no not that... my MOTOR!

ive decided that at the power levels im attempting, the stock rods in the shortblock are just going to be too weak...... so the shortblock is coming apart anyway

poking on ebay, i found a guy selling 4" stroke cranks... after a little research and tracking down some of his previous buyers, ive decided its a safe enough bet for me...

now i just have to decide if i really need get the crank or not... and im still un decided on the rods too...

motor is going to be a 400 block, solid roller, with ported Dart heads ( 200cc intake runner, 2.02 intake 1.60 exhaust, 72cc chambers)......


the block has been bored 30 over since its a reman job, but its still fresh and you can see a nice crosshatch... im not sure if im going to call that good, or if im going to bore it over.... and i need to have the machinest check out everything else.....

i did this myself, so if its wrong someone tell me:

so the questions are....

will i see enough of a increase in power that its worth the extra effort to stroke it? any downsides? hidden catches to stroking it that ive might not considered? why doesnt everyone else do this?

 

i thought id list my main worries:

• hidden cost.... i know im missing somthing
• Pistons.. will they clear the crank!? do i need special ones? can i get off the shelf ones and still get a reasonable iron head street compression?
• cam... will my cam clear it? how much more is a small base circle roller cam? i'll probly end up needing a custom ground one since its still a street car, how much more is that?
• block... will it hold together? how much do i have to clearance it? where do i have to clearance it? will a short fill add enough strength?
• what else am i missing!?

 

I've done some reasearch on big small blocks. I don't think I would use a stroke longer than 3.75" or maybe 3.875" on a stock deck height block because the rod to stroke ratio and piston pin to top height are severely comprimised. However, on a tall deck Iron Eagle you gain about .3" deck height which allows a 6.125" rod and a piston to pin height compairable to regular 6" rod 383 or 400. Puting the piston pin too close to the top requires thiner rings and pushes them closer together. This is a huge comprimise in durability, esp with high cylinder pressures and heat from NOS or forced induction.

In my opinion, I would stay with a 3.75" crank for your engine.

 

I would agree, a 4" stroke on a used 400 block you are asking for trouble. The right piston will definitely clear the crank. Stroker profile rods such as Eagle or Scat will clear most size base circle cams. In my case a Scat 4340 3.75" stroke crank, Eagle 6" I-beam rods & KB122 pistons cleared a Comp XR276HR cam. But always check & double check all clearances, you never know if something could be off spec. 0.60"-0.75" clearance on everything moving is common practice.

 

yea... well the idea is out anyhoo...

everything just adds up and when you get down to it..... its not really worth it for this motor.


someday..........