65 C-30 mileage check (after 114 miles)

[66Submarine]

Alright, I put 114.4 on the clock since I last checked it, and the results are in. I bought exactly 5.00 gallons in a can to check, and it was 30lbs worth of fuel; so the scale and math works.

In 114.4 miles of mixed driving, driving normally, I atomized 7.9 gallons of 87 octane with that little Rochester 2 bbl; for a total of 14.5MPG.

I'm pretty happy now, the truck drives great; and 14.5MPG I can live with. Only "mod" to speak of is that I bumped the timing up. To 12 degrees initial, IIRC. Carb is stock jetted, idle mixture screws turned in a bit lean from max RPM/vac reading for economy. The engine is a 195HP 283, the 2 barrel car version with the small chamber "power pack" heads. Rams horn manifolds running to a y-pipe and single small outlet OE type muffler. Transmission is the wonderful, indestructible, SM420 truck four speed. I think the rear gears are 4.10, with a 7.50-17 bias mud tire @ 620 revs per mile.

[Captainfab]

That's pretty decent for a 1 ton.

[Reyals Bemus]

I'll say!

[hopped up]

Better than my c/10
Posted via Mobile Device

[66Submarine]

Yeah, I'm pretty happy with it. 14.5 not even trying for it, bias ply mud tires and all. I'm also hoping to also find an auxiliary trans (twin stick setup) for split shifts and a little OD; that should help a bit, too. It's been a real good truck for me so far.

[K98AL]

I wish my C-10 with a 235 got that good...

[66Submarine]

I would think it should. Are you running a clutch or an auto trans? Check the idle adjustment and make sure it's not rich, like I said, I go lean past max speed/vac; turning it in until it runs rough then backing out until it just smooths out seems to work pretty well; of course do this when it's hot, go for a drive first to get it to temp. Make sure you don't have vacuum leaks, check the timing and plug gaps; see what color the plugs are, too. Maybe see if it likes a bit more timing, my 250 seems to. What RPM are you turning on the road? My C-10 had 31x10.5r15 4x4 tires on the back and 3.73 gears, runs about 2,100-2,300RPM. A three speed, 250, and a Monojet completed the driveline; and that truck got 18MPG like that once I got it tuned in.

[awbrown]

my 65 one ton got 15mpg with a 6 cylinder and a mono jet carb ....

[66Submarine]

292 or 250/230? I've heard of a few other people getting 14-15 with the 292 powered one tons. Never saw any reason they shouldn't, myself. In fact I'm putting a 292 in this truck soon.