does anyone one know if a 351w will drop in place of a 390 or will i need to re do the mounts?

 

Motor mounts, bellhousing and or transmission, exhaust, and accessories brackets are just some of the things that need to be changed. Might be easier to rebuilt the FE.

 

Why would you want to ditch the FE in favor of a Windsor, especially considering all that's involved.

I would think the money required for the swap could be better spent on rebuilding the FE.

 

The 351 has more options and gets better mpg than the 390

 

On the more options part i beg to differ, but i can't argue with you on the mpg's, the 351 will do a little better, but don't expect miracles.

 

I had a 79 4x4 lifted with 35s 351w and 4 speed 12.5 mpg. My 76 4x4 lifted with 36s 390 and a c6 8mpg. Just trying to find a way to get better mileage with decent power and not selling my truck

 

I hear ya, with 4 dollar gas being the new reality every mpg counts.

My '75 Highboy with a 390, 4spd, 35's and 4.10's gets 8mpg too.

 

It sucks I spend almost $130 in fuel a week for work. Love my truck but it's killin me to drive. Tryin to come up with a way for some better mpg

 

I feel your pain, my truck is pretty much just used for recreational cruising on the weekends.

And even then i'm still dropping 50 bucks a week in gas.

 

Got any good ideas for some better mpg?

 

Buy a Honda civic. Ok that wasn't funny sorry. Switching your c6 to a manual might help some.

 

Nothing more than the obvious tried and true mileage saving ideas.

These trucks are what they are, and economical isn't in the equation, unfortunately.

Most get anywhere from 6mpg 16mpg, with the average being about 12mpg.

A diesel swap would be my recommendation for any vast improvement in mpg's.

Though the 300 IL6 can pull down some pretty decent mpg numbers too.

 

Quadrajunk carb will make it a little better.

 

Sounds like your 390 needs a tuneup. Lean out the carb and up the timing.

Josh

 

I'm not sure if that was directed at the OP or me, but i'll answer anyway.

Yea a tune-up is probably in order, the motor's running a little on the fat side.

The timing is advanced as far possible (just shy of detonation) 12 initial, 38 total.

The truck tips the scales at just under three tons so i don't expect any huge improvements in mileage even with a tune-up

It's always hovered around the 8-8.5mpg range.