Thread: Engine build/rebuild first time

So this summer I plan to lose my stock motor viginity and build a motor on a stand! But I'm in need of some help and direction.

I'm debating back and forth between a 3800 or a SBC.

Either way, I have a few questions:
1. If I don't want to "rebuild" per say, like the rotating assembly is is good shape, do I need to do any machining? Minor machining is fine but I wanna avoid costs in that department.
2. If I replace all the bearings, is it okay to reinstall stock rods and crank without machining?
3. If I do get a block that's .030 over already, pistons need to match right? What about the rest of the rotating assembly?

Thanks in advance, also gimme some votes on 3800 vs SBC! Lol

The hell would you put a 350 in a WBody, for?

If you're putting a motor in a WBody, get an L36...toss some decent punched out heads on it with a cam, let it breathe and you're good to roll.

For the latter, LS swap it. Whatever it is. Heads/cam LS will poop on most anything 350~ related for the money.

I had those 2 motors in mind becasue the 3800 could go in my GP or the SBC could go in the '68 firebird we have

LS swap the **** out of that thing. I wouldn't even consider anything else unless you had an old school BBP to toss in it.

I have been trying to rally for the LS swap but my dad says it's gonna be WAY more work than just building a motor lol maybe if I just do it, he won't have a choice haha

Also, so what I'm understanding is that you don't need to go .030 to build up an LS or 3800 even if it's used?

Lets put it this way, there is no building a 3800. The second you unbolt the main cap/rod cap it's straight to a machince shop for hundreds and hundreds of dollars worth of work and most motors that get "rebuilt" or "built" end up dying within the first 100 miles because something wasn't done right. The 3800 is very picky about certain things and even making it a bored over stroker motor isn't worth the money.

The SBC 350 works and that's a given but the cost to build one is more money than what a 5.3 LS motor can already make in stock form or just with a small camshaft upgrade. Figure roughly 200-250 crank hp stock for a SBC and 285-315 crank hp stock for a 5.3 LS motor depending on year.

The LS based motors don't even need machine work if you take them all the way apart, if the rod bearings look great and the cam bearings are still nice you can slap them back together with no real worry because it'll run just fine.


If you go the LS route, I suggest trying to fine a mid 2000's motor for the extra bump in horsepower and better heads but then use a cable throttle body setup and computer from a 2001-2002 silverado. Cable setups are easier to use on a older vehicle swap, no need to wire in a DBW throttle pedal or any of that jazz. If you use the same year harness as the computer with a drop in 4L60e to match, tuning will be easy. Disable the VATS, delete the emissions codes and it will run just like a stock truck motor.

If I go LS, would the eventual swap into a Camaro/Trans Am be relatively simple? I definitely want to avoid the machine shop as much as possible

It's not very complicated to do the swap, might take a custom part here or there though.

They make aftermarket motor mount conversion brackets and crossmembers for these swaps. It might need a different oil pan if the truck pan is too large. I think people run the LH8 pan, from like a hummer because it's shaped a little different and doesn't hang down as far.

Then you have the exhaust which will have to be custome made for than likely.

That isn't that bad, and way down the line anyway lol

We're doing an old school 427/T56 swap on the '68 Firebird we've got. Don't go small block, either big block or LS. It's just not worth the money, and the swaps are being made simpler by aftermarket stuff, especially for the 1st gen F bodies

Originally Posted by PaintChips97

We're doing an old school 427/T56 swap on the '68 Firebird we've got. Don't go small block, either big block or LS. It's just not worth the money, and the swaps are being made simpler by aftermarket stuff, especially for the 1st gen F bodies

I hear the first gen F bodies are really easy to LS swap anymore. So many companies that make plug and play harnesses and stuff.

427!? That's sweet! There is a cammed, 4barrel 350 in it now. But I have looking to take on a project for it

Originally Posted by Slick2500

I hear the first gen F bodies are really easy to LS swap anymore. So many companies that make plug and play harnesses and stuff.

^this is exactly right. Almost nothing custom is required anymore, it's all available from vendors

Originally Posted by Dadkota

427!? That's sweet! There is a cammed, 4barrel 350 in it now. But I have looking to take on a project for it

Nice! Ours has a 400, 4 barrel, and it definitely sounds cammed to me, but we didn't put it together lol. Yeah, the 427 is gonna be fun (the little bitty stroke in those things makes them run like hell), I'm really looking forward to the 6 speed though. It's got a TH400 with a shift kit in it now

We almost picked up a 455 Pontiac for it but it feel through sadly lol We have the TH350 with a kit too lol it will chirp gears but I would love a manual!