hrcslam

I thought it was crappy. My last tank was about 80-85% city and got me right around 16.8MPG (I track every tank). But this current tank I was able to drive about 120 miles all highway and use about 1/4 tank. I usually get about 190-230 miles per fill up (13.5 to 14 gallons) mostly city (80-85%). On the highway it really jumps. It really depends on how much right foot I use.

Last time I went to the track I used about 1/2 tank on 13 passes.

Your cam probably has faster ramps than mine; mine are 54/50, not overly aggressive but not too tame either. I'm sure that is helping me with these springs at those RPMs. They are 120 on the seat 375 open as installed IIRC.

hrcslam

I can't wait for winter weather. I may head to Phoenix and see if I can get some 1000ft DA runs in.

According to some DA conversion calculators my 106-108 converts to114-117 traps at SAE conditions for 0ft DA. I still need to work on my launch to get my crappy times down. 13.3 sucks even at 6200DA with my set up. I'm on all seasons, but would like to crack 12s at least with my DA and tires.

I looked over some of my logs and I'm stalling my clutch release too long. The log will jump to about 20mph, then hover there for about a second, then continue accelerating. I need to get my foot too stop doing that.

hrcslam

I called Howards Cams and verified the spring rates (120@1.8" and 430lbs/in) which gives me 128.6 lbs on the seat and 371.5 lbs on the nose as installed. I then called Lunati to verify these springs on my cam is good to 7000 rpms. They said yes, but the HR's are not. Damn. They told me my 6700 right now is the limit on hydraulic lifters.

Anyone revving to 7K on HRs?

Shownomercy

iTrader: (1)

Just accept that you will need high quality link bar lifters or similar top end non link bar stuff. ~$500 and up.

The tech guys at Lunati/Crower laughed at my open spring rate with my cam on entry level LS7 or similar stuff.

hrcslam

I can't tell, is this sarcasm? I could see NSA rockers and such, but for what I'm doing I shouldn't need link bars.

I'm just wondering who's running hydraulic rollers to 7K? Don't LSx's do it all the time? We share lifters and springs. And the LTx has lower RR ratio's....

Shownomercy

iTrader: (1)

no sarcasm.

Thats a lot of open spring pressure and I assume a fairly aggressive ramp rate.

bowtienut

iTrader: (1)

I'm revving to 7k on stock LT1 HR's. 160 lbs on the seat.
Adjusted 1/8 turn past lash point.
I shift at 7000-7100 at the strip. 6800 on the roadcourse. 5 years now.

hrcslam

Thanks. How aggressive is your came lobes? I currently have my rev limit set to 6750. My preload is at 1/4 turn (I wonder if it's worth going to 1/8 turn).

Not sure if it's worth the risk of going higher without seeing it on the dyno.....

How would you all go about testing for valve float? Or should I just leave it as is?

hrcslam

My cam specs are 280/288 @ .006" and 230/238@ .050" so a 54/50 ramp rate. Not too aggressive, it's probably helping. Not sure if my seat pressure is too low though. So 371 open is high?

Why did they laugh at your open spring pressure? Too low? Too high?

bowtienut

iTrader: (1)

280/286 @ .006
228/234 @ .050
.617/.617 lift w/1.6's
Running the "bigblock" style beehives. I forget what brand they are; they were prior to the Manley Nextek that AI uses now.
I've not replaced them yet. Kind of scared to !

bowtienut

iTrader: (1)

1/4 vs 1/8 turn is splitting hairs. The idea for the bare minimum is just some insurance against (pumpup) hanging a valve slightly open in the case that you do get slack somewhere in the valvetrain.

Looking at your dyno curve is the most practical way I know of spotting valve float. If it tapers gradually after peak hp, rather than dropping suddenly or looking jagged, you're probably good.

hrcslam

Your ramps come out to 52/52, but your duration @ .050" is less than mine with more lift, so the ramp rates after .050" should be more aggressive on yours than mine.

Ahh, so torn.

Why you scared to replace the springs?

bowtienut

iTrader: (1)

Because since I'm past the "infant mortality" period where a failure is more likely to occur, and from the car's performance I don't seem to be losing any power. It's still running the numbers and pulling hard at 7000.

hrcslam

According to Lunati, there's a run in period where the springs will loosen up a tad bit on their first heat cycle. Then they'll hold that for years until replacement. Maybe just test one or two at random every 3-5K miles and when they start dropping in spring pressure replace?

Something like this would be easy to pop a valve cover and check spring pressures without removing the springs. Hell, you could check them all every oil change with ease. I didn't know these existed until 5 minutes ago, it's now on my short list....

In Car Valve Spring Pressure Tester

96capricemgr

iTrader: (1)

What he is getting at is that spring failures within the first few hundred miles are fairly common and then at the end of their life you get sort of a warning where they will usually float before breaking. He is currently seeing no float so why take the gamble on fresh springs. A friend lost a motor to this just this year, brand new set of Nexteks one broke at 35 miles and did no harm then one broke at like 135miles at low speed cruise on city street, heard a rattle went to roll down the window to hear better just that quick the valve broke then the rod. Had a lot of miles on the last set of Nexteks and they were allowing float.


On the lifters, I have run original LT1 lifters and the "Cadillac racing" ones to 69-7000rpm.

Shownomercy

iTrader: (1)

I have a lil over 400lb open but factoring in boost its a tad less than that. Either way, I am going overkill and the route of spending more money to feel safer later on this time round. Hop on YB and ask to run stock/LS7 stuff.

hrcslam

The dyno curve rolled over smoothly to 6700 rpms (6400 indicated on the dyno). I'll just wait until I can get on the dyno again before pulling to 7K.