I have a sbc 350 vortec approx 1100hrs. Just did tune up on engine and went to check timing and it was way off. Couldn't see the mark off.
Timing light is on the #1 wire
if I try To set it at advanced time it wont start
if I use shunt to set initial base time it dies
the spark plugs looked terrible when I pulled them fried electrodes
it's a reverse rotation motor
new plugs wires cap and rotor and module ,distributor and block 2 yrs old
cant figure it out

If this isn't right forum could someone point me in right direction please.

Was it running ok before you did the tune up ? If so you probably have the plug wires on wrong, especially if it is reverse rotation.

I did them one at a time. Always do

If u use a digital timing light, which typically only go from zero to advanced timing with the digital adjustment, on a reverse rotation engine, you will be trying to set the timing very retarded... gotta mark balancer and leave light at 0*, set old school with balancer marks

The balancer has a mark. Are you saying instead of 8 before tdc it should be 81? On a digital gun? I think it counts down from 90?

also beware the reverse rotation needs a modified dist with a needle bearing under the reluctor shaft as the beveled gear now pulls the shaft downward you can test by how much up and down play. also pull number one plug bring it up on compression ck your balencer the big groove is the mark to use the dist still rotates the same direction but the firing order is different on a vortec do not exceed 26 degrees on top as thats what counts the more idle timing the better we try to get 18-20 at 600 you can do that with delco est system it makes a very smooth and quiet idle for fishing and trolling long hrs

I dont think distributor is the problem. Came from mfr that way and ran for 1100hrs without issue. Started backfiring when quickly revved which is why I decided to do tune up. Thanks for all the replies. I appreciate it. I will continue today and hopefully figure it out.

What kind of distributor do you have? Had a similar issue on a Crusader 270, ended up being the mechanical advance was corroded/rusted and was sticking open or shut.