schwarz633
Member
- Oct 1, 2019
- 35
- Boat Info
- 1989 Weekender
- Engines
- Mercruiser 5.7 Inboard Straight Drive
I recently replaced the distributor caps and rotors on my 1989 300WE. The rotors were seized onto the distributor shafts and very difficult to remove. It was necessary to crank the engine to rotate the distributors in order to pry up on the rotor from opposite sides. This was done with the HT lead removed from the coil (bad idea, should have been grounded). On one of the engines I observed arcing from the HT tower on the coil to both of the small studs. Upon reassembly the engine wouldn't fire, no spark. The arcing had apparently taken out either the Thunderbolt IV module or possibly the hall effect sensor in the distributor.
After doing some research I decided on upgrading both distributors to DUI Marine HEI units from Performance Distributors. I liked the fact that the coil was incorporated into the cap and the installation would be clean and easy, eliminating the TB module and the coil. The only connections to the DUI distributor are +12V and the tachometer wire. The other option was the Delco EST which was ~ $100 more per distributor and not in stock. My starboard engine is reverse rotation so I assumed that I needed a reverse rotation distributor which was +$70 for the DUI and +$300 for the EST.
After spending a couple of hours trying to get the reverse rotation DUI distributor to drop down into the starboard engine I discovered that my reverse rotation engine doesn't use a reverse rotation distributor. I did however get the dead starboard engine running again using the standard rotation DUI distributor that was intended for the port standard rotation engine.
At this point I've only set the DUI distributor timing by ear, as neither of the (2) digital variable advance timing lights that I have will work with the DUI distributor. This has been confirmed by Performance Distributors, something about their extended dwell period throws them off. I recently located an old school non-digital timing light and will be using it soon.
I have sent the reverse rotation distributor back to Performance Distributors for conversion to standard rotation and hope to be installing that on the port engine in the near future.
After doing some research I decided on upgrading both distributors to DUI Marine HEI units from Performance Distributors. I liked the fact that the coil was incorporated into the cap and the installation would be clean and easy, eliminating the TB module and the coil. The only connections to the DUI distributor are +12V and the tachometer wire. The other option was the Delco EST which was ~ $100 more per distributor and not in stock. My starboard engine is reverse rotation so I assumed that I needed a reverse rotation distributor which was +$70 for the DUI and +$300 for the EST.
After spending a couple of hours trying to get the reverse rotation DUI distributor to drop down into the starboard engine I discovered that my reverse rotation engine doesn't use a reverse rotation distributor. I did however get the dead starboard engine running again using the standard rotation DUI distributor that was intended for the port standard rotation engine.
At this point I've only set the DUI distributor timing by ear, as neither of the (2) digital variable advance timing lights that I have will work with the DUI distributor. This has been confirmed by Performance Distributors, something about their extended dwell period throws them off. I recently located an old school non-digital timing light and will be using it soon.
I have sent the reverse rotation distributor back to Performance Distributors for conversion to standard rotation and hope to be installing that on the port engine in the near future.