I was just looking through a Jegs magazine and I see they sell 4.000inch stroke cranks for small block chevy's. This crank in a small block 400 will make a 427ci engine!! Does anyone have any experience or knowledge building an engine like this? Will the crank just fit right in or will there need to be some major block modifications? They sell pistons for this crank with 6 inch rods. This looks like a fun little project. Just imagine a 427 small block, I like the sound of that!!

Guess my first question would be WHY?

There is alot of extra work created by a four inch arm, including small base circle camshaft, cam-cutting the rods, and extensive reworking of the pan rail and cylinder bores for rod clearance. Keep in mind the cost of balancing a setup like this as you will probably need alot of mallory metal {expensive} to balance your reciprocating assembly. You will need 230 CC intake runner heads to utilize all of those cubes. You can make a bad unit out of it, but you'll spend some money to do it right.

yea, Ive been planning on building my small block 400, this winter is when im putting it all together. Ive already got dart aluminum 2.08 intake 230cc runner heads, and a set of manley aluminum 6in rods, hydrolic roller lifters, im not sure of the cam specs are going to be yet, but its going to be a hydrolic roller cam. The crank that I was looking at is a forged steel crank and its internally balanced. It does sound like alot of work though with machining, but man that would be an awsome motor, the weight of a small block with the torque of a big block.

I think your going to have problems with those aluminum rods, they're sheer bulk will cause clearance problems. {I'm sure of it}, I would re-think the aluminum rod deal { go to some good steel rods}
Aluminum rods in a street engine is like fooling around with a bag of rattlesnakes, sooner or later you'll be bitten .

yea, i think im going to return them for the steel rods, Ive been talking to some people who have used them, and they say they can get some serious rpms but you have to put new bearings in them every 2 races. I guess they are for the serious racer who rebuilds their motor every few races. I figured lighter is better, but I wasn't thinking reliability, thanx for the heads up.

The 427 will need some extensive modes as listed before, but it would be ******. I did some research and concluded that the few extra cubes was not worth the money to me right now. I think that you might be able to build a 415 without the issues of the 427. I believe that uses a 3.85 crank.

Go for the steel rods. Get a good I beam billet if you are planning on making alot of power. I sould stear clear of H beam if you are making alot of power. The tend to not withstand the twisting force the piston places on the rod as well as I beam.

Think about the last time you went to a swap meet, or ebay.....How many partial sets of H beams did you run across? If you were looking, probably quiet a few.

Chris

There is an article in the winter issue of "Hot Rod" "Engines" mag on the 427 small block. If I remember right, that guy uses a Motown tall block for his 427. If you used a standard OEM 400 block, I'm sure that there would be quite a bit of machine work needed. Without a small base cam, your probably looking at grinding the rod bolts for cam/rod clearance. I believe most dirt racers that build big cube steel small blocks use the Dart Little "M" or Iron Eagle tall blocks.

Thanx for all the input, sounds like to many head aches to deal with, Ill probably just stick with the 3.75 stroke.

Since im getting new rods, I've seen some 6.125inch and 6.250 inch rods for a small block. Will these make any noticable difference, and do they require alot of machining? Is it worth it? Or should I just stick with the 6 inch?

The longer stroke will possibly make the motor live longer due to the better rod angle. It will also help with cylider side pressure which can cause problems on oem blocks. Much over 500HP with out grout and you are chancing a cracked cylinder anyway with oem block.

I have read that the linger rod will make a fraction more power due to the longer dwell time at tdc. I have also read that the shorter rod will yeild a higher VE which should make more power. I am not sure what is right....

Chris

get a motown 427 SB, it is a new world casting block, the reciprocating assy you are talking of buying. Heads to match, and it is all assembled, it works, it comes with a warrany and its cheaper than you can ever build it...

my 2 cents worth

[quote]Originally posted by deuce_454:
<strong>get a motown 427 SB, it is a new world casting block, the reciprocating assy you are talking of buying. Heads to match, and it is all assembled, it works, it comes with a warrany and its cheaper than you can ever build it...

my 2 cents worth</strong><hr></blockquote>


Yeh, I gotta agree unless you want to shop around for a year or so on the net untill you can scrounge up all the parts for cheap. I did that cause I am a cheap *** , but if you got the money go for the complete motor. They will make around 600hP I believe.

chris

That sound very appetizing, but I really don't have the money for it. Im gradually getting the parts I want slowly but surely. Plus I want to build the motor myself so I can say I did all the work myself. Ill figure something out. Thanx alot for all the input.

Building it yourself is the only way to go in my opinion. Part of the love of cars and hotrods is the sweat put into them. Build yourself a healthy 400 and you will be happy I am sure. Have fun.

chris