How to "read" Lakewood Offset Dowel Pins?

[Cobra 29]

I searched with Google for "bellhousing alignment" and had many internet sites to select from. One of these is http://www.pro-touring.com/forum/sho...d.php?p=127948

The text that helped me is;
Checking bellhousing alignment
1. Making sure that dowel pins are clean and free from dirt and/or paint, securely mount bellhousing to the engine block, and torque all bellhousing-to-engine bolts to specification. If you are using a scattershield, make sure the block plate is installed. Make sure your stock dowel pins protrude out far enough to let the scatter shield and block plate fit on the flat part of the dowel and not the tapered part. If the scattershield is resting on the tapered part this can cause inaccurate measurements. It may be necessary to tap the stock dowels out far enough to allow this. Moroso makes longer straight dowels for this purpose.

2. Install dial indicator base on the flywheel and adjust plunger to contact the inside edge of the register bore of the bellhousing. If you need to create space for the dial indicator base to sit flat on the flywheel, remove two of the flywheel bolts that are directly across from one another.

3. With the dial indicator mounted correctly, rotate the crank 360* and note the indicator readings. Using an inspection mirror to read the gauge as it rotates is helpful. Mark your readings at the 12:00, 3:00, 6:00, and 9:00 positions. This will give you an indication of which direction you need to move the housing - if necessary. Make sure to double check your readings. The total travel of the needle, divided by two, equals your reading – this reading is the amount of misalignment between the crank centerline and the bellhousing bore. Tremec specifies a maximum misalignment, or “runout” of 0.005". If you have more than .005” runout you will need to correct this by using offset dowel pins. If your reading is 0.005” or less, your bellhousing is within tolerance and you are finished with this process. If you have between 0.005” – 0.040” misalignment, you can correct it by using the correct offset dowel pins (proceed to step #4). If your misalignment is greater than 0.040” you have either measured incorrectly or there is a problem with your bellhousing and it will likely need to be replaced.

Bellhousing alignment procedures
1. To correct misalignment, you will need to use offset dowel pins. We have found an excellent set of offset dowel pins from RobbMc Performance Products (www.robbmcperformance.com). The job is much easier with these dowel pins.

2. Start with the indicator at the 12 o’clock position and turn the engine 360 degrees (one full turn). Mark the locations where the reading is highest and lowest. These readings may cover a large area but will help determine which direction to move the housing to correct misalignment. Now put the indicator in the center of the area of the LOWEST reading and ZERO the indicator (for example, if the lowest reading was between 7 and 9 o’clock you would put the indicator at 8:00. Now rotate the engine until you get the highest plus or positive reading – in this example it should be somewhere near 2:00. If the reading is .014” you would need to move the housing towards 2:00 by .007”. If it were .020” you would move it .010”. After the initial learning curve you will understand how this process works. Remember that all readings are divided by two. This can be a frustrating process. Have some patience and use a notepad to record your measurements, not the face of the bell housing as it will get full of measurements quickly. After your dowel pins are in you can turn them as needed to get the required alignment.
To install offset dowel pins, first remove the stock dowel pins by driving them through from the back with a brass drift or by using gripper pliers – sometimes this can difficult to do, especially with the engine still installed in the car. Another way to remove the dowels is to remove stock dowels with a slide hammer. To do this try using a 1/4"-28 attachment on the slide hammer. Next, drill the dowels and tap them to accept the 1/4"-28 attachment and then use the slide hammer accordingly.
Properly clean engine block dowel pin holes and lightly coat with lubricant.

4. Lubricate dowel pins and install them into engine block. The slot of the dowel pins DOES NOT indicate the direction of maximum offset. You must find the high spot on the dowel with the dial indicator and mark it so the dowels can be installed parallel to one another.

5. Install bellhousing and torque bolts to specification. Re-mount the dial indicator and recheck runout by repeating step #3. Small corrections can be made by loosening the bellhousing bolts and turning the dowels with a screwdriver to bring the bellhousing within limits.