need advise bolt removable

-
pagilman

pagilman

Well-Known Member
Joined
Nov 19, 2005
Messages
790
Reaction score
5
Location
farmingtonPa SilverSpr FL
:angry7:I was putting rocker shafts on a 340 and broke off the center pedistal bolt at 30lbs of torque. It broke off flush at the top of the threads and will be hard to work on. I plan on starting small and working up with the drill bits untill I can get an easyout in it, if they make one that small. Has this ever happened to any of you and how did you repair it, i don't want to remove the (iron) head and take it to a shop. thanks for any advise, Walt:angry7:
 
Try a left handed drill bit. They'll often grab the bolt.
 
hi, he's right, left twist drill bit will get it out. also, 30# torque is too much.
20# will do the job quite well. I tighten mine with a short handle rachet. guess, I'm lucky, never broke or had one come loose in 30 years of racing small block mopars.
 
One book says 25 lbs and the other 30lbs. I started to torque the other side and with an 18 torque wrench I quit because I was afraid to break another. I am going to buy all new bolts and try 20lbs. Thanks men for your input. Walt:cheers:
 
After it happened to me 2 times in the same head I got tired of drilling the center and easyouting it so I replaced the crappy old soft bolts with new ones. Im not going to trust bolts that are that soft in my motor.
 
Make sure your threads are clean, and oil them up a bit so that your torque readings are accurate. I'd put a good glob of grease around the area too, to make sure you don't get cuttings falling into the engine.
 
I don't use anything but the grade 8 chromeloy. They will withstand 25 ft lbs with no trouble. Never broke one either.
 
I don't like grade 8's for the rocker shafts. More torque is needed to get enough bolt stretch, then I worry about distorting the shafts. Some loc-tite could lessen the need for more torque, I guess.
 
i just checked my service manual because i thought your numbers were high my factory service manual showes 210 INCH pounds which is about 17.5 foot pounds
 
If the bolt is 5/16" in diameter (not the head) #30 is way too much. #15 pounds is resonable. Here is a trick I have used, Drill the hole as you suggest and drive in a Torx bit with a hammer. This cuts/deforms metal making a socket. I have seen too many ez-outs break. They spread the bolt making removal more difficult, when they break they are very hard to drill again (the metal is very hard). They often break in a spiral, making re-drill nearly impossible.
 
I also had this problem mainly cos one well known book tells you to torque them to 30Lbs . I now torque to 17!
Anyway, I carefuly used a hammer and centre punch to knock the bolt round. It worked, just be careful not to peen the top of the bolt over
Took about 15 mins.
 
Two approaches if the other suggestions don't work. 1. Weld a bolt into the top of the threads & remove with a wrench. 2. Fill in and re-tap the hole.

If I'm not re-using factory bolts, I always use US sourced hardware in Grade 5 unless a Grade 8 fastener is specified. I've had real problems in the past with Chinese sourced fasteners. They put the markings on the head but do not back it up with the product on the thread. Steel is frequently very porous.
 
Like others here mentioned I`ve seen at least three different torque specs on various websites, in manuals, etc. Around 20lbs. seems to be correct with a grade 5 bolt. We had the same issue with Fishmans 408 just a week ago. The Chinese bolts that come with many of the new rocker shafts are crap! They stretch and break and as 72 Demon said , their markings don`t match their strength. We were torquing to 25# when we broke one. The remainder of the bolt left in the head wasn`t real tight and we were able to take a small punch and unscrew the bolt by just tapping the screw on one side in a counter-clockwise motion. It came out without much ado. I had a set of those Chinese bolts on some tie rod sleeves and again they stretched before reaching the correct torque.
 
What they did to mine is weld a nut to the stud and back it out. You weld in the middle of the nut to the stud.

Good luck
 
Gtx youre spot on. that is the best trick ive ever been shown and no chance of chips or shavings in the motor
 
With any broken bolt.. first thing I do is center punch as close to dead center as I can.I'll hit them pretty hard too which will undo atleast some of the thread stretch. Next I spray it with wd-40 and use a tiny punch off center to peck at it in the outward rotation. If it moves I know I can back it out this way and often drop the punch and hammer . Scratched them out with a dental pick.
 
I will try backing out with a small chisel and then drill and easy out as I have no welder, but that sounds like the best. Thanks to all who replied, Walt
 
You must log in or register to reply here.
-

Back
Top