Angle or straight plug?

The first time I heard of this was in the early '70s when the Trans-Am series was big and American V8s were racing in camaros and firebirds and mustangs. There was a lot of factory support and people like Smokey Yunick consulted with the factories, so there was a lot of dyno work done. One of the areas being looked into was the combustion chamber. I don't know if it was always known, but there was power to be gained by moving the spark plug closer to the exhaust valve. Given the layout of the smallblock chevy, the only way to get the plug closer to the exhaust valve was to put the plugs in at an angle. People were actually machining cast iron plugs to press or furnace braze into the plug hole, then drilling a new plug hole with a milling machine. I think the angle plug was worth about 25hp on a 5 liter chevy. At some point chevy high perf heads were available over the counter with angled plugs.

How this applies to Mopar heads I don't know. Smallblocks already have angled plugs. Bigblocks were designed with straight plugs. When Edelbrock brought out their head the plugs were angled. While this probably made a power improvement, it also made some clearance problems when used with headers designed for straight plugs. Some in the Mopar community breathed a sigh of relief when MP's version of the Edelbrock head came with straight plugs.

R.