Overheating 2.2... need some help (LONG READ!!!)

Alright, here's my battle:

Truck is an '87 B2000, with a 2.2 swapped into it at some point (as far as I know - it has a 2.2 timing cover and non-adjustable lifters).

Weber carb, mechanical fuel pump, pacesetter header, electric fan (on all the time w/ignition). Other than that, motor looks stock.

New radiator cap and 160 degree thermostat installed today. Also back flushed the radiator and heater core, and did a full coolant change.

Just did a good complete timing check to ensure the timing belt wasn't installed incorrectly, and reset the timing to 6 degrees BTDC.

Spark plug electrodes are white - running lean. Truck idles good, runs fine at anything up to about half to 3/4 throttle. Anything after that, it starts to buck like it's running out of fuel. Anything over 60 MPH makes it buck like mad too.

At idle, the temperature will climb over a period of 10-15 minutes, and eventually it will reach a high enough pressure to blow past the radiator cap.

At 60 MPH, I can drive for about 30 minutes before it gets REAL hot - but it will stay right close to the upper limits of the water temp gauge and stay there.

I spent some time with a can of starting fluid around the carburetor today... Found it would idle up when I sprayed near the base of the carb. So I took it all apart, left the "carb heater" out, and made new gaskets between the intake, aluminum plate, carb adapter, and carb. I have less of a leak there now, but it still idles up slightly when sprayed with starting fluid.

So... I'm stumped. Seems like I have a vacuum leak causing the lean condition, but is this enough to make the truck overheat all the time? Or do I have something else going on, like a bad radiator?

If I back the timing off even further, it takes longer to overheat...

Totally stumped, looking for some advice.

make sure that your fan is blowing in the correct direction. also, if it is running to lean it will cause it to overheat. if you have a vaccum leak than it will run lean. fix the leak. if you fix the vaccum leak and it still overheats give it a little more fuel or a little less air. when you flushed your radiator did the water come out of the lower hose connection. if so than your radiator should be fine. if you have done any work to the engine lately and got something inside, you may have clogged the coolant passage. if all this doesn't work try pulling off your thermostat and your lower radiator hose and blowing air through the system to try and unclog it. if i think of anything else i will try to help out.

Thank you for the reply, Ryan.

The electric fan is mounted on the engine side of the radiator, and is in the "suck" configuation - pulling air through the radiator.

When I back flushed the radiator, the water seemed to come out a bit slower than it went in - but always came out clean (no chunks or anything like that).

When I did the thermostat and flush, I blew the system out as best I could with compressed air...

The truck was overheating before I did the work today - which is why I went ahead with the flush and thermostat change. The old thermostat was so rusty the edges of it were falling off.

I'm kind of leaning towards a lean condition and bad radiator combining to cause me a bigger headache... The previous owner installed silicone vacuum lines, which I think are a hair too big, and too slick to seal up properly.

You might want to check your cat. If your cat is slightly plugged up it would explain the bucking and stuttering after a certain rpm. Also could explain your overheating. But also could be caused by other things. A quick way to cross out exhaust restrictions is to unbolt it at the header and take a quick drive to see if it acts any different. One third of your engines heat goes out through the exhaust, one third goes out through the coolant system and the last through the oil.

has it always overheated since you've owned it? how many vaccum lines do you have? should only have a couple with the weber if i remember right. also, if you replaced all your gaskets for your carb but it still revs up when you spray at the base, make sure your base is not cracked. they are made out of aluminum and crack easy if installed wrong, i know from experience. hahahaha. i don't remember how i did it but i installed mine wrong when i first got it many years ago and i had to order a new base. just a thought. good luck man.

I don't THINK the cat is clogged up... When I bought the truck, it just had the pacesetter header and a cat bolted up directly to the header. It ran hot on the way home (the day I purchased it)... Within the top 3/4 of the gauge. That was about a 60 mile trip, all highway driving.

I now have a (brand new) turbo muffler on the truck - with about 2 ft of pipe between the cat and the muffler.

The header seems like it gets VERY hot after even short trips - maybe this is indicative of a cat problem?

Vacuum line - I have the one form the carb to the distributor advance... And a few others that just loop from one vac port to another on the intake. That's about it.

Another question - should I be setting my timing with the vacuum advance connected, or disconnected? It runs SHITLOADS better if I set the timing with the advance disconnected.

i didn't even think about the cat. does your exhaust start glowing? if so it is 1 of 2 things. either your cat is clogged like slammed said. or your timing is off, either in the cam to crank timing or off by carb adjustments. i had my timing set perfect on my 83 but the carburetor kept screwing everything up. you have to make sure your carb is RIGHT before you can accurately set your timing. if you set your timing with your carb adjusted all wrong, than when you get your carb right, your timing will be off. also make sure that you have the number 1 piston at tdc when you put your dizzy in and the dizzy needs to point at the #1 plug as well, which i am sure you already know. but your dizzy may be off by a tooth causing some issues as well.

im pretty sure you gotta set the timing with the vaccum advance off of the dizzy. as for the silicone hoses jumped from one to the other, id go to the local parts store and buy some vaccum caps and that may help out better. when you spray at the base of the carb, is it at the front of the carb around the pvc hose? mine was cracked right there where it attaches to the intake in front of the carb. it made it idle bad.

my previous job for 2 years was at a radiator shop.... your radiator should flow water as fast as your house water hose can put into it.... if not then you can take it to your local radiator shop and ask them to "rod" it out (flush kits don't dislodge the debris built up in the tubes, they just help the looser material to un-stick from the metal).... also a way to check to see if your pump is pumping water is to take the hoses loose from the radiator and put the bottom hose in a five gallon bucket, also put your house water hose in the bucket, run the house hose wide open, (don't do this if the motor is hot) crank the truck.... the bucket should empty or stay close to empty.... also a clogged heater core will cause you to run hot... the heater core should also flow like the radiator (as fast as your house water hose can run through it).... if your radiator is clogged, chances are the heater core is clogged as well.... i've never "rodded" a heater core, its usually cheaper and wiser to just put in a new one if your going to do all that work to get to it (removing most of the dash)

I used this as a reference for setting the timing with the vac advance connected...





But when I set the timing with the advance connected, it runs like crap.

I drove the truck to work today, 17 miles at 60 MPH. Truck stayed cool (wow!), and hit halfway on the gauge as I pulled into my parking spot. All the way down the highway, it bucked going up hills and when trying to accelerate with any more than a very light feather throttle.

It was only 60 degrees this morning, so that may have helped keep the truck cooler, along with the 160 degree thermostat.

I pulled the filter out of the carb last night, and it had a bunch of hair and grit in it... So I think I will need to pull the carb off and clean it out real good.

Checked the idle jets, both primary and secondary are 50s.

Can anyone give me a good starting point for idle, main, and air corrector jets? I have absolutely no faith in this carb being jetted correctly.

I know the main jets should have been 140s from the factory, and the air correctors should have been 170 and 160. Haven't check to see what I've got in the carb.