I have a stock chevelle ss 396/350 400 auto 331/posi rear.I have added a 280H cam and 1 3/4
headers with Dyno/max mufflers. All else is stock.What do you guys think I have for Hp now and what kind of 1/4 performance do you think i will have

Easiest way to find out is find someone with a dyno and spend the 50$ or so for 3 pulls.

I just did it with my 327 and came up with 363/310

I think you are running 280 to 310 rear wheel h.p.
Torque 390 to 425 rear wheel.
1/4 mile depends on the weight of your car.My guess if all metal and stock no air,no power steering,etc. Mid 14's!
Just a guess so have it dynoed or take it down the track!

The dragstrip is the ultimate dyno - go run it! I too think it will be somewhere in the mid 14's.

Thomas

Reading this in HPBooks "Big-Block Chevy Performance", (by Dave Emanuel), you are right at 399 hp at 5500 rpm and 433 t at 4500 rpm!

Page 168. Test A is almost identical to what you've done b/c he wanted to see how a stock engine would do with not much at all done to it!

(Dave started with an old about stock 10 to 1 CR., 325hp/396 motor that was bored out to 408"s! He kept the about stock 10 to 1 CR., added a 750 Holley, a CC 280 Magnum hy-cam and a set of 1.75", 4-tube, long headers is all..

Imho, an EXCELLENT STREET MOTOR!!

pdq67

Mango,with that cam & headers & al else stock i would est 375-385 hp & 430-440lbs trq.

Make sure your running 16-18 deg btdc intial timing with that cam.

How does the motor/car feel since you added the hotter cam & headers?

But if your q-jet is stock you need to do the following mods to it in order to get the most from your new higher rpm perf cam & headers:

* INSTALL A LARGER HIGH FLOW NEEDLE & SEAT. (like .135 or .145 that edelbrock sells)

* MAY ALREADY HAVE THIS BUT RUN APPROX 72 PRIMARY JETS WITH 45B PRIM METERING RODS.

* RUN AX OR BG SECONDARY RODS

* INSTALL POWER PISTON SPRING GM PT# 7037851 TO ACCOMIDATE THE
LOWER IDLE/LOW SPEED VACUUM A PERF 230 deg @ .05 CAM WILL PRODUCE in your 396.

* TRASH THE IN CARB FUEL FILTER AND RUN A LARGER INLINE HIGH FLOW.

* RUN A CARTER STREET/STRIP 6-7PSI FUEL PUMP ,BUT NOT THE HIGHER PSI STRIP PUMP THEY OFFER WHEN RUNNING A Q-JET BECAUSE THEY DONT LIKE HIGHER FUEL PSI AND YOU DONT NEED IT FOR YOUR SETUP.

* JUST FOR INSURANCE RUN THE LIGHTER FUEL PUMP ROD RATED FOR 6K PLUS RPMS IF YOU RUN THE CAM OR ONE LIKE IT I PASTED BELOW.

NOTE:SEAN MURPHY INDUCTION can setp and restor/re-dye & plate your q-jet carb this as i mentioned above if your not comfotable doing it so check out his site as he does good work at a decent price. The prices are cheaper if you supply the carb so there is no core charge.

Scott

Mid 13's, might go low 13's or high 12's with a RPM intake and a 750DP carb.