[Tilar]

Hello all,

I have a 1994 3/4 ton Chevy 4x4 with a 305 engine. I bought a 454 that came out of a 1995 Chevy step van. I want to put this engine in my truck because the 305 just won't pull my trailer very good.

I'm not exactly sure which transmission it has, but I'm thinking it is a 700R4 or some variation of it. Maybe a 4L60 or 4L80-E. Haven't looked to be honest but it is an overdrive transmission.

I've asked a few people what all I needed to change other than bolting the engine down into the truck and have got so many different answers that I'm not sure what I need. I do have all the brackets and accessories for the front of the engine, and I think my radiator is plenty big. I don't remember if I have to move the engine mounts up or not but thats not much of a chore if I do.

Here are the things i've been told:

1) Just bolt it in and wire it up using a 454 harness, the computer that runs the 305 will compensate for the 454.

2) The 454 has to have it's computer and harness but everything else should be fine.

3) You have to use the transmission that comes behind a 454 in a 4X4 because the 305 transmission can not be controlled by the 454 computer.

4) You have to change everything including the wiring harness, computer, transmission cross member and the transmission. You have to cut down the drive shaft because the transmission is moved back a couple inches. This person also happens to have a 95 3/4 ton 4X4 that has the 454 in it that could be a donor truck and it is for sale... Imagine that.

5) A guy told me last night that I could use the existing harness but some of the connections might not reach sensors on the 454 and i'd have to splice longer wires, but that I would have to change to the 454 computer. He said that my transmission would work.

There is a transmission behind the engine, but it won't work with the 4X4.

Does anyone know?

[lookatme]

you will need the 454 computer for the engine. you could measure how long the output shaft of the 4x4 transmission is, and cut down the one that is on the transmission in back of your engine to the same length. that is assuming that they are both automatics. usually the only differences in the 4x4 versus regular car transmissions of the same model is the length of the output shaft.

[joe_padavano]

The 305 is a TBI motor. Is the 1995 454 a TBI or a port-injection motor? If it's TBI, the existing computer may work, but you'll need the correct PROM for the big block. If the 454 is port injection, the computer, harness, and everything else is different.

[oldbogie]

Originally Posted by Tilar

Hello all,

I have a 1994 3/4 ton Chevy 4x4 with a 305 engine. I bought a 454 that came out of a 1995 Chevy step van. I want to put this engine in my truck because the 305 just won't pull my trailer very good.

I'm not exactly sure which transmission it has, but I'm thinking it is a 700R4 or some variation of it. Maybe a 4L60 or 4L80-E. Haven't looked to be honest but it is an overdrive transmission.

I've asked a few people what all I needed to change other than bolting the engine down into the truck and have got so many different answers that I'm not sure what I need. I do have all the brackets and accessories for the front of the engine, and I think my radiator is plenty big. I don't remember if I have to move the engine mounts up or not but thats not much of a chore if I do.

Here are the things i've been told:

1) Just bolt it in and wire it up using a 454 harness, the computer that runs the 305 will compensate for the 454.

2) The 454 has to have it's computer and harness but everything else should be fine.

3) You have to use the transmission that comes behind a 454 in a 4X4 because the 305 transmission can not be controlled by the 454 computer.

4) You have to change everything including the wiring harness, computer, transmission cross member and the transmission. You have to cut down the drive shaft because the transmission is moved back a couple inches. This person also happens to have a 95 3/4 ton 4X4 that has the 454 in it that could be a donor truck and it is for sale... Imagine that.

5) A guy told me last night that I could use the existing harness but some of the connections might not reach sensors on the 454 and i'd have to splice longer wires, but that I would have to change to the 454 computer. He said that my transmission would work.

There is a transmission behind the engine, but it won't work with the 4X4.

Does anyone know?

This is close to a bolt in.

- Structurally you'll need the 454 mounts for your year truck, which the 94 and 95 s are probably the same but I haven't taken time to look it up.

- I think you'll need the 454 throttle cable, I went thru this about a year ago, but is was a 454 into an S10, and didn't write a note so I'm pulling out of my less than fantastic memory.

- I don't think the transmission will live long with the 454, this just based on putting either freshened or larger engines against automatics for years and having found that old automatics don't take well to more power suddenly being run thru them.

- While the 305 and the 454 are both TBI engines, you will have to either lay you hands on the 454 computer or have a custom chip installed into your current computer. The reason is that each engine and the vehicle are mapped in the PROM. The computer can learn and adjust for about a 10% difference in air flow but the stretch from 305 to 454 is a lot more than 10%, therefore, the computer won't be able to match sensor computed flow to real flow and the appropriate fuel and ignition maps. Since this is also related to the transmission shift schedule, that will also be off what's required. Just google "Custom TBI Chip" and a bunch of folks that do this should show up.
Here's some I deal with:

http://www.fastchip.com/

http://www.tbichips.com/

http://www.hypertech-inc.com/

http://www.tpis.com/

- Cooling, I'd plan on a 454 radiator and you might as well do the heater core and hoses while you're in there to head off post swap cooling problems, which will be there, guaranteed.


Bogie

[Tilar]

Thanks for the replies. I must definitely have the 4L60 transmission because it is basically a square pan. The trans behind the 454 is the 4L80-E.

Can they create the PROM to run the 4L60 transmission behind the 454?

I'd rather go through and put new clutches and seals in that transmission than have to buy another transmission and transfer case, I just want to be relatively sure that the 4L60 will hold up even with a rebuild.

Again, Thanks for the replies so far.

[va4cqd]

the 454 will destroy the 4l60e you currently have

[oldbogie]

Originally Posted by Tilar

Thanks for the replies. I must definitely have the 4L60 transmission because it is basically a square pan. The trans behind the 454 is the 4L80-E.

Can they create the PROM to run the 4L60 transmission behind the 454?

I'd rather go through and put new clutches and seals in that transmission than have to buy another transmission and transfer case, I just want to be relatively sure that the 4L60 will hold up even with a rebuild.

Again, Thanks for the replies so far.

Running the 4L60 behind the 454 isn't a problem but getting it to live will be. They can be beefed up check out some of these:

http://www.tciauto.com/

http://www.bmracing.com/

http://www.crttransmissions.com/

http://www.tsiracing.com/

In addition to beefing up the innerards, temperature management is of extreme importance to long life. You need to add an oil cooler of appropiate size to keep the trans oil around 180-200 degrees. A system that protects the transmission against excessivr heat with out over cooling it is important, this usually involves more complexity than just sticking a heat exchanger in the wind somewhere. A good system design is to take the oil out line and run it to a by-passing temperature control valve. This will manage whether the oil goes to an add-on oil cooler then to the heat excheanger in the radiator. Or whether it just goes to the radiator's heat exchanger. The point of this is to use the heat exchanger as a way to heat the transmission oil in cold weather; while providing a seperate cooling unit when it gets excessivly hot.



Bogie

[Tilar]

Ok, Thanks. Maybe I should consider a 350 instead... I wonder if it would give me enough power to pull a 14,000 lb GVW trailer?