Need some tips or tricks for driling out a timing cover bolt on a SBF

Got one timing cover bolt that broke in the block.  Someone tried to drill it, got off center and boogered the hole up....  Any ideas on how to drill it on center??

Will most likely have to drill/tap oversize and install an insert.  It's the top pass side timing cover/water pump bolt...

Machine shop said no.  Table won't go low enough on the Bridgeport to get the block on it.  Was thinking of strapping the block to my drill press base and doing that...?

Ideas?  Tips?  Tricks?

You know anyone with a mag base drill (anyone who works up on steel beams)?  Could spot-face the broken bolt with an end mill, and re-drill on center while magged to the block..

jbozzelle wrote:Got one timing cover bolt that broke in the block.  Someone tried to drill it, got off center and boogered the hole up....  Any ideas on how to drill it on center??

Will most likely have to drill/tap oversize and install an insert.  It's the top pass side timing cover/water pump bolt...

Machine shop said no.  Table won't go low enough on the Bridgeport to get the block on it.  Was thinking of strapping the block to my drill press base and doing that...?

Ideas?  Tips?  Tricks?

I used a dremel to get mine out went to Wal-Mart and bought the smallest debur bit they had worked out good takes a little time to get it all out then I ran a5/16 tap to clean the treads up

If you can get a steel hollow dowel pin you may be able to weld the pin to the broken bolt through the inside and weld a nut on the outside, if welding is out then fab a bracket using surrounding bolt holes and make your own centering guide (press) grind the end flat with a flat end cutter and then use the guide to pilot the new hole.

Once you have the end of the bolt as flat as possible, bolt the timing cover in place and use it as a drill guide. Protect the timing cover by slipping a piece of 5/16" tubing into the hole and using a smaller drill bit that fits snugly in the tubing and keeps the bit centered. GO SLOWLY and maybe you can go deep enough to get an easy-out in there. Worst case, an insert or an oversize bolt. Good luck....these things always bring out my potty mouth.

I had to drill some out (3 or 4 if I recall correctly) on a 5.0 last year. What a major pain in the but. Like was said take your time, and I would get several new drill bits.

Thanks guys. I did some googling and found where a guy used a hardened drill bushing in the timing cover. I'll go that route and hopefully the hole that is already drilled slightly off center will not pull the bit into it and make it worse...

Get a Tig welder to to build it up ( the broke bolt ) with enough weld to get vise grips on and it with come right out.

The bolt is mostly drilled out but the hole is drilled off center. I need to be able to drill the rest of it out, check threads and be able to drill on the proper bolt center for an oversize bolt if possible.

I'm past the point of welding...

We typically just break the cover.  The things twist off at the cover to waterpump junction, siezed in the cover.  The covers are pretty cheap compared to time.  Once the cover is out of the way, there is 2" of bolt yo grab onto, it usually comes out the block with a simple locking pliers and a shot of liquid wrench
  Out of probably 15 or so busted off bolts I think 1 needed a little map torch heat on the block.

If all else fails, take it to a larger machine shop with some old school guys still working. They'll have it out in a few minutes. I could do it in my shop no problem.

Thanks. Going to try to drill bushing in the cover trick first. If it doesn't drill on center I'll find another shop...

jbozzelle wrote:Thanks.  Going to try to drill bushing in the cover trick first.  If it doesn't drill on center I'll find another shop...

Probably a whole lot less hassle to just get a new one? if you can't get it out yourself.

I don't have an issue with the timing cover itself... That came off with no issues.

The bolt for it broke off in the block and my dad tried to drill it out and got the drill off center...

jbozzelle wrote:I don't have an issue with the timing cover itself... That came off with no issues.

The bolt for it broke off in the block and my dad tried to drill it out and got the drill off center...

Ahhh I thought you broke on off in the cover itself.

Nope. I mentioned the timing cover so you guys would know what bolt I was talking about. Reading some of the replies above it seems I confused some of ya'll...

Hoping the drill bushing trick works. If not I'll track down another machine shop. Hate to trash a good block over this

What I have done in the past would be to use a torch and cut/blow it out, especially if you already have a hole drilled through it, run a tap in hole to clean up the threads. Torch does not cut cast material.

I'm no expert but I've herd to use a peace of copper tubing put into the hole that bolt Is broken off in and weld inside tubing until you have something to grab. A friend did something of the sort when the bolt broke off his skidoo clutch about a inch inside the clutch build it up till he could weld a nut to it weld don't stick to copper