Tonight while working on the car, we lowered my idle from 1050 to 750 and we started to hear a knocking sound.
Sounds like it is coming from either the timing cover area or the oil pan. Also, there is a lot of air coming out of the oil cap hole in the valve cover.

I am going to buy a used 305 TPI motor from an 87 Formula. It has 150K miles on it and ran when pulled from the car. It blows a little smoke when it starts up I was told. It's only $50 for it.

I don't have the money to build buy the parts for my 350 block I have in my garage so I think that getting this motor for $50 is ok and should last till the winter. What do you all think?

Thanks

 

I'd start looking at getting a shiny new double roller timing chain 'cause that noise is your old streched out one hitting the inside of the cover, soon you'll give it some gas and it's going to skip a couple teeth and it won't run right or if it skips allot of teeth you'll bend a couple valves.

 

I didn't even think of that.

Also, why do I have smoke and air pressure coming from my oil cap when I remove it? I was told the air coming out of it wasn't normal. I do know that smoke shouldn't be coming out of there as well.

 

All those fumes(oil) coming out of your valve cover is called blow-by. THis is when the rings are weak.

If the motor is KNOCKING, you have a prob. How severe is not difficult to determine. if you have an oil pressure guage (mechanical in PSI) it will help you determine what kind of shape its in. If the knock gets louder with RPM, it's a rod knock.

I would check the preliminary stuff including rockers/studs ect...

But if you say it's coming from the bottom, it isnt usually a good sign.

If you really want the 305, go for it but just so ya know you dont want to do the job twice so MAKE SURE its a good running engine!