugs and 4 bolts have 3 plugs your referring to freeze plugs? flame if need be but what in the hell does iirc mean?

my 2 bolt 400 has 3 freeze plugs

I've seen the overheating problem with 400's before. and they do tend to run just a tad hotter than other smallblocks. but thats normal for any block with siamesed cylinders. my uncle ran his 406 for YEARS without overheating PROBLEMS. make sure the block is clean when you start and practice routine maintenance

that might be why i never had any over heating problems. i got a all new cooling system. new waterpump, radiator, hoses, also got a heavy cooling fan clutch.