hey everybody, im aiming for an engine swap next spring and am going to begin collecting parts here shortly. i want to get 427 cubes, and right now i have a 400 block that has been decked and bored and all that. so i was planning on putting in a good 4" crank to get my CI goal (since its bored 30 over i know it would actually be around 433 but id still call it a 427 ) but recently someone told me that with a 400, when you put in a 4" crank you have to take so much material out to clear the crank that you can cause lots of problems (ie leakage from the jackets) and i was just wondering if this is true and if anyones had any experience with this combo. should i got with a different block like a dart or world? or what other combos are possible to get the cubes i want?
thanks

 

talk to ski_dwn_it.

He knows what is up.

 

Hi neighbor!
You are going to have to have the 4" stroke to get anywhere near the cubes you want. Personally, I don't know of anyone that has done it with a production block. But I'm sure it can be done. Check with your favorite machine shop. I used a Bow Tie block.

RACE ON!!!

 

For that many cubes use a Bowtie block...

 

you would have to have a 4.125" Bore, 4.000 stroke, and 6.000 rod(according to Summit) is 4.125" even safe for a small block?

 

4.125 is the standard bore for a 400 small block. Mine is bored to 4.165 no problems...

 

Thats what I was thinking. It didn't specify a 400 block..I was thinking that was a lot for a 350.

 

You can fill the block the the bottoms of the freeze plugs with block fill or whatever they call that stuff. Thats what my machinist does to assure that there are no leaks when they grind away for crank clearance. Plus that stuff stiffens up the block as well. It can be done, but its not cheap and of course the best way is with a Dart Little M, Bowtie or other aftermarket blocks.

 

You really want a block that is already set up to do what you want.

The biggest issue is crank clearance in both the bottom rails AND the cam. When you go to a 4" stroke, the cam will need to be a small base-circle to clear. This causes the cam to be weaker, and could cause issues down the road depending on lift, duration and spring pressures. You'll also need to have rods that don't have too much material on the big end to clear the cam.

They'll also need to notch the pan rails to allow clearance.

Like TJ said, an aftermarket block is the way to go in this department. I'm building a 427 SBC right now, and have been for over a year. Start out with a block that has a raised cam and widened pan rails. We are going with the Rocket block, but Dart and World Products make excellent pieces as well. They also have more material in the webbing to reduce flex internally in the block.

Sell the 400 block to someone who wants a mild street motor and get something that lasts. You'll get at least 2-3 rebuilds from the aftermarket block. Once you bore that 400 out, you'll need to sleeve it the next time. There isn't enough material left in the walls to bore it again. And sleeving isn't cheap, either....

 

hey

we built my brother a 434 out of a stock 400 block .

what you need to do is:


1 half fill the block only if you want to drive it on the street.

2 you need the smallest base circle cam you can get . i went with an .875 . you could go with an .850 give you little bit more room btween the rod and the cam.

3. if plan on using H beam rods you would have to grind in the side of the rod to make room. so i would go with an I beam rod you get more room i think .

4. make sure you mock up everything before you balance . if everything clears rods , cranks balance it .

5. make sure you dont get a 4 bolt main block . because the stock 4 bolt sucks . get a 2 bolt and convert it . if you want find some one that can put some dauld pins on the mains .

6. if you use head studs make sure you use alot of that arp bolt sealent, because stock 400 block like to leak coolent from the studs. it sould be fine with just bolts.

if you got the money i would go with an aftermarket block . it would make your life so much simpler and you would be able to spray the motor all you want . a friend of mine if going high 8's with a stock factory block . they are strong if you spend some money on them .

thats all that i can think of right now . feel free to give me a call if you want more info ill PM you my number

 

My advice.....if you want that many cubes, get an aftermarket block. By the time you do all that is necessary to make a 4" stroke work, you could sell your block and get a new, better aftermarket block for not much more $. If you're willing to live with a 406, then the stock block is fine.

 

 

thanks everybody, i guess the best route would be to go with the aftermarket block but man, they sure are expensive hmm, ill have to think about it

 

"Those not wealthy cannot afford to be cheap..."

My favorite quote from a customer of mine when the engine I built him cost more than originally planned.

A standard 400 block can be built into a 427/434 with clearancing of the pan rails for stroke (rod clearance). You'll be limited on the amount of power it will withstand if concrete isn't used, however. The better bet is to use an aftermarket block; whether a Dart, Bowtie, or World as others have stated. Don't cheap out on your build, you'll wish you hadn't
-Jeb

 

Found this while I was looking around.

http://www.theengineshop.com/sbkits3.shtml