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EmmyJ · 11-26-2013, 05:41 AM

Just as I was bedding the rig down for the winter and gathering my off-season upgrade plans, an unexpected bonus fell into my lap: a '92 Chevy commercial-chassis van similar to my '76 GMC Avion Class C, with a crate fuel-injected 454 under the doghouse. Sure would be nice to replace the tired old carbureted 400 with that big-block...does anyone have any experience doing engine swaps in vans or Class C's. Most of the Internet advice I can find comes from hot rodders who are just ripping the motors out of vans, with no intention of putting them back together again. I'm pretty sure that I should NOT cut all the subframes with a plasma torch...

trackman · 11-26-2013, 06:11 AM

It might be a good idea to compare torque and horsepower between the 2 before you decide. That tired 400 if rebuilt will out pull the 454 and get way better gas mileage. Unless you are planning on going on the road for long trips I would stay with the 400 and rebuild it. You can upgrade the carb to newer applications

rickf · 11-26-2013, 05:49 PM

I would go for the 454 in a heartbeat due to the F/I. It will most likely still get better mileage. The main issue would be the wiring, you need every bit of wiring that comes with the engine. That means ALL of the external sensors also. The O2 sensor would be easy but the speed sensor could be problematic depending on where it is. Some are in the transmission and some are in the rear differential. If it is in the transmission and the transmission is with the unit then just swap the whole shooting match. If it is in the rear differential you have options because there are aftermarket units out there that work off of the speedometer cable. I am not familiar with the Chevy chassis but the Ford Chassis you have to remove the intake manifold and have a special lifting attachment that bolts in it's place and has an eye to hook the hoist to that sits down below the head surface. Even then the vehicle has to be high enough so the hoist will lift the engine without hitting the cowl. TIGHT, TIGHT, TIGHT!!!!!!!! I don't picture the Chevy as being much different.

terry735001 · 11-26-2013, 06:51 PM

yes i have did this and its not hard at all

there is alot of after market stuff for the 92 and would not be hard to move over

only thing you can not do is make your own drive shaft thats if you cant find one that would work

EmmyJ · 11-27-2013, 08:29 AM

Thanks for the responses!

The good news is that I have the entire running donor vehicle, so any fussy bits (wiring, sensors, etc.) are already in hand. The donor vehicle is actually a cut-down van body on a commercial chassis, so I can transfer axles if I need to, though the driveshaft may not fit (I think the donor vehicle's got a slightly longer wheelbase than my 23' Avion).

Trackman, I considered exactly that, and I do plan to use the moho for extended (3-6 month) trips on the road, so I decided to go ahead and do the swap.

Now, just have to figure out how to remove the front fenders and radiator support.

Argosy · 11-28-2013, 05:32 AM

I'd definitely go with the 454, longer stroke, no siamese cylinders, and EFI. Big blocks and small blocks each have their place, a big block is much better moving heavy vehicles.

TBIs were pretty simple without a lot of sensors and wiring. With any luck in 92 they still used a cable speedo, if so it will have a pass through adapter on the trans for the ECM. Other than that the biggest thing is tearing harnesses apart to get the wiring you need. If you're good at wiring it's really simpler to build your own harness.

Good luck!!

Daveinet · 12-29-2013, 09:57 AM

I would not use a '92 FI. The computer is primitive, with limited adjustment. I would opt for pulling the ECM from a '94-'95. There is plenty of info on doing the conversion, wire harnesses ere easily purchased. You can purchase a wire harness from Howell, but use all your old sensors, or just build your own harness. That ECM is well documented, both from a wiring and programing standpoint. Join Thirdgen.org. Search on 16197427 ECM. There is gobs of info, as it was the most advanced pre-OBDII ECM available. You can set it up to run without the trans, or speed sensors. Actually all you do is disable the trans alarm codes, and you are good to go. You can add a speed sensor to the drive shaft if you want to, it does add some functionality to fuel cut off in off throttle situations, but you don't need to. The thing about the 7427 ECM is that the fuel tables and spark tables are huge with a ton of resolution, so you can fine tune it for maximum power and mileage. OEM is pretty conservative, so there is some adjustment improvement available. Ebay is your friend for finding a 7427. You may even find one with the harness, although that will be more money.

EmmyJ · 12-30-2013, 09:09 AM

Davinet: I may be in luck there, actually. The 454 in the '92 is actually a crate engine, so it's newer than the truck. Have not yet torn into it to see what kind of FI it has. Thanks for the Thirdgen.org advice though, I'll probably be on there at some point to find out what the story with this engine is...

Daveinet · 12-30-2013, 12:26 PM

ThirdGen refers to third generation Camaro. But what the deal is that these guys that hotrod their Camaros have to retune their ECMs to manage the performance mods. As a result, there are some computer gurus who have written their own software to burn chips. In the process much knowledge has been gained about GM ECMs from that generation car. That is where I gained most of my info to tweak my engine in the Revcon. I would say that I got lucky with my purchase, as when I made the purchase, I didn't know anything about what I was getting. After diving into it, and reading some issues with older ECMs, I have found that their is a substantial jump in capability in the '94-'95 ECMs compared to the older ones. OBDII I'm sure is another bug jump, but is not as widely published on the net. You can pay for OBDII info, but if we were rich, we would not be posting in the vintage forum.

Most likely if this crate was installed in a '92, they likely used the original computer as well as the original program. Messing with ECMs is usually a DIY thing, so less likely for it to be changed. You could pull the chip and read it, and then do a compare to a stock read (BIN), as that would tell you if the engine is stock.