sunsetorang01TA

i'd like to know how many of you guys have different rockers. i'm just curious i've heard you can gain lift with new rockers on your cam which would be more power i'd think. is this true. i've also heard that it has to do with the geometery of them. right now i have a 588lift cam. if i got rockers would it be like a 595 or 600lift cam? looking to squeeze any hp gains out of a cam only set up on my t/a to get into the 11s next year.

mrr23

iTrader: (3)

i use the vinci/crane 1.8 accelerated lift rockers. netted my 17 rwhp on the stock cam. with your .588 lift, your new lift with 1.8 rockers will be .629. you might have piston to valve interference issues. you can get the 1.7 accelerated lift rockers.

JakeFusion

iTrader: (7)

Lift has nothing to do with P-t-V clearance since the piston is at the bottom of its stroke when the cam is at max lift, pushing the valve down into the cylinder.

I'd make sure you have enough spring pressure before putting an XE-R lobe on a 1.8 accelerated rocker. Though, I will say the Crane Golds are awesome, lightweight rockers.

mrr23

iTrader: (3)

well, duration, but lift does have something to do with piston to valve clearance issues. especially with vinci/crane rockers. they aren't anything like other aftermarket rockers. IE stock rockers come off the seat at 1.54 ratio and don't really hit 1.7 until just about max lift. using the 1.7 accelerated lift rockers, they come off the seat at 1.79. after about .250 valve lift. they convert over to 1.72. and go back to 1.79 at about .250 valve lift again. this, in effect chages the valve duration.

to make matters 'worse' would be if he went with the 1.8 accelerated lift rockers. they come off the seat at 1.89 ratio. so, what you would have for lift at .050 duration, will now be happening much sooner.

and yes, also make sure the springs will be up to the task.

JakeFusion

iTrader: (7)

True, but on a 228 XE-R lobe I wouldn't be that concerned. If he had a 234 or bigger, I might be.

mrr23

iTrader: (3)

good deal

vettenuts

iTrader: (4)

What valve springs are you running?

junior28570

iTrader: (22)

I'm getting ready to take my Crane Gold 1.8's (VHP) off. I'm going with a larger cam so I won't be needing them anymore. .. let me know if you're interested!

WS6TransAm01

iTrader: (13)

Um... what about the exhaust valve that is chased by the piston? If you hang it open for longer then it should that piston is going to catch the exhaust valve and then you have an issue...

sunsetorang01TA

alright thanks guys i appreciate it. i can't believe he picked up 17rwhp i think i will go with something like this. hopefully i have no problems. i run dual valve springs right now so hopefully everything will be okay.

JPH

iTrader: (2)

i am interested in the rockers?

mrr23

iTrader: (3)

17 rwhp is pretty common for these rockers. when they tested them in a 5.3L motor, it still got 17 rwhp. here's my dynosheet.

sunsetorang01TA

wow thats awesome dude. i'll prolly go with the 1.7 ones later next year cuz im worried about the 1.8s with piston to valve clearn issues. also i dunno how dual valve springs will like .629 lift. thanks for showing me your dyno.

vettenuts

iTrader: (4)

I have run both, and am currently running the 1.7's on my Dart heads.

JPH

iTrader: (2)

engine looks good vettenutts. how did them heads work out for you? any port work, or did you put them on as cast out of the box?

PREDATOR-Z

Can't redesign 4 stroke dynamics man. JakeFusion is correct. (with standard rockers)

GuitsBoy

iTrader: (4)

Could always keep your stock rockers, get a more agressive cam, sell your current one, and come out ahead on cash.

Phil99vette

iTrader: (11)

We just tried a set of the Comp Chromoly adjustable ones and really like them. You can get the right length pushrod to make the sweep right in the center of the valve. Its a great plus if the heads have not had the tip height set correctly.
Phil

vettenuts

iTrader: (4)

I bought them almost a year ago, and since its too crappy here in the winter to do anything, I disassembled the Dart heads and just cleaned them up a bit and played with the spring shims so that they were within a few thousanths of each other on the seat. So basically, they were out of the box.

Now that we are back into winter again, I am re-doing my stock heads. I think I have to find a warmer climate