MPG Pt.1

[Stewart G Griffin]

Well, this is the first tankfull that i've run with the digital speedo/odometer.

Initial figures, while not "disasterous," were not too "comforting" either;  15.83 mpg.  Mostly highway driving.

The setup:   
350 Crate engine---260 horse version, everything stock--all vacuum, emmisions, air cleaner installed.  Stock, non-CCC quadrajet.  Stock exhaust manifolds.
AC delco R45TS plugs----for now.
TH-350C
2.56 rear diff gear.
Off brand 235/75 15 tires aired to 35psi.
Dual exahaust with dual cats after the stock manifolds.  Flowmaster 40 series.
Truck is at stock height---not raised or lowered.
Weight unknown, but probably between 3800 and 4200
The engine turns 1800 at 55 and 2100 at 65.
As far i know, and to the best of my ability, the engine is set at 8 degrees BTDC initial.  Also, the non-esc dist, we think, is out of a 76 chevelle station wagon, but this is really unknown as well.

At first, since this is not my daily driver, i was going to pretty much leave everything as is and not really worry about it;  .24 cents per mile fuel cost for something i can use to go to home depot, move furniture and large stuff around is not too bad---if this was a stable price.  But since, lately, gas seems to be rising at .10cents per week, this is unstable.  So we'll see.  i may very well have to go to high-compression heads and water injection.

For now, the short-term items i'm proposing are:
1) Since i need an oil change badly, i'm probably going to go with synthetic.  What weight oil should stock SBCs run?

2) Aerodynamics.  i think this could really help.  Tonneau cover, the open grill area can be made smaller.
The underside.

[VileZambonie]

Didn't we already talk about all this stuff?

Advance your timing and make sure the distributor advance and vacuum advance are working correctly, forget the synthetic, Adding the tonneau cover is going to add weight, and your high compression heads aren't going to help either. Change your final drive ratio and plop a 700R4 in there. Those are your best most cost effective mods.

[ccz145a]

do a cost analysis, too. if you only drive a couple of thousand miles a year in it, it will take a long time to recoup the cost.

planned savings at $4/gallon:

1mpg increase at 1000 mi/year = savings of 1000/4 = $250/year

[zieg85]

Your almost 16 mpg will likely be 11-12 around town going to Home Depot.  I'd say your probably close to ideal with what I would expect.  That is about what my 454 does but I put less that 1500 miles on it a year.

[N2TRUX]

I have found that a bed cover will give you about 1 mpg improvement on average. As mentioned with your minimal driving it would take several years to recoup your cost. But then again gas is on the rise once more....

[werewolfx13]

my '84 with the holley when I first got it set up right was getting about 15-17 w/ a 305/th350c/2.73 out on the highway at 65 mph..when that trans died, a non-lockup th350 was installed and mileage dropped to 14-16, I started using the soft tonneu cover again (very lightweight), and my mileage went down to 12-14 average, took the tonneu cover back off, mileage went back up. Dropped the tailgate, mileage went down to 11-14. Took the tailgate off, 13-15 mpg. Best mpg was no cover, tailgate up, windows up, AC on, cruise on. Gave it to my dad, before it ate a cam lobe, he was getting 10-12 with all the junk in the bed. These aren't one tank readings, thats the mileage i got making regular 120 mile trips.

+1 on the cost analysis..if you only drive 1000-4000 miles/year, it will take awhile to recover what you spend to improve the mileage by 1-3 mpg..even at $5/gallon for gas..

[Stewart G Griffin]

For the second tankful,  16.89.  i'm not sure of why the big jump;  The only thing different this time was i switched to Mobil 1 synthetic 10-30W oil.  And i don't think synthetic would account for a 1 mpg increase?  The previous oil was the same oil as when i bought the truck---i have no idea what kind/weight it was and how long it was in there.

But i do everything the same;  i put the nozzle all the way in and let it click it off---i don't top it off.

It was 305.7 miles and 18.09 gallons to fill up.  $74.69 ouch.   i will get my previous figures when i get a chance.

[Bitzer!]

$74.69 ouch.  ha ha ha ha try $143.40 over here!!

I guess cost comparisons are always relevany tho

[Lt.Del]

Move closer to Home Depot.

[werewolfx13]

Move closer to Home Depot.

  nice..

[Stewart G Griffin]

Let us please not joke around at a time where gas is over $4 per gallon.

Thank you.

[eventhorizon66]

It doesn't hurt to keep a sense of humor about it since there's no point in getting upset.  It's just the way things are, get used to it.  You could always sell your truck and hire contractors to do everything around the house.  But that would cost alot more than keeping fuel in your parts/supplies go-getter, depending on how much work you've got to do.  And if its your play thing or hobby truck, suck it up, fun/hobbies cost money (lots of it), always have.

[SUX2BU99]

Hey, just find yourself an 82 Special Economy C10 and you're all set:

http://www.73-87.com/7387info/ads_GM/82_20mpg.jpg

[eventhorizon66]

LOL, that's back when they tested fuel economy downhill, gearbox in neutral, in the slip-stream of a semi-truck, with a 30mph tailwind.

[Stewart G Griffin]

i don't doubt that the truck could make 20mpg, but 28 is a bit of a stretch.

i was reading more about that engine---it was a special 305 with 9:5ish compression, special heads, special Q-jet.  i'll try to locate a link shortly.