There are a couple of things you will want to sort out in your quest to get some accurate base line timing. First, confirm the year of the motor. Then, pull the cap off the distributor and grab the delco number.
Here is where it will get tricky. Different year flywheels were set up for different year motors. So if you read the above article, you will note the common uses of the same casting number on the flywheels, but different part numbers which reflects some variations in the bb placement and other marks.
So for example, 57 235 motors are set at tdc and the bb for that motor is at tdc. 59 is 5 degrees advanced and others can be 2 degrees. Most of those flywheels are marked for that advance, but not all. So you may have to draw out what’s on the flywheel and if it looks like no indication of anything other than tdc, you may have to make an assumption for the time being, that it is.
In terms of total timing, some of the distributors were set up for 12 degrees of distributor advance, others 14. Which means the motor will see 24 or 28 degrees, if the distributor is working properly. And there lies the rub. With these old distributors, they rarely come up to spec. I have had about 20 of them on my Sun machine before I take them apart and I will bet only three or four were advancing properly. One, an nos 2403 was so gummed up with old delco factory grease it would not advance more then a couple of degrees. Others were rusty, gunk laden, broken springs, or worn out with far too much end play.
So if you really want to see if you can build a little accuracy, maybe start with the year of the motor and the distributor part number and let’s eee where that takes us.
Last edited by Dragsix; 09/04/2025 2:18 PM.
