topless68

OK guys, I have another post going with cylinder head selection so help me out with this one. I grew up racing Ponchos so I don't keep up with SBC as much.

I have seen articles where a 400 is stroked out to 427cid with a crank kit. Can you use an original block? Does it need to be modified? Or is this a crate order option only?

Anyone with the sccop?

Monty

I would recommend an aftermarekt block. I tall deck block like I used is preferable, such as the Dart Iron Eagle/GM Rocket lock, but a Dart Little M or World Products Motown, or some of the GM Bowties would work well. Most SBC 427's are based on a 4.00" stroke with a 4.125" bore. Not all production blocks can take that much stroke without hitting the water jackets, and the aftermarket blocks are designed for that, as well as up to a 4.200" bore - among other block structural improvements and design features.

Pete79L82

To come up with a 427 combination you have to use a 4.125 bore (stock 400) and a 4.0" stroke crank. You can do it with a stock 400 block but you have to have it sonic checked to assure minimal core shift. It also reguires "stroker" rods preferable with cap screws rather than rod bolts and nuts. You will need a small base circle cam to clear the rods. It will require a lot of grinding on the block to get the crank to clear everything and either a "stroker" oil pan or a lot of massaging to a stock pan.

The rods will try to hit the block at the oil pan rails which is where the majority of grinding will be required. If the budget allows it would be desireable to use a Bowtie, Motown or Dart block as they have thicker castings and can be gotten with a raised cam which will help with cam to rod clearence, besides a host of other benifits. But it can be done with a good stock block.


[Modified by Pete79L82, 9:07 PM 6/30/2003]

topless68

So they have a 4.125 bore...that would be .060 over in a 400? Not possible, right?

Pete79L82

4.125 is a standard bore for a 400. .060 would be 4.185. Most 400 block will take a .030 overbore (4.155) but it take a good block without core shift to be able to do a .060 overbore.

Pete

69vette66

I would also recommend a aftermarket block. We went as far as we could on my 400 block. Which come s out to a 421 stroker. I am not sure how far it was bored out. but it has tons of torque. Runs on pump gas, I can adjust timing all the way to 38 degrees total and no pinging on a 10.2 to 1 CR. I use Dart Pro1 aluminum heads, and air gap intake. Also went with a comp cam hyd roller 288/294 Degrees advertise duration gross lift 520/540 with 1.6 rockers. It has never been hot, never gets over 180 degrees. I also had 4 bolt splayed caps done also.
:cheers: Larry


[Modified by 69vette66, 10:06 PM 6/30/2003]

Kevin Mason

Hey, 69Vette66, what hood are you running with this setup?

Matt Gruber

i like the SB, but for that much money i would go BB. It has the WOW factor(you don't have to explain it to everyone that thinks it is a 350)

Monty

Matt, you're looking at it all wrong. You want everyone else to think it's just a 350. Makes it more fun when you smoke 'em at the track.

69vette66

I am using stock hood. I have a Barry Grant carb with no choke and a 1 1/2 inch drop base with k&n filter and top. 14 inch clears more than a 9 inch does.


:cheers: Larry