Wire my stewart-warner tach into a CHEV HEI ignition

Didn't find the right year, but reasonably sure the '94 Chevy HEI is nearly identical to following...

https://www.autozone.com/repairguides/GM-Firebird-1967-1981-Repair-Guide/High-Energy-Ignition-hei-System/Description-and-Operation/_/P-0900c15280080b4a

You will need the connector/wire that fits into the HEI distributor. It would normally be included in the tach install kit that I assume you don't have.

is the mallory an hei dist there is a plug on the side of the cap 1 says batt 1 says tach

It depends on which distributor you have. If you have one with a vacuum line going to it, simply remove the line from the distributor and plug it off so it won't leak. start the engine and time it the conventional way with a timing light hooked to #1 cylinder wire, which is the front one on the driver's side.

If you have the HEI set-up, with the coil in the top of the distrbutor, then connect a Tach to the TACH terminal on the distributor and the other lead to battery negative, UNLESS the instructions for the tach you are usung specify different. Some tachs will specify Tach term inal and battery Positive.

orange and black wire go from ignition module to plug into coil in cap the 2 out side wires are green and red , red for power and green for tach.

The green wire from the tach goes to the negative side of the coil or if its an HEI distributor it will connect to the left of the hot wire going. to the distributor.

HEI distributor and burning coils,it in you connection first make sure you install primary and secondary prorperly as it comes out of the cap , and inside the cap wire from modules dont make contact if you are burning its from primary circuit, this is the (B+) or (battery most likely), your secondary is your tach and that need to switch from postitive to negative for it to create spark obvously if tach was grounded or applied power you wont start,but there are times the condensor in the distributor does stays fixed and shorts out the coil (replace that condensor its for suppression) when the condensor is replaced run a fused direct wire at B+ (from ignition) run the vehicle and monitor the tach wire and check to see if that get hot

tach hook up for chevy with hei distribitor is 1)white wire ; 12volt source 2)red wire -12 volt ignition switch (+) 3)black wire -battery ground (-) green wire ; to tach terminal on dist. / if it not hei with points just put green wire to neg. (-) side of coil

need to know if its a HEI cap and rotor or not. HEI caps have the coil built into them , an all in one ignition as compared to a external cylindrical coil.
you need to know that. either the distributor cap is a huge hurken thing (HEI) or it has an external coil somewhere or the cap has a ninth distributor hole in the middle of the cap to put a coil. wire.
after you figure out which one it is then you have to either go to www.autozone.com and study chevy wiring or buy a haynes manual for the similar vintage engine. for the external coil I would try a chilton manual for a chev truck before 1972. for HEI anytime thereafter. I may be off by a few years on the age of the engine. but hopefully you got an idea of what to do, or just google chev engine wiring? and study away.
good luck

jm

If you have the one I'm thinking of, it is just to the left of the main power terminal on the cap (usually marked tach)

I have heard of this happening when the tach is wired to the coil incorrectly. Most (if not all) tachs call for the signal wire to be connected to the NEGATIVE side of the coil. Trace your wiring to/from your tach and go from there...

I hope this helps! -Nick