i have an 85 chevy blazer 4x4 with a puny 2.8 liter engine and i want to drop either a 5.7 or 4.3 which would you reccomend and where could i get it? id like to convert it from carb to EFI is this possible? thanks.
My brother did an 85 with a 350 fuelie. You'll find a bunch of resources on this board about the conversion if you do a search. I did an S-15 pick up and he loved it so he converted his Jimmy.
1. Basically we both used the Heddman plates. There's enough clearance in front of the engine to run a flex fan, and enough in the back to remove the distributor. You'll need to bash in the pinch welds at the firewall to clear the transmission. I would recommend using engine mounts and cups from a '78 Impala over fabing up your oun mounts since there is actually some rubber to absorb shock. Install the plates and mounts together and just pin them with bolts (weld them solid once you have the engine in position). You'll have to add washers as spacers under the mounts and cups to get the engine in the proper location. Use a straight edge so the engine isn't sitting crooked in the bay.
2. There are many transmission choices, I would recommend one from a V8. I started out running a TH350 but it was a daily driver and I couldn't afford the fuel so we both used 700R4 transmissions. His was from a Chevy van and mine was from a Z28. I used the stock trans cross member and moved the mount from the front of the cross member and welded it on to the back after I adjusted it for the correct angle to the differential pinion. This is important because U-joints can only take motion in one direction. If you don't align the rear of the transmission with the differential pinion, you will be blowing U-joints all the time. We both had the drive shafts shortened. I did mine myself, and he had it professionally done. I'd have it professionally done.
3. We both went with floor shifters. I used a Hurst shifter and he used a B&M ratchet. I would go with the B&M ratchet, it has a lit gear selector and a cable connection. Way easier to install.
4. I went with a two core rad and he went with a 4 core, again follow little brothers truck and go with a 4 core, I never had a problem, but I used to sweat in traffic jams.
5. The differential gears will probably have to be changed. I had 4.11's so I was in overdrive before I started moving (a lot of smoke though!!!). I ended up putting the gear set out of a Camaro, and had a good mix of power and enough gear to actually make the 350 cheaper to run than the original 2.5L. My brother ran the stock gears until he chipped the teeth off in the second year of the conversion, he's now running the same gears out of the Camaro. I think 3.73, but I'm not sure, could be 3.55.
6. Mine was carbed, and I wasn't with my brother when he installed the ECM so I'm only going by what he told me. The ECM just slid in under the dash behind the glove box. He used the stock wiring from a Chevy van, just plugged it into the engine and trans, and through the firewall at the stock location. He added a VSS on the speedo which had a grommet that it just plugged into--just like stock. He disabled the Park/Neutral switch. He did mention that some of the idiot lights on the dash had to be rewired, but it wasn't that hard. He also added an O2 sensor on the Hooker tuned headers. These headers make a lot of power, but one tube goes on the outside of the chassis and it rubs the tire if you turn too hard. I used heddman ram horns with the collector cut off and mandrel bends welded on. I've seen corvette manifolds or camaro manifolds with slight modification. If you plan on going with the camaro manifolds you'll need to cut part of the end and weld the cast with nickel rods.
7. We both went with stainless exhaust. I went with Dynomax and he went with Bad Boy. Dual cats, dual mufflers. I had mine done by a local shop. My brother also went to that shop. After two weeks, we picked up his truck and went to another shop. They did the exhaust in about two hours.
You don't have to cut up the body to do this conversion. If you go to cruise nights you can see a good mix of well done conversions and absolutely butchered jobs. Don't be the latter. My brother also added Air conditioning because someone said he couldn't. He took the compressor out of a Chevy van and the rest was donated from a Jimmy including the controls on the dash. He also added an electric fan because he tows the car trailer once in a while. (just extra insurance) He's a bit of a S/T truck fanatic, one of his trucks is in a magazine and this 5.7L fuelie is going to be a cover in an upcoming issue. If you have any questions post them on the board (This is an excellent resource, lots of people did this conversion, and did it well. Check out the rodders journals, there are some awesome projects.) or PM me directly. I'm pretty sure that you'll get all of your questions answered.