Hey Guys,

I'm afraid this thread will be a slow build, because I'm broke. Rather I should say, I don't have the money to put into toys right now.

None the less, today I had an opportunity to pick up a '99 L31 5.7L core. Minus crank.



It's from a '99 Suburban 1500. It's a two bolt mains, virgin engine. It has not been previously machined and was replaced by a crate L31 from the original vehicle. The crank was pulled out of the block in two pieces and looks like it split due to casting flaws, after 80K miles.

The heads are going up for sale now on CL:





My plans for this engine:

4.040" bore x 3.75" stroke = 385ci
Balanced rotating assembly
Splayed 4 bolt main caps
Flat top 4vr pistons
10.5-1 static compression

Transfer over from my current engine:

Patriot 'Vortec' heads, 2.02"/1.6", 185cc Int runners
Comp XR276HR-10 cam & the rest of the Comp valvetrain
Professional Products single plane intake manifold
Speed Demon VE 650cfm

..if I feel the 650cfm is a bit small for the 385ci I'll either try to bump it up with a different mains body or different carb.

The only big purchase for this build will be the rotating assembly, splayed main caps & the machine work. It will be a while before I can even begin to order parts.

If I get my ducks in a row I should be able to pull my 357ci, transfer over the valvetrain & heads to the 385ci and get it back in and running in a weekend.

Cheers ~Mykk

 

So you swapped in a SBC into your late model truck?

 

I still understand why...

 

Where have you been? I thought the notorious SBC swap into a GMT800 was a known thing, the controversy, the drama...


But yes, I have a built SBC in my '04, and carbed too

 

Please don't take this offensively, but why would you want to build a 385 rather than a 400 small block? I never understood why guys built stroker 350's when you can just start with more cubes and cheaper. Hell for what it cost to do a 385, you can get a roller cammed 454 big block crate engine new from GM for $2200. Stuff a small cam in and destroy 80% of the trucks on this forum.

 

400ci's are rare, and most cores are cracked thus driving the price of good 400 cores up. 350's are dime a dozen, parts are cheap and easy to come by. Even stroker kits are cheap. The kit I'm looking at is a complete rotating assembly including pistons, flexplate & dampener for $800.00


GM's beginning big block crate motor starts at $3,400 + $600.00 core, my 385ci will be a sub $2000.00 short block not including the heads & valvetrain I already have.

 

Where are you located? If I could get you a good 400 core cheap? Would you do that instead?

 

He's in Prescott Arizona

 

Ever thought about doing a 4/7 swap cam? Thats all I run in my 355 dirt track motors.

 

I'd like to hear your thoughts on it on the 4-7 swap cams, I think it's interesting but I've read that there isn't a reason to do it on a street driver/performance build. But I don't have any first hand experience with them.