4.1 mpg?

[84prspctr]

It smells like it’s running a little rich at idle, but over idle it doesn’t seem like it’s running rich at all. Has a slight miss when not fully warmed up at around 1000 rpm but goes away at anything above that. Engine revs up to 7k rpm no problem. I’m going to try to find a number on that vacuum advance and replace it

 

[85K304SPD]

I think that we already determined that your motor is probably worn out, and needs to be rebuilt, or at least pulled out and gone through to fix all of the problems that it has. Until you do that we are basically wasting our time trying to diagnose multiple problems.

 

[Redfish]

It feels like it might be in the secondaries on the highway, and does not have much pep at full throttle

Engine revs up to 7k rpm no problem.

Really? A 350 that is able to turn 7K with no issues sounds pretty peppy to me.

@Ricko 1966 says " Lets quit arquing about what his milage REALLY IS or couldn't be etc. and help him fix his problems."

I don't think we have enough solid, real information to work with here. Is this engine really turning 7K RPM?

 

[SquareRoot]

Engine revs up to 7k rpm no problem.

 

[Ricko1966]

.^^^^^^ Unless of course, his problem isn't with the carburetor. Its got 2 crossed plug wires worn out rings a flat cam, etc.etc. etc lets stop WAG and shotgun repairs and diagnose. Thats the only efficient cost effective way to fix cars. Customers would sh!t a brick if I did 100s of dollars worth of work to their cars and didn't address the problem. We know the ignition is 100 percent wrong and partially non functional and it has a vacuum leak-yea lets tackle the carbureation before we fix the for known issue's, or do any diagnostics. Doc I've got a bleeding through and through gunshot wound, could you look at this rash on my leg first.Im out.

 

[84prspctr]

In neutral if i floor it it will shoot up to 7k, at least that’s what my tach says. It’s a sunpro power curve tach. It doesn’t feel peppy under a load on the highway. I know the engine is worn out, oil pressure isn’t great, burns a little oil on a hot start, has blowby.

 

[KnuckleBuster]

Sometimes, as much as one might like to work on their own stuff, the problem is just a little beyond their ability. Considered a pro? Diagnosis will likely be cheaper than throwing parts at it and a whole lot faster. Just a thought. Either way, good luck to ya!

 

[kzguns]

I would avoid revving the guts out of it, the only limiter these old engines have is when it comes apart. I would get some of the previous mentioned issues resolved especially timing. Re check your firing order and then if nothing improves look into the carb but if you're not experienced you may want to find someone who is.

 

[84prspctr]

Carb is new and tuned with vacuum gauge, idle mixture tuned to where it held the steadiest vacuum. Timing is set with an old snap on timing light to 12 degrees initial. Firing order is correct. I know that the vacuum advance is now bad so I will change that out and reset the timing and check the tune on the carb again. And see if things get any better.

 

[Ricko1966]

Carb is new and tuned with vacuum gauge, idle mixture tuned to where it held the steadiest vacuum. Timing is set with an old snap on timing light to 12 degrees initial. Firing order is correct. I know that the vacuum advance is now bad so I will change that out and reset the timing and check the tune on the carb again. And see if things get any better.

Okay,now we are getting somewhere. Fix
the obvious and diagnose for the not so obvious. All vacuum advances are not created equal. There are different pressures for activation,and maximimum/minnimum advance. That's why I said get the Crane unit it can be set for what is right for your setup. Putting an 8 degree can that needs 18hg does you NO good, none if your only pulling 15hg and need 14 degrees. You're setup is a mystery. You need to do the work to make sure it's right. And all adjustable are not the same,some only limit maximum degrees.

 

[SquareRoot]

I will change that out and reset the timing and check the tune on the carb again. And see if things get any better.

7500 rpm?

 

[dvdswan]

Basic tune-up crap. How do the plugs look? the wires? air and fuel filter? Does the gas cap suck air when you take it off? Do you have a vacuum gauge in the truck? you should see right at 20 Hgs. at idle on a stock engine.

You must be registered for see images attach

when was the last time you packed the bearings? Are your brakes dragging? How heavy is your foot?

My 76 Blazer had a built 350, 4sp, and 4.10 axles on 36s, best mileage I ever saw was 18 mpg on the freeway between Phx and Tucson. But on average I got between 4-8 mpgs depending on how heavy of a foot I had.... and 90% of the time it was heavy.

 

[84prspctr]

Plugs are good I went through and gapped them all, wires are good, air filter clean, both fuel filters are new, gas cap does not suck air, front wheel bearings were just packed, don’t think the brakes are dragging. I’ve had a pretty heavy foot with it because it feels like it has no power, which makes sense the vacuum advance was bad

 

[84prspctr]

The number on the vacuum advance is 482 15

 

[Ricko1966]

The number on the vacuum advance is 482 15

Awesome is that the right one for the amount of vacuum you have, for the degrees of advance that you need?