scat 4.250 steel crank questions

[wrench87]

i have the scat 4.250 crank for my 390 stroker i am just gathering parts but today i pulled out the crankshaft to try the arp crank bolt wich is for the ford part number 150-2501 it does not fit. does any one know which bolt you use for this application.?

i also have the shelby timing cover and the shelby crank spacer that does not seem to fit also how are these installed is it a press fit i have the profesional products sfi dampner just curious why is the spacer needed
any info would be appreciated. steve

[wrench87]

the arp bolt does fit i guess no one chased the threads.

[philminotti]

I have a scat 4.25 as well. I had my spacer honed to be a slip fit. It doesn't have to be a press fit. You may have to grind the keys a bit if you do hog out the spacer. The balancer, on the other hand, needs a press fit. Mine is a .001" press fit.
phil

[Naumoff]

Let me give you boys some sound advice.
I have less than 2000 miles on my Scat stroker and the crank bolt loosened up and caused the crank timing gear to sheer off the woodruff key causing 16 valves and 16 pushrods to be bent all to hell.
I don't know if the crank bolt was not torqued correctly or it just came loose from a problem with the crank.
It is in the machine shop now being magnafluxed to check for any cracks in the snout.
My brother , who is a mechanic, says all new autos crank bolts have lock-tite
on them.
My buddy, who is an engine builder but not the one who built this one, says if torqued correctly there shouldn't be a problem.

The spacer should be snug but go on and off without being pressed on. Dampener should be tight enough to have to be pressed on by the crank bolt.

Just don't leave out any details double and triple check everything.

Scat is known for having snout sizing issues.
I will find out soon if the crank is cracked.

[lineslinger]

Originally Posted by Naumoff

Let me give you boys some sound advice.
I have less than 2000 miles on my Scat stroker and the crank bolt loosened up and caused the crank timing gear to sheer off the woodruff key causing 16 valves and 16 pushrods to be bent all to hell.
I don't know if the crank bolt was not torqued correctly or it just came loose from a problem with the crank.
It is in the machine shop now being magnafluxed to check for any cracks in the snout.
My brother , who is a mechanic, says all new autos crank bolts have lock-tite
on them.
My buddy, who is an engine builder but not the one who built this one, says if torqued correctly there shouldn't be a problem.

The spacer should be snug but go on and off without being pressed on. Dampener should be tight enough to have to be pressed on by the crank bolt.

Just don't leave out any details double and triple check everything.

Scat is known for having snout sizing issues.
I will find out soon if the crank is cracked.

Jeez Tony, that engine injury sucks big time.
After hearing that story I am headed out to the garage to add the Loctite and re-torque the thing.