C3 L89 Head Bolts

[Ted S.]

Does GM still sell head bolts for the L89? If so can someone tell me the part number? Thanks

[Michael H.]

Re: C3 L89 Head Bolts

Ted,

The head bolts for your L89 with AL heads would be the same part used for conventional cast iron heads for any big block of the era. The original head bolt part number shows still available from GM but I believe the configuration of the head is much different than those used in 1967-69. There is a hardened steel washer listed for, depending on how you read the book, an L89.

The original, and current numbers are...

3877668.....Head bolt, long

3877669.....Head bolt, short

3899696.....Washer, head bolt

Michael

[Bryan L.]

Re: C3 L89 Head Bolts

The set of GM headbolts I have somewhere have a much smaller head, like a 1/2 or a 9/16. At one time Paragon had them with the correct markings on the heads. Got a set of those too, somewhere.

BL

[Ted S.]

Re: C3 L89 Head Bolts

What's the proper head marking? On a '70 BB I have it has a "+" on the head bolts and corvette central says they have correct "M" head bolts. Thanks Ted

[Joe L.]

Re: C3 L89 Head Bolts

ted-----

All original big block head bolts had a raised "cross" (+) on the head. The cross was wide and the "legs" extended to the perimeter. The bolts were "untrimmed" (indented head) and they were a flange head type bolt. The wrenching surface was 5/8" across-the-flats.

The current versions of the bolts available under the original part numbers are configured "more-or-less" like the originals, but NOT exactly like the originals. They have a "cross" (+) on the head but the cross is much smaller and "thinner". The "legs" do not extend to the perimeter of the head. The bolts are "untrimmed", but the "indention" is less pronounced than the originals. The bolts are flange head, but the flange is less pronounced than the originals, too. They are 5/8" across-the-flats just like the originals, though.

Using new head bolts is a good thing to do, however. This is especially true if you don't know the history of the bolts and, consequently, their condition. "First run" head bolts (installed at the factory and removed for the first time) are usually ok for re-use. All others are suspect and I would not re-use them. You don't know what torque that some "genius" may have applied to them. Torqued to the yield point (or, nearly so) and the bolts are ruined.

So, keep in mind my old "axiom": reliability and functionality FIRST; originality SECOND. At least, keep this in mind if you intend to drive the car.

[Ted S.]

Thanks to all that responded *NM*