LSx rockers on 4.3 Vortec heads..

[Hammer Head]

Ok, anyone know if LSx rockers will work on the late model 4.3 Vortec heads? I know we use shaft mounted rockers & the LSx shares the 10mm rocker bolts. Instead of 1.5 ratio we'd get a 1.7 ratio w/ the LSx rockers.. if they work. We'd problably need to clearance for the pushrods just like when 1.6 ratio rockers are used. ..any ideas or anyone know if this has been done before?

[bespurcell]

I'm interested in this too. I was just thinking about it the other day.

[j894]

I remember seeing someone doing this on a late model 4.3
Not sure who it was or on what forum though. I'll see if I had a pic

[Mikz86TA]

Id like to know that too =)
1.7 is going to net quite a high ligt tho. The 1.6 rockers are suposedly OK with the stock cam as far as clearance. But IDK about going to a 1.7 rocker.
The one thing that would be useful is the stock cam specs. Ive only been able to locate up to 90s 4.3 cam specs. After that its been a dead end search.
But with that, we could figure out the lift at 1.5 (stock) and then what the 1.6s actually do. And then the 1.7s. We already know which of the CraneCams will work stock and which one has issues with the stock pistons. So if we knew what we had in terms of stock cam lift plus the 1.7s, then we coulds guess if its a doable bolt-in.

[Hammer Head]

Pulled from www.fullsizechevy.com (http://www.fullsizechevy.com)

"Factory 4.3L Cam Specs
* '96-'00, VIN W, w/ balance shaft
- Lift (I/E) - .415/.429
- Dur @ .050 (I/E) - .191/.195

* '93-'96, VIN Z, w/ balance shaft
- Lift (I/E) - .376/.402
- Dur @ .050 (I/E) - .183/.193

* '92-'95, Vin W, w/ balance shaft
- Lift (I/E) - .432/.440
- Dur @ .050 (I/E) - .208/.208

* '91-'93, ZR9/Z79, Syclone/Typhoon
- Lift (I/E) - .351/.386
- Dur @ .050 (I/E) - .179/.195 (Ductile)

* '90-'91, VIN Z, Astro/Safari
- Lift (I/E) - .403/.450
- Dur @ .050 (I/E) - .202/.213 (Steel)

* '87-'94, Vin Z, w/o balance shaft
- Lift (I/E) - .351/.386
- Dur @ .050 (I/E) - .179/.195 (Ductile)"

[Hammer Head]

Also keep in mind, as a rule of thumb, add 1 degree of duration for every .05:1 rocker ratio over 1.5 (or whatever the stock cam was)..

[Hammer Head]

so.. 1.7 would make the W cam .470/.486 lift & duration would be around 195/200.

1.6 would be.. .443/.458 & dur about 193/197.

[Hammer Head]

.. pistons should be fine to just over .500 lift but I wouldn't expect much more. Maybe up to .550 before they'd need to be fly-cut but then again I could be wrong.

[Hammer Head]

I just wonder if the PCM needs a tune or if it'll throw codes w/ the added lift & duration.. hmmm W/ the 1.7s add .055/.059" lift & 4-5 degrees on the duration. That's almost adding 1/16" to the lift (.0625"=1/16").

[Mikz86TA]

Probably since the vaccum will change. IDK
I have a 03 with the X motor. Im sure the difference is in the cam. But Ive never found a X engine cam spec.

[White-V-6-S-Ten]

The people over at wait4meperformance said you would need a tune if i put a cam in. To make sure the computer is giving you the most out of it.

[shipper]

If my math is correct (LOL), I think you gain about .070" lift at the valve and 3 degrees duration before center and 3 after. Check me on that. If I'm wrong I want to know. By the way, this only applies to 1.6 rockers and stock camshaft specs. As always, my posts only pertain to 2001 model 4.3's. Again, set me straight if needed.

[rabidbandit]

Wow...this was a while ago..any follow-ups? Well...you could get by without a tune...the MAF will add the fuel and the IAC will adjust for the idle load and vacuum differences will be very minor with that ratio change and that little of duration and tight LSA. But to get the most out of it...I wouldn't get a mail order tune...they get you in the ballpark...but to me they are useless accept for gear swaps and shift programming. I'd rather grab a wideband and autotune or take it to a dyno that has the capability to hold a speed and load for accurate cell logging for V/E Tables and Spark Maps...ie. axle dyno or electrically/hydraulicly controlled roller dyno. Your truck your call:)

[91sonoma]

you showed all the different stock cam spect's. will the cam from the astro/safari van fit all non balance shaft 4.3. if so a friend of mine has a new cam for the astro van and said he will give it to me.

[white00s10]

a motor machinist also told me that one of the major differences between the vin w and vin x motors was the piston. Apparantly the vin w motor has smaller rings (metric), a shorter piston skirt, and a smaller wrist pin than the Vin x motor, which uses the stock LT-1 Internals

[jim75]

Pulled from www.fullsizechevy.com (http://www.fullsizechevy.com)

"Factory 4.3L Cam Specs.........

* '90-'91, VIN Z, Astro/Safari
- Lift (I/E) - .403/.450
- Dur @ .050 (I/E) - .202/.213 (Steel)

* '87-'94, Vin Z, w/o balance shaft
- Lift (I/E) - .351/.386
- Dur @ .050 (I/E) - .179/.195 (Ductile)"

so can i i just run a 90-91 astro cam in my 90 s10 without issues?

it looks like it would help perk it up a bit.

[Hammer Head]

Yes, so long as you go non-balance shaft to non-balance shaft or balance shaft to balance shaft.

[jim75]

now i just need somebody to point out the difference between "steel" and "ductile" i know it has to do with the different types of metal but how does it apply to the application? does it make a difference? i am ready to go to the junkyard and hunt one down.