94 Bravada. 4.3 "W" CPI

Does anyone know why my truck has great acceleration at 1/3 or 1/2 throttle, but at full throttle it isn't as snappy. It's not stalling out or bogging at full throttle, but there isn't a difference in throttle response after 1/2. At 1/2 throttle it will squeak the tires and slam you in the seat like it should, then I progressively smash the gas and she keeps pulling until redline.

At half throttle it will squeak the tires but at full throttle it won't?

I get decent gas mileage (about 19mpg average) and the truck runs quite well. Always starts on the first key (but it sometimes stalls unless I hit the gas?) If it stalls, it's a little harder to start the second time.

The cooler the ambient temp is the better she runs, of course.

My truck has 245,000 miles, so I know it's getting a little bit tired, but I see how it runs at 1/2 throttle, so I know there is room for improvement.

I have changed the plugs (Stock Delco's) and the wires (Accel 8.8mm) cap and rotor (Delco) and bumped the advance up a few degrees (If I advance it any more the idle surges) What's next?

The other thing that puzzles me, I put in a 180 degree T-stat, but the coolant never gets hot. The gage on the dash never reads above 100? I can go for a 100 mile drive, stop at a rest stop, open the rad cap and stick my finger in the coolant because it's only about 125 degrees?

On a cold morning (40F), I drive for 3 maybe 4 minutes and I am getting warm air through my heater, but the air isn't a good "HOT" blast... Just kind of "bath-water" warm.

Any ideas? Could the problems be related?

I am open to all suggestions and all opinions are welcome!

Thanks, everyone!

 

You could have a faulty thermostat ( stuck open ). Try a new 195* ( factory spec. ) Stant thermostat and clean the throttle body if you haven`t already done so. A warm/clean engine will perform better. I would put the timing at factory spec. 0*-1* BTDC.

 

A faulty T-Stat has crossed my mind... And that probably is what's wrong...

Thanks for the input.

If I drop the timing back to 0, this truck totally falls on it's face and gets horrible gas mileage.

I set the timing using the old gearhead method: Loosen and unplug the distributor, chock the wheels and step on the gas until the tires just barely start to spin. Then lock the distributor down. It sets it's own timing. I used this method on my old 70 LS5 Chevelle (with a ridiculous 310 duration cam) and it set itself at 32 degrees BTDC!!! and she ran like a top. Of course with the Chevelle, I didn't have to unplug the distributor.