A couple R&Rs I need to get advice on...

[AL_Brad]

1985 720 Sport Truck

 

Carburetor - I pulled the stock carb and a lot of emissions stuff last week and swapped in a new Weber 32/36. I didn't do anything to the carb like adjusting the idle mixtures or adjust the out of the box fast idle/idle settings. I did this because I wanted to get a baseline for idle, choke, drivability, and mpg. So... Choke rpm is a little high for my taste - 1800RPM. Idle has been good at 900-950. It runs really well on my 70-mile RT commute. I filled up from near empty and estimate 25.5 MPG. 

 

Q - what is everyone getting for average MPG? Can I get closer to 30?

 

Eng temp - Replaced the radiator and thermostat Sunday. I put in a 180 degree thermostat. Temp gage read 1/4 way up the scale prior, now it barely registers and heat barely blows. There was no legible mark on the previous thermostat. Should i have gone with a 195? Air pocket? What do y'all think?

 

 

[ElliotV]

27 minutes ago, AL_Brad said:

1985 720 Sport Truck

 

Carburetor - I pulled the stock carb and a lot of emissions stuff last week and swapped in a new Weber 32/36. I didn't do anything to the carb like adjusting the idle mixtures or adjust the out of the box fast idle/idle settings. I did this because I wanted to get a baseline for idle, choke, drivability, and mpg. So... Choke rpm is a little high for my taste - 1800RPM. Idle has been good at 900-950. It runs really well on my 70-mile RT commute. I filled up from near empty and estimate 25.5 MPG. 

 

Q - what is everyone getting for average MPG? Can I get closer to 30?

 

Eng temp - Replaced the radiator and thermostat Sunday. I put in a 180 degree thermostat. Temp gage read 1/4 way up the scale prior, now it barely registers and heat barely blows. There was no legible mark on the previous thermostat. Should i have gone with a 195? Air pocket? What do y'all think?

 

 

my truck for the most part appears to be stock and wont get warm no matter what unless its 100 degrees out and i have a trailer so during the winter I end up blocking the cardboard. that is the only time I have watched the thermostat open. as for mileage 25.5 is very good mileage for a 40 year old truck and I don't know if there is much you can do about getting more.

[datzenmike]

Change the thermostat. Thermostats set the lowest or minimum temperature. The engine should easily produce enough heat to boil the coolant. At 180/175 F the thermostat should open and maintain that temperature. If not getting up to temperature, the thermostat is probably stuck open and over cooling. Change the thermostat.

 

Another less likely thing is the sender or the gauge is bad and reading low. The sender is located just below the thermostat and has a Yellow/Black stripe wire to it. Pull it off and hold against the grounded intake manifold. With the key on the gauge should read full HOT.

 

The engine is designed to work most efficiently at about 180F. Metal parts have expanded and closed up the tolerances and oil lubricates best when hot. 

 

25.5 MPG is very good.

[iceman510]

1 hour ago, AL_Brad said:

1985 720 Sport Truck

Eng temp - Replaced the radiator and thermostat Sunday. I put in a 180 degree thermostat. Temp gage read 1/4 way up the scale prior, now it barely registers and heat barely blows. There was no legible mark on the previous thermostat. Should i have gone with a 195? Air pocket? What do y'all think?

 

 

You could have a faulty thermostat, or it does need more fluid.  If there is too much air in the system it will not transfer heat properly nor register on the gauge properly.

 

As long as the system is healthy, a 195 would likely be better and might increase your mileage.

[datzenmike]

1 hour ago, AL_Brad said:

1985 720 Sport Truck

 

Carburetor - I pulled the stock carb and a lot of emissions stuff last week and swapped in a new Weber 32/36. I didn't do anything to the carb like adjusting the idle mixtures or adjust the out of the box fast idle/idle settings. I did this because I wanted to get a baseline for idle, choke, drivability, and mpg. So... Choke rpm is a little high for my taste - 1800RPM. Idle has been good at 900-950. It runs really well on my 70-mile RT commute. I filled up from near empty and estimate 25.5 MPG. 

 

Q - what is everyone getting for average MPG? Can I get closer to 30?

 

Eng temp - Replaced the radiator and thermostat Sunday. I put in a 180 degree thermostat. Temp gage read 1/4 way up the scale prior, now it barely registers and heat barely blows. There was no legible mark on the previous thermostat. Should i have gone with a 195? Air pocket? What do y'all think?

 

 

 

Thermostat is likely crap. Should read at or just above half on the marked 'run range'. 180 F is fine I wouldn't run hotter this isn't 1 2000s engine that is designed to run near boiling. This is 40 year old technology.

 

Idle RPM should be up to 750 but 650 if you can. Higher than this the distributor mechanical advance starts adding in and you won't be setting your base timing properly.

 

Stock carburetor fast idle is 1,800-2,200 RPMs so you're fine. This is not an EFI car or truck, this is normal for carburetors.

[AL_Brad]

Good info. I'll tweak here and there in the next couple days. I appreciate the replies. 

[ElliotV]

3 hours ago, datzenmike said:

 

Thermostat is likely crap. Should read at or just above half on the marked 'run range'. 180 F is fine I wouldn't run hotter this isn't 1 2000s engine that is designed to run near boiling. This is 40 year old technology.

 

Idle RPM should be up to 750 but 650 if you can. Higher than this the distributor mechanical advance starts adding in and you won't be setting your base timing properly.

 

Stock carburetor fast idle is 1,800-2,200 RPMs so you're fine. This is not an EFI car or truck, this is normal for carburetors.

I cant seem to find a good thermostat for my truck no matter who I buy it from truck always sounds like a plane taking off too but when I bought a new fan the resistance felt the same. At some point I will go to a electric fan setup most likely but for now Im worried about getting it running again.