I've got a chance to buy a 400 block that is just "hone and go" Its bored .030 over and has been run but there isn't any ring groove or scratching. I may be able to get a crank with it but it would need to be turned. Because of a ****ty job and college I'm not sure how long its going to take to build it, but it would be next spring/summer. I've never worked on a 400 before so i don't know much except external balance and drill steam holes in the head, also something about redrilling the starter...

I've got a running almost dead 350 tbi out of a 92 caprice 9C1 Does anyone know anything about the cop car engines-strength/block alloy? I'm driving it through the winter, it burns a lot of oil, but has good oil pressure. The plan is to build a new long block and swap the long block out of the gta into the caprice before next winter.

I want a pump gas daily driver with over/around 400hp and good driveability, For the 383 i'd keep my roller cam (218/224 and 495/503 lift), but the 400 i'd probably buy a 224 or larger hydraulic lifter cam. The plan is to use either engine with pro lightning 200 or 220 cc heads and an LT1 intake.

So what do you guys think? Which would be cheaper the 383 or the 406(remember it is a bare blcok) and by how much. Finally which would produce the most hp?

 

There is no replacement for displacement!!!!

 

let me get this straight. you are thinking of taking a sbc 400 cui motor bored.030 and DEstroke it to get a 383? i know its possible but a 383 is a sbc 350 bored .030 with a 400 crank just in case you are confused cuz i know i am a little.

 

The 406 with the 220 heads will out perform the other two hands down. With either the 383 or the 406 you will need a new rotating assembly. If I had not had as much as I do invested in roller valve train i would have gotten a 406 shortblock instead of the 383.

 

A 400 destroked to 383 would be a 3.48 stroke with a .060 over bore, but that is not what i'm building. If you read the entire post i've got 2 blocks, a factory roller 350 and a flat tappet 400 block i can buy, for the cost of boring out the 350.

Rick Tpi thats a nice z28 you got there. Hows that cam idle? I'm thinking that would be a good overall cam for a 383 and i'd like just a little bigger for a 400, but in Desktop Dyno it is showing hydraulic lifters reaching peak rpm at about 500 rpm later and i'm not sure i want to peak much past 6000 rpm. Does this make any sense?

 

alright sorry i misunderstood.

 

400 no question about it. More cubes, and better bore/stroke ratio... cant go wrong. Use 5.7 or 6 inch rods/pistons and an internally balanced crank, and youll be set! No need to have external balancing done.

 

Same here, when I was looking at the options for a new shortblock availability is what made my choice.

1. I had a 350 roller block, factory block with low limes, I knew the history.
2. Didnt have a 400 block, sometimes they are hard to find, alot of times they are beat or already worked over
3. Retro roller parts a bit more expensive

So I ended up with a 385, and I like it! If a 400 was in my garage I would have ran it.

I also have a XR276HR-12, here is a clip @ idle.

Audio Clip ~225KB

 

406 + retro-roller = Optimal, but of the above options the 383 roller will be the way to go, all other things equal.

Flat tappet cams are poop.... It's all about intensity. Not to mention flat tappets that are large (in the flat tappet world) like to eat camshaft lobes.

 

I'd stay away from the 406 myself. Everything is custom on those engines and parts are expensive. Everything you buy is going to need some sort of modification to get to fit right.

383 is where its at, cheap regular SBC platform, without any extensive modifications. Lotsa cubes, and lotsa power.

 

A 383 isnt exactly cheap. A new rotating asembley and additional block preparation and machine work is required.

 

Thanks. It idles great. Just the right amount of lope to it without affecting driveability. That is due in part to the programming of the C950 ECU. The ideal cam for my app would most likely be the next one up in the XR series. This one was chosen to go with my 350 HSR setup & I later decided to switch over the complete top end over to a 383 shortblock. The same cam on larger cube engine will always peak at a lower rpm, given all other parameters stay the same.

 

What parts are custom on a 406? What parts are more epensive and need to be modified to fit right?

 

The only thing "custom" on a 406 is the crank has to have 400 sized main journals. Most all the crank companies make them & generally cost the same as 350 mains.

 

outside of the block? only the balancer and flywheel.
everything else is 100% stock SBC... heads, cam, accessories, ect.. a cast oil pan may not fit, but it wont fit a 383 either....


the diff is really that its externally balanced instead of internally balanced. once you have the shortblock and flywheel/flexplate, its really just the same as everything else.



i say, save up the $300 more and get the conversion roller lifters for the 400.. you're going to buy a new roller cam for the 383 anyway, so its not like that costs more....

 

well, the 400s really run, I reference mine. But like mentioned earlier that retro roller will get you in price. If i were you I would put the extra cash in the heads (afr, afr, afr) and do a 383 out of a roller block. that would make your car the fastest for the least dough. and that is what it is all about, right?

also, my Cat crank lended itself to be internally balanced. for some reason the machine shop said my rotating assy. would be easier to balance like that. so, i have no special parts on my 400. :lala:

 

I think i'm leaning either toward an eagle 383 kit or building the 406 and installing a retrofit roller cam and lifters at a later time when i have the money. Desktop dyno really likes the big roller cams...

Thanks for the input, keep it coming

 

Nobody will argue against that. Try to avoid a flat tappet cam if possible, there is a night and day difference between running flat tappet Vs. roller.

 

yup.. huge diff with rollers....

look here, a lil more then halfway down, where the charts start:

http://www.compcams.com/Technical/Products/Camshafts/

see the diff between a flat tappet and a roller.... makes all the diff in the world..

 

I have ran with a 406 for about 3 years and about 35,000 miles. I had MAF and SD . Actually I started with a 870 then upgraded to the 165 and finally the 730. The cam was a stock 305,the tpi intake ported with a 58mm tb,30lb injectors. I averaged about 30mpg and could smoke an ls1 or lt1. But there was way too much torque. So that is why I upgraded to a HSR intake and crower cam. The 400sbc will bolt up to your current setup w/o modifications. You can even use the stock valve covers, waterpump etc. Just bolt it in and go. I paid $1160 for the longblock. But like any gearhead I have thousands of bucks on top of that. There was really no parts that was different than say a 350.Other than the flexplate,balancer and internals. I went with a 400 because that is what was suppose to come in my car. But GM didn't have enough ***** to do it. Not to mention that the 400 was killed in 79. But my 87 formula is a 6.6l, just like the old days. The benefits of having a 40X small block is many. You can get away with murder on the streets. You can get a bigger cam and it'll take a smaller stall because of the massive low end. The engine is actuallly more effient in our chassis than a 305/350.

 

I run a 406 myself and I know what works and what doesn't. I was just interested in this fella explaining what he meant by his post.[

 

Hydraulic Tappet cams are just fine. Instead of worrying about the 10-15 hp youll lose from not going roller, start building a MATCHED combination of parts, and you wont have to worry about any power loss.