What makes the 974 head more desirable than other J heads for a 318 swap? I've done some searching but wanted to ask while this post is still somewhat current.
They're on the small side compared to other castings, port volume is usually around 150cc and the exhaust ports, 'smaller than a j head exh port l' but with a lot better shape qith a raised floor. J head is a great head, for a 340/360.
People lump them all together because they tend to overlook or are ignorant to the small , but quite significant... and mostly people judge them by max potential or by them flowing within 10 cfm as cast..."same size valve"..ill also add that MOST who tried a set of ported factory iron didnt have the right person performing the porting.
Sadly most who fall into that group, for that reason, will never try another set thats actually done right...in their mind they tried it and it wasnt all that.... but neither was their head porter.