E30 Engine Swap, now no Tach

So I cooked the 325is motor in my 87 e30, swapped in a spare and now I don't have a working tach, plus the motor is acting like it can't advance the spark. A few more mystery details: 1. I swapped the instrument cluster at the same time, so not sure if my tach is dead in the cluster 2. In a fit of stupidity and rage, I pulled the old head off the blown motor (with intake and exhaust manifold attaches) and chucked it to the recycler, with the BRAND NEW spark plug wires on it. So the current motor is running some very old wires, and the tach signal wire is a totally different color, so it COULD be a replacement or who knows. 3. New spark plug wires are $$$$, so I wanna make sure they are the issue before I buy a new set.

Soooo, how do I check this out? This would appear to be the rarest damn e30 problem ever since all my usual web sources have nothing listed, and even google failed me.

Since you swapped in a different cluster I would imagine that either the tach in the new cluster is bad, or you missed a connector on the back side. Also, if the batteries in the service indicator board on the back of the cluster are bad the speedo/tach may or may not work correctly.

In reply to stuart in mn:

Checked Connectors, three times, all look good. I think it is probably the battery. If I don't have a working tach in the cluster, will that keep the ecu from controlling the spark?

Since you have no advance I will also assume the ECU is not getting a good signal - since it runs we know its not the crank position so... check your lead from the spark plug wire back to the harness.

Are you using the same distributor? Also, you might as well go ahead and get some new wires. If they aren't causing this particular issue, they''ll cause another.

will check the connector for the signal next.