Review on Inboard Ignition Coil Replacement for MerCruiser Thunderbolt IV and V Ignition Systems with HEI - Replacing 18-5438, 392-805570A2, 392-7803A4, 392-805570A1, 72115, 40511 by Chris Benton

Both the primary and secondary coils did not meet the requirements of the flash ignition system. I'm not going to ruin my ignition system with a non-standard coil. Not even installed, just returned and bought one that fits the manufacturer's specs. After contacting the seller and unimpressed by customer service, he couldn't and wouldn't answer questions about unqualification, instead being advertised and sold for a flash ignition system. I'm worried that the warranty won't be better. I'm glad I bought it from Revain so I could return it hassle free.