Im working on a 1977 F100 351m with 2 bbl vacuum advanced carb emission engine. Definitley not a performance engine It was a crate engine about 15 yrs ago. I assume it was rebuilt to oem specs but not sure so I’m questioning the timing set (maybe someone can tell by pics below if it’s straight up ?). I have a brand new CLOYES Street true 3 keyway set. If it’s to specs and I want to put it straight up, I’m thinking the the 8 deg retard is built in to the original keyway on the crank, so would I need to put the new crank sprocket on 4 degree advance slot to get it straight? Will it work well with a 20 degree distributor curve? so I can advance ignition timing and vacuum advance as much as possible without pinging?
I’m not sure why this zero is stamped to the left of tdc
Also they

 

Nevermind , found out they stopped retarding the cam in 1977 trucks

 

Can you share your reference for this info? In my searching, I saw the following on Bubba's M-Block page:
"Some truck engines used the original non-retarded C8SE crankshaft sprocket, while others used the retarded D7TE sprocket." The table associated with this statement shows '77 and up trucks with both the D7TE (retarded) and the DOAE (not-retarded? Unclear).

Link:
http://grantorinosport.org/bubbaf250/parts/parts03.html

Hale

 

just install your timing chain set with the -4, 0, +4 and set it at 0 witch is straight up.

 

If your not degreeing your camshaft how are you going to know your cams ACTUAL timing events? Parts are not always boxed right nor the correct spec. The devils in the details. And most cams have 4* ground into them, so installing the timing chain strait up still puts the cam 4* advanced.

 

The machine shops here used to run a 400 gear set on the 460 back when, in order to compensate the 460 retard, seemed to work when that was all we had. I am sure degreeing a cam is a good idea, I will get stung one day I am sure, but of all the quality out of the package components I have installed, I have yet to really come across any aspect of the build that was out of print, so I stopped degreeing cams about 2 or 3 builds ago. The local machine shop has done engines since the early 80s, he said that the only times he recalls seeing an issue with this was after a line bore of a block which moves the location of crank/cam spacing, changing timing and often necessary to pursue corrective action.

 

but if you don't check, how do you know?

 

You won't. One could be leaving some h. p. on the bench when electing to not degree it in. I degree everyone, It doesn't cost anything to know for sure. The worst are those "dog bone" gear drives, I have never not had to move one of those.

 

My gear drive spec dead on, and it was a cheap E gay set from my first engine build 15yrs ago.