Visit The Dirt Forum for More Information

Author Topic:   2bbl vs. 4 bbl
DEEDDUDE
Dirt Maniac

Total posts: 111
posted November 27, 2002 05:51 PM
Track is trying to merge to classes. Street Stocks and bombers. If you run a small chamber head you are limited to a 2brl. carb. open chamber heads get the 4brl. Min. 58cc. Vortecs ok. What would be the better choice of the two? Also if using the vortecs and running the 2 brl. What manifold would have the advantage? 3/8 track. .500 lift rule. Thanks for any advice.

Flatlander
Dirt Freak

Total posts: 310
posted November 27, 2002 11:29 PM
Vortecs with the 2 barrelwith the OEM manifold made for the vortecsand use an adapterand let someone fix your carb for youthat has all the equip. to do it right

tilley88
Dirt Freak

Total posts: 353
posted November 27, 2002 11:53 PM
Can't argue with that!

DEEDDUDE
Dirt Maniac

Total posts: 111
posted November 28, 2002 06:45 AM
Thanks guys, Who is a good carb. rebuilder? I believe we will be using aluminum manifolds. Would the 2bbl. victor jr. work better than the perfomer rpm? Thanks again. Deed

tilley88
Dirt Freak

Total posts: 353
posted November 28, 2002 08:38 AM
Get an intake for Vortecs. I believe Edelbrock makes one. Go with Kinetic on the carb.

KPLugnut
Dirt Freak

Total posts: 408
posted November 28, 2002 10:30 AM
Since the Victor 2V intake is now made for Vortec heads, that would be a good choice for big torque off tight corners. But for a longer sweeping track, a good 2bbl carb, Vortec heads, and a Super Victor intake matched to the heads is the top end power maker (as long as the carb is built to feed that much rpm and the bottom end can stand it).
You didn't mention which 2bbl carb you're talking about, tho, but as far as the heads go, and for your application, Vortecs with a good valve job done on the stock size 1.94 valve sizes will be fine.
Just keep in mind that too big a plenum volume in the intake under a 2bbl will require some altering of carb placement will be needed to maximize torque and EGT balance across cylinders. And if you leave the stock valve size in the Vortecs, there should be no need to go with the Super Victor, just stay with the 2V and beat 'em off the corners that way.
I'd go with the Edelbrock Victor 2V #2912, port match it and the heads, maximize your cam rule, and carb rules as well, and build the bottom end to help that head combo keep its torque curve flat and long. 6" rods if legal, and deck the block to about .005" piston to deck and you'll make plenty of compression.

Hope that helps, and if we can offer more info or assistance, just ask.

And happy Thanksgiving everyone!

Dayton Umholtz, owner
Kinetic Performance

rico 08
Dirt Freak

Total posts: 372
posted December 02, 2002 01:44 PM
what about using the open chamber heads and taking advantage of the 4brl carb?it seems like you may be handicaping yourself just for more compression.can you run popups?

KPLugnut
Dirt Freak

Total posts: 408
posted December 02, 2002 01:54 PM
That thought had crossed my mind as well. And even if you can only flat mill the heads, it's still possible to mill plenty off them to decrease a 76cc+ chamber down some to help that.
Heck, there's probably 10 different ways to make a good motor with either a 2bbl or a 4bbl under those rules.
And is it specifically spelled out as to WHAT constitutes an "open chamber" head as opposed to a "closed chamber"? Obviously Vortec's are being classified as "closed", but a 461/462 head on a good 4bbl might easily beat a 2bbl Vortec combo, I'd think.
Especially if you could run a Victor 4bbl intake as well.
But if you're limited to the 2bbl, then go with the 2V intake, Vortecs and a good 2bbl.
Plenty of limited LM's around here make good power with that combo....the only difference is they're allowed Bowtie heads.

Hope that helps,
Kinetic Performance

Back to the Archives