i've searched and learned a decent amount this topic. but heres my situation. when i bought my 383 it had 1.6rr's on it and i ended up having to redo the top end and the guy who did it convinced me i should go with 1.5's. he said i would lose probably 10 rwhp or so but it would drastically reduce me slapping a valve with a piston if i missed a gear and over revved the motor. now this was a ford guy that told me this, he's an old man and he's built plenty of chevy's but his expertise is in fords. now im wanting some educated lt1 opinions on the issue. because i see a whole lot of folks running 1.6's and have not heard much about smacking a piston.

and the reason im questioning this is because i have what seems to be a good deal on a brand new set of NSA 1.6 crane gold rrs. and yes i have guideplates. thanks for any input

 

thats a good question, my new motor has 1.52's as well on a mild cam only setup. I would be interested to see others opinions. my assumption is that yeah we might lose a little but the valve train is gonna be a lot happier in the end.

 

Dunno, I'm under the impression LT1s like lift more than duration, 1.6s is a way to get it, and I don't see kissing a valve as a problem if the valvesprings are right. Course, a LOT of folks tend to go cheap on their valvesprings. Springs at the limit of their ability don't do well when overrevved, and worse when using a higher ratio rocker.

 

In general most LT1 based cams are ground in the expectation of running a 1.6 rocker. unless the cam your running is so big on a 1.5 and the 1.6 ratio pushes it over the top, you can run a 1.6 rocker with out issue.

 

the cam is not enormous, just a cc306. 230/244 not sure on the lift on 1.5 rockers. but i know im missing some horsepower because of it.

 

I noticed my friend that is into ford was surprised about the PTV clearance that we had with stock pistons. You will be fine with 1.6 NSA.

 

That's the news I want to hear lol (inside joke of sorts)

 

think about it this way Lingenfelter always kept duration down and the lift was up(530-600) and had 112-114 lobe sep. LPE had no problem making gobbs of power and being smog friendly. 1.6 is the route.

 

Don't listen to another word that comes out of that guys mouth.

 

what would the power loss be with 1.52's versus 1.6's on a mild cam only setup?

 

i would say depending on the cam specs you have vs what your combo wants
will determine the amount you gain with 1.6s....some get 10rwhp some get 15rwhp.

 

yea i heard 10 - 15 as well. but i guess its in the cam to determine how much lift will be added with 1.6's

 

It's in the math. I think the lift added is static across any cam. It'll add X amount of lift no matter what. But I'm not 100% sure on that.

Our stock cams are around .450/.460 and go up to about .480/.490 I think with the 1.60s. I could be wrong and is more like .470/.480 then.

EDIT: My first numbers are correct Thanks to this nice tool anyone can figure out their lift change.
http://www.wallaceracing.com/rockercalc.php