i have done the valve job on my engine to 8 and 18 thousandths. i have installed a bhaf on the stock air tube and still no change in mpg. it doesnt matter if i goose it or im driving it like a grandpa, or pulling my 23 foot horse trailer and running empty it gets between 10 and 12 mpg. the only thing i havent done is have my timing advanced. is it safe to advance timing with 276 thousand miles and without head studs?

 

Yes you can bump timing. Generally its advised not to go past 17* without studs. I would put it at 15.5*

What are you getting empty?

Chris

 

im getting 12 on a good day. but even when im loaded it doesnt change much.

 

How fast do you normally drive? Got a lift or big wheels and tires on it?

 

this may sound stupid , if so forgive me but
fuel filter been replaced ?
i would do a volume test for lift pump as a starting point mainly because
low side pressure is just as important as the high side
pressure might be good but volume bad, 12mpg is pretty low even hauling
4.10s and a combination of other stuff wrong could produce bad milage like that

good luck
scott

 

Real low. But like was already mentioned, bump the timing for more MPG.

 

My 95 done the same thing, i went from 285 MTs to a 265 MT and gained 3mpg.

 

Meanwhile, I went from 265 ATł's to 285 ATł's, and I also gained 1-2mpg.
Apparently, there are no hard and fast rules about this without considering all the case by case pages of semantics.

 

Do you have 4:10s? im in the same boat as the OP i have finally just put my truck back stock with intake and exhaust and hope for better than my last tank which was 12.9 mpg, and that was absolutely babying it. i would love to know how people are getting 20+ mpg

 

I'm not positive, but I'm pretty sure when I rebuilt the rear last year it had 3.73's.
Sliding my fuel plate forward gained me a couple, I used to get 19-20 once in a blue moon when everything went just right while running the tank, now I can do it easily. Everyone I know who I have personally witnessed get 20+ has bumped their timing. The 12V guru around here is running twins, ran low tens at the track and gets 25mpg with his daily driver, his is bumped to 22 degrees. The conventional wisdom I've picked up here says this is insanity, but other than being a little harder to start when it's cold out he hasn't had any issues and he's been building these trucks for like, fifteen years. Still, most of the guys I know are running around 17 degrees and had noticeable improvement in mpg.