OEM: Replacement single valve springs for M30 engines up to 08/86. It is a good idea to replace these when doing a stock cylinder head rebuild.
HD: Heavy Duty single valve springs for the M30 engine. These springs will work well with the any upgraded camshaft below 300′ duration.
Technical note regarding late-style dual valve springs: These HD-Single Springs are nearly identical to the spring pressure rates of the dual valve springs found on the late M30 heads made after 09/1986. This means that this is an inexpensive replacement option for those springs. No additional hardware is needed. In other words these are HD for early M30 and stock replacement for late M30.
Race: We recommend these for all track cars and any M30 using high lift cams. Sold in a complete set of 12 inner and 12 outer springs. Installation notes: When installing these springs, you’ll either need to use aftermarket spring retainers (we have them in steel or titanium) or you’ll need to perform a very-slight modification to the factory steel retainers due to the smaller I.D. of the inner valve spring (contact us for more info). Also, you must use later-style valve guides with these dual valve springs, as the old style seals (as found on E9 heads) will interfere with the inner spring.