Today, I finally got to try the new top end out. Don't really have to much track experience, so there is definitely room for improvement. I am having problems launching with the 306, bogging alot, what rpm should I try launching at. I have a 9", a mcleod twin disk, and 11.50 ET's. My window switch is set to kick in at 3K. Also, what should I be spinning the 306 to on a stock bottom end? Today I was shifting at 6400.

HP-- 477
TQ--468
on 100 shot

Times--- 150 shot
1st run 60(1.9), 1/4(11.94), MPH(118)
2nd run 60(1.7), 1/4(11.67), MPH(121)
3rd run 60(1.7), 1/4(11.47), MPH(122)

 

Oh my......I haven't sprayed my car yet with my top-end. And those times sound a bit promising.

I've been shifting my car around 6800 N/A, sometimes I rev her out to 7k. I plan on shifting around 6600 on the spray (150 shot; once I get my damn MSD box fixed, she is getting sprayed at the strip).

Really, the only way to know for sure is to either run her at the strip a lot and figure out where to shift that gets you the best times, or toss her on a dyno and see where you are making power. I need to get mine on a dyno badly. For launching, I highly suggest launching on the spray and you won't have a problem with bogging.

 

thanks Joe

 

But I thought you would be running 118mph on motor alone and quite a bit faster with the nitrous.

 

Like I said, there is definitely room for improvement. I think when I start launching a lot better, and raise my shift point, my times will show it.

 

118 N/A on a stock bottom end hydro-cammed car isn't exactly an easy feat. IMO, some serious weight reduction needs to be done, along with a really nice set of heads and perhaps something bigger than a 306. I'll be happy if I see 114 out of mine N/A (my car is also heavier than stock ).

 

I agree Joe. My car is heavy at 3700lb and look at my MPH. I don't believe that my heads are very good and have had some launching problems, but I would be real happy to see 114-115 out of it.

 

nice runs, now you just need to get that 60 foot into the 1.6 range.

for what its worth, i'm only pulling a 114-115 with my 306 and ported heads.

 

What's your launching technique? What tires are you using?

Those are the kind of times I want to get out of mine.

If I can drop my 60' time by 0.2 seconds is that going to give me 3 MPH more in the 1/4?

 

i launch around 4000-4500 with 10.5 et streets but im only pulling 1.70 60s. i wish i would of gone with the 11.5
i dont think a lower 60 is going to help your mph much.

 

I launch at around 4800-5000 when I'm not on the two step...4200 when on the two step and in the low mid to high 1.5s..low 1.6s according to track prep.. But I'm running 28" drags so that makes a big difference. Try 3500-4000 if your bogging. What you want is alittle big of tire spin to keep the rpms up off the line but they need to recover quickly. You may also try slipping the clutch very slightly out of the hole to help with the bogging problem. YOu need to shift a couple hundred rpms above your peak hp. Look at your dyno sheet and look at the power curve.

 

Who did your guys heads?

 

Mine were done my Modern Musclecar (subbed out to Ron Sharp at Advanced Airflow). I was told that they flow 285 intake & 215 exhaust at 0.600", but somehow my numbers don't add up to verify that.

I am going to pull one off and have it flowed and then have a local guy that has been building racing engines for over 30 years port the bare set that I have to match the cam.

 

ARE did mine
they only flow 252 and 178

my car misses after 6000 rpms, Valve float is my guess but i think i could at least get 1 more mph out of it if that was fixed.