460 Ford Forum banner
Cancel

Broken keyway crank sprocket again!

3020 Views 6 Replies 5 Participants Last post by  HEMI-HUNTER, 
H
i have ran this motor in my mavrick flawlessly for 3 1/2 years now and broke a wood drift key that goes in the crank sprocket. originally, i had installd a cheap summit ($39.95) doubl roller chain which appeared to have strechted after the long drag strip srvice. i then installed new keys from Lem in the crank and also a billet roller chain from summit $98.00, with the 9 key way adjustable retard/advance and when restarted ran like a dream at the shop. loaded the car uo into the trailer and got to the races friday night and the car was shooting flames 2 feet long out of the exhuast and poping a cracking real bad, could not launch the car and babyed it down the trACK AND BACK TO THE TRAILER. i believe now that i have broken another key and i can't for the life of me figure out why. while replaceing the old timing chain i went as far as pulling the intake and the cam, checking everything from the roller lifters to the pushrods and also done a compression test which was OK. the cam spun freely in the cam bearings, any thoughts?
Reply
Save
Like
1 - 7 of 7 Posts
R
This is a longshot:
For whatever reason the crank sleeve on the front of the engine is not exerting enough pressure onto the fromt of the timing gear. This is usually caused by a NOT properly torqued crank bolt or the crank snout protruding beyond the dampner.
Reply
Save
Like
H
Randy,
originally, the the cheap CAT balancer loosened up on me and i think caused the sleeve to back off and cause the key to break. when i reinstalled the new key i installed a new proffesional products balancer, but use the same sleeve. i will check the crank bolt and to see if it bottomed out before pressing the sleve against the slinger washer and sprocket. maybe a new sleeve? or longer sleeve?
Reply
Save
Like
jarhead58
I know that you canget the external balancers in difference lenght. You may have the wrong one. Like the man said.
Reply
Save
Like
L
HEMI-HUNTER said:
Randy,
originally, the the cheap CAT balancer loosened up on me and i think caused the sleeve to back off and cause the key to break. when i reinstalled the new key i installed a new proffesional products balancer, but use the same sleeve. i will check the crank bolt and to see if it bottomed out before pressing the sleve against the slinger washer and sprocket. maybe a new sleeve? or longer sleeve?
Click to expand...
Chip, I think Randy was thinking the snout could be going past the front of the damper...letting the washer touch the end of the snout and not the damper.
The crank bolt bottoming out in the snout threads would give the same condition.....crank gear not clamped.
Reply
Save
Like
norm
i broke a key once also ,and i bent a bunch of valves when it happened. did you make sure you didn't bend any when it happened originally?
Reply
Save
Like
H
Like i said Norm, it ran like a dream when i put the new keyway and timing chain in. plus i did a compression test, a bent valve would show up i'm sure. i think what has happened is that my crank bolt has bottomed out against the crankshaft and has not compressed the sleeve against the sprocket. probley have to get a new sleeve from Lem and probley washer the back end of the balancer to get that stacked crush effect on the crank sproket.
Reply
Save
Like
1 - 7 of 7 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
460 Ford Forum
A forum community dedicated to Ford big block owners and enthusiasts. Come join the discussion about performance, modifications, horsepower, tuning, build specifications, and more!
Full Forum Listing
Explore Our Forums
Engine Tech Chilly's Garage The Auction Block General Tech 4x4's, Pullers, Crawlers and other HD rides
Top