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Broken starter mount hole on engine block

  
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Broken starter mount hole on engine block

 
glenn160 glenn160
New User | Posts: 1 | Joined: 02/07
Posted: 02/03/07
03:58 PM

Hi,
I broke about half of the mounting hole on the sbc engine block for the starter in a 80 camaro.  I can go about two weeks to a month without loosing and then retightening the mounting bolts. I have been told that this isn't really fixable.

The engine block has the offset starter mounting holes, but it has three holes. Two of the holes are next ot each other and are closest to the center of the block. The single other hole is the one that is half broken.
I have seen mini-starters with four holes for mounting, but they all have been straight and not offset. Could I use such a starter using just the two good holes on my block?

Thanks,
Glenn  

oldbogie oldbogie
Guru | Posts: 1195 | Joined: 08/03
Posted: 02/06/07
02:51 PM

I wrote a response last night and then discovered it's not here today, must have screwed up with the link's load.

Anyway, I guess first out of the gate is a question; broken how and where?

I have a hard time imagining this is a broken casting vis-a-vis a stripped thread, so fix my assumption if I'm wrong.

A stripped thread can be fixed with a Heli-Coil or equivalent brand thread restorer gadget. Cost would be about 40 bucks for tool and part as a kit. Being able to get a drill bit up there with everything installed in the vehicle could be difficult depending on what this is in. Basically the stripped thread is drilled out. A special tap from the kit is used to make a new thread into which is threaded a steel coil insert that on it's ID restores the original thread size.

Getting to depending if the casting is actually busted or cracked; Chevrolet over the years has used a 153 tooth starter ring gear or one that's 168 teeth. The 153 tooth uses the straight line bolt holes and the 168 uses the angled holes. Unfortunatly one hole is common to both so if that's where you're busted changing flywheel/flexplate from one tooth count to the other won't help. But if Lady Luck is with you? You can get around this problem by changing the flywheel/flex plate to the "other" ring gear and using that matching starter.

The 153 fly/flex and the 168 use a different dia. clutch or torque converter. The 168 is usually drilled at the factory to accept either the large dia clutch or torque converter. The 153 tooth is usually drilled only for the smaller versions of clutch or torque converter. However, some of these can also be had drilled for the larger dia. components, or they can be redrilled to accept them. Obviously this kind of drilling needs to be done by a competent shop since this stuff can't be off more than some few 1000ths on an inch.

The Chevrolet starter uses a special body fit bolt to attach the starter. Some folks replace these with Home Depot bolts, this is a no-no. A regular bolt will not make a tight fit inside the starter's gear housing allowing the starter to move around a bit. This movement slowly pounds out the boss holes and begins to shear load the bolts in their threaded mounts eventually damaging things. So make sure to use the GM bolt. Of course when buying a rebilt starter, you can get this effect from a previous owner who switched out the factory bolts.

The other thing to be sure of is where the gear teeth mesh. Often the starter mount has shims in it. These are to insure the gears don't crash together with too deep an engagement.

Bogie