So I got my 81 318 converted to electronic ignition with the orange box and proform distributor/cap/rotor,a mechanical fuel pump, new gr4 spark plugs, and a summit m2008 carb, 1/2 wooden spacer, and performer intake.

I got it running, but had to bump up the idle because it shakes around 850rpm.

My timing light shows rpm and advance, and at 850 rpm, the lowest I can get the advance before the backfires through carb is about 30 btdc. and it runs like garbage. My spark plug wires are routed correctly, #1 and #8 generally point towards radiator with advance can (which works correctly) points toward passenger side of car. No vacuum leaks detected.

Now, at 1000 rpm idle and an advance of about about 41-ish btdc, the car runs fairly smooth, but slams into gear. Unless Im missing something Im pretty sure my balancer has slipped, or my timing chain is stretched, but could a stretched chain add 20+ degrees to a reading?

Correct me Im wrong, but putting #1 to tdc and drawing the mark on the balancer would give me a correct mark to get an actual timing reading right?