F350 losing power..... Help!

[86-350-460-dually]

I have the same carburetor on my 460.

With 4.56 gears you shouldn't have a problem pulling that trailer, let alone just getting the truck going at 55 mph.

That's what a rig like this was made for.

You say "mountains". Is altitude a factor where you live?

Carburetors don't compensate well for thin air, but rich is not the same as running lean.

There is no catalytic converter on your truck.

You should check for fuel volume at the carburetor (after the vapor separator T, if it's still there)

Bill can better explain how to jumper the fuel pump circuit to enable this test.

But I think your friend is on to something.

Given your symptoms the secondary throttle plates may well be blocked from opening.

Let me ask. If the AIR pumps and emissions have been removed, is there still an EGR spacer under the carb?

Check for clearance by removing the carb and looking to see if the base gasket is clear of the rear pair of venturis and then seeing if the intake ports do not obstruct that same gasket in any way.

I know I was unable to find a spacer that worked with this carb and had to resort to a die grinder to open up the rear ports for the butterflies to clear.

If the fuel volume test goes well this is the next thing I would check.

Just my 2c.

Good luck with your trip and your new tiny home.

Grumpin,

The clutch was replaced two or three weeks ago.

ArdWrknTrk,

Altitude is a factor. I live at 6k ft currently, and those passes were around 7-7.5k ft.

As for the EGR plate and gaskets, I honestly don't know if they are free and clear of the venturi's. I will pull the carb off today and look at them, because I just used what was on it before, assuming it had to be what would work best and put the new carb on top. I believe the old carb was the stock one. Motorcraft Holly.

[ArdWrknTrk]

Grumpin,

The clutch was replaced two or three weeks ago.

ArdWrknTrk,

Altitude is a factor. I live at 6k ft currently, and those passes were around 7-7.5k ft.

As for the EGR plate and gaskets, I honestly don't know if they are free and clear of the venturi's. I will pull the carb off today and look at them, because I just used what was on it before, assuming it had to be what would work best and put the new carb on top. I believe the old carb was the stock one. Motorcraft Holly.

Adam,

What caused you to swap carbs?

Check fuel delivery before you go to the trouble of pulling the carb, but I know it was an issue when I went from a Holley to my 650 AVS.

I used a scribe but you could just use a Sharpie marker and the Edelbrock's proper base gasket to match the ports.

Your gearing is going to cause your truck to have shorter legs than mine and a stock cam will run out of steam on top, but you should be able to easily pull 14k at 3,000 rpm with your rig.

If looking for more power on the cheap consider a straight up timing chain set.

BTW, how many miles are on the engine?

, Jim

[86-350-460-dually]

Adam,

What caused you to swap carbs?

Check fuel delivery before you go to the trouble of pulling the carb, but I know it was an issue when I went from a Holley to my 650 AVS.

I used a scribe but you could just use a Sharpie marker and the Edelbrock's proper base gasket to match the ports.

Your gearing is going to cause your truck to have shorter legs than mine and a stock cam will run out of steam on top, but you should be able to easily pull 14k at 3,000 rpm with your rig.

If looking for more power on the cheap consider a straight up timing chain set.

BTW, how many miles are on the engine?

, Jim

To answer your questions:

The carb did not have a choke on it when I bought it in December. It was a royal pain to start cold. Haha.

....as for the miles on it........ Well.... Not a stinking clue. Haha. I bought it and it says 6,000 miles. I have no clue how many times it has rolled over. Are you thinking of doing a compression test?

I do have access to a free 460 motor out of a motorhome that's been sitting for several years with only 48k original miles. The possibility of doing a motor swap has crossed my mind, but I'm a little pressed on time.

[ArdWrknTrk]

To answer your questions:

The carb did not have a choke on it when I bought it in December. It was a royal pain to start cold. Haha.

....as for the miles on it........ Well.... Not a stinking clue. Haha. I bought it and it says 6,000 miles. I have no clue how many times it has rolled over. Are you thinking of doing a compression test?

I do have access to a free 460 motor out of a motorhome that's been sitting for several years with only 48k original miles. The possibility of doing a motor swap has crossed my mind, but I'm a little pressed on time.

Stock timing chain with nylon gear is good for only 75,000 in my experience but if you have no trouble with the carb spitting back then I don't see that as the issue.

But wear will retard the cam even more than the stock eight crank degrees, and will cause a loss of power.

Consider dropping $50 on a Cloyes steel roller set if you ever need to replace the water pump.

At least the AIR pumps are out of your way already.

[86-350-460-dually]

Stock timing chain with nylon gear is good for only 75,000 in my experience but if you have no trouble with the carb spitting back then I don't see that as the issue.

But wear will retard the cam even more than the stock eight crank degrees, and will cause a loss of power.

Consider dropping $50 on a Cloyes steel roller set if you ever need to replace the water pump.

At least the AIR pumps are out of your way already.

That's good to know. What about timing? I set it to 11° without the vacuum advance hooked up to the distributor. I bought the truck and it was at 13°-14°. Any thoughts on that?

[ArdWrknTrk]

Stock timing chain with nylon gear is good for only 75,000 in my experience but if you have no trouble with the carb spitting back then I don't see that as the issue.

But wear will retard the cam even more than the stock eight crank degrees, and will cause a loss of power.

Consider dropping $50 on a Cloyes steel roller set if you ever need to replace the water pump.

At least the AIR pumps are out of your way already.

So, I was really thinking of the timing chain when I asked about mileage.

This is different than ignition timing.

11degrees sounds like a good place to start.

My truck made it to 280,000 with regular maintenance before it spun a rod bearing on a bitter cold morning.

Another 150k in the past 11 years on a reman motor, and I wouldn't expect a dedicated tow rig to see nearly that.

But if it's 106,000 on a stock nylon gear you are past due for replacement.

[ArdWrknTrk]

That's good to know. What about timing? I set it to 11° without the vacuum advance hooked up to the distributor. I bought the truck and it was at 13°-14°. Any thoughts on that?

Was the truck having an issue with spark knock at 14°?

If you want to know how to optimize ignition timing go to the Jeg's site and look up the Crane adjustable vacuum advance unit for '70's Ford & Mercury. Under documentation they have a PDF of the instructions.

These are detailed and have to be followed in proper order.

Bill (85 Lebaront2) owned a tune-up shop and can detail what to do.

But if it was working before the swap I wouldn't mess with it now.

You have too much else to do in the coming weeks.

[86-350-460-dually]

Was the truck having an issue with spark knock at 14°?

If you want to know how to optimize ignition timing go to the Jeg's site and look up the Crane adjustable vacuum advance unit for '70's Ford & Mercury. Under documentation they have a PDF of the instructions.

These are detailed and have to be followed in proper order.

Bill (85 Lebaront2) owned a tune-up shop and can detail what to do.

But if it was working before the swap I wouldn't mess with it now.

You have too much else to do in the coming weeks.

Ok. That's really good to know. Thanks. First things first, check fuel pressure at higher speeds.

[ArdWrknTrk]

Ok. That's really good to know. Thanks. First things first, check fuel pressure at higher speeds.

It's an electric pump.

It's either off or on.

This is why Bill said to check volume not pressure.

And why I said to check after the screen of the vapor separator.

You can jumper the fuel pump relay to test while you have the hood open looking at the fuel flow.

[FuzzFace2]

It's an electric pump.

It's either off or on.

This is why Bill said to check volume not pressure.

And why I said to check after the screen of the vapor separator.

You can jumper the fuel pump relay to test while you have the hood open looking at the fuel flow.

I was thinking plugged cat till I saw the truck and would say it does not have a cat.

Now if the fuel volume checks out I would take a rubber or dead blow hammer to the muffler and give it a few hits.

I am thinking 1 of the baffles broke loose inside and is blocking the flow.

I have seen this happen and when the muffler is hit you will hear it rattle as the baffle moves around.

Or could if easy drop the muffler out of the system and take it for a spin.

Dave ----