My Silverado, engine swap coming soon

**04SilveradoMykk** · 08-12-2008, 11:45 AM

Hello Everyone, this is my 2004 Silverado

It has a 4.3L V6, 4L60E - 4:10 rear gears.

The engine I am building to swap in place of the 4.3L is a 350 Vortec L31

The engine is a .040" 350ci, 4 bolt main, one piece rear, roller cam block.
ZZ4 forged crank & rods
H3445NCP-40 pistons, .004" below the deck .045" quench with .041" compressed head gaskets. 10.13-1 compression with the Vortec 64cc heads

The cam is a LT4 Hot Cam with Proform 1.6 aluminum roller rockers. Comp Beehive springs, retainers & 8 degree locks.

Lift @ .050" : .525"/.525"
Dur @ .50" : 218 Int / 228 Exh
112 degree lobe sep
108 degree intake centerline

3000rpm stall locking torque converter for the 4L60E, to make this cam drivable in a 4380lbs pickup.

The heads are 916 Vortecs, currently getting bowl hogged but will also be gasket matched, polished chambers, polished exhaust ports.

So, why not a LS/LQ swap?

Because the L31 is the perfect candidate for a 4.3L to V8 swap. The fuel injection is practically identical and all of the 4.3L accessory brackets, serpentine belt system & pullies and engine control sensors can all be used on the L31 V8. Even the v6 distributor can be used with a new cap for the v8.

I can retain a few currently used 4.3L performance parts. The K&N intake can be modified to work with the V8. The 74mm CFM-Tech throttlebody will transfer over. I already have HPTuners to write the V8 computer tune. The only custom work to be done will be modifying the trucks wiring harness for the v8 injectors, exhaust work,a motor mount adapter plate to adjust for the V8 re-located motor mount provisions.

Cheers ~Mykk

**SIERA*123** · 08-12-2008, 02:32 PM

badass, BUT I WOULD GO WITH A 408 LS1 YUST ME, GOOD JOB

**04SilveradoMykk** · 08-12-2008, 03:42 PM

Originally Posted by SIERA*123

badass, BUT I WOULD GO WITH A 408 LS1 YUST ME, GOOD JOB

Yea, right on. You've got one to give me?!

**dozerdan** · 08-12-2008, 07:41 PM

you coulda got a 5.3 from a junkyard for like $500 or less...

**04SilveradoMykk** · 08-12-2008, 08:24 PM

Originally Posted by dozerdan

you coulda got a 5.3 from a junkyard for like $500 or less...

And spent way more for the internals.

The engine, heads & F.I. were free... I've got $500 in what you see here.

Anyway you look at it LSx performance parts cost way more than performance SBC parts

**SIERA*123** · 08-13-2008, 04:57 AM

Originally Posted by 04SilveradoMykk

Yea, right on. You've got one to give me?!

HE MAN, THAT 350 WILL DO GOOD YOU DON'T HAVE TO GET OFFENDED

**04SilveradoMykk** · 08-13-2008, 04:00 PM

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

Here's a cool trick for ya with valve covers.

Plain ball milled covers.

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.

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

Cheers ~Mykk

**04SilveradoMykk** · 08-19-2008, 05:39 AM

Finished up the long block.

Pinned all 16 rocker studs, gasket matched the heads & intake manifold. Bored the Vortec upper plenum from 72mm to 74.4mm to match the CFM-tech throttlebody. New swirl polished valves and cleaned up the rough casting in the exhaust ports.

Got the geardrive & CKPS reluctor wheel in behind the timing cover.

Did need to use a couple valve spring shims notched for the crank keyway to space the reluctor wheel away from the crank gear as to not interfer with the geardrive.

Best of all, everything turns over and spins freely... No binding. No PTV interference. no coil bind, no retainer to seal issues. No geardrive to CKPS reluctor wheel clearance issues... so all is well, thus far.

Today, the updated vortec fuel spider will arrive. And coming soon; March 3 piece underdrive pulley set, Summit aluminum vortec distributor, MSD wires and the SBC to LSx adapter plates.

Cheers ~Mykk

**04SilveradoMykk** · 09-08-2008, 07:06 AM

The Swap has begun:

Sept 6th & 7th: I'll let the photos do the talking.

Cheers ~Mykk

**SIERA*123** · 09-08-2008, 07:26 AM

Good job man

**1fastcamarosss11** · 09-08-2008, 08:33 AM

looks good is it running yet?

**04SilveradoMykk** · 09-10-2008, 05:27 AM

Day 4: Sept 09.

I only had a couple of hours to work on the truck today. When my shift ended at my job tonight I rushed over to work on the truck with the intention to get as much done as possible, work all night if I had to. But I'm afraid mother nature had other plans, it was clear all day today untill I got to the truck and it began to storm, hard! Even though I am working under cover the ground under the truck floods quickly and the winds just about tear the make shift "Tarp Garage" apart.

While I was working, I did notice a few problems.

1) The driveshaft does seem to be binding. The yoke is pressed all the way in to the trans tail housing. I'll pull the driveshaft tomorrow to have it shortened & balanced, a local shop here does that for about $100.00

2) Because the engine is back a bit from an OE location, I can't get the trans dipstick tube back into place. So I'll be looking into an aftermarket piece, like a Lokar flexable.

3) With the engine mated to the trans, the flexplate is pushed right up onto the torque converter. And it's tight, so tight I can't spin either the torque converter or the engine over by hand I must not have the torque converter in all the way. While I have the driveshaft out I'll seperate the engine & trans a bit to see if I can't get the TC to slip in another click.

I'm beginning to think I should have used the adapter plates that had the LSx mounts & SBC mounts 1" away from each other, if I had I would run into major header & motor mount interference issues. Oh well, The majority of the weight behind the front wheels equals better weight distribution.. right?

Once it got dark and the ground became flooded I switched to the topside of the engine and finished up the wiring of the V8 fuel injector harness as well as lengthened the A/C high pressure sensor leads. Pulled the temp sender harness out of the loom a bit, made new heater hoses and a crankcase air supply hose.

The old 4.3L throttle cable bracket will not work on the L31 intake manifold. GM needed to order the new bracket and I didn't want to wait, so instead I bent and modified the 4.3L bracket to bolt on to the V8 intake manifold. Seems to be working thus far.

Hopefully tomorrow will prove to more prosperous. I don't work at the job tomorrow.

This swap is taking a bit longer than I had hoped for, but I also knew I'd run into a few unforseen problems doing a swap like this.

Cheers ~Mykk

**00z28bubba** · 09-10-2008, 03:54 PM

check on that throttle cable they are easy to break when in wierd positions.

**04SilveradoMykk** · 09-10-2008, 06:27 PM

Originally Posted by 00z28bubba

check on that throttle cable they are easy to break when in wierd positions.

Thank you, I had already routed it differently before bolting down the AC lines

**Black-Jacket** · 09-10-2008, 06:45 PM

well look who got some work done

**adam3566** · 09-11-2008, 06:09 PM

Nice looking truck except for that sticker 262ci and those ugly ass rims. Otherwise you got a nice ass truck. Swap looks good too.

**04SilveradoMykk** · 09-24-2008, 05:45 AM

So close guys, todays the day.

The new TC arrived yesterday. Despite it's different design compared to the OE converter, it fits like a glove. So yesterday I got the entire truck bolted back together and on the ground.

And this is what the CPS in the distributor looks like after getting upclose and personal to the firewall.

I robbed the CPS from the V6 and moved on.

The very first test fire, there was no fire. It just kept cranking. So I plugged in my laptop and saw, via HPTuners scanner, that TPS signal was 98% at idle and it wasn't reacting to my right foot. Upon closer inspection, I had the TPS harness plugged into A/C high side pressure sensor and visa verse. (Doh) So I put the right plugin in the right sensor and tried again.

It wants to fire up, it spits & spudders... I have a feeling it's a timing/distributor thing. So this morning I'll go put the #1 cylinder to DTC and see where the dist rotor is pointing.

More updates soon.

Cheers ~Mykk

**jaslivers** · 09-24-2008, 06:37 AM

hell ya, when you get it running we need vids

**04SilveradoMykk** · 09-24-2008, 03:29 PM

Well gents, I got as far with it in the amount of allowed time that I could. In the name of getting my truck running I hired out the rest of the job. So the truck was towed to a freinds shop where he will set the distributor to 0 degree via scan tool, make the new Y-pipe from the long tube headers back. And will fix a newly formed problem, one of the hard lines on the power steering rack was somehow busted and spewing PS fluid. (as you can see by the spot as itwas getting loaded on the flatbed)

All in all I feel good about the project... I hand built my motor from a bare block & heads, and made it fit in a frame never intended for it. I just might have my friend wait to fire it up until I get there so I can be there for the intial run (with camera in hand)

Cheers ~Mykk