drilling magnum heads
One other thought here... I think there is a way to do this like some earlier posted suggested, by using an intake manifold as a guide. But you would need a few specific things.
1) a 2-barrel intake manifold. The section under the carb is much smaller and allows access to all the holes. I laid this on my block/heads while waiting for the drilling rig to arrive, using some paper board to approximate the thickness of the gaskets, just wondering about possibilities. This should work:
2) A drill bushing for a 5/16" bit, 5/16 being the tap drill for the 3/8" sized LA manifold bolts. $12 from McMaster:
The only catch with that is, while you can get the right ID, they don't come in the required OD. I recall the holes in the 2-barrel manifold were 29/64", but don't quote me on that. You'd have to get someone to turn a portion of one of the ends down to fit the holes in the manifold. Shouldn't be hard for a machinist.
3) A longer than standard drill bit. Based on some rough measurements I took from the required depth of the holes, the thickness of the manifold, and the height of the runners, you'd need about 6", plus a little more for the chuck to hold. So something like this, again from McMaster is $16:
Again, just thinking out loud here, but this may be a viable option for someone who can't wait for the fixture, or who doesn't want to remove the heads.
One other thought here... I think there is a way to do this like some earlier posted suggested, by using an intake manifold as a guide. But you would need a few specific things.
1) a 2-barrel intake manifold. The section under the carb is much smaller and allows access to all the holes. I laid this on my block/heads while waiting for the drilling rig to arrive, using some paper board to approximate the thickness of the gaskets, just wondering about possibilities. This should work:
2) A drill bushing for a 5/16" bit, 5/16 being the tap drill for the 3/8" sized LA manifold bolts. $12 from McMaster:
The only catch with that is, while you can get the right ID, they don't come in the required OD. I recall the holes in the 2-barrel manifold were 29/64", but don't quote me on that. You'd have to get someone to turn a portion of one of the ends down to fit the holes in the manifold. Shouldn't be hard for a machinist.
3) A longer than standard drill bit. Based on some rough measurements I took from the required depth of the holes, the thickness of the manifold, and the height of the runners, you'd need about 6", plus a little more for the chuck to hold. So something like this, again from McMaster is $16:
Again, just thinking out loud here, but this may be a viable option for someone who can't wait for the fixture, or who doesn't want to remove the heads.