400's are they any good?

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Doosterfy said:
I just got my hands on a 72 400. I'm new to Mopar so I'm not an expert. I want to know; If the block checks out good with magnaflux and a sonic check, and I spend the money on doing the aftermarket cross bolted mains and good high quality reciprocating assembly, say a four inch stroke for a 480 cube motor, what are the limits of this block? How much power and RPM can these motors handle? Where/what are the weak links? Can they take say 1000 HP 8000 RPM? How strong are these blocks?
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sounds like 451 maybe the limits of the block from what I gather, and that would be with a stroker kit
 
Doosterfy said:
I just got my hands on a 72 400. I'm new to Mopar so I'm not an expert. I want to know; If the block checks out good with magnaflux and a sonic check, and I spend the money on doing the aftermarket cross bolted mains and good high quality reciprocating assembly, say a four inch stroke for a 480 cube motor, what are the limits of this block? How much power and RPM can these motors handle? Where/what are the weak links? Can they take say 1000 HP 8000 RPM? How strong are these blocks?
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A 4.00 crank would cost more money that it's worth. If you're going that far, just a good, in-stock anywhere 4.15 crank...use shelf stocked pistons and rods...

Can the block handle 1000HP with a stock block? Maybe it would...once.

If you're spending at the 1000HP level only choice is an aftermarket block. Are they're even aftermarket blocks available in the low deck version...??
 
can any factory block handle 1,000hp? i wouldnt really put much hope past 750 hp n/a in a stock block. for max hp i think id try a block girdle im not real crazy about adding the cross bolted mains to a block.
 
mopar7172 said:
if don't skroke it out it won't go that fast.because of the low compression it has. they are only good for if u stroke it out.
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??

The 400 is much like the 383. Put some hi comp pistons in it,a big aggresive solid cam and some max wedge ports and you will be well over 600 h.p. But it will be a peaky unstreetable engine. The difference with the stroker is torque,and lots of it and hp in a lower rpm range,and usually a much flatter torque curve.It will make that same 600 + h.p but be streetable,lol..

Everyones definition of streetable varies.
 
66plyValiant said:
sounds like 451 maybe the limits of the block from what I gather, and that would be with a stroker kit
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Incorect. Actual cubic inch max is limited by the 2 factors of it's max bore and max stroke the block can handle from the crank.

A 498/500 cube engine is easy and cost little in difference over a 451.

mopar7172 said:
if don't skroke it out it won't go that fast.because of the low compression it has. they are only good for if u stroke it out.
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As said several times before, the 400 just lacks compresion and then a decent head on top....shold the stock head not be enuff with or without it's stock valves and in a fully ported condition.

In order to get a high compresion engine, you need not have to stroke it. A new set of pistons is all it takes.
 
seems like people still think that. thats ok, keep them cheap. its not like the chances are all that great of walking into a junkyard and finding a high compression 383 or 440 that is still in good useable condition.
 
i had a 400 with 906 heads,torker intake and 510 lift cam in a tubbed 78 p/u. it made good power and gobs of torque. it took 4 years at the track before i blew 3 mains , now im building a 451.
 
All you need to make a 400 go is these simple hot rod rules. Compression,heads and camshaft.
An 11:1 400 with a solid cam would be way to much fun in an a body!
 
mopar7172 said:
no i'm not wrong.400 stock isn't that fast. it only has 170-230 hp. compared to 383 thats stock. your wrong!
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I think he meant you're ignorant. The ratings you're quoting are not apples to apples. If you knew they changed how the power is tested for those ratings in 1972, you'd see they are the same output as a similar 383. Not a big deal, but I wouldn't really take an aggressive stance on your stated factoid...

Dooster - You've already read more than you probably need to in terms of what you "should" or "need to" do. What is your plan? Maybe start a new thread on it... And by the way, always nice to see a fellow Connecticutian on here.
 
What I was actually contemplating is this; Build a good short block with a high quality crank kit with around a four inch stroke, maybe a little shorter on that. Do some sort of reinforcing of the block, either cross bolted mains or a girdle. Go with either INDY or Edelbrock Victor heads with good parts in them. Keep the compression around 9 to 1, a solid roller cam, and a fairly large Pro Charger centrifical blowing through a carb. No intercooler but use one of the metanol injection kits from Snows or equivelent. I'm figuring a combo like this should be capable of 1000 HP. So what I'm hearing so far is "no", or I'm simply asking too much from this block.
 
I'm figuring a combo like this should be capable of 1000 HP. So what I'm hearing so far is "no", or I'm simply asking too much from this block.
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Yea, preety much, it's not like you can fling parts at a engine build and get what you wrote.

First up, IMO, less than 9.0-1, skip the meth. injection kit and boost it modestly with the cam and Indy head set up. You'll make some crazy power but not a 1,000 worth.

Also, big blocks can get a 3.9 stroker kit or a 4.15 stroker hit. You weren't talking small block in a big block thread were ya? LOL! JK!
 
Doosterfy said:
What I was actually contemplating is this; Build a good short block with a high quality crank kit with around a four inch stroke, maybe a little shorter on that. Do some sort of reinforcing of the block, either cross bolted mains or a girdle. Go with either INDY or Edelbrock Victor heads with good parts in them. Keep the compression around 9 to 1, a solid roller cam, and a fairly large Pro Charger centrifical blowing through a carb. No intercooler but use one of the metanol injection kits from Snows or equivelent. I'm figuring a combo like this should be capable of 1000 HP. So what I'm hearing so far is "no", or I'm simply asking too much from this block.
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Since it's a 400 we're talking about and 1000HP is the target then I'm sure that you'll have to go to cross bolted main caps and since the stock caps really aren't sized to do that then you'll have to go to custom made caps. The corresponding area of the inner block skirt will also have to be machined flat to except the new caps so everythings snug. Rods and pistons shouldn't be a problem as far as finding ones strong enough but the crank is another unknown. You're talking a custom crank, pro stock racing strength and you're talking big bucks. With all the money that's going to be thrown at this engine you might want to touch base with Indy engines and see what they've got to offer with short blocks.
 
Just a question here? Why does everyone say that a late 400 or 440 needs high compression to make power? From what I know starting in 70-71 383 block even some HP blocks had their pistons down in the hole pretty good. I understand quench makes more horsepower but, tell that to a guy who owns a 73-74 Super Duty Trans Am. What was the true compression on those? I think it somewhere around 7.9.1 or something like that? I think cylinder pressure is just as important as quench.
Ever drove a 69 383HP with a Mopar 284/484 cam and the rest of the setup was stock? My 360 feels stronger in comparsion than that combination.
Selecting the right cam and getting some head work done is important as well as the converter and the gears. If anybody sticks with the low compression slugs stick a cam on the small side that builds cylinder pressure and doesn't bleed too much of it off is what I was told.
 
a lot of people are just misinformed, like MOPAR7172. compression ratio is just one piece of the whole puzzle. if you dont get out there and try different things, then you only know what you hear, and for many years guys have been saying 360s are junk, 400s are junk, late 440s are crap... some people jsut dont know any better. you can make power with low compression. you can also raise the compression without stroking any engine out there, not only the 400. you can mill heads, run closed chamber heads, thinner head gaskets, and higher compression pistons. stroking is not the only way to raise compression, and it isnt the only way to make power.
 
Mag-mind;

To a degree, your right. A tight quench is good, but not needed. It's just the later and other low compresion engines lack the ratio to run a bigger cam. Most cams are not ground for use on low compresion engines and this is where the mistake comes in.

The cam selection is not fully thought out. The timing events must be thought out before the purchase is made and the cam slid in. Just grabing a Purple 284 and expecting added performance can be a bad move. That cam is a poor choice on a low ratio mill.

Places like Hugesengines advertise on there site a cam for such a low ratio mill. The timing events are customized to add cylinder pressure. Then, like James was saying, milling the heads down some will add help to the mix.

The stock engines should allready have the thin gasket, but, the replacement gasket in kits or blindly ordered will be double the thickness. Having the gasket first so you know you have it will help speed the work. Sometimes, there not easy to get. IDK why, but I have seen complaints here time to time on it's availability.

(The SD Ponco T/A's focused on mad torque production in that 455. And the Poncho motors sure made alot of that! My fav is the 5spd car, Blue and White)
 
I think the 400 or any low compresion engine needs to be looked at carefuly and have some time spent on it with a mic to know exactly where you stand.

Where does that piston sit in the hole? How far down is that thing?

How many cc's in the head chamber? How far can I mill it down without creating issues with head sealing?

Once milled, how much valve lift can I get away with?

Sealing the intake a problem? You have to mill the head on the intake face, but, there is only so far you can go. There can be a problem with milling away the land where the valve cover gasket sits. If you take to much off, the valve covers will not seal.

How much is to much? (IDK.)

If the valve cover rail gets thin, you'll have to go to the intake and mill that, creating a one off intake for your combo.
Write down that number should you want another intake because you'll need to mill that intake to fit before useage.
 
I just took a look at Hughes engines to see what they have for crank kits to go into the 400 block. They have two kits, both with a 4.15" stroke and 4.375" pistons. That makes 499 cubic inches. I'm sure there are plenty of other companies selling crank kits for them too. When I build mine I'm going to aim for what ever the practical power limit of the block is. So far what I'm hearing is that is somewhere around 750 H.P. I think that power level should be able to be reached with a pump gas motor and no power adder. Probly Edel Victor heads or INDYs, a solid roller, and around 11 to 1 comp. All that in a nice low deck motor sounds soooo good to me. In an A body thats a ten second car.
 
I just disassembled my 72 400. the pistons were .100 below the deck and the heads have big open chambers with no quench at all. The head gaskets were thin steel. The pistons are flat with no valve reliefs. Very low compression. I suppose it would be possible if someone wanted to stay low buck to freshen up the stock short block and get heads with smaller chambers. I definately would not blindly order head gaskets and see what you get because of the compression problem. Like I've said before I'm new to Mopars so I'm no expert but did'nt 383s built in the 60's have small chambers? if so those might make a good choice. I also saw on Edelbrocks web site a few months back they had new RPM Xtreme heads with 220cc runners and 80cc chambers so those would help but they kind of push the budget. One other thing worth mentioning is possibly using a flat hyd cam with Rhodes lifters to help out the cylinder pressure at low RPM. They have two styles now, the original ones and a new style called vmax that require adjustable valve train. The vmax ones are adjustable with the amount of lift and duration you can bleed off and they can shorten the duration up to 20 degrees. I know alot of people think/say that the Rhodes are a gimmick but I have used them in a Pontiac and a big block Chevy and both times they worked absolutely exellent. The Chevy was a 9to 1 454 in a 4200 lb car with 3.36 gears and it ran 12.80s
 
Im using the mopar stage vi max wedge heads on my 451 build. These particular heads have a 74-75 cc (measured professionally) combustion chamber.Rhoads lifters have been suggested to me as well,as I need a compromise somwhere due to the car being both street and track.Cam will be borderline streetable .600ish lift.

I cant see using old iron heads for thier smaller cc chamber as being worth while. They take a lot of $$ to bring up to snuff and then you still have heads that will give you 550 ish h.p

The victor heads sound good,should support upwards of 750 h.p without trouble. There are certain 400 blocks rumoured to be capable of 800+ h.p but I think that with studs and billet caps most 400's will survive at this level.
 
capped and studded 400 is from what i've seen is good for 750-800 h.p. the 451 is a great combo but the 498 is better!!! ;-)
 
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