Pretty simple premise, im sourcing a junkyard but running 4.3 1998-2000 to rebuild for pure reliability, going to the wall overkill with everything (bearings, seals, brass coreplugs, melling M55 oil pump with steel coupling and shaft, etc) to eventually daily drive and have on standby incase the one currently in my rig fails out, Are there any special things about the 4.3 over a 5.3/350SBC rebuild or are all procedures the same even with the roller rockers and physically missing two cylinders?

 

Exactly the same as the 5.7 Vortec (including the roller rockers and lifters), except you have a balance shaft and 2 less cylinders to deal with. Even takes the same pistons. Don't do the high volume oil pump unless you are increasing bearing clearances over factory specs. Doing so keeps the oil pump against it's bypass pressure most all the time and causes excessive wear in the distributor gear. STD vol/STD pressure is what you need. It's not a race engine.

 

It also uses the same motor mounts, and all the same sensors. I keep reading the 4.3s have slightly shorter piston skirts, but they also have two fewer cylinders, so, yeah.

Situation like this.. I also want to build up the 4.3 (probably the one that comes out and I'll keep in the back in bins, taken apart I assume) to a monster beast. But. Then. If you do the same thing to a 350SBC, and end up with a bored and stroked 427.. why not just drop that in? Because then you have to change everything else.. yes?

(I, also, am buying a "yard 4.3" this week and would LOVE to do more, but at this time, the dollars are dictating what I can do. In the future I may go for more power in another engine too so.. interested in this.)

I have heard of people putting turbos or NOS on these engines, at least the Gen1s.....

 

Alright, Thanks. Most of what i know about rebuilding comes from the 350 Smallblock so i'll have to do some reading on the 5.7.

 

5.7 Vortec is a late 1990s 350 small block

 

Ah, then same genesis of design, The only thing im not clear on is the roller cam/lifters/rockers, how is rocker preload set? i know on a 1980's or thereabouts its zero lash + half turn on all valves.

 

The factory roller rockers on the Vortec 5.7 and 4.3 are non-adjustable. You just torque them down.

Lots of people use the 5.7 Vortec heads for performance applications on early engines, as they are about as good as you can get for iron heads (same for the 4.3 v6). From the factory they flow better than the old double humps even with porting. However they do require a unique intake manifold to put a carb on top of them. For those applications, most are scrapping the factory rocker setup and going with the adjustable-rocker screw in studs, guide plates, and using aftermarket rockers for the older heads.

The bottom end on these engines are almost identical to the early engines, except that they use a 1-piece rear main seal crankshaft.

 

Is anyone dropping in 5.7 engines (built or otherwise) along with associated 4L80-E into 4.3 footprints?

 

The 1996-2000 5.7 Vortec engines are a natural for the second gen Blazer as you retain the same PCM in the Blazer to run the factory fuel injection on the 5.7 as well as the original 4L60E trans which bolts up and the accessory brackets work out nice. But you have to make room for the extra two cylinders by moving the radiator forward and exhaust is always problematic. Contrary to popular opinion, they will not bolt onto the factory mounts and oil pan can get in the way - so aftermarket is the way to go with that. Personally I wouldn't do it for the 40 or so HP extra that you get. The 4.3 is a pretty powerful V6 at 200 hp. I think it's hilarious when people take them out to install a 135 hp 305 v8. That said, here's my 1989 S10. https://blazerforum.com/forum/street...rs-seat-94815/

 

i think the main reason for a V8 swap on anything is for the torque the extra 2 cylinders and (in a 350's case) the extra 88cu of displacement brings.