Okay, I purchased this truck about two months ago and have all intentions of fully restoring it as time passes. The truck is a '78 F150 with the 351M 2bar Carb.

To date, I have replaced the following:
Starter
Alternator
All four belts
Timing Chain and Camshaft Sprocket
Ignition Control Module
Distributor/Rotor
Wires
Plugs
Carb
Water pump
Starter Solenoid
And the little box nearest the starter solenoid (just had a brain fart as to what it was called.)

Now I have an issue and I'm a n00b as to how to diagnose said issue.

The truck was gutless for awhile, adjusted the carb choke and now it seems to have a little better acceleration. But while I am accelerating, it feels as if my transmission is "sticking." It will get about 3,200 rpm and shift...and when it does, it jerks the truck. I am guessing the transmission is slipping.

It has the C6 trans in it.

But today, I noticed that when I got the truck around 45mph, I heard about 4 loud pops coming from the engine compartment. Resembled a backfire like when you cut the exhaust off and have straight pipes but muffled. And when it happened, my accelerator pedal "popped" continuously. Hard enough it actually pushed my foot back about a quarter of an inch. The accelerator "popping" action happened once before but I shrugged it off thinking the accelerator linkage got bound up somewhere but when I stopped the truck, nothing was bound or caught up on anything.

I was only able to get the truck above 45mph after backing off the accelerator and just gradually pressing the pedal...even then it acted like it was losing power and wanted to die during acceleration.

Once I got home and turned the truck off, I heard some pinging coming from the engine compartment. I thought it was the components cooling down, which is typical do to the fact that metal expands under heat and pressure...but this "pinging" had a sound to it as if the motor was trying to start back up.

Scenario: Pulled in driveway, parked the beast, turned it off, pulled keep from ignition, stepped out of the truck and heard the "pinging" and it was acting as if it was trying to start back up...the ignition switch/cylinder is in the "off" position.

P.S. The guy I purchased the motor from said you can hear "grind" of metal once the truck gets to 50 to 55mph...which is confirmed. Not you don't hear it too much. Instead, it's now the "knock knock knock." And she leaks oil like a siv but we are having issues trying to locate the oil leak.

But while it was doing, you could hear what sounded like a rod just doing the happy dance within my block.

Sorry for the rambles but wanted to provide enough to hopefully get some help.

 

I would start checking the block for cracks or holes.. Whatever was knocking might have escaped!

 

Trans sounds like it has a shift kit.

Engine sounds like it's about to blow up. Metal grinding, backfiring, knocking, pinging, oil leaking,,,, why are you still driving it?

 

Drivin her til she blows...but from what I've read, that is not the best idea seeing as how it could result in a violent ordeal if sh** hits the fan...literally.

As far as a shift kit, care to elaborate? It is a 4x4 but the transfer case does not care to shift out of whatever drive status it's stuck in. Got up underneath it earlier this evening and that sucker is rusted to hell...

And when I say it takes awhile to accelerate, we are talking about a two miles to finally get up to 60 once on the highway.

When I said I was a n00b with these issues, I was not joking. I do work at an auto parts store but this is the first time I've ever encountered issues like this of my own. And no customers have come in asking about things like this, that is why I went ahead and just purchased a new motor.

I figured there is more internal problems than are being identified. I, more or less, am concerned about the severity and if it's something I can get away with for another week or if y'all recommend I just park the thing for the time being.

 

Forgot to mention, when the vehicle is parked, the oil pressure is sitting where it should be. After about 10 minutes of driving, the oil pressure drops as if it no longer exists. Checked the oil level in the truck and it has not shown any signs of being below threshold. Advice?

 

As far as I know a shift kit changes the rpms each gear will shift at and also how aggressive the shift will be. That would explain your kick, or it could be low on fluid.

Since you have already ordered a new motor.. You might as well drive her till she blows like you said. I would only worry about the tranny if something went horribly wrong.

 

After I drop the motor in, the transmission rebuild is my next adventure. Going to take that one in to have it done because I do not feel like messing with all the components inside that sucker in fear I might get something off and screw more things up.

 

I think you are onto something, 61steven. The truck does "accelerate" aggressively while in first gear but second and third are the horribly, sluggish ones.

 

The engine shifts by rpm and vacuum, if the engine is running poorly it can effect the shifting, the tranny may not have a problem at all.

 

Thank you for the heads up, Eric.

Appears the motor finally took it's last straw today.

 

Would that explain why the motor likes to take a dump right after some hard shifting?

I notice that when the motor gets ready to stall out and 'randomly' die, it will shift into second, has no power, then pop back into first gear, then slams back into second, that back out and into first then dies.

 

Ive read this about 3 times and other than leaking oil and a hard shift I have no clue what you are trying to say.

 

the higher the gear the harder the engine has to work, if it's running like crap it WILL get worse as it goes threw the gears.

I wouldn't do anything with the tranny until you swap out the engine and get it running right.

By the way, what did you actuallly buy, and from who.

 

It sounds to me like your cylinder temperature is way too high and you're getting detonation. What do you have the ignition timing set to? Are you sure your valve timing is set up properly? Has this done this from day one, or just since you did the timing chain and distributor?

That engine is why your trans is flaking out. ...but just to be sure, make sure the vacuum line to the modulator on the trans is hooked up and in good shape.

The popping in the gas pedal is a violent back fire through the carburetor, but the running engine, "swallows" it. That's why it sounds different. It's usually caused by a burnt valve seat, but could be caused by a sticking valve, a worn cam, or a cracked head.

No oil pressure hot is an indication of worn main or cam bearings .....or both.

No matter how you look at it, it's time to tear the engine down before you cause damage to the trans or the rest of the drive train. It's all good. Think of it as an adventure.

 

@EricJ- 1978 Ford F150 Ranger XLT 4x4 with the 351Modified. Purchased from some guy about 2 hours away.


@eartquake68- After I finished redoing the timing, I had the truck taken down to two different smog shops. Both confirmed, according to their timing lights/guns, that the timing was set at 8 degree TDC.

The motor did run better after the timing/tune-up was done on the truck. Then about 3 weeks later, it started having issues again. When I did the initial tune-up on the truck, the gomer who changed em before me had two wires crossed. So it was more of a V6 than a V8. Idled extremely rough before readjusting the wires.