Part# 12301-22
MFR Model# 12301-22
Engine/MagnetoPart No.
0-320/S4, 0-360/S412301-22


Note: Photo is for reference only. Individual items may differ.

Production ignition harnesses at remarkably low prices. Late type 5MM wire constructed of 16 strands of tightly braided copper wire impregnated with scuff resistant white silicone. All strands must fracture before a complete open circuit type failure occurs thus extending lead life. Lead flexibility is retained from -65 to 400F. Moisture & cleaning solvent penetration is eliminated by the impregnated silicone coating.

This extremely flexible wire lends itself to sharp bends thereby eliminating the need for old style harness elbows. No soldered joints in the grounding circuit. Custom made for most 4 & 6 cylinder engines using Bendix or Eisemann magnetos and 4 cylinder engines using Slick magnetos.Cable outlet plates are not furnished for Bendix & Eisemann mags as these are already installed on the magnetos in service. They must be purchased separately for new magneto installations. Harnesses for Slick magnetos are furnished with the backplates installed. Standard harnesses for the Bendix S4/S6 mags are fitted with a male nut which screws into the threaded outlet plate on the back of the mag. Harnesses for old style Bendix SF4 and SF6 magnetos are fitted with female nuts.

ACS Products ignition harnesses can be used on experimental aircraft or on certified aircraft with field approval (FAA Form 337). If FAA/PMA harness is mandatory or if for use with 3/4" spark plugs, use Slick Bendix, Aero-Lite or Champion harnesses.
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WARNING: Cancer and Reproductive Harm -


Engine/Magnetos Part No.
Cont. A-65/S4 12301-02
C-85/S4 12301-05
C-90/S4 12301-06
0-200/S4 12301-05
LYC. 0-100/S4 12301-21
0-235/S4 12301-21
0-290/S4 12301-21
0-320/S4 12301-22
0-360/S4 with screw-in fittings 12301-22
Cont.A-65/SF4 12302-02
A-75/SF4 12302-03
Lyc.0-100/SF4 12302-20
0-235/SF4 12302-20
0-290/SF4 12302-20
Cont.E-185/S6 12305-10
E-225/S6 12305-11
O-470/S6 12305-13
C-145/S6 12305-09
O-300/S6 12305-09
Lyc. 0-540/S6 12305-22
IO-540/S6 12305-22
Franklin165/S6 12305-41
Cont.C-125-SF6 12307-08
Lyc.0-435/SF6 12307-23

Replacement Leads

Replacement Leads For Bendix & Eisemann

Description Part Number Price Buy
Replacement Leads to 48" (Specify Length) (Bendix & Eisemann only) Call for pricing

All Harnesses Furnished with Cable Ties and Clamps


Not happy. Ordered this when arrived found fine print not certified. Mentioned in description online that filing Form 337 may be needed. Mechanic says form will not be approved unless stranded on Artic Tundra etc. Returned but I have to pay shipping both ways!

Edwin M Verified Purchase


September 25, 2022

When ordering make sure you order the item with Magneto caps.

Doug Verified Purchase


June 28, 2022

I have ordered the harness made for the slick magneto...excellent. This one, not so much. Why are the leads considerably shorter? Why would the manufacturer not label the leads with the intended position (they have to cut them, so they obviously know) I had to use 2 of the leads from the old harness (luckily tested good) as this package has leads that are short . Leads are well done, however the above mentioned issues should be corrected.

Ken T Verified Purchase


January 4, 2022

Good product, Eastwood to install as long as you havé à sub D cripper.

Richard A Verified Purchase


July 13, 2021

The ignition harness looks great and came with installation instructions. The price was decent as well

Terrall P
August 17, 2020

Good Value

Joe B
May 11, 2020

Nice harness, well made.

Jeffrey M
November 9, 2019

Garry L
August 14, 2018

Good harness . some type of elbows would be helpful on most cylinders.

Stoner A
June 19, 2020

They look pretty good and should work but I only needed half of them since I have half an EI system.

March 2, 2019


Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.

Q: Does the 12305-11 set have 90 degree ends at the plugs? Also, can you confirm this is the proper set for an A35 bonanza with E 225 engine.

The ACS Products harnesses do not have 90* elbows, and are not FAA approved. Intended for use on experimental aircraft only.

Q: Regarding the shielded ignition harnesses for Bendix mags: Are the prices quoted for magneto harnesses per magneto or per engine?

These are priced and sold per engine. You will get a left and right harness.

Q: I am in need of a complete harness assembly including the rear distributor box for a Bendix S6lN-21 mag for my Continental 145-2. Do these ACS harnesses come with the rear block or do I have to make the ends up to fit?

ACS harnesses are made to be used with 5/8" barrel spark plugs, and the magneto cap is not included for Bendix mags, they hare threaded leads. The harnesses for Slick mags have the magneto plate swaged to the harness leads.

Q: These leads are advertised as suitable for use on a certified engine so long as a form 337 is filed... do these leads come with the proper reference data to file with the 337?

The units do not come with the documents for a 337. The aircraft owner will need to discuss the approval process with the A&P and possibly work with the manufucaturer for specific details.

Q: Are installation instructions included for the ends that go in the mags?

There are crimping instructions included.

Q: For an A65 with SF4s, is the harness completely assembled and ready to install?

These would need to be installed into your current harness plates.

Q: do these suit Bendix Dual Mag ? original harness # (10-384405-303 )

No this will only work with s4/s6 mags. You would need a Kelly aerospace harness for a dual mag.

Q: Will 12301-05 work for a Bendix s4ln-21 with REM40E spark plugs?

This will work with S4 mags and REM/UREM plugs on C-85 and O-200's.

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