help loud knock

a friend is looking into a 1977 911S targa.
good body decent interior. 200K miles.
rebuild trans less than 300 miles ago(brumos)
the engine had a top end job 12K( 3 years) ago. engine starts easily, idles smoothly, revs good, lack of power and LOUD knock. its not a metallic knock though. it happens every
1 sec (or so). sounds like a bearing but
the bad bearings i've heard have been faster.
it would knock with the engine rev. , right??
could it be the oil pump?? seems to come from
back of engine.(center) has carrera chain tensiors. could be bad tensioners?? pleaser help the price on the car is good(3500)but friend does not have ton of money to put in engine. he could do the work himself, any suggestions?? please help also oil leak from rear , above heat exchanger.thanks in advance

I would think that if the body is rust free and the tranny has been rebuilt, the car would be worth the $3500 without the engine. The oil leak could be valve covers, or it could be the oil sender or return tubes. None of those are expensive or difficult to fix. Then again, the oil could be blowby as a result of something else more serious (as evidenced by the lack of power and knocking). I'm not terribly familiar with the 74-77 cars, although I have heard that the engines did not last much past 50k miles.

What the knocking might be, but it would seemt that it would be faster with more rpm is that a head stud may be broken.

The 2.7L engine had a major problem with this issue. That is why the engines were rebuilt way before they needed to be rebuilt. The engine might also need a complete rebuild anyways if it has a lack of power. Have you had the compression checked?

If you really want and know a good Porsche mechanic, about $100 will tell you the complete condition of the car. The car will have what is called a pre-purchase inspection to find out what exactly is wrong.

Hope this helps,
Paul