Ive searched for this If there is a post about someone please point me there. I have a 2001 Blazer LS 2 Door 2WD. I have a 99 5.7 v8 I want to put in. besides engine mounts what else do I need to change? Do I need the computer or can I use my existing one with some mods? I read somewhere about adding a wire to the harness. I have built many of these v8 swapped ones but in the older square body generation. I had changed to carb or throttle body, I want to keep the vortec EFI for a while. My 4.3 is starting to knock, loses oil pressure. doesnt go above 10 psi when it gets warmed up.
Anyway. I want to drop the 350 I have into it but cant keep it apart for any long amount of time as Its my only vehicle. Im heading east in about a month and want to take a travel trailer too. small one!
I still have access to the truck to get the computer, its a 4x4 is the only difference other than mine is 4.3.
Again sorry if this post is already been covered, Im in a time crunch. lol
Thanks again!

 

you can keep the computer, you just have to run injector driver wires to the 2 extra injectors assuming that you have the correct kind of 5.7, the vortec name was bastardized to hell and back and can be anything from what we have stock up to iirc certain LS motors got that name as well. Should look like the motor you have in the truck with the intake hat taken off but obviously longer.

 

A '99 5.7 is the "correct" engine, and about the easiest V8 swap available. In addition to what has already been mentioned, you'll need to have your PCM reprogrammed, and you may need to switch to electric fans for radiator clearance.

 

its a vortec out of a 99. I know what you mean. its the same engine only longer.
Thanks. Im starting the project next week as soon as my mounts get here.!

 

Guy is a little pessimistic, but pretty good info here.

https://www.reddit.com/r/Chevy/comme...e_to_swapping/

2wds really can use a different oil pan like the Milodon S10 Swap pan and sump (this is what I have in my S10). Otherwise you will have the front of the engine too high and have exhaust header/trans tunnel clearance problems and drive line angle will be wrong. Then people bitch about how stuff doesn't fit right. Use the JTR mounts and grind off the lower parts of the ears to use the upper mounting bolt holes and get the front of that motor down where it belongs. Then the header loop around the steering column will clear, the headers will not hit the firewall, and you won't have to beat in the trans tunnel. Hint: reference the center of the crank pulley on the 4.3 to something on the vehicle. That is how high you want the center of your pulley on the V8.

Radiator will need to be in forward position, so get the 85 Corvette radiator and do that with the JTR radiator mounts (rubbers can be sourced on ebay). Put an adapter and fill cap in the upper radiator hose.

I used a modified Taurus electric fan to pull air through cause mine is a racer, but I used to have a shroud I built from a Summit shroud kit and there was enough room for 7-blade metal flex fan.

 

rather than running the 2 extra wires, could i use the harness from the 350? I have all the engine harness for it. I know the trans mission part can be taken away from it and married to my existing one.
Ive built many of these but they were throttle body or carbed trucks then. I want to keep the EFI. Its going to be a daily driver and will be commuting from Eastern Canada to western US twice a year. Id love to do an LS swap but not in the cards right now time and money wise. to have my pcm programmed do I go to the dealer or send it out to do it?

 

To be honest, I don't know about using the V8 harness. It very well might work, but I have no personal experience.

There are a number of mail order PCM reprogramming services. I used pcmforless.com to have mine done (manual transmission swap, not engine swap). The dealer probably wouldn't be able to do what you need (or just wouldn't do it).

 

I saw from the reddit link that part of the harness can be used. Im a mechanic too, but like I said, been a while and where Im from its not a common thing anymore with the price of gas there. I have an old caddy that Im going to do a swap on too, but its going to be alot simpler than this. its TBI all I need is an adapter plate for the TB to mount to a 4bbl intake, which I have.
I have a really good old 44o and a 727 tranny, but Im sticking with the GM brand for the engine swap! lol
Thanks for all the info guys. Im tackling this next week
1 more question! Will the blazer start before I have it programmed? Im just ordering a computer, sending mine in once I get it
I have to be able to move it around a little because of space and location.
My 4.3 is about done. shes knocking pretty bad. almost sounds like a broken flex plate, but I know its not. lol

 

I would guess it will run, but only on six cylinders. You don't want to drive it, but I wouldn't worry about moving it in and out of the garage.

My old 4.3 was knocking pretty good before I replaced it. I haven't had a chance to do a full autopsy on it (and maybe never will), but I did notice when I pulled it that it had a TON of crankshaft end play. Like 1/8" or more. The only time I've seen an engine worse than that was an old Ford truck that drove into the shop with the crank completely broken in two pieces.

 

I've seen a few nightmares too.
the 4.3 are pretty rugged I have to say. I had a 95 astro that the cooler line blew off and pumped all the oil on the ground. Drove about 5 miles. Put hose back on. Topped it off. It was hammering but it lasted until I swapped it for a few weeks. I just try to keep the rpm down & stay off the freeway. Gf uses it for door dashing she shuts it off if shes waiting for orders, it's been knocking about a week and a half.