The Stovebolt Site Forums The Shop Area Engine Shop 261 timing marks

hey, i just found out i have a 1959 261 with 235 heads which i thought was a 235 as i was told when i bought the truck. anyways im in the process of installing an hei dizzy i got from langdons and it tells me to rotate the engine to 10-18 degrees before top dead center, the tdc mark on the flywheel is a indented circle, right before the circle there are two lines an inch or so apart, a couple inches before the lines there is a triangle. where exactly is 10-18 degrees btdc? and what are these other marks?

I looked in my '59 shop manual and can't find any reference to all those timing marks. The ball is considered TDC, but even that may have the distributor firing at 4 degrees BTDC. Not much help. I would think Langdon could help you out on timing. Give him a call.

I was thinking that the circle is where the ball used to be, and it was somehow taken off. How shall I time it after I install the distributor

A recent discussion about setting timing using a vacuum gauge.

Also, a dwell meter may help getting the timing right.

FWIW, If you are unsure of the marks, You can always put a piston TDC stop in the #1 hole as well.
With #1 coming up on the compression stroke but still at the bottom of the stroke install the stop and by hand bring up piston till it just touches the stop. Mark the Fly wheel where the pointer sits.
Then by hand reverse the rotation until the piston just touches again. Mark this and 1/2 way between the two marks it true TDC.