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Author Topic:   421 ??
brownstone
Dirt Maniac

Total posts: 120
posted November 17, 2001 08:43 AM
Please tell me what chevy combonation will make a 421 ?

Thanks

cmiller51
Dirt Full Roller

Total posts: 68
posted November 17, 2001 07:23 PM
3.875" stroke crank, and 400 block (sb)

ford5
Dirt Freak

Total posts: 298
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

REDNECKL64
Dirt Roller

Total posts: 7
posted November 17, 2001 11:16 PM
what is the usable RMP's for a 421?


ford5
Dirt Freak

Total posts: 298
posted November 18, 2001 08:24 AM
6500 is safe. it should make alot of torque at much lower rpms.

fury
Dirt Full Roller

Total posts: 75
posted November 19, 2001 01:13 AM
So whatt do you need to put together a 413 chevy small block ?

ford5
Dirt Freak

Total posts: 298
posted November 19, 2001 07:21 AM
fury, a 400 sbc plus .060 is a 412, fyi

cmiller51
Dirt Full Roller

Total posts: 68
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..

36k
Dirt Maniac

Total posts: 138
posted November 19, 2001 04:27 PM
cmiller51, is that were the 415 come's from, 4.00 stroke in 350 block??

cmiller51
Dirt Full Roller

Total posts: 68
posted November 20, 2001 11:23 AM
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.

3dirtLm
Dirt Full Roller

Total posts: 39
posted November 24, 2001 10:32 PM
The majority of the 414-415 cu in engine youll see advertised by the late model guys are 3.875 stroke 4,125 bore engines the difference being the overbore size. The reson there so popular is they seem to drive so much easier and better than the 4inch stroke stuff. One of these engines with good flowing heads will make power till 77-7800 rpm. good internals and 84-8600 rpm isnt out of the question

dirtracers
Dirt Full Roller

Total posts: 74
posted November 25, 2001 01:02 AM
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

dirtracers
Dirt Full Roller

Total posts: 74
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

fridge
Dirt Full Roller

Total posts: 71
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

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