Help with identifying an issue

[cougswan]

I’m looking to get a bit of help diagnosing an issue. I have a 1970 250 with a 390 in it that was completely rebuilt about 450 miles ago. The first 75 miles were put on driving local roads, the oil was changed, and then the next 350 miles were put on driving it across the state to where it will be stored.

During my drive I noticed a sound that sounded like loose metal when I accelerated the RPM’s to a higher level . It’s kind of hard to describe. I checked the oils level multiple times throughout the journey and it was fine each time.

I also noticed a new noise a couple of days ago when I was taking the truck on a quick drive after this long journey. This one sounds like a knocking noise. This happens in all gears. It doesn’t happen right off the bat when I turn on the truck but it does start a couple of minutes into the drive.

The mechanic who rebuilt the engine is across the state so taking it back to him isn’t an option. Any ideas to what is going on?

I don’t see a way to add videos to this post, but I posted videos to this question that I posted on the fb page for this group.

https://m.facebook.com/?_rdr#!/groups/1 ... up_comment

[6Delta]

Sorry to hear you are having problems but, I don't do Facebook so I didn't hear the recording. Check your timing. Your first description sounds like your timing could be a little to fast. Retard it a bit and see if it makes a difference. Also try using a hight test gas. Some companies are putting out some crappy gas. The rebuild could have left you with higher compression than you used to have and regular gas may not work anymore. It is even possable the mechanic got the camshaft installed off a tooth or the marks were off on the timing gears..

Good luck.

[jzjames]

Let the engine rebuilder know about it? Might be a problem.

[pcmdub]

Welp...tough to say but I highly suggest opening the hood and finding the location of the noise. Watch the belts, but lean over and flip the carb open and closed. To me it sounds more simple that others commented on FB. Loose spark plug, or something on the pulleys or pumps. You can usually listen with the hood open and find the noise fairly quickly. Some even use a stethoscope.

I would not drive it with the noise thou. If it is something knocking around in the engine, you are causing more damage each time. If you can't find anything obvious, then an exhaust leak could do that too. For that, find someone who smokes still...with the engine making the noise, blow smoke over the manifolds and look for little tornados. (I am sure someone else has a better method, but I don't smoke either, and always used this method...)