Well I have a 400 block bored .030 over (4.155) and I have a 3 inch forged steel crank thats is going in the 400 block to build a 325. What my question is what rod legnth and compression height pistons will work?
(becides 5.7rod and 1.8 piston) like a dz302

I know (1/2 stroke + rod length + desired piston to deck) - deck height= Piston compression height. But what other length rods/pistons do they sell? and who sells them?

I think .025 is the right piston to deck clearance right?

And is it better to have longer rods and shorter compression height pistons or the other way around?

 

See who has an off the self piston first. Sounds like an oddball combo to me. I don't think I've seen longer than 6.25" rods for an sbc. Call Diamond pistons and talk to mike panette. He is sbc knowledgeable and their piston are top notch.

 

Longer rods require a raised wrist pin location and don't affect the compression height. I run 6" rods on my 3.75" stroke crank and the wrist pin bore cuts into the oil ring groove. The benefit of a longer rod is increased torque as it changes the leverage on the crank. Piston deck clearance can be much less than .025. I've seen some builds that actually run the pistons .005 out of the block for increased quench with wedge heads. The pistons don't hit the head because of the head gaskets. If you can find pistons to fit your application you will have a very high-revving small block and will need to buy valve train hardware accordingly.

 

The deck hieght on most 400 blocks are all over the place. google automotive math calculator and u will find some cool online calculators to get the answer u want. I know i tried to get some custom pistons for a tall deck motor and was told expect 1500.00. I can buy a complete stroker kit for that. The part that worries me is the high revving 400 block. I have seen alot more 377 destroked 400's blow than a 427 turning low rpms. The webbing on the 400 seems a little weak for sustained high rpms. But nonethe less it sounds awesome. I would have tried it back in the day

 

read this article , it covers your questions
http://www.purplesagetradingpost.com...%20engine.html

 

Not sure why you would want to de-stroke that motor so much....but off the shelf parts will work with for you.

6.250" rod (Scat 2-350-6250-2100)
1.250" comp height piston (Mahle Powerpack SBC250155F05)

This with your 3.00" stroke crank will yield a 9.0" assembly height which is the standard block deck height after surfacing to "zero deck".

 

Yeah, for the most part those 400 blocks are junk.

Spend the $2000 on a Dart block.