gurkgurkgurk

so after figuring out what i want. i have decided to go with ls6 valvetrain for the heads that are going on my 383. im just looking to see what you guys think and any problems i might run into.

basically im gonna get the yellow z06 valve spring
ls6 stock valves and retainers and keepers

but now my questions is will these valves fit in the stock seat? i was originally planning on going to larger 1.6'' valves but since im not too familiar with LS stuff. are they the same dimention? or will they require new valve seats on both intake and exhaust? if so i will probably just use the z06 springs and regular valves and just get the special retainers to use them.

any insight would be a great help. thanks

Atilla the Fun

The springs, you can use, but nothing else. To use the springs, you'll need retainers from COMP, for the same reason you can't use the LS6 valves: the Vortec heads use 11/32" stems, while the LS uses 8mm. Also, the LS valves are the wrong length, and are 2.00/1.55", while the Vortec heads come cut for 1.94/1.55". Putting bigger intake valves in a Vortec head is an excercise in unnecessary expense. Instead, just get some undercut, swirl-polished, 1-piece stainless valves in the stock 1.94" size, and have your local machine shop put a 30-degree back cut on them. You don't need a lightweight valvetrain anyway, since these heads will be out of air by 5500 rpm on a 383, and you can get there just fine without any exitic stuff.

gurkgurkgurk

thanks, thats what i was looking for.

also will i have to get drilled in rocker studs if i wanna run 1.6 ratio roller rockers? the lift with stock rocker arm ratio was .487 and with 1.6 ratio rockers id be looking at .519 intake and .522 exhaust. is this pushing the limits of the z06 springs?

Atilla the Fun

I've never checked those springs, but I suggest you stick with 1.5:1 rockers on the intake side, because the intake port stalls hard above .475" lift, and even after remembering that the lifters will make the theoretical .487" lift actually run closer to .481", that's still pushing it. Your choice of springs will determine whether or not you need pinned rocker studs, but you can run COMP's 26981s (not 26918s) without any special head work beyond verifying keeper-to-seal clearance.

3rd gen Will

iTrader: (8)

Z06 springs on an Gen3 heads are rated at .560 max lift IIRC.

Not sure what exactly they would be on Gen1 heads, I think you run into retainer/seal contact before maxing out the spring. There is a great thread on here about putting LS1 valve train components (rockers, valves, springs) into LT1 heads, you should find it with a search easy.

gurkgurkgurk

so your saying that 1.5 ratio would be too much for the intake. but what about on the exhaust?

tt 383

So has anyone on here "built" a set of vortec from bare castings? Instead of spending money on machining for seals and retainer clearance, using 2.05/1.60 valves that are .100 longer and using the cheap LS6 springs appropriately shimmed. Seems like a good bit of low lift flow can be had by blending in the new valve job and it would not cost much more than the new casting ghetto grind cost with the benefit of more flow and added valve lift.

gurkgurkgurk

ive built a set of vortec heads from bare castings. i went with a larger exhaust and kept the original intake size. 1.94/1.6. new exhaust seats, and bronze valve guides for all of them. pocket ported. three angle valve job. only trouble we had was getting a good seal on the intakes. for some reason we werent pulling good vacuum. so we re cut the already brand new valves. and it was fine. also we had to shim acouple of valves since i used ls6 springs

305sbc

iTrader: (3)

I've done the conversion many times.
The Z06 springs will work great with the right installed height.
You can use LS1 or the lighter LS6 valves. The retainers and keepers are the same no matter LS1 or LS6. I normally use used or take-out valves, retainers, keepers, and spring locators from LS1 heads.

Using K-line part # KLI851ST bronze guide liners you can easily convert an 11/32" guide to an 8.0mm guide.
Stock valve seats will need to be opened up (done during bowl porting) to seat the larger 2.0/1.55" valves. It's a great opportunity to cut 30* seats if that what you want to do, due to the larger diameter valves.

Stock installed height on 083/416 heads with stock retainers is in the 1.70" - 1.72" range. Sorry I don't have my own measurements for Vortec heads, but you can search them on here.
Installed height of LS1/LS6 valves in 416 heads with LS1 retainers is 1.835" on the intake, and 1.969" on the exhaust.
The installed height will have increased, so you use valvespring shims to set the height you need.

Z06 springs vary a bit over the years, but they will measure:
1.80" = 80 to 100 lbs
1.77" = 91 to 108 lbs
1.74" = 100 to 117 lbs
1.70" = 110 to 120 lbs

I've measured bind for these springs to be from 1.125" to 1.175"

If you go with a 1.80" install height it gives you 0.625" of spring travel.
The positive style Viton seals I like to use are 0.150" thick, so that leaves 0.475" for valve lift. If you want more lift you'll have to run a thinner seal (not my first choice) or swap to a spring with less bind height like the comp 918 spring.

Depending on your cam lift you probably will want to have the guide tops machined down some. I usually cut mine by 0.200".

Here's a link to some more info on the swap and a link to pictures.
https://www.thirdgen.org/forums/tech...ml#post4432686



Maybe I didn't catch it, but what heads will you be using?

gurkgurkgurk

i used a 416 casting i believe. the engine has already been built and is waiting for rockers pushrods, lifters and manifold.