350 Vortec: Need some build tips/help

[thefarmboy21]

I'm getting ready to start my first Vortec build and need all the tips and advice I can get. I know there are some things in the heads that need modified and I also have a few questions about a few things. IF there is a good vortec thread point me in that direction. However this is for a truck, not a 2500lb car etc, so I figure you fellow truck owners would be the best for my info. So before we get too deep, let me give you some background info: I know my way around a small block pretty well. Built several SBC's in the past few years, along with a BBC and had my hands in a few other oddballs. This motor (if all goes as planned) will be the new Heartbeat for my all original 86 K20, that came from my Papaw. It's 4-speed truck with 4.10 gears and I have no plans or desire to modify the truck in anyway other than maybe level the front an inch or two and drop in the new motor. I just want a nice torquey small block to get me around while not killing me on fuel. At the most it might pull a derby car on a trailer once in a while but will likely never have more than a spare tire and some kids in the bed. Plan is Carbureted, HEI ignition and I ALWAYS run 93 in everything.

The motor: supposedly came from a 97 Tahoe at a salvage yard. Has the 906 casting heads. The valve tips all look good, no burs, rough spots, or excessive wear. The heads do need cleaned up, so I'll likely port/gasket match them. The bottom end is nearly torn down and looks like it had some oiling issues.....rod bearings were starting to eat the crank.

1. I've gotten mixed results from the internet but....WHAT is the MAX lift the stock heads can handle without any modifications?
2. Cam recommendations? I'm thinking a Comp 4x4 in OE roller
3. Keep the stock pistons, stock style rings and thin head gaskets, OR get different pistons old style rings and use a Felpro 1003 style gasket? Reason I ask is I don't want to lose the high ratio.
4. What timing set do I use?

This thing really surprised me when I tore into it. 2-bolt main rather than 4 in a truck, windage tray, different rod design, different piston rings and I'm not done yet. I'm sure there will be more.

[BADAZ chevy guy]

You have a contradiction here. Either you want a torky motor for towing OR you want a high lift cam. Stock cams offer the best low to mid range tork for towing. The bigger the cam the higher on the power curve you get before it comes alive.   

[KWKENUF]

1.  I believe .480 is MAX lift.
2.  HT383 roller cam from GM
3.  Keep everything stock 1997.  Why mess with a good thing?  Old style is old style for a reason.
4.  Should be able to run stock 1997 timing gear.

Remember they made quite a few updates in 1987 from the "original" small block.  That may be some of your "surprises" if you have only really messed with the old stuff.  At your power level  2-bolt vs. 4-bolt mains is a non-issue,  IMO.

[thefarmboy21]

I didn't contradict anything. I do want a torquey motor.....but some articles say that .450 is max lift! That wouldn't be enough even for a small comp 4x4 roller. I mean I would love to have some outrageous cam like a thumpr or a tractor pulling cam, etc
....but mainly I want to make the best use of what I have. Parts that work good together. The nastier the idle the better but I want something that makes power from stock parts and I don't want to throw a thumpr in tree for noise and LOSE power.

Anyway I've read .450" lift all the way to like .480+' but I NEED to know because I don't want to cross that fine line lol.

[thefarmboy21]

Well I have an 87 roller block but the cam wasn't in it and the rods were the old style and it was a 4-bolt block. I'm not concerned, just wasn't expecting all the different stuff. But I agree the new stuff has it's pros. The main thing was the head gaskets....I'm used to running the thicker 1003's on everything.

[travisr1988]

I'm using vortec heads and a lunati cam with .454/.468 lift. If you're getting rema. heads call the reman. and let them know your cam lift and they'll usually check any set they send to make sure they clear. I ordered mine through my brother at advance auto parts and he emailed them the cam specs and they sent me heads, after installing them we rotated the motor and checked clearances and to my surprise I could of actually went a little bigger on the cam. The issue with vortecs is inconsistency within the manufacturing process, I've seen many builds with vortecs using between .450-.500 lift cams that didn't need machined, again have them checked by making sure the head guy knows what lift you'll be running.

[ehjorten]

You want to shoot for 0.040" quench, so use a gasket that works best for that!  There is nothing wrong with a thin gasket.

You want to match your cam to your dynamic compression ratio.  You say you run 93 octane in everything.  Do all of your engines require it?  You are throwing away power if your engine is not setup to use the higher octane fuel.  Run the lowest octane fuel you can that does not cause knocking.

Also...max lift means nothing.  You want to match lift to what your heads will flow.  No sense lifting the valves past max flow.  For example...if you have your heads flowed and they max out at 0.600 lift and you are running 1.6:1 rockers then you only need a 0.375 lift cam.

[thefarmboy21]

I run 93 in everything because I get better fuel mileage and have less issues with it. I used to get water in my gas a lot, random misses and clogged fuel filters frequently until I switched to 93.

As far as cam lift, I just want to run about .465-.470ish lift.

[ehjorten]

This is what?  Shell V-Power?  If so...Shell V-Power 93 is supposed to be ethanol-free.  That would be the source of the improvement.

[thefarmboy21]

Yes, I prefer Shell, then BP.....BUT lately I haven't been able to get anything but speedway and Marathon.

[78BIG-TEN]

I was told and everything I researched said max lift at .460 but machine shop can fix that for you.As far as ports I would leave them alone unless you plan on spinning up some high revs.These things are pretty darn good for as cast factory units.If you can get hold of a copy of car craft sept 2 and check out the budget vortec 350 build .That's very similar to what I have and couldn,t be happier

[305chevy c-10]

One of the main issues with  factory V's is rocker studs have been known  to  pull out under high lift that y 450-480 is recommended.also vortec are designed to make max power at low lift unlike many aftermarket heads needing 600+lift .there have been flow test done on V's and flow numbers show it flows the same if not better than other heads with more lift .I have after market engine quest V's and had screw in studsand guide plates installed with beehive springs .that being said u be ok with a slightly larger than stock low lift cam .from past experiences do it the first time and be done .I understand budgets trust me but sometimes saving $100 ends up costing u a $1000.if u are sending heads to machine shop get screw in studs  installed and use a .480 lift cam .during my initial  355 build howards cam recommended me 214 duration 480 lift  110 lsa (mild lope and torque) stock converter.but went with 383 --230 dur/490 lift /108 lsa (need 2500+stall,headers,3.73 gears , rough idle )

[80chevtruck]

The reason .480 is the max lift on a stock vortec head is because the valve spring retainer will come in contact with the valve guide (first crushing the seal).  If you want to run a slightly larger cam or are concerned about running things alittle to close you can have a machine shop will the top of the valve guide to give you more room.  I am not sure how far they can go but .530 sticks in my head, that should be way more than you will need to build an engine for low end torque.  As far as flow the stock vortec falls off around .500 valve lift.

As far as the head gasket goes the engine stock in 9.5:1 so if you do not intend on doing any milling to the block or heads I would stick with the stock head gasket or go with a slighly thinner one.  GM Performance parts makes a composite gasket the has a compressed thickness of .028 that would work well.

[lyndoncp]

I'm just a amateur engine enthusiast that has too much time on their hands to research things and take on DIY projects. Ive built a few small blocks in my day but dont claim to be an expert by any means. The following is my opinion, please anyone feel free to correct me if i'm off base here.

I just finished building a Vortec with exactly the same checklist as you. Streetable with a bunch of torque for my daily driver.
I ended up porting and polishing the exhaust side only on the heads. I have heard many times that is the restrictive point on the flow. As far as the intake side I lightly deburred the obvious flaws but left it well enough alone to make sure I never messed with the already very good swirl pattern and atomization the factory shape and texture were famous for. In my opinion in order to make much noticeable flow gains with these heads with minimal work concentrate on the exhaust side. Bigger valves would be my next suggestion but then we have to start comparing how much money you want to throw at these factory heads and the cost of an out of the box aftermarket set.
As mentioned above, I would agree with not exceeding .480 without modification. I went with Comp BeeHive valve springs and retainers that allow more cam lift with no machining needed. With only these valve springs you can safely handle .520 lift.
 I went with 0.450 int./0.480 exh. http://www.summitracing.com/dom/parts/cca-08-300-8/overview/make/chevrolet Comp Cam for a EFI engine (I'm running Fast EZ EFI) I know the computer controlled cam wasn't necessary for the FAST system, but it had the lift and duration I was looking for.

As far as the timing set, depending if you want a double roller or just a factory replacement I could make some suggestions. A double roller will require a different timing chain cover and you may have to drill and tap a few holes to use it.

I went with a bit of a bump in compression with some -10cc speed pro forged pistons and went .030 overbore. With GM Composite gasket.

Ive had this combo running for a few months and am super pleased with the engine. Very snappy with excellent power throughout the RPM range. I have a TH350 and 3.73 gearing and absolutely no problem barking my 33x12.50 tires on command.