F150 StrokerCobra

it said on the internet to tight the bolts to 65-75 FTlbs of trq

we set the trq wrench at 70 and becan tighting 3 of the 5 clicked they got on good but the other 2.. didnt.. we overtightened them now the question is now.. is the bolts bad of the crank?? oh and we tried to loosen it and it wont come oout just keeps spinning...


can i use larger bolts instead?? or something like that? any ideas???

mjr46

your gonna have to extract the bolts and see if the bolts stripped the crankshaft, I've always used 85 ft lbs if they stripped at 65-70, either the bolts were stretched or the threads were damaged or weak in the crankshaft end.

F150 StrokerCobra

im gonna extract them tomorrow.. lets hope the bolts where weak.. they where cheap ones.!! soo

if i cant find the correct bolts? can i buy other bolts with differend heads on them? i know a store i got good bolts there but the heads are L wrench ones

mjr46

they need to be a hardened bolt for use with flywheels, not your everyday hardware store bolt, I wouldn't take a chance, your legs are worth more than a few bucks and some time aren't they?/

86 5.0L

Grade 8 FTW? yes?

arnt they some grade from the factory? I remember seeing some markings on the top of the head, not sure if it was those grade markings though

Liquid_02

Exactly. Get some ARP ones, they're like 20 bucks for a set and you'll never, ever have to worry about it again... unless they bind in your crank half way down and have to pull they crank out to get it milled out... like I did. Not a good day for me... Of course it had to be the balancer bolt too.

And no you cannot use larger bolts. The crank is hardened, and I personally wouldn't even attempt to use a tap in them to cut threads, repair them, sure, but not cut them. You'll just have twice as much hardened steel to cope with in the end after a tap breaks.

67mustang302

Good grade 8 bolts will work. If the threads in the crank are bad then you should be able to tap them out using a steel threaded coil insert kit(Helicoil, which is actually a brand name) and insert new threads. And taps break because they're used improperly, they're made from high grade tool steel which is usually VERY hard.

F150 StrokerCobra

thank god.. the bolts i got where some how weak and short...

i got some good ones at napa they are like 1/2 longer.. and the threads of the crank where fine

zebo87

85 ft/lbs is the spec.

F150 StrokerCobra

thanks peeps.. i torque them at 75 ft/lbs with loc tite and the engine is in already!