Building a S.B.C.

[04silveradomykk]

Hello everyone,

Here is my build thread of the Small Block Chevy I am going to replace the anemic 4.3L v6 in my 2004 Silverado with.

The plan:

The L31 Vortec 350 (production stoped for U.S. in light/medium duty in 2002, but was stoped being used in pickups in 2000) has alot in common with the LU3 4.3L V6 still being produced in fullsized GM trucks.

They have similar types of fuel injection, share the same throttlebody, use the same motor mount bolt pattern (different locations) , same bore x stroke, same bell housing bolt pattern, all of the accessory brackets & pulleys will work.

I can retain a few currently used performance parts on my 4.3L

The K&N FIPK can be modified to work on the V8. The 74mm CFM-Tech throttlebody will transfer over. The march 25% underdrive crank pulley will work.

I also intend to use the current; water pump, distributor (with a v8 crab cap), accessory & serpentine belt system.

The only major mods to get this engine to sit in the frame of my GMT800 chassis will be: Motor mounts, exhaust, wiring harness and computer tune.

What I started with:

A freshly rebuilt, freshly blown up. 4 bolt main, one piece rear, roller cam block. 86-95 350ci

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/engine002.jpg

And a pair of Vortec heads and Vortec L31 fuel injection.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/truck029.jpg

The engine was a TBI motor that someone swaped to carb, jetted way down and detonation from consistently running lean claimed the cyl # 5 piston. There was minimal damage to the cylinder wall, but was cleaned up with another hone job.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/cyl5.jpg

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/piston5.jpg

The heads were cleaned up, the pushrod holes were drilled out to 1/2", and are currently getting bowl hogged.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/blasted.jpg

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/headwork.jpg

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/pushrodholes.jpg

The engine is bored/honed to match the Hypereutectic flat top H345NCP-40 pistons.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/engineblock.jpg

The forged crank, rods & pistons, 4.3L V6 dampener & flexplate were all balanced to each other.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/rotating.jpg

The valvetrain is:
GMPP LT4 Hot Cam
Proform 1.6 ratio full roller, self aligning rockers
Comp Beehive 26918 springs
Comp 774 retainers & 648-16 locks
Summit quiet geardrive
Comp 7940-16 Hi-tech pushrods
GMPP 12371042 roller lifters kit

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/cam.jpg

[04silveradomykk]

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/rockers-1.jpg

Also on order is a 2800-3000 stall locking converter for the 4L60E trans, that will help this cam be drivable in a 4380lbs pickup

The studs in the vortec heads will get pinned, I am also gasket matching the intake manifold & heads. As well as polishing the combustion chambers & exhaust ports.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/gasketmatch.jpg

The exhaust will get run through a set of Hooker Headers 2462 long tubes, a new Y-pipe will be made to my current single 3" mandrel bent exhaust with a Flowmaster Super 40.

In order to get this engine to drop right in on a frame intended for the V6 or LSx type v8 engine blocks I will use an adapter plate that is used for installing an LSx on to factory location SBC mounts.

However I'll run the adapter plate theory in reverse and mount the SBC block to LSx motor mounts that will bolt up the GMT800 frame.

http://matt.undiagnosed.org/ls1/images/engine/ls1_motor_mount_plate.jpg

As you can see, the adapter has the SBC mount & LSx mount sharing a single hole. Here is a mock up of the motor mount on the block

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/engine-1.jpg

The passenger side clears the headers, close by no interference.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/passside.jpg

The drivers side mount needed to be modified, the corner notched to clear the Hooker 2462 headers.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/driveside.jpg


As far as the computer is concerned:

I have the entire engine wiring harness from a L31 in a 98 tahoe...

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/wiringharness.jpg

however, I only plan to graft the V8 injector plug-in onto my trucks current LU3 harness.

Here's the old poppet spider climbing the walls of my work

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/spider.jpg

and flash the PCM via HPTuners usuing a modified 2002 G-van 0411 PCM tune. Due to valvetrain noise (roller rockers, geardrive) I will gradually write down the sensitivity of the knock sensor until no false KR.

...And that is where I am at. Next week the engine block will get all the freeze plugs & pipe plugs installed, next I can put the entire bottom end together before finishing the head work.

Cheers ~Mykk

[csmith4153]

Cool :thumbsup:

[04silveradomykk]

I had forgot to mention, since I am using a forged crank & rods I wanted to step up my nitrous shot from a 75hp to 100 or even 125hp. I don't want to go too nitrous happy, the weak point will be the hypereutectic aluminum pistons... but as long as there isn't any detonation 125HP wet shot should be alright.

http://i40.photobucket.com/albums/e227/mykk/1.jpg

http://i40.photobucket.com/albums/e227/mykk/mykkscamera1002.jpg

Also a big reason I wanted to keep my K&N F.I.P.K on my new engine

Desktop dyno estimated power output for my engine is:

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/dyno.jpg

When carcraft magazine did my exact build with the same valvetrain & vortec heads they squeezed 401HP @ 5600rpm and 428 ft-lbs TQ @ 4200rpm.

But they were on a stock 4.000" bore and had lower compression than I will.

So, what do you guys predict the 1/4mile E.T of a 4380lbs truck with a 400hp small block, 3000 stall converter, 4:10 rear gears and 125hp shot of nitrous? 14.xx maybe?

[04silveradomykk]

I assembled the short block.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/Camin.jpg

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/crank.jpg

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/geardrive-1.jpg

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/longblock1.jpg

Check out how far down the flat top pistons sit in the cyl, .004" and from everything I've read they are supposed to sit .018" - .020" I might need to rethink milling my heads.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/inthehole.jpg

Just as I was torqueing the last rod cap bolt the 3000 stall converter arrived, and it doesn't mate up to the flexplate that the same company had sent me last week.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/TC.jpg

Apparently the TC is correct for my application, however the flexplate isn't. The flex is for a 88 astro, good thing I had it balanced with my rotating assembly.

The company says they are un-able to make a stall converter that will work with my current flex... and instead I'll need to have the correct flexplate for my app.

The balancing shop says they can't balance the flexplate alone and will need my crank again...

So I pulled the rod caps, slide out the pistons, pulled the main caps and have the crank out.

I'm not pissed off, there would be no point... at least I've got nothing but time. And can still have this engine finished by the end of august

because I am using and older block with vortec accessories, I need to plug the coolant
bypass in the block.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/coolantblock.jpg

Cheers ~Mykk

[five7kid]

Hypereutectic pistons with nitrous is a very, very bad idea (don't even consider it).

You say the pistons are .004" in the hole: Zero is best, but what you're really shooting for is .040" combination of deck-to-crown plus compressed gasket thickness. In other words, if they're .020" in the hole, use a head gasket that is .020" thick when compressed. If they're flat with the deck, use a .040" thick head gasket. If they really are .004" down, leave the heads alone and use a .036" compressed thickness head gasket. Shaving the heads will accomplish nothing other than cause pinging. There is absolutely nothing "magic" about .018"-.020" other than that's what most rebuilder pistons leave you with. 5cc relief pistons, .040" quench height, 64cc chambers will give you about 10:1 CR - too high for anything but the best pump gas (and we already covered the no nitrous w/hypereutectic pistons thing).

"Hogging" Vortec heads usually makes them flow worse. Hopefully whoever is doing this has a lot of experience with Vortec heads verified with a flow bench. If they can't provide evidence of that, tell them to cease and desist immediately.

The top of the valve guides should be cut for valve travel, positive type stem seals, and spring choice compatibility. Beehives are good, but (in my opinion) not a cure-all.

The rotating assembly can be balanced with any one-piece rear main seal V8 flexplate or flywheel. If they want to modify the flexplate or flywheel to achieve assembly balance, gather your stuff as quickly as possible and take it to a shop that knows what they're doing.

On "normal" SBCs, a V6 distributor won't work on a V8 engine with just a V8 cap, as the trigger wheels are different. But, I'm not completely familiar with the Vortec system, I guess it's cam-triggered. Just don't want casual readers to get the wrong idea.

The gear drive is over-kill. A pure waste of money that will cause more problems (as you already seem to know) than it could ever possibly be worth with this level of build. Does it even accomodate the cam sensor? Seriously reconsider using it. A simple double-roller chain set-up will do just fine and not cause other problems.

I'd be surprised if the V6 harmonic damper is proper for a V8. Maybe, but I seriously doubt it.

Somehow I can't shake the feeling that it would have been cheaper to pull a 2004-ish V8/tranny/harness/PCM and build it up than what this will end up costing you. But, it's your truck.

[04silveradomykk]

So, pretty much you are against building and modifying an engine. Gotcha

[five7kid]

Not at all. Notice I said "build it up" regarding the LS-type truck engine. The Vortec engine was a good performer, but I haven't heard a lot of praise for the performance upgrade potential of the induction system. The later type engines are a completely different story.

Regardless, I saw quite a few misassumptions and misapplications and wanted to offer advice and alternatives. I hate to see people disappointed after expending a lot of money and effort on a project.

Understand you might take exception to the last statement (and I could have left it off, I suppose). But, the important thing is, do you disagree with anything in the first 8 paragraphs? If you think I'm off-base on those, I'm afraid you're going to spend even more money fixing what could have been avoided. I don't know you, you don't know me - one of the issues with internet advice. I don't know how much experience you have building engines, but what you're putting together looks like a mish-mash of advice from disconnected sources.

I hope you can believe me when I say that my intent was to help, not simply to criticize.

[04silveradomykk]

A mild shot of nitrous will be fine on hypereutectic pistons, just as long as the necessary precautions are taken and a few degrees of timing is taken out of the comp tune. Just like in any nitrous application, do not detonate.

my pistons sit .004" in the hole. The head gaskets measure .045" thick (probably .041" when compressed) that will be an ideal quench height. And you're right on the compression ratio, it comes to 10.13-1 static.

I trust my guy doing the head work and my balance shop. The 906 Vortec castings with the hardened pressed in seats are notorious for lack of flow on the exhaust port. The intent isn't to remove as much material as possible. As for the balancer, the reason why he needed my crank again was because he did not have one that the flexplate could bolt up to.

The idea behind the 4.3L balancer was to insure that the 4.3L brackets, pulleys & accessories would bolt up and line up on the SBC. I did doubt the balancers efficiency because the of the small diameter and low mass compared to a SBC balancer. However, the 4.3L has more vibrations, harmonics and out of sequence pulses due to the splayed crank, un-equal power stroke degrees and reverse rotating balance shaft compared to a 350 SBC. So I figured if that balancer can compensate for all of that on the 4.3L it can work on a V8 with equally split power stroke degrees as long as the entire assembly was balanced.

Race/Performance balancers advertised in Summit have a larger diameter than the 4.3L balancer but weight about the same.

The geardrive is unnecessary, and will not provide any performance gains. However, to me building a car is about fun. Although the majority of rodding is "Go" there is a fraction of the culture that is "show" and a geardrive is just a noise that catches your attention.

I am familiar with all the cons associated with geardrives. But I have one in a 454ci in a 69 Chevy truck that I built 8 years ago that is still going strong. And I do know what needs to get compensated in the computer tune to prevent the geardrive from triggering the knock sensor.

I choose the Beehive springs because of Carcraft article, they had already built my exact engine with the same valvetrain (minus the fuel injection) Carcraft ran a Vortec headed SBC with the LT4 hot & 1.6 rockers with out any machining to the head.

http://www.carcraft.com/techarticles/vortec_valve_spring_upgrade/index.html

Than on another build Carcraft took a crate 350HO (vortec headed) and added the LT4 Hot Cam & 1.6 rockers again and squeezed 401HP @ 5600RPM / 428ft-lbs TQ @ 4200RPM

http://www.carcraft.com/techarticles/ccrp_0403_350ci_small_block_chevy_engine/index.html

On this build they had less bore and less compression than I will.

The Vortec series of distributors uses a hall effect sensor that has a 50/50 duty cycle that acts more like a cam position sensor than a distributor trigger and is interchangable between the v6 and v8 the only difference is the crap cap and either a v6 cap or v8 cap will bolt down to the same base.

As for the cost; the engine, heads & fuel injection were free as well as a take out L31 engine wiring harness

The ZZ4 crank, rods & LT4 hotcam were purchased off craigslist for $400. I also received a balancer, flexplate & valve covers that I couldn't use in my app.

The most expensive part of this build so far is the roller lifters, but all in all I've got less than a grand in parts & labor and thats including the 3000 stall locking converter. (Did I mention I run an Auto Parts store)

If I recieved a LSx based engine free, I probably would have gone that route. But I didn't, and this SBC will fit, work and drive with a little persuasion. And will still be cool, sound good through the long tubes and Flowmaster Super 40 and will be a head turner. :rockon:

Cheers ~Mykk

[five7kid]

I've seen the Car Craft articles before. I do like the beehive springs, I'm using them on the 396.

Let us know how it works out.

[04silveradomykk]

The roller lifters, retainers & cage arrived today. As well as the valve covers, although I don't have the heads back yet.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/cage.jpg

Here's a cool trick with the valve covers.

Plain ball milled covers.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/cover1.jpg

Paint over the top of the cover. In any color, I chose black because my block & heads are black... but you could do your engine color. Red, chevy orange, blue..etc.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/paintedcover.jpg

Than take a few brakcleen soaked shop rags and rub off the paint on the cover, and the recessed parts of the cover remain.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/painted2.jpg

Cheers ~Mykk

[04silveradomykk]

The pushrods had arrived, that was the last piece of the engine internals puzzle.

The heads came back from getting bowl hogged. I finished up the gasket match work and cleaned up the rough castings in the exhaust ports.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/pushrods.jpg

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/gasketmatch-1.jpg

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/exhaustport.jpg

I am having difficulty pinning the studs, I might pull them and tap them for screw ins... I'm not sure yet.

[five7kid]

Can you get pics of the bowls?

[04silveradomykk]

Finished the longblock

I apologize for the cell phone pics, I had forgot my camera today

I pinned all 16 studs today, than washed, repainted and assembled the heads.

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/pins.jpg

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/assembly.jpg

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/rockers-2.jpg

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/longblock.jpg

Everthing roatates smooth, no PTC issues or coil bind. The retainers also clear the valve seals... so all is well, so far

http://i40.photobucket.com/albums/e227/mykk/Project%20383ci/waterpump.jpg

Cheers ~Mykk

Can you get pics of the bowls?

Dude, if I would of known sooner I would taken some better pics of the bowls.... but now the heads are torqued down

[White02SS]

So, what do you guys predict the 1/4mile E.T of a 4380lbs truck with a 400hp small block, 3000 stall converter, 4:10 rear gears and 125hp shot of nitrous? 14.xx maybe?
I had a 2001 silverado that put 295hp to the ground, which would be about 340-360hp at the crank... I had 4.10 gears and a 3500 stall, no nitrous, and it weighed about 4500-ish with me in it. On heavy-ass 20" wheels with goodyear 275/45/20 gtII tires I ran a 13.87 @ 95mph. All my time was made out of the hole, as you can tell by the low mph. My 60ft time was 1.91.