Quote:
Originally Posted by ElCoSix
Aargh!
I have a 67 El Camino with the 250 inline six that I'm restoring. I'm going to use the six for now - and maybe forever. I'm trying to get a broken bolt out of the crankshaft without tearing it apart. There's no radiator or even core support yet, so I can get right at it. I was thinking that if I had a new bolt, I might be able to get a machine shop to drill right through the center so it would make a nice guide to drill in the very center of the broken bolt. Then I could start the bolt in and drill a pilot hole right where it's supposed to be. That way I could try a reverse direction drill bit or some kind of extractor. Does anyone know the thread size and pitch of the bolt or where I can get that information? Or better yet, does anyone have one? Or any other ideas for getting the broken bolt out?
Thanks a lot,
Scott
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Not all 250s were drilled for a Harmonic Balancer retaining bolt, like the 292s had. Such a [stock] bolt hole would be a 7/16-20 UNF X1.0'' deep thread. Leo Santucci, author of the ''Chevy Inline Six-Cylinder Power Manual'' recommends drilling and tapping the crank snout fot 1/2''x 20NF x 2-1/2''.
[Same as a Chevy V8.]
El Caminos could possibly have a 230 [car] engine, which looks just like the 250 from the outside. Run the ''dress numbers'' stamped in the pad just aft of the distributor hole. The 2- or 3-letter code at the end can tell you.
A retaining bolt for the HB is a great idea on any L6, as that allows you to use a fine-threaded HB installer tool to press the balancer on smoothly, which is a lot better than bashing it on with a deadblow hammer. The cruder assembly method can cause bearing damage if not done right.