Locating knock
Thread Starter
|
New User
Joined: Oct 2003
Posts: 10
Likes: 0
From: Jewett
Locating knock
Here's the problem, I have a 72 F-250 with a transplanted 351C and C6 trans. Motor was rebuilded not to long ago, all machine work was done by a guy I have used for years and trust completelly. After the motor got about 1500 miles on it, it developed a low knock at hwy speeds. I have checked the rods caps mains and rerun the valve lash. But still can't find out the cause of the knock. Years ago I had another F-250 and the bell housing bolts had backed off some and the flywheel would tap the top side of the housing, So I checked this too, and still no luck. Any suggestion where I might look for the knock. 
Senior User
Joined: Sep 2003
Posts: 212
Likes: 1
get a stethascope and check it out. I would guess bottom end but you did too. Did you plastigauge the engine? Also, did you use aftermarket valve covers. I had a buddy put a big cam in an engine once and the stock valve covers weren't tall enough and the rockers smacked the tops and it was only noticable at highway speeds when he wasn't on the motor (exhaust was too loud at other conditions.)
Good luck.
Erik
Good luck.
Erik
Thread Starter
|
New User
Joined: Oct 2003
Posts: 10
Likes: 0
From: Jewett
Thanks for the replys, I check each cylinders, and yes I did plasticgauge the mains and rods both. The suggestion about Aftermarket valve cover is a ideal I hadn't thought of, it does have edlebrock rocker covers , so I will check into it. and again Thanks.
Senior User
Joined: Sep 2003
Posts: 212
Likes: 1
great way to check bottom end, not that yours is a problem if you checked it is to go up a hill and really load the engine (get on it!!!) BTW now would be a good time to mention that you need a true reader oil gauge. Load the engine on the hill for around 15 seconds then let off completely. The oil pressure should go up 1 or 2 lbs but if the bottom end is loose then it will go up more than just two pounds. Helpfull hint.
Erik
Erik
Thread
Thread Starter
Forum
Replies
Last Post
indy440
Ford Inline Six, 200, 250, 4.9L / 300
5
Sep 1, 2006 08:02 PM
