Hot Rods Chevy 235 gets shitty gas mileage

Why did I think you had dual 2bbl carbs?
those shouldn't be too big at all.

OTOH, the heat riser is supposed to turn off when the engine gets hot. That's why it has a thermostat spring on it, stock.

You can't really turn this one off.

 

Correct. It's always heating the intake. Is that bad?

 

Depends on the climate where you live.

I lived up past Johnstown NY way back when, and it was pretty cold in the winter, but nothing like Duluth or Ogden.

I always ran the heat stove and riser in Utah & Minnesota, but I tossed it when I moved to the desert.

 

I'm an hour north of NYC.

 

You'll probably be OK if you avoid the hottest days.

Out here it's over 100F for weeks, so not the best thing to have on all the time.

 

couldn't you turn the heater to a water unit ( would have to make a outlet on the plate ) as this way you could put a on off valve on it and it will not throw excessive heat into the manifold ,some of the old gas trucks I worked on had that set up and it was great took a little time to heat up ( had to idle it for a few minutes as it also drew air off a manifold stove for the intake ) but in the summer when vapor locking or hot days could cause perculation we could shut it off or adjust it , it tapped into the heater outlet so it would warm up quickly in real cold weather ..

 

I thought about using water but figured I'd try the easy way first. The weather hit 90 today and I drove it about 50 miles. So far so good. No vapor lock. Fuel economy appears to be a lot better but wont really know till I tank up again.

 

I run a 261 with 2 5200 holleys, cam from patricks, fenton split exhaust and 2.8 electronic distributer. The distributer was worth 2 miles per gallon increase. I used Langdon's spacer for thermostat for water line and ran to intake and to return on heater. This kept my carbs from icing and better driveabilty.

 

Nice! Do you have a photo of this setup? It sounds intriguing.

 

Glad to see you put the heat plate on it. The copper should hold up. The heat plate i made is connected to the headers by copper tubing. All it has done is turn brown blackish but nothing else. The permanent heat shouldnt be a problem. I have permanent heat on mine and im in texas and havent had a problem. The only difference between your heat plate and mine is that its also connected to the second header to have a bit of a circulation.

 

in the photo you can see the lines below the logo the left runs to a plate behind the thermostat and the right goes to a homemade t in heater line

 

I got a 235 in a 53 2 door sedan and did a 2300 mile road trip a couple of months back. With dual 2g's, fenton manifolds and a t5 with 3.55 rear I get an honest 16.8 mpg with mixed street and open road driving ( we don't really have highways ). But I don't have carb heat so will hook that up and see if it changes, but I wasn't getting any fuel stench either.

Have you got any figures since you hooked up the heat ?




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Since hooking up the heat, the mileage is now in the 17mpg range. No more stench, and I'm getting a snappier throttle response. An amazing improvement.