I am building a 406 for my 1988 IROC I have a 400 block (509) casting bored 0.030 over (4.155). I was wanting to know how much horsepower the 400 block will handle with Eagle splayed cap and ARP main studs. I am think about up grading to a Bowtie block. I Have a Eagle 4340 forged steel crank (3.75) and Eagle 6.0 H-beam rods and I am going to buy SRP forged pistons. I want to spray the motor with a 200 shot and maybe a 250 shot. My goal with my car and the 406 is to drive to the track in stock trim with ET streets and run mid-low 10's and drive back home.

 

That is a very good question and one I am looking forward to hearing a knowledgeable answer to because I am in the same predicament.
I do know that the new dart street block is about 1300 bucks, and if you have a factory block, you can spend 1000 dollars in machine work really quick, so that makes the far superior dart block a real good buy.
I am kind of curious as to what one will handle with just main studs and factory caps as well, because if you do this you can stay under 500 dollars in machine work and may make using a factory block worthwhile.

 

Considering the last 400 block was produced in 1979, there are much better aftermarket blocks produced since then. As mentioned above, it can be cheaper to just buy an aftermarket block.

Typically a high HP 400 block is designed for racing. The biggest improvement is to fill the block to stiffen the thin cylinder walls. Coolant only needs to flow around the top part of the cylinders. Filling the block up to the water pump holes makes a big difference in the strength.

Because of the larger mains, there isn't a lot of material in the web around the crank. A 2 bolt casting is preferred over a 4 bolt casting for this reason. I really don't know how much better using splayed caps will do. Simply using studs for the mains is a lot stronger than using bolts.

You're putting a lot of expensive parts into an old block. How much risk do you want to take to make a lot of HP? Is the risk worth a new aftermarket block which will be far superior to an old factory casting? The cost of aftermarket parts is much lower than what they were decades ago. There's no reason to use factory production parts to make big HP.

The only thing factory about my engine is the alternator.

What kind of 10 bolt do you have that has 30 spline axles? Factory 7.5/7.625" 10 bolts are only available with 26 or 28 spline axles.

 

friend of mine is using a factory block runs mid tens on motor and 8.8`s on the hose, got some videos somewhere.

 

Will a GM Perforamce Parts Bowtie block with splayed caps be a good aftermarket block to use?

 

How long has he ran the motor? Does it have splayed caps and main studs? Does it have forged internals? Do you know what casting block it is the last 3 numbers of the block number? How much nitrous does he use?

 

What kind of 10 bolt do you have that has 30 spline axles? Factory 7.5/7.625" 10 bolts are only available with 26 or 28 spline axles.[/quote]

The rear end was in the car when I bought it, I was told it has 30 spline axles and a bigger 10 bolt so it is either a 8.5 10 bolt or its a stock housing with 28 spline axles. The previous owner did not tell me about the rear end. Someone else did. So I don't really know The rear end is pretty strong I have launched it with slicks on the street a few times and the previous laughed it on slick every time he went to the drag strip and he launched it with nitrous many time too. I plane on upgrading to a 12 bolt or 9inch when the 10 bolt breaks. How can I tell if its a 8.5 housing?

 

No other factory differential will be a direct fit into a third gen other than from another third gen or a fourth gen.

It's possible you have a Dana 44 diff. Look at the rear cover. 10 bolts on the cover doesn't tell a lot since many diffs use 10 bolts.

Smooth rear cover, 7.5/7.625" 10 bolt
Metal fill plug in rear cover, Dana 44
Rubber fill plug in cover, 9 bolt.

GM also produced an 8.2" and 8.5" 10 bolt but to use the third gen's torque arm, there would need to be a lot of modifications done to attach the torque arm. The shape of the cover is different between the 8.2, 8.5, 7.5/7.625 10 bolts.

Personally I think you probably have a factory stock differential. Your 88 will have a 7.625" (7-5/8") ring gear (everything is the same as a 7.5" but with a slightly larger ring gear) with 26 spline axles unless a previous owner changed something.

 

http://www.myspace.com/drivelinesolutions


I know he had it filled with hardblock to the waterpump and it had all 5 main with splayed caps, I`m sure he was using at least a 4130 crank/rods and I know he has two kits one set at 300. past tense because of a problem with the #4 bore, had some ring gaps to tight and tore it up.

 

How long did he run the motor? What does block filler do to the block?

 

I am not sure about the bowtie block, but the new dart special high performance block is only 1400 dollars. It is also a better block for street use than the motown or iron eagle due to the casting materials, according to what I have read about it so far. It is plenty stout for the kind of motor you are building, so I could not see spending any more money on a Bowtie block.

 

I agree. The new Dart SHP block is the way to go. All you have to do is the final bore size.

 

It's a form of cement. It flows around the cylinder walls to make them stiffer. The downside is that it adds a lot of weight to the block. Aftermarket blocks have thicker cylinder walls eliminating the need to fill the block.

 

I know he had at least two seasons on it before the mishap

 

Sound like you rotating ***. will be fine. the block use for street and tract as you indicated with the power you want to use needs the block hardner as a short fill, but this should be done b4 bore and hone the block filling makes the bore smaller. then plug the water jacket hole on the top of the cylinder bore and drill them out smaller,just like the head gasket, this adds the most strength. what happens is the block wants to twist and crack at high hp levels so you must make them not flex. also cylinder wall thickness is what will limit your hp. main studs and girdle also help along with head studs too. are the part lightened for high rpm and is the block a 010 020 block?
i would limit to 600 hp and tq for mid 10's and still drive to the track. instead of getting a after market block go with an LS motor and have 600 hp on pump gas w/o nos, turbos or superchargers

 

How does hard-blok make a block heavy, it just replaces water which weighs a lot, so it may seem heavier before the motor is installed, but will make no real difference once filled with coolant.

 

I am going to buy a 400 Dart little M sportsman block and get it bored to 408 (4.165 bore) (3.75 stroke)
Does anyone know how much horsepower a 408 will make with Dart pro 1 heads a big TPiS cam and a TPiS mini ram intake?

 

Do not bore a block for 8 cubic inches, the cost and waste of the block life are so not worth it, just leave it standard bore so you can rebuild or repair the block as many times as possible.by boring it over you are effectively taking two rebuilds away, and after your first,when you need to go .060 over you can buy shelf pistons, but any other rebuilds will require custom pistons.
If you want more displacement, buy a stroker crank, you can get 3.800, 3.875, or 4.00, You will get way more bang for the buck than a .040 bore.

 

Check this thread on factory 400 blocks.

http://www.speedtalk.com/forum/viewtopic.php?t=14195

 

I am glade you posted this, because I never thought about taking two rebuilds off of the block. What cubic inch will a standard 400 with a 3.875 stroke make and what will a 4.00 stroke make?

 

After read this thread ^^^^ I think a dart block will be a better choice. With a stock block its a 50/50 chance I maybe able to run my stock 400 block with nitrous and not have a problem but the block might crack a year latter.

 

I believe a stock bore will make 415 ci with 3.875 and 427 with 4.00. I was under the impression that you had already decided to buy a new dart block and bore it .040 over with my last post, a factory block will probably have to be bored .030 or .040.

 

Using a factory 400 block for high horsepower is like playing Russian Roulette.

 

I had a 406 that was spitting out 600hp,briefly.You have WAY too much money tied up to drop it all in a stock block.I split cylindrs in a block,and I cracked the main webbing out in another block.The only thing I can figure is,you can only make so much power before a stock block breaks.
Dart or World Products is the way to go,you'll be safe now,and you can make a big cube engine later in the same case.

 

I am going to buy the dart little m block. If I buy a 4.00 eagle crank and use the 6.0 eagle rods I already have that will be a 427? Can I use a normal TPiS cam and not a small base circle cam? Would a 427 sbc be street able?

 

one of my dads friends use to run alcohol cars most of his life and he is retired now and just "plays" as he calls it. he swears by a well built 400sbc. he is doing an s10 pick up tubbed, 4 link, cage...ect.....i do not know what all he did with the engine but it is a 400sbc not aftermarket and he twin turboed it. he says it will be around 1200 hp and depending on boost even more then that. but this is whats cool, the A/C will work to....lol. he is old and says **** being hot...lol

 

Yes, a 4 inch stroke will give you 427 with a stock bore, You will more than likely need a small base circle cam, a small block 427 will want a large cylinder head, 220 or bigger, you will also want a big intake, a super victor will work, but there are other intakes designed for big inch motors like this. You will also need to consider header primary size, I would say that 1 7/8 would be minimum, but others may have a different idea.
Building a big inch motor is the best way to get good horsepower, but do not forget to that you will need to feed those cubes. Most small block parts are designed for 350-383 ci motors, You will be running big block displacement in a small block package so plan accordingly.
I am not sure of your plans for this motor, but I believe you are probably better off with the dart SHP block, It will handle just about anything a NA street strip motor will throw at it, is cheaper by about 700 dollars, and only needs to be honed to be ready to run. The Litle M block needs decked and bored and honed before you can run it, and from what I understand has to hard of cylinder walls for a good street motor.

 

Friend of mine ran a stock 400 block bored 0.030 over with a 3.800 stroke, hit 9.9 in the 1/4 with a 150 shot in his 74 bird

that motor been going for a few years now

 

Pontiac or Chevy?

 

SB Chevy, sorry not stock to the bird, I ment stock as in not an aftermarket block

 

Lots of people have had good luck with stock 400 blocks,some do not have good luck and it cost them dearly, plus you have to spend nearly 800$ on machine work,(billet caps, hard-blok, decked, bored, honed, aline honed, hot tanked, clearanced) plus 200$ for the block, is it worth it to spend 400 more on a block that has several rebuilds in it, plus the added strength? I would say yes.

 

I am think about just buying a 6.0 LSX and building it.

 

dont forget the stupid steam holes and the siamessed cylinder bores. i always heard that stock production blocks are good up to 1000hp before being prone to spliting.

in any stroker aplication its wise to go small base cirlce camshaft.

im running a 350 block bored .40 and stroked to 3.75, its pretty stout and snappy, my machinest said 150 shot should be my max, he estimated with my componets around 500fwhp n/a.just be sure to have it balanced, and have good internals espesially rods.

 

If I were building another motor from scratch I would go the ls route as well, some parts are more expensive, but the blocks are awesome so that will save you a good amount, not to mention great cylinder heads, I would say that LS is the way to go!

 

I've read that some of the 400/509 blocks were bowtie casting.
so you could have a heavy duty 400 sbc.

I've often wondered if it was the blocks that have the 509 cast into the side of it?

 

gm took 10 years and spent 100 million dollars designing the ls series motors.

I want one but I have 3 400's and it's hard to let them go because i know the power i can make for little cash.

 

Like I said in my above post it is like playing Russian Roulette. Will it hold the horsepower or will it not? Some 400 blocks will hold more power than others.

 

"A successful 400 buildup requires slightly different techniques than the ones normally used on its shorter-stroke sisters. The long 3.75-inch stroke combined with the 400's short 5.565-inch connecting rods yields a 1.48:1 rod/stroke ratio, which is not conducive for building a high-winding engine. The 400's rather severe rod angularity and high piston speed put high thrust loads on the cylinder walls. For these reasons, the savvy 400 builder would do well to concentrate on building for low and midrange torque. Premium head gaskets and precision machining and assembly techniques are recommended to avoid head-gasket problems on this siamesed cylinder-wall engine"....

-Car Craft

 

nice quote, dead on!

 

Incomplete, I'd say.

5.7 rods & pistons are simple to come by and improve the situation significantly.

More care is required picking a factory 400 core, but after that it's the same basic SBC principles in play. But, if anyone asks me how much power a factory 400 block would handle, I would answer, "Wrong question. The correct question is, 'Do you like my aftermarket block 400 SBC build-up?'"

 

Just to touch on this, I built mine about 5 yrs ago, found my block had .020 core shift, had another block that had a nicked cylinder. I decided to try the one with core shift - I kept it 2 bolt main, just studded,scat cast crank, Cat 6" rods and SRP pistons. Engine has been running high 10's N/A for most of the duration, pump gas and had always been driven to track and sometimes driven to Maryland 5 hrs up and back. I did spray it a few times with a 150 shot to 10.09 best. Has treated me well, I pulled apart last year for bearing freshen-up, decided to keep same rings being they were just broken in. Car does spit a puff of smoke every so often likely due to the core shift, but runs great, has not failed me yet. I would say it has 10,000 or more street miles. I do not run steam holes either.. Just my experience.
May not treat someone else as well, but I did not have the 2k to spend on a dart block, If I had it would be a 434
I am not scared to throw more N2O to it either, will be soon I hope.

 

Here is a picture of a GM 400 block in action.

 

I am happy to hear of your good fortune, and I do believe people don,t give the 400 block enough credit, I believe it is a fine block for most cars under 500 hp, the problem starts when people want to do billet main caps, hard-blok, and all the other machine work, the machine work is so expensive that it is just not worth fooling with a stock block, especially with the new dart shp block, which does not cost much more than what you will have in a stock block when it is all said and done.
Which brings me to another point, cranks, rods and pistons, I see way to many people spend there hard earned money on a high dollar bottom end for cars that would be fine with stock parts with good hyper pistons. Why do people feel the need for a 600 dollar crank in a 450 horse motor, or whats even worse, an american crank in the same motor.Wow, I have run several motors into the 11s with stock cranks and rods with ARPs, granted, an aftermarket cast crank and cheap I-beam rods would have been a better fit, but how many times have people seen a broken cast crank? The only ones I have ever seen have to do with motor mis-assembly, not cheap parts as they will so quickly assume, The same with pistons, The only hyper pistons I have seen fail are always because of detonation or miss-assembly, any piston will fail under these circumstances, and they should be avoided now matter how much money you spend on pistons.
Well, sorry to ramble, I just noticed how 87-ta managed to build a motor without huge amounts of cash, and it has served him well, and felt like sharing my opinions.

 

1455 from summit but its not machined. CNCBlocksNortheast sells them for 1800 machined plus few more bucks for cam bearings/free plugs. Thats what i'm getting for my 400

 

I was under the impression that all the machine work an shp block needed was a final hone to your piston, what else may they need?we know the decks on a new block are going to be paralell, dart align bores them, what else is there, is that other place charging 350 dollars to hone them?

 

no i'm not sure what else they need but they are far from ready to go from what i'm being told. Its more than a hone the cylinders type deal, they needed checked everywhere

Two dealers of these blocks are saying the same thing

The block all machined and ready to go means Main line is line hone, deck to your demension, blue print bored and plate hone, llifter bores checked and clearanced if needed, oil galley holes tapped deeper if needed cleaned and shipped for 1795.00

http://speedtalk.com/forum/viewtopic.php?t=12112

 

All the machining should be done on an SHP, except for the cylinder wall finish.

 

Dart advertises these blocks to be ready to go with just a hone, I believe if I bought one and the line hone was out, I would send it back, same for all the other measurements, they are supposed to be ready to go, but every new part needs checked before assembly.The same for a set of heads, if I bought dart headsa and the guides were out of spec, I would send them back, it sounds like some people just have a machine shop fix these quality issues, but I believe Dart would stand behind there product if given a chance.

 

It's not a quality control issue. They're sufficiently finished, they may just not be finished to someone's desired specifications.

 

Well alot of the shops i've talked to have a great reputation. Spending a few extra bucks to make sure your getting the quality the block should have is wise. Mass produced products arent all the same, so i'll pay a few more bucks to have the block prepped properly to verify the dimensions, and decked to my specs. CNCblocks ship the blocks for free so 1800 compared to 1455 plus shipping seems like a good call to me to ensure your getting what you need