July '21

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64 THE SHOP JULY 2021 JULY 2021 EDITOR'S NOTE: This is the fifth and final article in a multi-part series detailing the build of a 422-ci small-block Chevrolet Gen 1 engine. Part I appeared in the July 2020 issue of THE SHOP magazine, Part II in the October 2020 issue, Part III in the January 2021 issue and Part IV in the April 2021 issue. ROCKERS Our 18-degree cylinder heads require the use of offset intake and exhaust rocker arms. Our application calls for an intake rocker offset of 0.550-inch and an exhaust rocker offset of 0.220-inch. We chose pro-level aluminum full-roller rockers from Jesel, fitted with heavy-duty roller bearings and precision-hardened pushrod cup adjusters. Standard Chevy rocker arm ratio is 1.5:1. Since our camshaft lobe lifts measured 0.432-inch intake and 0.430-inch exhaust, with a 1.5:1 ratio, our effective valve lift would be 0.648 intake and 0.645 exhaust. We opted to increase lift by going to a 1.6:1 rocker arm ratio, which provided us with a 0.691-inch intake and 0.688-inch exhaust lift. This is still within the max range of the Trick Flow valve springs, which are rated at 0.700-plus-inch max lift. The Jesel rocker system fea- tures a full-length steel rocker stand that bolts to the head, with precisely located positions for each pair of shaft-mount rockers. The stands are secured with eight 7/16- inch screws that feature female Torx drives. Be aware that the bolt holes in the heads on each intake side are open to the lifter valley, requiring the use of thread sealer on these intake locations. The recommended t o r q u e v a l u e for all 7/16-inch s t a n d m o u n t Another go-round building a tried- and-true Gen 1 small-block Chevy. Back to Basics By Mike Mavrigian Part V Engine Products p.72 Since we're running a Jones Racing vacuum pump, the crankcase is sealed, using no passive breathers. 64 THE SHOP JULY 2021

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