Is the 4.3 this much of a turd!?
 

I daily drive an 87 chevy silverado 2wd with a 305TBI with some minor mods so I know the performance of a stock 4.3 is tough to compare.

With the colder/crappier weather here, I have been daily driving my 1992 S10 blazer 4x4 equipped with the 4.3TBI and 700r4. It's a very reliable vehicle and a great plow truck. My father purchased this from his friend a few years ago. His friend was meticulous when it came to maintenance of the blazer. We have 2-notebooks worth of maintenance records from little things like light bulb replacements to things like water pump replacement. The truck has been well-maintained.

Has high miles at 200,000. It does not leak any oil. I never have to add oil. It only smokes on startup. It has the 3.42 gear ratio and stock size tires. About 5,000 miles ago I did a full tune up (fuel filter, cap/rotor, AC DELCO plugs/wires). Fuel pressure is good at 13 PSI. Base timing is right at 0. Truck idles great and runs great but here is where I am dissapointed:

This truck is such a turd! Around town fuel mileage and performance it is not bad. I calculated fuel mileage and the blazer gets the exact same mileage as my silverado... 18mpg (except the silverado obviously has more power/torque).

I have been doing some highway trips now (our highways are hilly) and this is where I notice the blazer is poor performing. Also, in rural hilly areas as well. This thing just has no torque. It is a chore trying to maintain a decent speed of 65-70 on the highway, constantly having to mash the pedal on uphills or take out of OD.

I am not trying to sound like I am bashing the 4.3 and blazer. I know the TBI is somewhat limited in performance, especially with the heads they have, but this is rediculous. I do not want to put money (or atleast not alot) trying to get this thing to atleast decent standards. Is there something I am overlooking? Should I try the lid-flip and maybe advance the base timing 2 degrees?

I know the 3.42 is a decent gear to have behind a v8. I'm assuming a 3.73 would be better suited for the 4.3 in hilly areas.

sounds normal to me. lid will help a little but use more fuel u cant have both. 18 mpg is good for that let alone a late model is very lucky to get that. timing a liitle odd to me, i think those were 10 btc. but check ur rad suppot tag. when u check the timing u have to disable the timing module, there is a brown and black wire with a plug in line u have to find, location will be listed on the same rad support tag. then u can set the timing. may be off im sure the timing chain is wore some will help low end if u have some spec for adjustment to advance it. a thing to look at too is the injectors, run with lid off at idle and look for droplets coming from injectors instead of a fine mist, maybe time for new or a clean if they are drippy.

3.73's would help your motor from laboring, the 4.3 has to strain to much in the blaze, actually you mpg might even be better with the change.
If the tuneup didn't help, I'm sure gearing will.
I'm basing this on my own experience.

Not sure how much of a weight difference there is between the 87 fullsize pickup 2wd and the s10 blazer. I'm guessing they would be fairly close since the truck although wider than the blazer, has an empty bed.

It's too bad this blazer is rotting away. If the body was half way decent, I would consider taking the 305 out of the pickup and dropping it in the blazer since I eventually want to do an L31 swap in the truck. I bet the 305TBI would be a great power-plant in the s10 blazer.

The way I have understood things is that Torque gets the vehicle moving, but Horsepower keeps it moving. They go hand in hand.
Have you taken a vacuum reading to make sure you don't have a small leak that could be affecting things? Maybe the EGR is causing issues on the highway? Catalytic converter not flowing well? Maybe exhaust upgrade... seems pretty small for the size of the engine IMO. At least on my '95.

Gears would be your best bet as far as raising your engine's output on the highway. Just remember that 4x4 gears means twice the work and twice the cost. I would first start with simple/cheap things and work up from there.

I'll take the 4.3 any day over a 305, hands down. I wouldn't waste my time putting a 305 in my Blazer. One of the most underpowered engines GM ever put in their trucks.

You say you have some minor mods to your 305 and this may be why you feel it is better than the 4.3. Do the same mods to your Blazer and you may end up a happy camper.

The 305 in stock form when I purchased the pickup had way more usable torque than this 4.3. Both engines have similar wear/tear mileage as well. Also, the truck has 3.08 gears compared to my blazer's 3.42 :icon_shrug: Gearing wise, the blazer should be at the advantage.....