Setting a timing tab?

[79dentside]

Hey all. I have 2 timing indicators on my 350, both are apparently wrong? 1 is straight above the balancer, the other is about the 2 o’clock position on the balancer. I bought a piston stop tool to see if my balancer slipped, but my balancer mark is on TDC. The Balancer is an 8” diameter and have put MSD timing tape on it to figure out its total timing. Of the 2 tabs, the closest shows 8 degrees ATDC at idle which I know isn’t right. How do I precisely make a reference point for total timing? Thanks in advance

 

[79dentside]

Looks like I misunderstood my timing tab... 8 degrees ATDC is really 8 degrees BTDC. I had it opposite in my head. I reved it up until it wouldn’t advance anymore and it seems to be around 26 ish total timing. Man do I need to advance it. I ended up cleaning up the tabs because they are crusty, I am not sure why I have 2, but now I can sorta get a baseline on this motor.

 

[75gmck25]

The 12 o’clock tab was used in earlier SBC engines, and it was probable tack welded to the cover.

Summit and other places sell adjustable tabs that attach to two timing cover bolts. Just verify TDC with your piston stop and bolt the tab in the correct position. My crate engine came with tabs for the 8” and for the smaller balancer, so make sure you get the right one.

Bruce

 

[Craig 85]

I know my '79 K15 with a 350 had the mark at 12 O'clock.

 

[75gmck25]

I just reread a wiki that tried to explain the timing tab locations, and now I'm even more confused than before. Apparently it went back and forth from the 2:30 position to the 12 o'clock position a couple of times from the mid sixites to the late eighties, but even then it wasn't consistent from cars to trucks. The only good solution is to find real TDC and use a bolt-on tab.

Bruce