Hello all, new guy with questions

[spartman]

Okay did some work on my truck and found the following.

Timing was way advanced.  I have it set at 10 degrees advanced at about 800 rpm.

I now have a rebuilt Q-jet carb with new throttle bushings and 70 jets with 36B rods.

Also have DP secondaries with a H hanger.

Also running manual choke.

So far truck is running better but is still sucking gas like it was before.

Maybe this is supposed to only get 10mpg?

[ccz145a]

Just a thought... Are you using your odometer to check milage? If so, is it accurate.

I don't think anyone mentioned that, yet.

[spartman]

Yes I am using the odometer for mileage.

I know that it is off by about 1/10th of a mile.  The speedometer reads 10 mph faster than it is.

I do have about a year or so of mileage logs and so far it keeps coming out the same no matter what.

[Captkaos]

How about a little information on what you are working on?  Year, series, drivetrain etc..
My built 73 C10 454/4pseed truck got 12 if I was nice to it, otherwise I got 8mpg.
My 81 K10 350/4speed got 15.
My 87 R10 305/700R4 gets 18 (had gotten 22.6 on trips)

[ccz145a]

The speedometer reads 10 mph faster than it is

So your acually getting worse than 10mpg, or are you adjusting.

Say that after a trip, you looked at your od and it says you went 100mi but you actually went 90mi. You used 10gal --> 90/10= 9mpg. ouch!

if it was .1 off the other way, you would be getting 11mpg. .1 every mile is pretty significant. 

[spartman]

Okay here is what I have for ya.

1980 1/2 ton 4x4 pickup that is now a 2wd unit only.
I took out the transfer case when the last tranny blew and all I could find was a 2wd 350 lockup.

It has a GM Goodwrench 350 engine I bought new with about 20,000 miles on it.

When I put the engine in I installed an Acell dizzy new, and Edlebrock intake.  Also have 2 1/2 inch dual exhaust pipes on it also.

The series is a Custom Deluxe with a silverado interior.

Hope that helps

[VileZambonie]

reatarding the ignition timing will not help fuel mileage unless all you are doing is idling the engine. You baiscally want as much advance as possible without any adverse effects.

What kind of driving are you doing? What do you have for gears?

[spartman]

95 percent of my driving is highway at about 65 mph.

I live about 25 miles from my job and its all open road.

The rear end decoded as being a 2.79 I believe.

I know it has no take off and is not a towing vehicle.

My wifes Durango with the small V-8 tows better than this truck does.

Also my stepdad's 1/2 ton dodge with a v-6 could out tow me.  He did when I helped them move.

He also had a larger trailer and load than I did.  He also used way less gas than I did.

In a 250 mile trip I used almost 4 tanks of gas at 16 gallons a tank to his 1/2 tank at 30 gallons a tank.

[VileZambonie]

You probably have a 2.56:1 ... lousy combination... a 3.73:1 and 700R4 trans would definitely help but if your fuel mileage is that bad and everything is tip top, timing set the next thing I would do is put a gas analyzer on it and check your tail pipe emissions. Do you know anyone who has one or a shop capapble of tuning via emissions data?

Basically look for this...
High CO2 Carbon Dioxide... The higher the # the better. 15.5% would be delicious!

Low HC Hydrocarbon should be low, as close to zero as possible... the higher the # the more unburned fuel you have leaving the engine. This can be caused by many things and does NOT indicate rich btw.

CO Carbon monoxide levels should also be low, as close to zero as possible.... High CO readings indicate a rich a/f mixture.

O2 Oxygen should also be low ...This can really help you fine tune the engine if you know of a shop that will let you play around with it with the probe in your tailpipe.

If they have a 5 gas, look at NOx levels too.

Now since this thing is such a loaf, try disconnecting the EGR valve and see how it performs.

[spartman]

I will see if I can find someone that will do it I will see what I can find.

The truck doesnt have an EGR valve since the intake doesnt have a provision for it.

Most shops round here look at you stupid when you mention anything older than the 90's.