SVC707

iTrader: (33)

are they supposed to feel like a torque spike. when i go wot from a roll off first gear when i hit say between 2500-3000 you feel a big hit in torque.. my buddy was like that had to be on the juice and i was like no i wasnt? are the 1.7's supposed to gain 15-17 hp and the 1.8's gain even more?

btw: i got a check engine light but im hoping it the o2 sensor again since that has come on how many times already and i havent changed it.

Kraest

iTrader: (3)

You'll gain nothing.

LS1s already come with 1.7 roller rockers.

IMO, bigger roller rockers are too much trouble to change out for the small amount of power you gain with them.

Mike

vettenuts

iTrader: (4)

Not sure I fully agree. The stockers start opening with closer to a 1.5 than 1.7 ratio and only peak at 1.7. The Cranes start closer to 1.8 and then at full open are at 1.7. Completely different curve.

Did you dyno before the installation? Just curious as to what you did gain as the 1.7's wouldn't require a major spring change like the 1.8's and I am concerned with the stock timing chain with heavier springs.

2000_Silverado_SS

I put the 1.8's on and am now .3 to .4 tenths slower. What is going on here?

mrr23

iTrader: (3)

.3 to .4 from when? last week, last month, last year? what else did you do at the same time?

SVC707

iTrader: (33)

i wouldnt be able to tell you what my gains would be on the dyno. fromt the last trip i have since put on the GMMG, EWP, Clutch, and fuel rails

mrr23

iTrader: (3)

that's what the rockers do. gives you more low end torque by design. i'll find the post on corvette forum where a person gained 17 rwp with the 1.7 rockers.

99Fbody99

Valve springs not stiff enough for the added weight of the rocker

Dave

2000_Silverado_SS

Bullshit! the rockers are aluminum and they sit on Patriot dual springs.

vettenuts

iTrader: (4)

Were other changes made? What history, i.e., pulled one time then did installation and went back with similar conditions and was slower? Wondering what other variables, if any, contributed to this.

SVC707

iTrader: (33)

i just reread this. do i really have to comment on this? do i have to take a picture of the stockies to show they are not with bearing on the valve end

mrr23

iTrader: (3)

it's not the roller tip that makes the difference. it's how they come on/off the seat. the stock rockers come off the seat at 1.54 and do not reach full 1.7 until just about max lift. the vinci/crane 1.7 come off the seat at 1.79. then at about .250-.300 valvelift. they start to revert to 1.72 by max lift. the go back to 1.79 at about .300-.250 valve lift before returning to the seat. it's this desing that opens the valve sooner and longer off the seat to get more into and out of the cylinder.

My90Iroc

iTrader: (26)

These were with crane rockers only? Did you gain torque? Do you have the part number for the rockers?

Thanks.

4mula

with 1.85 rockers i gained 10 rwhp and 18 rwtq.
none of the gains were till past 4000 rpm.

mrr23

iTrader: (3)

i have the 1.8 on the wife's 99 formula. i still haven't found the post for the guy on corvette forum with 1.7 yet. yes they were the vinci/crane rockers.