88camaroscv6

iTrader: (1)

Hey guys, im currently about to do the L31 5.7 350 crate swap into my 1989 formula. The question that i have is about going from 1.5 roller rockers to 1.6.

"The main problem with the vortec heads as many people know is the lift restriction of .480. If you use the GM LS6 beehive valve springs (GM PART # 12499224), Comp Cams retainers 787-16, and change the umbrella valve seals to Sealed Power Part # ST2015, you should be able to get up to 0.550 lift. (I am currently only running .492 lift with this combination with no problems"

and with 1.6 full roller rockers giving me a lift of .525

Ive done hours of searching around on here and ive only found one guy saying that 1.6 wouldnt be do-able based off of his measurements,

https://www.thirdgen.org/forums/tech...ortec-lt4.html

^see post #17


but then i also found a guy that used 1.6 rr on his lt4 vortec setup here
https://www.thirdgen.org/forums/tpi/...-tpi-dyno.html

...so now im left confused and I was not able to find much about this when researching so i would be very appreciative if someone can give some input on this topic because i will be doing this engine swap soon and my guy wants me putting in 1.6 rr when im not sure it will be possible

heres my specs:
L31 Vortec crate
GM LT4 Hotcam-hydraulic roller with 1,500 - 5,800 operating range, 218/228 at .050, .492 lift with 1.5 rockers and a 112 lsa
GM LS6 beehive valve springs (GM PART # 12499224)
umbrella valve seals to Sealed Power Part # ST2015
Comp Cams retainers 787-16

88camaroscv6

iTrader: (1)

bump

88camaroscv6

iTrader: (1)

never mind i found the answer to my question here...posting for anyones future reference
http://www.performancetrucks.net/for...estion-355261/

By using some +.050 valve locks you can use a cam with more lift without the retainers smashing the valve seals. Here they are http://www.sdpc2000.com/catalog/3550...alve-Locks.htm

Along with some beehive style springs and the above plus size locks, the Vortec heads can handle .550" of lift.

if you use Vortec heads with 1.6:1 rocker arms, you will need to enlarge the pushrod hole, you can use a dremel or simply run the next size drill bit thru the hole to provide clearance. I installed a LT4 Hotcam into an L31 with 1.6:1 roller rockers(GM Hotcam Kit) and the pushrod holes required elongation, no big deal though, yoou just dont want the pushrods rubbing on the heads. the Vortec heads dont use guideplates, so self aligning rocker arms are needed.

gbettner

iTrader: (2)

Gathering info and researching for the same build right now.

So just to be clear, you didn't machine valve guide bosses or spring pockets at all? Only drilled out pushrod holes to 1/2" diameter.
Very helpful info found here using . Thanks!

vetteoz

iTrader: (13)

Drop in Vortec springs good for .550 lift

http://www.alexsparts.com/valve-spri...rf-hyd-roller/

gbettner

iTrader: (2)

I actually read about those but I thought thet were alot more expensive. Thanks for the link, it REALLY helps!

vetteoz

iTrader: (13)

https://www.thirdgen.org/forums/tech...formation.html

gbettner

iTrader: (2)

Done!

IBrockZ

iTrader: (3)

Thanks for the info!

stew'86MCSS396

I was leaning in that direction to gain more lift for a set of Vortec heads. Did you have to shim the LS6 springs for installed height to obtain correct seat pressure?

TylerSteez

iTrader: (3)

Deeply looking into this build for my trans am, good to see some clarification. thanks