I've been working overtime on my truck and more or less have it together. The motor is out of a 79 F350. It ran pretty good in the F350, and I feel like it ran ok when I first swapped it. It was running like crap and I found an unplugged vaccuum port. Plugging it made things a lot better. Today I took it out for a short drive and it wouldn't rev at all, feeding it throttle just made it sound raspy and it was just limping along.

The EGR plate is still under the carb, although its not hooked up to anything. All the vaccuum ports are plugged off and the valve cover vents are just open, for now. If I could find the right fitting for the valve covers I'd like to hook those back up to vaccuum.

The truck starts right up and idles fine. Sometimes when you put it in gear it wants to die. Sometimes it revs fine and drives fine, but it feels short on power all the time. A lot of the time when you first feed it throttle, if you don't baby it, it tries to fall on its face.

It also sounds like it has a miss. Just messing around at idle, I pulled each spark plug wire one at a time off the distributor. Pulling the #4 plug made no difference in the idle, so I'm thinking its not firing for some reason. Of course my truck has factory AC so thats the hardest one to change spark plugs on, as well.

I need to lay out a plan of attack, but I'm not super familiar with carbs and I've read enough to realize that I may need some advice in tackling this.

I'm thinking my steps are:
1) remove carb and pull the carb plate. Install a phenolic spacer in its place.

2) change spark plugs. Additionally, I was getting shocked just touching the wires at the distributor, so I'm thinking it would be good maintenance to change the wires. While I'm doing that I'd probably just go ahead and change the cap.

Any other advice?? I'm stabbing in the dark somewhat.

 

fuel pump? Fuel filter clogged?

 

You are at a middle point on the EGR.
You need to either restore it or jet the carb, rework the distributor advance curve, remove the plate, change the vac lines and hope you don't go down in gas milege.

Personally I have tried both, and I think it was slightly easier to restore the EGR.

Contrary to popular belief, the EGR is your friend. It allows your engine to run super lean without high combustion temperatures and engine damage.

 

the EGR was not hooked up on the '79 either, and the manifolds on the engine do not appear to have provision for the EGR. Maybe they are older manifolds. At any rate, this is not a daily driver, its just a play truck, but it still needs to be reliable or I can't take it out any trails. I was invited to a sweet trip in a few weeks but I don't want to trailer this thing 4 hours and spend the weekend at camp cussing at it cause it won't run right. lol

Fuel filter is newer, looks clean and has fuel flowing through it. Problem doesn't appear to be fuel related at this point.

 

Sounds like its time for cap, rotor and wires. Shocks and a dead #4 are strong indicators. I'd do that first and see how she does. I also agree best is all or noting on the OE setup. If nothing, a recurved distributor and new or re-calibrated carb are on the list.

 

I don't have that much experience, so how exactly to you re curve a distributor, or will I be looking at replacing it? My long term plans for the truck include long tube headers, edelbrock RPM intake (already have it), probably an aftermarket carb (I have an edelbrock but not sure if I'll use it), and a cam. I'd like to get the heads ported due to the huge gains but if I do that I'll probably tear about the engine and do a full rebuild... I have a spare 460 in the basement. So I don't mind improving the ignition with an eye towards better performance and long term durability.

 

bump, I'm ok with retuning. I just need to know what settings and equipment to change. I really would like to get the truck to where I could drive it to work on a friday, or have it reliable enough to go wheeling for a weekend.

 

To check the EGR reach inside behind it well running and push on the bladder if it opens the truck should sputter and die or if there is no change you may have found the problem.

It does sound like you may have a lean condition...Try opening up the idol screws under the carb...unscrew until the idol stays steady,Do one then the other then repeat after checking the EGR valve.

 

it will idle all day long... it idles fine. It idles high when you first start it, and then if you tap the gas the idle drops right down into a nice lope. Even when its not running right, it idles ok...

 

If you drop it into D and it dies...It isnt idling right

If you have a dead cylinder or a vacuum leak it wont revv right so a compression test is in order.

 

I don't have a compression tester, and i doubt one would fit in the #4 cylinder anyway. Its very difficult to get to with the factory AC. If plugs and wires and a cap doesn't fix it, I may be able to beg and borrow one.
It idles fine in neutral, and it will idle ok in D as well, its just when you first drop it in D that it starts to want to die. I found and plugged an unplugged vaccuum port and it significantly helped that issue.

btw, in reference to your signature, idling is on every manufacturer's severe duty schedule, not just the 6.0.

 

Sorry trying to help its really hard to diagnose a bad running motor over the internet.

# 4 isnt that bad just takes a small extension and a mini extension and a compression tester will fit..

I guess you dont go to the 6.0 forum....

 

I know... I am planning on changing plugs, wires, and cap, and then making a video that might be better for diagnostic purposes. But my radiator now has a leak so that all got put on hold. But a new radiator is prohibitively expensive right now so...