i recently bought a 1979 ford ltd and the engine knocks real bad, i picked it up for $50 but the body is real nice. the kid that sold it figured it ran for at most 10 minutes with the knock and at most 2 miles. what i what to know is if the block would be likely trashed or if there is a possibility it could be saved. other wise could i fit a 351m into it? sorry my question doenst concerna truck lol

thanks
Adam

 

The block is probably fine, but you probably have a bearing or rod issue. As far as a 351modified motor going in I couldn't say, whats in it now?

 

To determine if the block is trashed without pulling it and tearing it apart you need to find out what it is that's knocking.

The block will be fine if it's just a rod or main bearing knock, but if it's a wrist pin knock it could be toast.

When the engine is running start pulling plug wires off the cap. When you come to the affected cylinder it will either stop knocking or get worse. If it gets worse it's a rod knock, if it stops it's a loose fitting wrist pin.

The other possibility is a sticking wrist pin, which the plug wire test will not pinpoint and will trash your block and possibly a head. The cause of a sticking wrist pin is from debri in the oil getting caught in the pin bore. This will make the piston to stick in one position instead of rocking as the piston moves up and down. It will egg shape a bore in a hurry.

If it's a rod knock a 'simple' teardown and inspection will tell you if you need the crank or rod resized. New bearings are a given.

If it is a loose wrist pin you can just remove the one piston and replace. It's possible to just fit a new pin to the piston, but a new piston and pin may be cheaper anyway. However, if it's a broken wrist pin...It's a crap shoot! (count on a lot of damage)

I have a loose wrist pin on the 'pit' and have been told a number of times that if I replace just the bad one, another may show up shortly after. So, I'm researching and picking my parts for a new build while it sits. This time I'm going with a new block (from Summit) and either going to build a new 302 or a 327 (leaning toward the 327). I don't want the 347 for ring land issues and I want to keep the 4" bore of the new block.

 

Oh, also i forgot to mention that after the knocking started he checked the oil and he had to add like 4 quarts of oil. It either burned oil or leaked it once in awhile. sorta moddy if you ask me lol. but thanks for the tips I'll try to pin point the knock tomorrow