Visit The Dirt Forum for More Information

Author Topic:   421 ??
posted November 17, 2001 08:43 AM
3.875" stroke crank, and 400 block (sb)

posted November 17, 2001 07:30 PM
you can build a cheap one by offset grinding a 400 crank to desired stroke and use older 327 small jornal connecting rods and KB or similar pistons i have built these they work well

posted November 17, 2001 11:16 PM
what is the usable RMP's for a 421?

posted November 18, 2001 08:24 AM
6500 is safe. it should make alot of torque at much lower rpms.

posted November 19, 2001 01:13 AM
fury, a 400 sbc plus .060 is a 412, fyi

posted November 19, 2001 10:22 AM
You can get the same cid engine with the 350 block as well... 4.00" stroke.

I tried turning a 3.75" large journal to a 3.875" small journal crank... engine ran good for a little while.... R.I.P..

posted November 19, 2001 04:27 PM
Actually, the cid for a 350 bored .060" over and a 4.00" stroke is a 414 cid engine. If you use a stock block, I strongly recommend splayed caps and get ready to relieve the block for crankshaft clearance.

This engine will build good torque, but will require good parts and proper machine work to live.

posted November 24, 2001 10:32 PM
in the 421 instead of using a small journal 327 rod they make rod bearings for it that fit stock rods but are 92 dollars a set simular to the 3 and 9/16 I have also ran one these they both work well

posted November 25, 2001 01:06 AM
3dirtLm, who wants to turn a motor up that hard when your not going any faster and I personally dont think it will stay together I know someone who is running one in his truck and his only twisting it 6800 rpms and his gone through 5 motors and is on #6

posted December 09, 2001 11:41 PM
my friend had a 415 before, 60 over with a 4 inch stroke crank, he used je pistons summit 4340 nitrated crank with i believe crower 6 inch rods, i also believe there was a ton of machine work down, i am not sure but you might have to clearance the camshaft, another good motor woudl be a 350 with a 3.85 stroke same as the 420 but using a 350 block, but you will have to get the journals cut to a 350 main, i think this comes out to abotu 393 or something

Back to the Archives