Got a nice 509 casting 400 block with 2 bolt mains. Looking to build around 800 Hp with a Gt 42 We have laying around. Actually we have 2 of them. After talking with my machest, He said if I do any thing to put a Steel crank in it and just keep the RPMs around 6500 or less and just use ARP studs in the bottom end and I should be just fine. That would minimise the twisting that I would get with a cast crank. Also he said that Filling the block or splaying it would not really gain any thing for this type of set up...

I have never actually done a turbo set up So I am looking for advice before I get the machine work done... Boost will probally be around 10 PSI and maybe Up to 15 PSI at the most. I will be putting a steel crank in it for sure. Usually we just put Studs on the bottom mains, reuse the cast crank and keep the RPMS around 6500. Personally I have Never gone over 600 Hp with about 550 Foot pounds of tourque Naturally assperated on one of these blocks. I know guys that have run them to 7000RPM and made close to 700 HP on stock block and cranks.... The blocks are usually filled though...

My buddy did Crack the number 3 main cap in his camaro with a cast crank, But I am not sure how well the caps fit before he put it together... Mine fit really tight. They have to tapped into place before tightening them up. I was told never to force them by the bolts since it could damage them or cause them not to seat properly... So what would you guys recomend Besides the steel crank. I have just over standard pistons with a 6.0 rod combo or a 30 over with a 5.7 rod...


Should I just stud the bottom end???
Maybe Add a Girdle???
Or Go for the splayed Main caps???
Maybe do a 1/2 fill???

#ad


#ad

 

I had a filled stock cap 2 bolt block. With a good 4340 crank and pistons and keeping the rpm down around 6500 I made mine last a year! The weakest link in my opinion is the deck on the 400. Everyone told us not to use a stock 400 block and that we couldn't make 1000 hp and make it live. It lasted a year and we had a blast! I can credit my machine work to mine lasting. Just don't get greedy on the tuneup and have fun! We went [email protected] at 20 lbs of boost weighing 3430 lbs.

 

Good info Were looking at 10 to possibly 15 PSI.... I think 10 PSI would be fine. Only going in a little car that will be around 2500 pounds...

 

Generally, what I do to stiffen the deck up is to tap the 3 large coolant holes and and the 3 smaller ones on the other side of the deck screw in iron pipe plugs, then deck it and drill the coolant holds back the same size as the holes in the gasket. You can also plug the 3 upper steam holes on each side, I have never run into any cooling issues doing this. You need to do this before the final bore/hone job of course. It really stiffens the deck up.

For the bottom-end, if you use the stock main caps, at lest use good studs, but splayed caps will be stronger. The rear main cap on a 400 is the weak link. I would get a steel plate (a few companies make these with the oil pump mounting already on it, or you can make it). You'll have to mill the cap to put the reinforcement plate on, but it will help strengthen the rear cap. No sense bothering with splayed caps if you don't do anything with the rear cap.

Personally, I'd do a short fill. Why not? It's pretty cheap and easy to do.

 

is that a brand new block?

 

Nope had it Thermal cleaned and maged!!! Looks brand new....

 

What should I use to fill the block???

 

grout?

 

Hard Blok

 

Yup. You can get a short fill for around $55-60.

 

ok. what is a block fill and Is this a new bloc you have or cleaned up used? it looks very nice.

 

This is a used Block... I pulled the whole motor out of a Van at Pick Your Part. We took the short block assembly First off we were amassed to even find a 400 second off when we pulled it apart and found that it was standard we were even more shocked. Then I dropped off at my machinest and had it thermal cleaned... they bake it and cleaned it in a Hot caustic solution that removes everything oil bassed, even takes the paint off... they have to spray it down with wd 40 or else it will rust right away... the process pulls all the oils out of the block hence the brand new look...

Were is the best place to get it from???? any tips other then haveing the cylinders straight up and down when filling one side... Should I use a degreeser or acetone or something in the block to make sure there is no Oil contamination from the WD 40???

 

try Summit/Jegs for the fill.

 

The guys have gotten you off in the right direction.

I would NOT do 4 bolt caps.
Pro Gram makes some very nice steel replacement caps and add studs.
Yes, the block will/should be cleaned before filling.
Get a Hard Blok Tall Fill. It has two bags.
One is enough to do a short fill on a small block and you will have enough to do another.

 

I forgot to say that I have the big holes in the deck plugged with stainless plugs and the redrilled and then decked the surface. I also have a fill of hardblock. I guess you would consider it a 1/2 fill. It is almost to the bottom of the water pump holes. Like Robert said, stay with the 2 bolt. You don't want to take any metal away from the main webbing!

 

Thanks Robert!!! My machinest advised me Not to do the 4 bolt splayed. Said it actually weakens the Main Webing... I will stick with the 2 bolt caps and use ARP studs...
I will get the Hard blok this week and do a short fill.

What do you think about A stud Girdle on a 400???

 

definitely do a half fill, atleast, dont have to go full but atleast half

screw in deck plugs are a must to strengthen the deck, they acutally make special plugs just for this app

but it all comes down to GOOD machine work, I have an amazing machinist that has been working with stock 400 blocks since they came out

i have a stock 4 bolt block (weaker), not filled at all (long story), 406" on one stage making somewhere between 900-950hp at 7500rpm

no problems yet

make sure to do internally balanced, worth it for that front main if you plan to rev it above 6500



PS - I am involved with but don't own:
a half filled 2 bolt block converted to splayed mains making north of 1100 hp at 8k rpm on the bottle, so much for that making the block weaker
an unfilled 2 bolt block with splayed mains making just shy of 1000hp at 7k rpm on the bottle

 

just saw another b400 block cracked yesterday.......cracked ont he deck surface & ont he bottom of the block......

Listen.....if you're planning to make lots of HP dont do it twice......it will cost you more in the long run if those mains crack etc....ruinging the rotating assembly. Take the nice clean stock block & sell it.....its standard bore etc.....

You'll prob get $300-400.......and you'll save 600-700 on fully prepping a stock block (deck, bore/hone, align hone, block fill, etc.....and then you may encounter cooling problems even with steam holes.

Another $800 will get you a NEW Dart Little M....which needs nothing but a hone & deck....$1800 for a new Little M - shipped....with splayed caps, no cooling issues (redesigned casting), priority main oiling, and practically indestrucable.

I dunno....turbos make HP easy & if you build a 400 based motor you could be in for a heck of a lot of HP.

My $0.02

-Carm

 

Not trying to steal a thread just a question or two. Should you fill the block and then bore it or does it need to be filled aand then bored? Some people say a four bolt is weaker than a two bolt, some don't. Is there a higher nickel 400 block that is better to use {stock block not aftermarket}? I do agree with the idea that if your building a 400 or any motor and starting with nothing and want it to last you should start with a aftermaket block. By the time you start with a stock block have it cleaned, align honed, bored, decked, etc. you'll have over $1000 in it not including the cost of the block, verses around $2000 for an aftermarket block. It's just not a option for most folks. It use to be speed cost how fast you want to go. Now it's speed cost how fast for how long?

stiill building a 400 and when it goes, time for another one stock or aftermarket who knows,
John

 

fill the block & let it sit a few days BEFORE machining. Make sure you get in there with something (a coat hanger) and move the cement around the cyl walls.....i did this then tapped the block with a hard rubber mallet to make the cement settle (my old 350 block)

-Carm