Looking for some wise ADVICE. I'm new too the forum, but have some old questions that I've been pondering for my new project. 2 questions for 1 Thread

1). I have a 400 GM sbc. My plan is to stroke it to 421 ci. However, I'm unsure of the clearance between the oil pan and the cross-member of the frame, being that the oil pan will be different based on the changed demensions of the bottom end of the engine. Will this drop into the engine bay without modifications, or what/how changes are needed to fit engine. Also what part number for oil pan?

2). The 421 build will consists of a stout forged bottom end(of Course). AFR heads ( 195 for torque or 210,220 for balanced tq/hp), 10.5-11.0 compression, 750 or bigger carb, and Leaning for a 3000 stall for street/strip Use. I would love to have some advice on cam selection( hyr roller & hyr solid) but NOTHING from Comp Cams!!! I was considering a range of 236-260 @.050. For 195 heads shooting for 600tq and 550-ish hp. For other Heads 600/600 hp/tq respectively.

Please help me with My Weekend Warrior!!! looking to run 10's and possibly a 125 shot of H-2-O..LOL for low 9's...... OR SHOULD I JUST CONSIDER A 406 ci. Please PM me if you'll like. Thanks

 

The stroke of the engine will have nothing to do with the oil pan to k-member clearance. If thats what your asking.


Id start with a Dart Little M block for what your looking to build
421 cubes will like those bigger afr's 220s
11.5:1 if its your weekend warrior.

dont forget all the other stuff your gonna need. Tranny/converter and suspention.

expect to spend $10k up for a complete combo thats gonna all work together.

 

Closer to 600 hp, go with a custom solid roller... around 255 deg duration at .050", mid 600's lift, with AFR 220's. That setup will ROLL!!

More street/strip friendly, 500-550 hp, i'd go 210 heads, with hyd roller around 240 deg at .050".

Either one will want more like 3600 stall minimum. I'd go for 4000. Plenty streetable either way, especially for weekend warrior. Probably 850 ish cfm carb. DOnt skimp out.

Solid roller build will get you mid higher 9's on 125-150 hit and probably mid high 10's on motor. Needs a ported intake to match the head flow. Victor type ported out and flowed to match the heads.

 

What's your gripe against Comp? They're not #1 for nothing, and they're the only cam company good enough to give away all the lobe info the average enthusiast can make use of.
Or were you just trying to politely ask Atilla to not comment? If so, it appears to be working. He's the first guy I'd ask about this engine.

 

Custom from Comp will work ok on this motor. They have a large variety of solid roller lobes that will work.

My friend on this board, 87_TA runs a 406 with AFR 210's and a Ultradyne custom solid roller that specs in the low 250's duration at .050 and with miniram EFI intake, the setup made 460whp running lean. Probably 480whp or so now through a T56 tranny. Car runs 10.6's at 130mph on nuts alone. With a 150 hit I'd expect 9.7's at 140-142 mph. Previous combo was a milder TPIS 242 duration solid roller and AFR 195's and that setup ran 11.0's at 126-127 with ok slipping clutch 60 foot. Ran 10.0's at 136-138 in good air with 150 shot. His new setup has alot of power in it.

I'd do the same thing with a 421. Dont need to turn much over 6500 rpm to achieve these numbers with great heads like AFR 220's

 

I'd really,REALLY consider an aftermarket block on this one.The stout forged bottom end is kinda of the "$500 saddle on a $100 horse" situation.I lost a 421 and 2 406's to block failure in my last car,(the avatar).Concrete helps,but it won't save it.
I am in no way discouraging your build,you will LOVE the way it runs,it's quite similar to what I had,but the day it dies is a sickening one if it meets the fate mine did.
There's a lot you can do to the stock block to make it live,but by the time you pay for the machine work,your near or at the cost of a better block,and the block you have is fetching premium cash these days,which will also offset the cost.I hope I'm not coming off as negative,I just hope to save others from the poor decisions I have made in the past.

One more thing,if Attila chimes in,he is a sharp guy,and even if you don't agree with his theory,it IS worth hearing him out.

 

SHP block is reasonably priced and offers all the nice factory features of a 87-99 roller type small block so you can go roller cam without doing a retrofit type setup with expensive lifters.

 

That's the one I had in mind.I'm curious about the PBM blocks,but having no prior experiance with one,I'd have a hard time reccomending one.

 

do a 350 or 406 with a decent rod&piston.
spend all your money on the heads, intake, and nitrous system. run an off the shelf hydro roller. keep rpms around 6500ish to be easy on block and crank.
should be able to make at least 410+ rwhp on motor(with auto trans) and somewhere up around 600 on a 200 shot.

once thats done you will have to start working on the car. thats enough power to easily go 9's.

 

I used 200cc heads on a 10:1 350ci and it was awesome... I wouldn't even think twice about it with your 421 - use the 220cc heads. Don't f*** around with the little 195s and 210s. For a small block that big, use the biggest you can get. Forget about the idea that big ports will kill all your driveability - The small big blocks (366, 396, 427) used 265cc, 280cc, and 310cc heads from the factory, and even the LS engines now use huge intake ports too... the 'small' cathedral port LS heads are right around 200cc. The bigger rectangle port heads (L92, LS3) are up in the 230-240cc range. None of those big blocks or LS engines has problems making tons of torque when they used a moderate cam. Its all in the cam. Buy the biggest/best heads you can for the 421, then buy a cam to match the heads and the way you'll use the motor, then a converter to match the cam.