BIG_MIKE2005

iTrader: (116)

Now I know there are 2 castings and I know the arguements for both, let's not debate that. What I have is a set of stock castings off my 97' Silverado K1500, casting number 062. I have read about the regular upgrades like thread in studs, machine work for better springs to allow for more lift, ect..

What I'm most curious about is critical details that seem to be harder to get info on. Like, what is the optimal lift on this casting for best flow in completely stock shape, no port/polish work. This is open to better springs cause I'm thinking from what I have found that these stock castings will flow well beyond what the stock spring allows. So lift wouldn't be limited by springs in this case.

I have also heard a larger split duration cam works better with these heads, supposedly due to the exhaust side of these castings.

These heads will be going on a mild 355 that will be built for daily driving and towing. It'll be going in my 1999 Tahoe 4x4 4dr. I'm using my 97' motor as a donor since it's down. Haven't pulled it yet, still doing my homework with this goofy L31.

Gojira94

iTrader: (4)

I'd think since those heads are closely similar to LT1s, that they'd be similar in limits in cam selection for untouched heads, From there, it's what you want the heads/ cam to do together and where the power needs to be in the RPM range. 2WD truck I'd go pretty different from 4WD truck. I'd suggest the following parameters:

A cam that works with stock or close to stock stall speed for that 4x4 truck (unless you're manual, that's another set of variables) against 3.73s
Intake Duration - 207 up to about 226, favoring the 210-216 range
Exhaust Duration - 220 up to about 231, and yes, extra exhaust duration will help a heavy vehicle with these heads
Intake Lift - .495 to ..535
Exhaust Lift - .515 to .555
LSA no tighter than 110, preferably 112-113
IVC probably no later than 55* ABDC

LT1 step nosed hydraulic cam that used to be popular with heavy B body cars was the Crane 227, but I'd look for something slightly larger. That's just me, though.

BIG_MIKE2005

iTrader: (116)

The heads in stock form have lift restriction of .475" but it's not super consistent between heads. But since I'm open to spring changes and upgraded studs the larger lift will be fine. I recently read something saying the stock vortecs run outta steam around .500" lift without any porting. Also read the "ramp" on the intake runner is to be left alone if porting, only to port the exhaust sides. Something to do with the velocities over the ramp and the chamber design.

I was originally looking at the HT383 cam, guys seem to like it for a daily driver with it on stock tune and stock stall.

​​​​​​​I definetly don't care about peak numbers on this motor but power from idle to 5600 in a nice smooth curve would be great.

BIG_MIKE2005

iTrader: (116)

Found this info last night, should narrow down cam selection.
​​​​​​​

MuhThugga

Alex's Parts makes Vortec valve springs that allow for .550" lift without the need for any machining. I have a set of those springs on a mild 355 in my 81 El Camino.

I run a Crane 2032 cam with stock Vortec heads at 10:1 compression, and the car runs pretty damn well for a street piece. It isn't going to be blowing the doors off any new Camaro or Mustang, but it moves well for what it is. The one thing to look out for with the Vortec heads is their tendency to crack. I know one of mine needed to be repaired.

You also want to make sure you get good intake gaskets. I believe Fel-Pro MS 98000 T is the correct gasket to get.

Fast355

The casting to avoid is the Hecho en Mexico 062. I had a crate L31 that did not perform as well as the stock 1997 L31 with its 906 heads. Ended up cracking a head after a few years and pulled the heads off. I had someone with access to a flow bench put them on the bench. The Hecho end Mexico garbage 062 head only flowed 218 cfm @ .450 and actually dropped to 207 cfm @ .500". Same bench previously had the 906s at 238 @ .450 and 242 @ .500.

That being said I would NOT put a big duration split on anything you want to make good torque with. In fact I would run a single pattern grind. The single pattern cam will make more off-idle torque and do better on fuel mileage than a dual pattern especially if you are to tighten the LSA compared to the dual pattern cam. The dual pattern cams do not really take over and start to run noticeably better than a well spec'd single pattern until you are above 4,500 rpm. At that point you have to consider how much time you spend over 4,500 rpm with a street engine and an OD compared to how much time you are sub 2,500 rpm. The 305 in my 1999 Tahoe has a a 218/218 @ .050 flat tappet cam on a 110 LSA and advanced 4*. Off-idle and in the lower rpm range it feels like a stock L30, but get it up in its powerband at 2,500+ rpm and it pulls harder than the stock L31 that was in the Tahoe before I broke the crankshaft in it. Was also getting 22-24 mpg running 70 mph @ 1,700 rpm.

That being said I would not put a dime into another stock Vortec head casting. I have put money into a few of them and its not worth it. They can easily end up cracking on you with a relatively mild overheat. For my current L31 I ended up going with 200cc aluminum heads. Yes they are Chinese castings I bought bare and put good parts into. The machine work was flawless and the castings beautiful. 2.02/1.60" +.100" valves, double springs good for a hydraulic roller cam to .620" lift, and 7/16" screw in studs with guideplates. Assembled them for under $800.00 for the pair. Picked up a set of GM 0.028" compressed head gaskets, Jegs head bolts with washers for aluminum head applications, Comp hardened 5/16" .080" wall pushrods, 1.7:1 Scropion roller rockers and converted to older style cast aluminum tall older style valve covers. With the huge intake flow number to exhaust flow I had a very mild dual pattern grind custom ground. 215/224 @ .050, .578/.578" lift, 110 LSA +4* on a 106 ICL. With a ported L31 marine intake, 80mm BBK throttle body and doug Thorley tri-y headers into factory 3" dual piping and high flow 3" spun bullet cats and dual 3" in, single 4" out muffler my L31 pulls like a freight train from 1,500-6,200 rpm.

BIG_MIKE2005

iTrader: (116)

From all I read all the 1/2 tons got the 062 and all the 3/4-1tons got the 906. So if it's a 96-98 1/2 ton with factory longblock it's gonna have 062's. Both my 97 and 99 k1500s have 062 castings.

BIG_MIKE2005

iTrader: (116)

I got that gasket set. The heads will for sure go to a machine shop to be cleaned and checked out before money gets spent on any machining or springs.

Fast355

My 1997 G1500 had 906s from the factory, the replacement Hecho en Mexico 8800+ gvw 4bolt main engine had 062s. My brothers 1999 1500 Suburban had 906s. His 1999 Tahoe had 062s. My 1999 Tahoe had 906s. GM used 062s and 906s fairly interchangeably with one another. I have pulled apart a 2004 Marine L31 that had 906s as well. Only some of the 906 heads were equipped with the flow choking valve seat you often hear about as well. Mostly used on Propane and CNG engines for industrial and very heavy duty truck applications.

biketopia

iTrader: (5)

Yup, I've pulled many a valve cover off at the junk yard and seen both castings on various engines with no rhyme or reasoning. I have stock 906 vortecs on my engine in my camaro, used a special comp retainer I found searching online, a set of ls6 take off yellow springs, and a different valve seal and have room for the lift on a hot cam with 1.6's. Run's pretty well for what it is, the high rise intake probably isn't helping anything but it came with the heads at a smoking deal so I'm not complaining.

timothy_5326

We put a XR288HR in an absolute stock bottom end L31 motor, changed springs on the heads and screw in studs, and put a carb intake on it.....nothing else...went 7.60 on motor and 7.0 on 125 shot. Dont tell me stock vortec heads wont make power. I ran the same set for 12 years on 6 different bottom ends and sold them to a friend 2 years ago and he still running them now

BIG_MIKE2005

iTrader: (116)

Well, I'm about to pull the heads on the 99' tahoe. I have it stripped down to that point already. If the heads check out with no cracks I'm gonna clean them up, clean the valves, lap the valves as long as the seats are good, new Felpro valve seals, new Felpro head gaskets, new head bolts, LS6 springs, Comp retainers w/stock keepers. I'm sticking with the stock 1.5 rockers for now but was pondering getting some LS7 lifters, looks like they are now a stock replacement item for the L31 engine. I'm also gonna try to talk the wife into the chevy 395 cam as well. Nice little improvement over stock while still working with stock converter.

Has anyone on here done the LS7 lifter in a L31 with real stock vortec heads? As of right now I do not plan on the heads or block being machined. I have read mixed info on pushrod length. Some say this combo will be fine with stock pushrods, some say the LS7 lifter needs a .050" longer rod.

Fast355

395' cam is a DOG IMO. Better off putting in a little more cam like an Elgin E1136 and swap in something like a Dayco reman S10 4.3 W converter of the matching year to your truck while you have the engine out.

BIG_MIKE2005

iTrader: (116)

Engine isn't out. Shortblock is still in the truck. Heads are coming out. My wife drives this sometimes to take our daughters places and the 395 is about all she will want. She wants to retain stock like manners with just a little more power and I like it for the bump in torque for towing. I'm not going strictly performance based for this one. When I started this thread it was for the motor in my 97 Z71. The one I'm working on right now is my 99 Tahoe, I have to get it running first then I can start my truck build.

I didn't expect to pull the heads initially and didn't want to start a new thread since this one was already talking about vortec heads. I have a thread on gmt400 in the member rides following my progress. I just wanted to ask over here about the pushrods and lifters cause I figured I'd get more reaponses. This forum was my home daily for years and I have always got good advice from the guys here.

Fast355

The E1136 is hardly a race cam. It is 210/215 @ .050, 0.462/.470 lift, 110 LSA +4* advance on a 106 ICL. You could barely tell the Escalade I had this cam in was cammed and it drove very stock like until you put your foot into it. My L30 305 in my 1999 Tahoe had a Lunati High Efficiency 268 flat tappet cam in it and it idled and drove like a stock vehicle after I tuned the black box. It was 218/218 @ .050, .457/.457" lift, 110 LSA on a 106 ICL.

MuhThugga

I used LS2 lifters in mine. I had to use a 7.100" pushrod.

Either way, you should buy a pushrod length checker, use checker springs on two valves, and adjust the length until the wipe pattern is correct. Then order your pushrods.

BIG_MIKE2005

iTrader: (116)

Found a local racer with the equipment at his house to magnaflux the heads for me for free. So I'll be pulling them sometime soon, disassemble them and clean them up to take over there. I'm really hoping they check out solid so I don't have to buy heads. I'd much rather throw springs, retainers and valve seals at them and call it a day.