In reply to 03Panther :
400 got a bad rap because folks were trying to hot rod them without understanding it's not just a bigger 350. I mean, it is, but there are differences. Steam vents, external balancing... But the general stuffed them in all kinds of heavy box trucks and vans and all sorts of things that ran forever with serious abuse. Anyone who blindly spouts "400s are junk" probably believes that camel hump heads are better than those new fangled vortec things.
The only trouble with 400s is they're just thin on the ground. The 350 was introduced in the late 60s and gm is still churning them out. The 400 was made from 1970-80 and that was it.
Yea, def. never heard anybody call a 400 junk. Just that I heard they could be a bit more prone to overheating when hopped up. Like you said, not the same 'ol SBC.
Seems like it is mostly a matter of time. If you want to minimize time the truck is down, the 383 seems like the way to go, as it is mostly pull the old engine, drop the new one in, get it tuned, and go. The LS option probably makes for a better long term option, but the truck will likely be out of commission longer when little things crop up and need to be dealt with after the engine is in, even if you plan ahead.
Edit: I am planning on going LS in my S10, but I can afford to have it down for months at a time.
I dont know why a 383 and a 5.3 would be in the same conversation at all unless the OP specifically said "I dont care about low rpm torque". I think a better question is whether a lightly modded (cam and tune) drop-in 350 Vortec would be enough better than the 305 (or stock 5.3, fight me) to make the 383 a bad effort/return prospect.
If you're not planning to spend a lot of time above 4000rpm I would ignore the LS world completely.. my .02.
Ok, I have a 91 c1500 with a 4.8 swap. It is very easy to do. I’m running mine on n a mega squirt with the 700r4 behind it. Trans bolted right up. 1 bolt is off but that really doesn’t bother me. Just use strong bolts for the 5 that work. There is a company that makes a spacer to go between the crankshaft and the torque converter so you can use the early converter. You also have to slightly elongate the flywheel to converter bolt holes in the flywheel to use the older converter as the bolt circle is slightly smaller on the LS flywheel. I also used an off the shelf converter for a late 90s v6 S10 to get a little higher stall speed while keeping the lockup. There are also multiple companies that make motor mount brackets. Again, can’t remember which ones I used but they all work the same.I don’t remember who makes it but I got mine from PATC when I got my rebuild parts. I notched my frame to use the LS AC compressor, but that was 5 years ago. Holly makes a nice accessory bracket kit now that places the old style radial compressor in the same location as the old small block so you can use your old compressor and lines. I would do it again in a heartbeat. LS swaps are a dime a dozen and nowadays you can buy retired county trucks with a 6.0 at auction for cheap. I used the radiator for a big block truck with a couple of flex-a-lite fans on a thermal switch but I’m sure you could make the clutch fan work. I had to use a section of aluminum pipe to connect the upper radiator hose from the driver side of the radiator to the passenger side of the engine. If you buy a whole truck you could fairly easily just adapt the factory wiring to work with factory ECU if you are crafty with wiring.
the swap served me well and went through a ton of abuse but I recently bought a duramax truck and retired the old GMC. Prolly going to use the 4.8 in a G body next.
I think I should mention that a 350 isn't totally out of the question if it would be cheaper than a 383. Is the 0411 ECU happy with the Vortec harness, or is that strictly for an LS? An all new harness doesn't seem like a bad idea, but I have no idea what to expect for cost and I definitely don't want to lose any functionality of gauges.
Whatever parts I use, I'd like to make sure they are easily serviceable and replaceable in the future. I will own this truck for a long, long time and I will frequently be in faraway places where parts aren't always available quickly. That said, OEM parts for 10 year old vehicles can be easier to find than parts for 23 year old vehicles.
Low end torque matters, but so do gears. I need a highway biased final drive ratio, so having extra ratio in the transmission seems like it could make up for the 5.3. That said, I don't see why I wouldn't go for a 6.0. It doesn't seem like it would add much to the total price of the job and I'm sure it would still be more efficient than the old Vortec 305.
I do like the idea of the 383 being less downtime and if I'm going to be chasing silly bits down, I'd rather be working on a Porsche or one of my karts. Lots to think about...
383 vortec head, pcm program, done. Don't make this complicated, the vortec head 383 will out hp and torque a 5.3 by enough to really notice and all your everything is bolt back on friendly.
Haven’t done it myself, but almost put a 98 350 in my Astro van. I think you would be happy with the gains from that; decide on 383 or built LS next time it need work!
that’s the easy and cheap button.
I just did a quick scan of this article, but something like that...
https://www.fourwheeler.com/how-to/engine/1607-increased-power-for-your-1996-to-2000-350ci-chevy-vortec-5700-v-8-engine/
In reply to white_fly :
Nah them 6.0 cost 2x as much as 5.3's to buy. I can't find one in decent shape under $1200 just for the engine.
Patrick (Forum Supporter) said:
383 vortec head, pcm program, done. Don't make this complicated, the vortec head 383 will out hp and torque a 5.3 by enough to really notice and all your everything is bolt back on friendly.
This right here was what I've been wanting to hear from a knowledgeable source for a very long time.....thank you Pat G.....SBC's can be made to Behave or NOT!!!!.......Happy thanksgiving Y'all
yupididit said:
In reply to white_fly :
Nah them 6.0 cost 2x as much as 5.3's to buy. I can't find one in decent shape under $1200 just for the engine.
Guy here at Ft. Rucker had a 6.0 (lq 9, I think he said) $300. Said it does need some work, but he seemed like an honest guy, if you are looking for one to build from.
In reply to 03Panther :
Can't even find an lq9 in pieces for that cheap. I just want to throw it in the car stock with a cam and intake. Then probably turbo it.
yupididit said:
In reply to 03Panther :
Can't even find an lq9 in pieces for that cheap. I just want to throw it in the car stock with a cam and intake. Then probably turbo it.
I bought a carb. from the dude. Seems like a good guy. I could see if he still has it and send you his number for more info., if ya like.
03Panther said:
Yea, def. never heard anybody call a 400 junk. Just that I heard they could be a bit more prone to overheating when hopped up. Like you said, not the same 'ol SBC.
Back in the day (‘80’s to about mid ‘90’s) they were widely shunned by the hot rodding community. Boat anchors they said. Then some smart people figured out that they had potential. Then slightly oversized 406” became a pretty potent combination. Then everybody wanted one. Then the supply dried up.
The 383 is probably the easy button. Based on what I did to the 360 in the Jeep and how that turned out, I'd say bump the compression a bit, run good flowing heads a mild cam with fast lift rates and a decent bit of lift, plus good tuning. Should give a wide powerband, plenty of torque and likely better mpg then stock.
yupididit said:
In reply to 03Panther :
Too far. 
Oh,we could get it to ya... As long as you weren't in a hurry! I would go part way, just for a fun trip.
In reply to A 401 CJ :
Early 80's, I knew a couple folks built some nasty 377's. I guess there are always folks that repeat what they heard, but the guys I knew that didn't want one, didn't consider them trash. Just didn't want to build one themselves. But then the serious street racers I knew were mostly BB dodge guys!
In reply to 03Panther :
I'm not in a hurry at all. Honestly I can make it out there after the new years. What kind of work does it need. $300 lq9 is hard to pass up.
A 401 CJ said:
03Panther said:
Yea, def. never heard anybody call a 400 junk. Just that I heard they could be a bit more prone to overheating when hopped up. Like you said, not the same 'ol SBC.
Back in the day (‘80’s to about mid ‘90’s) they were widely shunned by the hot rodding community. Boat anchors they said. Then some smart people figured out that they had potential. Then slightly oversized 406” became a pretty potent combination. Then everybody wanted one. Then the supply dried up.
Because they all blew the mains out 
Lots of people make decent power with 406-421-434 engines, but not for very long with a stock block. Have heard as little as one night of racing at the 600hp level.
In reply to Pete. (l33t FS) :
That's 100hp more than a Windsor can manage and an extra night of racing. 
600 is a bit much on a platform that was designed to make 200, but they manage to survive quite well at a modest 400. It's not earth shattering, but more than enough to have fun with.
In reply to Pete. (l33t FS) :
When I was 17 I had a 86 Grand Prix with a "built" 400. It was orange with 22" rims and a system. I wish I could recover my MySpace account to get the pics lol.
I sold it to my neighbor when I joined the Air Force.
I would totally build a donk g body again lmao
In reply to yupididit :
I had a stock GP with original 400... But 76 was still using Pontiac engines, so no relation, and I'm just making a funny! BTW I loved that Pontiac 400.
Ok, back to the regularly scheduled forum...
