try working with the chassis set up. What are the 60' times? How good is this car hooking up? Also what kind of MPH is it running? How light is this car? Have you taken off everything you don't need or is it still in street trim?

 

Did you retune the carb and ignition timing after you changed the heads? have you pulled a plug to see what color it was after a run to make sure it`s not running out of fuel on the high end?

 

I have everything original on the car I am running 82mph in 1/8 mile 60 ft. reaction time 1.72 reaction time .622 the car is hooking great I have adjusted the carb but have not messed with the distributor i have a msd 6 al
box msd blaster 2 coil engine works distributor I have a single plane intake do you think a dual plane would give me more power.

 

The problem you are having is the combination of parts are not working
together. To get a heavy car to accelerate fast enough to run 6 second
1/8 mile ETs with a 355; the combination of parts should be selected for
high RPM engine performance. Some of your parts will support high RPM
performance and others will not.

To give you an example, your torque converter will flash into the 3000 – 3500
range but the intake manifold will work best above 5000 rpm, the mismatch
will result in poor acceleration, all parts must match a very specific RPM range.

What is the camshaft duration at 0.050” lift? This information will tell us what
RPM range the cam is best suited for.

 

How heavy is the car?To run 6.90'sor a little better in the 1/8th,you will need to run better then 95mph.Regardless of 60 foot times or even axle gearing or torque convertor selection you are still looking to be over 150hp short.This is assuming you have a car that is about 3400# with you in it.You woud need an honest 575hp at the crank to get into the 6.90's in such a heavy car.I would need to know more about your combo before I could offer advice.How much does it weigh?What are all the camshaft timing figures?What trans do you have?Tire size?

 

I have a 74 nova, mutileaf and with the 327 (425hp) I was turning 1.740 60" times running 7.88 89mph 1/8 mile with 28" tall tires and a 4.10 gear. I used PTL alum heads with a edelbrock RPM air gap intake, 800cfm holley with the proform main body, msd igintion and dizzy, I ran 93 with octane booster as well.

I now have a 6" rod 406, PTL ported 220cc heads, wiseco flat tops (11.2:1)
Lunati pro mod rods, Scat 4340 crank, Im using the super victor intake, 1050 dommy and the cam spects are 291/304 263/272 .645/.645 108*
the converter is a ATI 4000-4200, the tranny is a th350 and Im running 28" tall tires.

I ran 6.80 @99 1/8 mile first time out. Im not hooking like I want and I think it has 6.60's on motor fairly easy, Im not going back till the car is mini tubbed.

HTH 2wld4u

 

Tou didnt mention how heavy your car was.Even if your car weighed 3200@{74 was the first year of the really heavy Nova right?} it would have to be making close to 580hp.

Another thing to think of is that you cant really compare the 1/8 mile times of 1/4 mile combinations as the standard for a true 1/8 mile car.My own car weighs 3650# makes about 640 hp and runs 6.60's@102mph.It is a 1/4 mile car with 4.88's and a 5000 stall convertor.If I were racing 1/8 mile only tracks and I knew that traction werent an issue I could put this car into the 6.40's with a 5500 stall speed and 6.14's in the rear.

Another thing to think about is that my car is that heavy and runs a powerglide.The car runs 10.50's in the 1/4 at 127 mph but only runs low 1.60's in the 60 foot.It isnt spinning the tires,it is just that slow off the line.It comes off the line like a 12 second car,and hits the top of 1st gear at abpout the 330 clock.I move the shifter to high and it pulls the engine way down on the convertor and it lays flat at about 5500rpm and climbs real slow taking 1000 feet and about 7 seconds to make it through 2nd gear.I am sure that with a 3 speed it would be a little faster in the front half of the un,and with 6.14's out back it would be a bunch faster.