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Longhorn Man · 06-08-2009, 10:44 PM

in theory, they should help.
I know a member on here who had the same engine as you do, had a 5 speed manual and a 3.07 gear rear in a 71 C/10. When he installed the headers, MPG dropped. He also noticed a MPG drop with the performer intake. There was tuning done on each mod.
He ended up swapping the manifolds and cast iron intake back on for MPG gains.
What this says, is the 260 horse engine is optimized at it's stock tune and dress.
The over drive and tall gears may have been enough to make your aplication have the oposite result.

In the end, there are so many variables, there is no telling.

On my old well worn 300,000 mile old 350 in my first truck, the performer intake and crusty junk headers did improve my MPG, but only by 1 MPG. However, that was a 10% increase.... which is beyond considerable. My combination was an untuned edelbrock 600, a very worn engine, with a TH350 and 4.10 gears.
Compairing the two is apples to oranges.

06-08-2009, 10:44 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: Ramhorns vs. Headers for MPG gains? in theory, they should help. I know a member on here who had the same engine as you do, had a 5 speed manual and a 3.07 gear rear in a 71 C/10. When he installed the headers, MPG dropped. He also noticed a MPG drop with the performer intake. There was tuning done on each mod. He ended up swapping the manifolds and cast iron intake back on for MPG gains. What this says, is the 260 horse engine is optimized at it's stock tune and dress. The over drive and tall gears may have been enough to make your aplication have the oposite result. In the end, there are so many variables, there is no telling. On my old well worn 300,000 mile old 350 in my first truck, the performer intake and crusty junk headers did improve my MPG, but only by 1 MPG. However, that was a 10% increase.... which is beyond considerable. My combination was an untuned edelbrock 600, a very worn engine, with a TH350 and 4.10 gears. Compairing the two is apples to oranges.