The fourth-era 4A-GE engine was developed from 1991 to 1995. It's silver cam covers with chrome lettering, hence the nickname "silver top". This engine over again functions a completely new cylinder head which uses 5 valves for each cylinder as opposed to 4. It works by using Toyota's Variable Valve https://4ageblacktopengineforsale24567.tkzblog.com/39534982/toyota-4age-for-sale-things-to-know-before-you-buy