Safe amount of valve lift on stock VR heads??

[njmartin]

Hey guys i'm new too this forum and I tried a search but couldn't find anything.
What i'm wanting too know is.. I'm looking at doing a cam + rockers in my VR.
Cam im looking at is the Wade 992a. 214/214 @ .050 112 LSA. Valve lift is .472
That .472 is on 1.6 rockers and I'm thinking to do 1.7 or 1.8 which would take it too .502 & .532 respectively.
Obviously i'm gonna have to do valve springs aswell but just wanting too know if that will be a safe amount of lift?
Im presuming it will be since another wade cam has .525 and mentions nothing about fly cuts...
Any help would be good thanks fellas!!

Nick

[DevilDRake]

Well if it is some help, I can only go a rocker ratio of 1.75 with 216/216 cam in the ecotec..

If not disregard it lol.

[njmartin]

it could be helpful, don't know how different the motors are in this area. Do you know what the lift of that cam is? if not is it from mace or who supplied it??
cheers

edit: just had a look and would i be correct in saying that it is a mace stage 2??
if so, with the 1.75 rockers you will have .555 lift so if the motors are similar i should have plenty ptv clearance with .532

hopefully haven't confused you too much

[padrickz88]

This might be helpful(its for the ecotec)... might be similar, might not be..... maybe someone can confirm

Safely increasing cam lift or maximum engine RPM can require new valve springs. On the 3800 we use LS1 behive valve springs which means that when running new springs you will also need LS1 retainers.

90# springs are GM LS6 yellow springs*. The LS6 comes from the factory with .550" of lift and spins to 6500 RPM to give an idea of what the springs were made for. Seat pressure is lower than the Comp Cams springs but spring rate is higher so they do work well for aggressive ramp rates. There springs work well with the VS, NIC, or XP cam. Because of the higher spring rate, timing chain dampener life is lower than with the 105's. 1.80 recommended install height.

Comp Cams 105# springs are rated for up to .600 lift and work well with the VS, NIC, or XP cam. 1.80 recommended install height.

Comp Cams 130# springs have the same spring rate as the 105's but the seat pressure is higher. Use of these springs requires a double roller timing chain. Rated for up to .600 lift they work well for 1.7 rockers w/ the XP, XPZ or custom setups with aggressive ramp rates or high RPM. 1.80 recommended install height.

Comp Cams 150# springs have the highest spring rate, seat pressure and lift capability of all available springs for the 3800. Using them requires work on the head to cut a new spring seat. The install height is 1.90 and they support lift to .625

- Valve Springs #

[njmartin]

thanks mate thats interesting didnt know you could use the ls1 springs on the 6's...
what im more concerned about though is ptv clearance

[immortality]

The issue with the 3800 motors isn't PTV clearance. With the stock springs,retainers you can have a maximum of .520" valve lift. any more and the retainers will hit the valve guide seals.

Also the quoted section above is to suit the ecotec series of engines (which are referred to as s2 3800 engine in the US) which use 8mm valve stems, the older buick 3800 engines (VN-VR) use a 11/32" valve stem so to use the ecotec/LS beehive type springs you will have to find the appropriate valve spring retainers to suit.

cheers

[njmartin]

thanks for clarifying mate. ive decided if i go with the 1.7 rockers which will give me .502, ill be able to take 40thou off the heads too up the compression a bit. would you say some crow 105lb springs would be safe with only .502 lift??

taking 40thou off the heads ill definitely be checking ptv clearance and if i have too cut valve reliefs then so be it, but hopefully i should be alright