The 318 in my '77 D150 pickup has run rough ever since I bought it. It had only been driven 300 miles in the last 2 years, so I thought it just needed the old fuel run out of it. I put some fuel conditioner/stabilizer in it as well. It is hard to keep running when the engine is cold, it dies when I try to put it in gear. Once it warms up, it drives ok, it just stumbles/hesitates when I try to leave a stoplight.
This truck is almost 100% original, could I remedy the problem by getting rid of the "lean burn" carb?

Also, I am noticing fresh, wet oil on top of the water pump, below the A/C compressor. Where is that coming from?

Thanks!

 

SOUNDS LIKE YOU HAVE A INTAKE LEAK, SEE IF YOU CAN LOCATE THE SPOT LEAKING, SPRAY SOMETHING NON FLAMMABLE ON THE SUSPECTED SPOT WHILE REVVING THE ENGINE. SHOULD EVEN OUT IF THERE IS A LEAK. THE RUNNING BAD MIGHT BE BECAUSE OF THAT. ENGINE HEATS UP AFTER RUNNING AND CLOSES THE LEAKING GAP SOMEWHAT.

 

IF you still have the lean burn system I would definitely get rid of it...

 

Ok, thanks guys!

TVLynn, how do I tell if I have the lean burn system? I'm just assuming that I do because the truck looks to be all original and I know they were using that lean burn stuff in the late 70s.

What would you suggest I replace it with? I want to get fairly decent gas mileage (for a '70s truck) so I'd like to still use a 2bbl carb if possible.

 

It would have a big computer module hanging off the air cleaner. SInce you have a 2bbl you may have a standard ign. Check for the oil leak between the intake and the top of the timing cover, could cause a vacuum leak effecting the PVC valve. I would also check the EGR valve. I would lean towards the EGR for your running problem. Take it off and clean it. Sometimes giving it a good whack on the concrete can jar the carbon loose

 

I am not for sure if the trucks were getting the lean burn. in the normal states (ie:NOT Cali) that was the first year for the other 49 to get lean burn, as 1976 Cali vehicles had lean burn. The Lean Burn is a big square box hanging on to the side of the air cleaner as Lynn said. There is a "Lean Burn Delete" thread on this site.(I'll post a link after I post this) I would replace it with an HEI upgrade, if you are not opposed to using non-mopar parts. And you will need a pre Lean Burn electronic dist ( just thought about this, does your truck have a vacuum canister on the dist? If so its a non LB system, if it doesnt have the vacuum advance canister its a lean burn system) And preferably a pre LB carb.

Lean Burn Delete Thread

 

Stumbling when cold and oil on the water manifold? Sounds like you'll need to replace the intake gasket and some hoses as you may have a vacuum leak. If you remove the carb from the intake, replace that gasket and the gasket between the carb and air filter housing.

The trucks didn't get the lean burn system (that I know of) due to the weight and gearing of most of them. It would have hurt the trucks a lot more than the cars. I'd be willing to bet that your motor will look something like this (minus the MSD coil):


A properly tuned carb, clean motor (from carbon) and a smooth shifting tranny should net you ~12-15 MPG.

 

if you pull it you'll need a carb a 2 bbl carters are plentiful in the junk yards or at least they used to be,, and a distributor make sure the distributor fits hei dis have a large cap base of about 5 inches that wont fit in alot of mopars
a Mallory or msd electronic or unilight distributors have a similar base radius as your oem distributor but if u do have lean burn on it that distrbutor will not have vacume advance
oh yea make sure you use the recommended coil whichever brand you use

 

Thanks, guys!



Yup, that's exactly what mine looks like. So, no Lean Burn System, thats a relief! I hope the stumbling and hard cold start is the result of a bad/clogged EGR, or leaking carb gasket.

 

Also, I'm trying to decide if I even want to invest much in this engine anyway. Even after I had the oil pump replaced, it still has a ticking noise.

Also, it doesn't matter if it's the first start of the day or if I've started it 15 times, there is a big cloud of blue/grey smoke pouring out of the tailpipe every time I start it.

Is this typical of a 35 year old 318, or is something very worn out?

 

Could be related to your oil leak. If it is sucking oil through the gaskets. It could also be bad valve guide seals

 

318LA motors are known to have issues with valve seals. I've got a buddy who has rebuilt dozens and dozens of 318la cylinder heads. Afterwards they would last another 60k-75k miles.

The 318LA motor is one of the most reliable motors that Mopar ever created. I'd put the time/money into it. For what you'll get out of it, it's not as much as you might think.

 

Maybe start by tightening the intake bolts. Couldn't hurt.
Just thought I'd mention this as well.
A small 4 barrel carb will net better mileage, as long as you keep your foot out of the secondaries. Smaller primaries use less gas.
This willl mean new manifold so new gaskets. Might just fix everything at once. Oil on top the water pump is coming from the front of the intake. very prone to leaking on older motors. Spongy gasket there, front and back.
As mentioned could be the cause of the smoking tail pipe as well.

 

Oil leak is a big problem.
The oiling system must be properly pressurized to
keep the moving parts of the engine lubricated to prevent excessive wear. Most vehicles
use a visual indicator, which may be a light or gauge, mounted in the instrument panel to
alert the driver of low engine oil pressure.