When I went from an 11 inch converter to a 10" B&M holeshot I dropped .2 in the quarter! What is odd though is that my 60' times did not improve. (1.89-1.92) I'm assuming that I'm getting a stronger post 60' run due to the lack of traction with my BFG Radial TA's

Something that most likely detracted from my launches was going from no sway bar and 6 cyl springs to a 1-1/4 sway bar and HP lowering springs that have no real bounce to them.

I've got some BFG DR's that are going on next ... can't wait to see some 12'6's! If I get the 12.6 I think I my car deserves something larger than my 600 cfm holley. My mph is stagnet at 104-105.


(also posted in drag section)

 

Most likely the higher stall has you into a "beefier" part of the torque curve even after you pass the 60' mark. No improvement before the 60' mark sounds like you're traction limited coming off the line (but the converter is still helping a little shortly after you gain traction). Also the smaller converter is less rotating mass on the back of the motor.

Glad to hear it worked well for you.

 

I'd run a 750 Holley on that combo of yours. The 600 is probably maxed out. Theres a few more MPH waiting in there if you get a better carb. Good job.



Dave

 

Good looking Z dirt ... is it running now?

 

Thanks. It should be running within the next few weeks. The sumped fuel tank is in, and the engine is about ready to go in. I'll update the page once the car is done.

 

Good runs Cad! What's your setup in the '79? Thanks.

Gary

 

Car is a Berlinetta with:

Flat top cast 383
Performer RPM heads/cam/intake
Holley 600 DP
Somebodies headers w/2.5" duals & turbo mufflers
Stock Ignition
10" Holeshot converter
T350 w/shift kit
3.73:1 Posi
BFG Radial TA's
Hotchkis front springs
Z28 rear springs

It sure seems weak in the MPH for the equipment, so I will attempt to improve it with a bigger carb. I have BFG Drag radials that are going on before my next run.

 

Holee smokes cad - you are *way* under carbed there for the cubes. I'm willing to bet theres at least 2-3mph waiting in there with a 750 Holley up top, if not more.

Why are you using a such a small carb on a 383" engine?

 

The carb CFM formula I've always seen is (CI x RPM x VE)3456

383 x 5500 x 1 / 3456 = 610 CFM

Carb was originally on a 327, so it was fine. I'm not so sure about this formula as I've done many things to get MPH and haven't seen much for my efforts.

Car has incredible throttle response though!

 

Take that carb CFM formula with a grain of salt. Yes, you can run a 383 on a 600cfm carb, but will it run to its optimum when the tach is climbing? Methinks not. Sure it will work on a 327 or even a mild 350, but for what you're doing, you need a 750 Holley, IMO.

Dave

 

Methinks you're right Dirt ... I've seen that formula with a factor of 1.2 if using a dual plane manifold. That would then be 732 cfm ... much larger and maybe a few tenths and a few mph faster.

 

Exactly.

Dave