Hi guys, i have a 79 f250 with the 7.5 v8 that has been modified. Just today the engine started making a knock sound. Its fairly loud and every time i give it throttle it gets louder and faster and comes close to stalling. The truck has been sitting for about a month or so due to some electrical issues (electrical fires) and a bad starter. I finally got it back up and running good today and when i went to pull out of my shop it started making the noise. It could be the gas from just sitting. It sat almost on empty. I dont think it would be spark plugs because its ran fine up untill now. Within the past few months ive ran 2 or 3 bottles of fuel additive through it. Any ideas or comments are much appreciated. It was my great grandpas truck he bought in 79 and he modified it fairly heavily. Im pretty sure he put a cam, edelbrock 4 barrel carb, intake manifold, lifters, and 429 heads on it. Thanks for the help! ��

heres a video https://www.youtube.com/watch?v=SzLW...ature=youtu.be

 

Welcome to the site..

Being 'it just started' knocking with no oiling/pressure issues. Checked?

If the accelerated stall is due to it partially locking up, would be problem. You might install a mechanical oil pressure gauge and confirm pressure, also, take an oil sample and see if there is any suspended metals in the lube. Might confirm a base engine issue if metal is present. The 'coming close to a stall' accelerating in place (?) would seem to indicate a bind of some sort. Knocks, rattles, are hard to ID in script, any chance you can post a vid with sound?

 

thanks for taking the time to help me out. so when i said stalling it was in place not moving around and i think that was just because it was cold because today i started it up and let it warm up and i could give it throttle and it didnt try to stall. it still made the knocking noise but it did not stall. i actually pulled it out and drove around the block to see if it still ran the same with the knock. it ran but did not have as much power going up hill and the knocking was light at first then started getting louder as it ran longer. i checked the oil levels and it was low so i topped it off and it still makes the sound. how do i know if it has good oil pressure? i also want to throw in that the right side exhaust header smokes for some reason. thanks

 

I cant get a video to post. Ill keep trying

 

https://www.youtube.com/watch?v=SzLW...ature=youtu.be
this is where the video is

 

Nice look'n ol 79..

Header exhaust flange gasket to head leaks, or collector/flange cracks can often mimic a bad lifter/tappet or worse. You can hear the exhaust leaks in the vid. As a start, might be a good move to reseal the exhaust to see how it sounds.

 

Remove the fan belt and start the truck. ONLY long enough to see if the knock goes away as the water pump won't be working. Maybe 15-20 seconds.
Eric