20 mpg on a new 32/36 carb

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minimike
Posts: 257
Joined: Sat Apr 10, 2010 7:14 pm
Your car is a: 1979 124 spyder

20 mpg on a new 32/36 carb

Post by minimike »

My 2000 lump with it's 1800 intake and new in the box 32/36 carb is getting piss poor milage as far as I'm concerned.
Yesterday as it idled in my driveway for a minute, I could see unburned fuel spitting out the twin pipes.

Anyone have a fix to lean out this carb without rejetting? And if I need to rejet it, do you know which jets?

I've got an electric fuel pump, possibly pushing too much fuel.

Also, for economy sake, can I drop the old 28-32 carb back on this manifold and just plug up any ports on the carb?

My dodge minivan get better fuel economy than this.
So Cal Mark

Re: 20 mpg on a new 32/36 carb

Post by So Cal Mark »

rarely are those carbs jetted too rich for a 2L motor. I seriously doubt you are seeing raw fuel come out the tailpipe. The motor couldn't run with that much fuel going through it, nor would it get 20mpg. What you are seeing spitting out the pipe would be condensation, normal byproduct of the combusiton process. If your electric pump is making more than 5-6lbs pressure, you could be flooding but the car should die while idling or run with lots of black smoke out the pipe.

These cars were only rated in the mid 20mpg range when new, so you are not too far off the stated mileage. Poor tuneup settings, restricted air filter, vacuum advance not working, low tire pressure, slightly dragging brakes and driving habits all can easily take 4-5mpg from what you're capable of acheiving
minimike
Posts: 257
Joined: Sat Apr 10, 2010 7:14 pm
Your car is a: 1979 124 spyder

Re: 20 mpg on a new 32/36 carb

Post by minimike »

Thanks Mark,
I've got the vacuum tied into the manifold, tires are inflated right, one plug is a bit darker but the others are spot on. Probably
need to adjust the valves to correct that. I seem to recall getting about 28 with my 1800 in the late 70's.
I'll take it for a highway ride and see what it's really doing.

I'll have to put my hand next to the exhaust and collect some of the liquid. Also running a low restriction 2" high air cleaner
on this carb.


Mark,
Would swapping the old carb help with the fuel economy?
WBPDX

Re: 20 mpg on a new 32/36 carb

Post by WBPDX »

I have the exact same block\manifold\carb\filter and am getting the same or worse gas mileage with 99% in-town driving.

The only thing I know is not quite right is the valves. I'm not upset; it is about the same as my Subaru. :roll:
puddin

Re: 20 mpg on a new 32/36 carb

Post by puddin »

gotta 1800 with the 32adfa and avg 28 mpg on hwy -- burned a whole tank of 87 oct. not bad i think-- usually avg 24.5 mpg mixed hwy and city.. from 7-1-10 till today i rolled 10,000 miles so far and still pushing her daily== not bad form a $5000 car
Raze

Re: 20 mpg on a new 32/36 carb

Post by Raze »

Want better mileage, power, reliability, do the following:

1) Get an O2 sensor bung welded into your downpipe in your exhaust ~$25

2) Get a wideband O2 sensor ~$50

3) Get a wideband reader ~$150

4) Tune your engine...

Alternative method

1) Spend some money on a dyno, dial in your carb, but doing the above and driving it around will be better long term if you make other changes so you can adapt the carb to those changes...

I have a 32/36 and it spits out the tailpipe (water)...
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