MikeSammy

I accidently snapped a bolt off into the crank snout. Is it neccessary to put the big bolt the holds the balancer and pulley into the crank or can I leave it be and just hook it up. I heard that the keyway on the crank is strong enought to hold it and older 350's didn't have a hole for the bolt.

howy03

iTrader: (2)

I did the same on mine used an easy out.

MikeSammy

tried that and broke the easy out. This bolt is really in there

howy03

iTrader: (2)

is the motor out of the car? I would try and drill the bolt out as close to the threads as possible then use a thread cleaner or a tap!!! I dont think u would want 2 take a chance on no bolt.

davidearlcox

If the bolt is broken off somewhat flush with the end of the crankshaft, just weld an appropriate sized nut onto the end of the bolt with a MIG welder, then back it out with a wrench. If it's really tight, the best time to unscrew it is while it's still hot from the welding. Takes about four seconds to weld a nut onto a broken bolt like that, I've done it many times.

Bullydawg

iTrader: (7)

I did the same with my rearend... Works great. I used an impact gun while the weld was still hot.

cuisinartvette

Far as I know all 350s used a crank bolt. There were some 327s that didnt.

Broke one off as you did and couldnt get it out for the life of me without banging the threads up, good luck.

Guest

Define "accidentally".
Usually, "accidentally" in this case means trying to install the balancer with the bolt it came with. If that is what you did, and the bolt busted off an "easy" out, the threads in the crank are now garbage. I would have suggested drilling it out but you will not be able to drill that "easy" out. At this point probably the only way to get whatever is left in there out of the crank is take it to someone.

MikeSammy

I managed to get the easy out out. Im going to ace haedware tomorow to get a tap set. what size and tread size is the bolt on the 305 crank. Im just going to use the one from my 305. what would I have to drill it and what tap thread measurment do i use.

is it any of these sizes: 1/4"-20NC, 5/16"-18NC, 38-16NC, 7/16"-14NC, 1/2"-13NC
those are the sizes of the taps that come with the set. also, what size hole do i drill

also my friend who was helping just texted me to tell me that it was a head bolt the broke off in there. He said he "was trying to turn the crank over with a bolt and it snapped just the threaded portion. "

that explains why I had trouble getting any bolt in there the threads are all messed up.

cuisinartvette

A HEAD bolt?! Slap him, those arent even the same threads, crank is a finer if Im not mistaken.

MikeSammy

bump for any help, I just need to know what size tap to use and what size i need to drill the crank to be able to use the bolt from the 305 crank.

IROC343

The thread size is 7/16-20 it's a fine thread. If you're buddy forced a 7/16-14 head bolt in there and broke it off, you're in for a real fight. If this is just a driver and the balancer is a good press fit and it's all the way on, you probably don't need the bolt. Many early small block cranks weren't even drilled and tapped for one.

383 Power

iTrader: (2)

When using an Easy out, you need to remember that the Easy Out is HARDENED. As a general rule, the harder metal is, the more brittle it is. This is why padlocks are CASE HARDENED. The outside of the lock is hard, but the inside isn't. That way it will react to shock without breaking. you never want to put an unusual amount of torque on a hardened tool, if it starts to flex, Stop. Easy outs can get you in a heap of trouble if you aren't careful. When i was in the NAVY as a Machinist, we got alot of rework when people tried to use an Easy out. If the bolt breaks above the hole, you can grind it down flush and use a center punch. Make sure you start with a VERY small drill and work your way to one size smaller than Tap Drill Size. at that point, you should be able to pick out what's left of the bolt with a Scribe or Pick. If the bolt is broken off below the surface, you'll have to try and make a flat spot in the middle of the bolt with a bur on a dremel. Once you do that, you can center punch it and step drill. If you have the Easy Out stuck in there, you'll have to get a Chisel and shatter it out. You're not going to be able to drill it since it's hard, but since it's brittle, you can shock it again and again. that will break it into pieces. it's tedious, but the next time you'll know better.

Also, it's important to be CENTERED on the bolt before you start drilling.