Why? 'Cause it looks awesome.
I use my truck for work, I haul around 400lbs of tools everywhere, and often my 2000# tool trailer, plus there are the trips to the saw mill....
I run the dual W-1's, 547's, which have a smaller venturie than the later ones. My 216 is over bored, how much, I don't know, it was done about 20 years ago. I also have the Fenton headers.
What I have noticed, now that I have a few thousand miles on the set-up.
It idles much, much smoother. In fact, when at a stop light, next to a diesel, I can't tell if its running.
It does have more power, much more power. But, that's relative, stock I believe is what, 90 hp? So anything makes a dramatic change.
My gas mileage is exactly the same. Its two carbs, but each delivers half the fuel.
I do run way more timing than stock. The dizzy is 8 or 10 degrees ahead, I run regular gas.
I find I can run in forth gear where I used to have to run in third. So, my mileage has stayed the same, but I go faster.
Did I mention it looks awesome?
