350 Vortec to TBI conversion

[Edahall]

I've got a 1999 Chevy Tahoe with a blown engine and worn out transmission. I also have a very low mileage Chevy 350 TBI and 4L60E transmission out of a 1994 Chevy van. I want to put this whole 350 TBI and transmission setup into the Tahoe. I would like to keep it TBI if possible for its simplicity. How hard is this to do? I've got the complete wiring harness and computer for the 350 tbi.

[Ackattack]

Physically it should pretty much be a bolt in deal.

You will have to modify the fuel line. I believe the vortec engine runs higher pressure, but I think the TBI fuel pressure regulator will handle it.

One thing, IIRC, is the vortec ecm is under the hood, so I assume its water resistant. However the TBI ecm is under the dash and I would keep it inside. You'll need to figure out how to route it inside.

The wiring for the TBI engine is really easy. There is only about 5 wires you have to connect power to. When I hooked up my TBI engine and went to start it for the first time, I figured I'd have to go back and check this or that...but to my surprise, it fired up in like half a crank!

Good luck

[tommie]

are you trying to use the vortec ecm and fuel system on the tbi engine?

or are you swapping the tbi engine and tbi wiring harness into the tahoe etc??

do you have to deal with texas state inspection OBD2 testing?

[Edahall]

>>are you trying to use the vortec ecm and fuel system on the tbi engine?
No


>>or are you swapping the tbi engine and tbi wiring harness into the tahoe etc??
Yes, that's the idea


>>do you have to deal with texas state inspection OBD2 testing?
No

[ChevLoRay]

Just because I am curious: If you kept the intake and injection system that is on the original engine, will it bolt to the earlier block and afford the ECM the ability to operate the older engine with the OBDII parameters? Then, you would not have any wiring issues, at all, as long as you swap the sensors from the newer block to the older one.

What about the transmission in the vehicle...is it also a 4L60E?

[Boog]

For one the 94 engine will not have the crank sensor that the 99 does as far as just swapping long blocks goes.

[Restrorob]

Originally Posted by Ackattack

I believe the vortec engine runs higher pressure, but I think the TBI fuel pressure regulator will handle it.

This would be something to check into, The MPI pump puts out 54 to 62 psi while the TBI pump puts out 9 to 13 psi and the regulator restricts pressure to 10 psi.... It could be questionable whether the TBI regulator can hold such pressures back, And also not burn the MPI pump up from too much back pressure....

[Edahall]

Originally Posted by ChevLoRay

Just because I am curious: If you kept the intake and injection system that is on the original engine, will it bolt to the earlier block and afford the ECM the ability to operate the older engine with the OBDII parameters? Then, you would not have any wiring issues, at all, as long as you swap the sensors from the newer block to the older one.

What about the transmission in the vehicle...is it also a 4L60E?

I guess you have to use the Vortec heads to be able to bold on the Vortec intake and injection system. The problem is my Vortec heads have 160k miles on them and they're questionable. It's possible they were responsible for blowing up the original engine.

Also, GM made minor differences to the 4L60E almost every year so if I went with the Vortec, I would not be able to use the transmission out of the TBI Chevy van. At 160k miles, I doubt that there is much life left to this transmission.

Yes, both transmissions are 4L60E's.

[ChevLoRay]

Boog answered my question, stating that the earlier block doesn't have the crank sensor like the later block. I was just curious.

Carry on.

[BigBlocksRule]

Crank sensor is a piece of cake, just gotta have the balancer snout machined down so there's room for the sensor when the balancer is pulled fully on. Good time to replace the timing chain as well.
Have those Vortec heads checked, if they're fine, run 'em.
Most Vortec engines I've seen that died an early death did so from a bad intake manifold gasket. Antifreeze into the oil, that's all she wrote. Most of 'em still have good heads.
I never had any real problems with either a TBI or Vortec injection. I still think I'd try to reuse the vortec heads and injection, it'll be a ton easier swap.

[MARKDTN]

I would find another Vortec short block. TBI engines go forever, but the Vortec does have better power.

As far as the transmission, I had a '95 Suburban with 212K miles when I sold it and a '01 Tahoe with 240k miles and still going. Neither ever had transmission work. The 4L60E will go a long way.