Holley sucks🤬🤬🤬
Joined: Nov 2001
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From: Schiller Park, ILL Member: #317
To show you how in-depth the development process was, we ended up with 1970-74 and 1975-81 specific engine mounts and long-tube headers to account for the subtle differences in the subframe and floor geometries between them and maximize ground clearance in both instances. If you design a header that is tucked up tight to the floor on a 75-81 car and try to install it on a 70-74 car the collectors will bang into the floor...unless you tilt the engine down at a steeper inclination angle, which impacts the U-joint working angles in a negative way. Both configurations provide maximum ground clearance and awesome U-joint working angles without any modifications needed to the floor sheet metal...even on moderately lowered cars.
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Thanks for the explanation, I was unaware of these minor differences. I thought that only the crossmember would be different going from 1974 to '75, just to accommodate the cat, I didn't realize that there were impactful changes to the floor and subframe as well. I would have assumed that 1970-74 stuff would have worked with little/no hassle. Thank you for sharing this.
No problem
