[Robinson Robin]

well I agree that some of the 400 design was a compromise and yes it wasn't designed as a performance motor. The saimesed cylinder design no doubt was a compromise at the time how ever it one of those quirks of fate it kinda did turn out to be an advantage in that i made the block more rigid which is probably part of the reason for its continued use in some more modern engines

[rifraf]

A fine example,the ZZ502,the mellower 502 is the upgrade for the 454 trucks needing more pulling power,and if your pulling,your making heat. Also the 502 was used in offshore race boats,now that is pushing a motor,its like pulling a mountain pass nonstop.

[Robinson Robin]

Exactly

[406 ss monte]

Originally posted by killerformula
?? Well that was off subject 406. I have never once stated in this entire thread that the 383 was better than the 400. I also never said the 383 crank was better, all I am doing is defending the wives tales about the 383, just like you are doing for the 400 . My point, if you read, is that the 383 crank, even if it was once a 400 crank, is not weaker than a 400 crank just because the journals are smaller. If you don't understand that, talk to a machinist, because I've explained it as best I can and I know its true. As far as displacement is concerned, I doubt seriously that the 17 cubes really makes all the difference in the world either. I'm sure it makes some, but you'll make more difference with proper tuning and good parts than 17 cubes will promise you.

So yes, 406, it is a good one, and a true one. Read the posts and get your facts.

K

killerformula , chevy debated on using a 350 block & a 4" stroke, but instead went with the 4.125 bore & 3.75 stroke. the reason being siamese bores are stronger, just look at a few of the after market blocks. they also went with a bigger main for more strength over the 350 main size. the 400 put out over 400 pounds of torque bone stock. that was another reason they made the jump to a large journal over the small journal 327 blocks, they just took it one step further in the 400. now all you have to do is pick up a copy of "how to hotrod small block chevy" & it tells what all went into their design & why. i never said a 406 was better than a 383, but i will now (at least as far as horse power & torque goes). if you build a 383 & a 406 using the same parts & have them both tuned in right, the 406 will make more power & torque than the 383. no brag, just facts.

[cadallac]

one thing you all have forgot is what the engin will be used in if it is to drag race you don't have to worry about heat because the engin will only go a short distance and you can cool it when the run is over with

17 cubes think of a motorcycle with a 17 cubic inch motor and add that to your motor

[killerformula]

Ok, cool. I think we're on the same page now. First off cubes definately equal power. So yes, same parts, same tune and same car, your 406 is going to make it to the end of the 1/4 faster, no question. The problem with these motors in particular is that people get an education about engines through hear-say. They take something somebody told them at the track one day as gospel and it really needs to stop when we get into a technical conversation. I'm definately willing to accept anything people can prove to me about a 400 chevy, and I think this thread is useful to get rid of myths. THere's a reason that chevy never used their biggest cid smallblock motor for performance. THe reason they probably didn't want to use the longer stroke is more probably block design. With a stroke that long you'd have to use a different, weaker cam, and clearance the block a ton. BTW a larger journal accomplishes the same task. .200 of metal is not going to make or break a crank, it simply moves the center of the rotating assembly down a little bit more so you dont hit the cam.

Siamesed walls still bother me. They allow heat to build up in the engine and pass from one bore to the next. I think chevy was worried about them too, so they never punshed the motor too much.

K

[Steve karch]

I may be wrong here but this is what I think. GM didn't develop the 400sb as a performance engine because when this engine was introduced the performance era was over. This motor was developed to be used in trucks as a torque motor. The extra displacement was used to compensate for the effects that the emissions systems of that era had on power. GM would be remiss in developing this engine as performance motor as there was no market for a performance motor at that time and it would be money wasted. This scenario seem logical to me. It took a while before the performance aftermarket took notice of this engine and began to understand it. That is why performance development has bee lagging. Correct me if I'm wrong please but that is the way I see it happening.

[Robinson Robin]

Yes i agree theorieretically siamesed cyl shouldn't be as good at disipating heat how ever in the real world it seems to cause very few problems

[rifraf]

Killer,turning the crank .200 does not move the center of the rotating Assembly,it mearly accommodates the smaller mains. I say the cranks are weaker because Ive seen with my own two eyes a lot of broken ones. A better alloy crank is fine for that combo,but thats more money. Being an automotive machinist,I can tell you,a loss of material equates to less strength,thats a fact,and .200 is significant. Don't get me wrong,they have their place,I build 383 chevs often,but I recommend them for lower rpm torque applications,4x4s ect.

[406 ss monte]

Originally posted by Steve karch
I may be wrong here but this is what I think. GM didn't develop the 400sb as a performance engine because when this engine was introduced the performance era was over. This motor was developed to be used in trucks as a torque motor. The extra displacement was used to compensate for the effects that the emissions systems of that era had on power. GM would be remiss in developing this engine as performance motor as there was no market for a performance motor at that time and it would be money wasted. This scenario seem logical to me. It took a while before the performance aftermarket took notice of this engine and began to understand it. That is why performance development has bee lagging. Correct me if I'm wrong please but that is the way I see it happening.

YOU HIT IT RIGHT ON THE HEAD! chevy put these engines in trucks & LARGE cars for two reasons. emissions, & they had the torque to pull the extra accessories & the weight of the heavy cars/trucks. they didn't plan on hopping them up, thats why they never had steel cranks from the factory or even a 4 barrel carb, but the block design was done to make it as strong as possible to take the extra torque the 400's made (i have seen one with a 4 barrel & 186 heads from the factory) . i'm hear to tell you, if i hadn't found a 400 block i would have built a 383. 383's are great performance engines & shouldn't be over looked at all. for the average street car a 383 is all they will ever need. there's to many 600 hp 383's running on pump gas to over look them.

[rifraf]

If you look back to the beginning of the smog era,you will find that many popular motors used the increase of cubes as a remedy for loss of compression and other choking changes.396-402/427-454/350-400/429-460/430-455/383-400/ unfortunately they also realized they no longer needed all cool extras,but the foundation is there to have the best of both worlds.

[1BAD80]

I never had a crank fail either, or anyone I know of.
After I get one ground I have it magnafluxed and ultra sound for cracks just to be safe. But never had one fail.
This folklore is getting good.
There are at least 16 gearheads that have posted to this posting.
How many really built a 400 motor and have it in their ride, and not heard it from someone else?
The ones I know, no need to reply.

[Deuce]

[QUOTE
How many really built a 400 motor and have it in their ride, and not heard it from someone else?
The ones I know, no need to reply. [/B][/QUOTE]


I have NOT posted on this............it is all kind of silly....

Build what you want and just OUTRUN the rest.......

I have build 383's and 400's and had them in my ride.
I also built a 434.........Little M block and a Eagle crank

I prefer a 350 in my 32 Roadster.......
I know that the larger engines make more torque and Horsepower....but in a light car like my 32 (2240 lbs)........the 350 is quicker. It revs higher, faster and is easier to HOOK UP. The 350 lacks the low end of the 3.75 and 4 inch stroke engines and LEAVES better.........then revs quicker and higher once I get it HOOKED.......

[DragTour69XL]

BB Man!!!!

[lluciano77]

Originally posted by Deuce
[QUOTE
How many really built a 400 motor and have it in their ride, and not heard it from someone else?
The ones I know, no need to reply.

I have NOT posted on this............it is all kind of silly....

Build what you want and just OUTRUN the rest.......

I have build 383's and 400's and had them in my ride.
I also built a 434.........Little M block and a Eagle crank

I prefer a 350 in my 32 Roadster.......
I know that the larger engines make more torque and Horsepower....but in a light car like my 32 (2240 lbs)........the 350 is quicker. It revs higher, faster and is easier to HOOK UP. The 350 lacks the low end of the 3.75 and 4 inch stroke engines and LEAVES better.........then revs quicker and higher once I get it HOOKED.......


[/B][/QUOTE]

I built a 400. I can say from real life testing that it does not have any cooling issues. In fact, I think the old 307 I had before had more cooling issues.

I do however recommend a higher pressure oil pump. That myth I believe is true. The 400s will have slightly lower oil pressure.

As far as streetability and performance, the 400 is superior. If anyone heard my car idle, and then went for a ride and saw for themselves how effortlessly my 400 moves the sheetmetal, they would be convinced as well.

As far as leaving better, what kind of arguement is lack of low end torque! If you tune your suspension right, run the appropriate tire and rim, and have then proper traction aids, that is when you can say your car leaves harder. Based on the lack of bottom end arguement you might as well run a Chevy 6 or 4 cylinder, right? 2 hole spacers, ignition and carb tuning can help if you don't want to mess with the correct ways of tuning your launches.