LB9GTA

iTrader: (1)

Finally got my sbc 421 together and put it on the dyno

Here are the specs:
4.155 bore x 3.875 stroke, 421sbc nitrous motor
12-1 compression, 5.6 dome
Jones cam (lift.699 int, .659 ext) (dur @seat 316int 320ext) (LS112)
AFR245 unported heads with LGM shaft mounts (1.7 int, 1.65 ext rockers)
Edelbrock 2970 ported
Mark Whitner 1050 dominator
Used 1 3/4 dyno headers

With 110 octane fuel made 586 TQ @ 5200 and 686 HP @ 7200 with 34 degrees timing
https://ibb.co/nBMmpc
https://ibb.co/m2Kgpc

With 94 octane pump gas made 567 TQ @ 5400 and 657 HP @ 6500 with 30 degree timing
https://ibb.co/e3A1Nx

Overall really happy!
https://ibb.co/csTP9c
https://ibb.co/eQPLhx

Can't wait to spray a 300hp shot to the engine
I have to install my powerglide 1st before I spray, no way my th350 I have now will hold the power

bjankuski

Very nice. I am curious is the listed lift with or without the 1.7 rockers figured in? In other words is the shown lift with those rockers?

LB9GTA

iTrader: (1)

Yes, the lift is shown with the 1.7/1.65 rocker

That is what was advised from LGM and Mike Jones

Orr89RocZ

iTrader: (20)

Pretty solid for a nitrous motor

cardo0

I like it.

Also proves what Smokey Yunick said: costs 5 times as much to go from 500hp to 570hp with the sbc.

skinny z

Nice numbers.
Was that cam spec'd specifically by Jones?

Orr89RocZ

iTrader: (20)

Maybe to 670 lol. Todays head choices are much better than days of old. Up to 600 can be fairly easy to achieve at 400-434”.

Goin over 600 starts getting expensive and need more tricks and special treatment to do imo

cardo0

I guess I should have qualified that with reliable 570hp. It takes good parts to keep a motor together making that power.

LB9GTA

iTrader: (1)

Yes.
I talked to other cam companies as well.
Mike came highly recommended from other guys in the industry.
Plus, I have a 50mm roller cam tunnel in my Motown block, which narrowed down my cam options

LB9GTA

iTrader: (1)

Agreed.
Anything over 600hp meant me getting an aftermarket block, along with nitrous.
I could do it with a stockblock, but not reliably and less longevity

TTOP350

iTrader: (8)

Nice numbers!! Think there may be a couple more HP in a stepped or larger header?

LB9GTA

iTrader: (1)

On motor, I think the 1 3/4 header is almost maxed out

I have 1 7/8 Ed Quay headers on my car so that'll be better suited once I spray.
But yes, I am curious if a stepped header would help once on spray

HINKSON AUTO

What lifters did you use for this build ?

LB9GTA

iTrader: (1)

Crower 66292H