So my RS currently has the L03 305 in it, but I'm finally ready for a 350. I found a nice 350 for cheap and want to swap it in this winter, but I want to go with a carb, with no ECM. My question is how do I do this the right way? I want to do it right the first time....and yes, thus will be my first engine swap.

 

Before you get too far down this road, I'd take that 1970 350 to a competent machine shop and have them check it over from top to bottom. The engines from that era were known to have a lot of quality problems. Also make sure it has all three starter mount bolt holes.

For TBI to carb conversion info, go to the thirdgen.org homepage, click on the "technical articles" link in the left margin, and under "carbs/efi", click on the EFI to carb conversion article.

It would be a good idea to have a complete, total exhaust upgrade planned when you do this, too. The LO3 exhaust is inadequate for a 305, let alone a 350.

 

I'm trying to figure out if I can delete my ecm all together or if I have to keep it because I have the VATS key. My exhaust will be a custom dual set up with headers

 

That 350 may make less power than your 305. Most 350s were meant for trucks and were slow.

 

I'm going to add some good performance parts to make it worth the swap. Anyone know about the ecm, I read the tech article which says basically I won't need it but I don't understand how the car will start without it since it has a vats key

 

You can eliminate it. You must do a bunch of things to make it work. Electronic torque converter lock, manual fuel pump switch, maybe a manual fan switch. etc. Most of the wires going to the passenger side of the firewall are going to be eliminated but you have to take care to leave the HVAC/blower motor etc wiring alone as all that is on that side too.

Dont use anything above the deck from that block, it's most likely garbage or worth more to someone else for originality reasons than it is to you for performance reasons. The heads, intake, cam, lifters, rocker arms, valvesprings, and pistons are all garbage. If you re-use the rods, make sure to put new ARP rod bolts in them. The only exception is if you got lucky and they're the "good for their time" heads, someone may value them. You're better off getting stock thirdgen 083 heads than using heads from 1970. There are better heads, but stock thirdgen heads are probably the cheapest "acceptable" heads.

 

I knew about the torque converter lock, and fuel pump, just wondering mostly about the vats key right now, don't wanna do all this work and can't get my baby started lol

 

VATS is in the computer. No computer No VATS

 

Right....so.how can I delete the ecm and have my car start still?

 

Key on - hot wire to coil.
Key start - to solenoid to starter.
Am I missing something?

 

Alright, just didn't know where to start, never hot wired a car before lol

 

Youre not hotwiring anything. Without the ECM the VATS does nothing. You dont need to change anything. Just dont pull the ECM or VATS fuses in the fuse box, important wiring goes through those and it causes weird issues and things wont work.

 

I understand that but I posted that I want to know how to completely delete the ecm, and I think I know all the things needed to do so EXCEPT my ignition because of the vats system. So does anyone know how to get around the vats system due to not using an ecm?

 

You dont have to do anything to get around it. Just dont pull the fuses. No ecm = no vats

 

So just leave the ecm plugged in with all the wires?

 

Basically what they are telling you about the vats system is, that it is in the ecm, it is controlled by the ecm. So once you disconnect the ecm you don't have the vats system anymore. You don't have to worry about the car not starting because of the vats system, it will no longer be in the car. So basically all you have left from the vats system is a useless chip in the key that wont affect it at all. Then once you pull the ecm remove the fuses from the fuse box, so it doesn't cause any issues. Hope this clears it up a little more.

 

Ok, so are the vats fuses in the fuse box under neath the dash on the driver side? Thanks for the clear up!

 

Im pretty sure that pulling either the ecm fuse OR the vats fuse causes weird issues.

Removing the ecm fuse caused a no-start condition (even though the ecm is completely removed from my car) and removing the vats fuse caused the alternator not to charge if I remember right. I may have that backwards... but the fuses need to stay.

 

Wrong.



The VATS system is connected to both the ECM and the starter relay.


OP, the starter relay should be located behind the kick panel on the drivers side, sometimes if people have done previous work you can find it below the carpet in the area, it will have 3 large (around 12ga) wires going to it and a small black/white wire, cut the wire and ground the side the connects to the relay end. *this is if you are trying to completely remove vats, if you just leave it connected it will still be able to disable the starter, though most people want to remove it completely because of typical issues with the vats, key, tumbler contacts etc.*

 

You know I was about to lose my temper but you actually reminded me I did bypass VATS years ago. That explains why removing the VATS fuse wouldnt let it start. I still have it apparently. I had completely forgotten about that.

Bypassing vats is super easy if you wnt to go that route. I think its the two orange wires going to the ignition switch. Snip them and short them together and install a resistor in line with them that matches what your keys read.

 

That does work so long as the box is still working, re routing the starter relay ground that comes from the vats box does the same thing without the resistor and without being dependent upon the vats box.

Some people also bypass the relay, due to the way it being wired it doesnt technically take the load off of anything.