Whats your engine specs and gas mileage? - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jku72 · 06-11-2002, 07:21 AM

I am sorry if your trucks get bad gas mileage. If you spent as much energy going for good mileage, as you did for speed, you would see it is not only possible, but higher figures are also possible. Try running synthetic oil, and tuning the engine for maximum mileage. I run an accel HEI in both trucks, and opened the plug gaps to 55 thousanths. On the highway, keep the throttle position constant, and, if you go on long trips, advance the timing a hair more than you would for around town driving. And listen to Bush, keep the tires full, plus 5 pounds. It is possible, and not to hard to achieve. Headers, as you know, work great as well, along with an h pipe, and duals.
I also have squeezed 19.8 mpg out of a 67 catalina, with a 400 cid and t-400, with 3.08 gears, but the true secret is compression ratio.

bobs409 · 06-11-2002, 07:32 AM

'69 short step that weighs 3700lbs with a stock 1974 350/350. Can't give exact mileage until I fix inaccurate speedometer but im guessing 15-17 or even higher in town which is great! It seems to get a bit better gas mileage than my '69 Chevelle and that one I have checked at 17 in town. (307 w/powerglide and 3.08 rear)

My truck's gas mileage seems to suffer on big highways. The gears are somewhere around 355-373. Still trying to confirm that.

My old '69 4X4 Blazer got a consistant 10 mpg in 2 wheel drive. That sucked!

Huck · 06-11-2002, 08:20 AM

72 LWB 1/2 ton = GM crate 350, headers, HEI, Edelbrock 600cfm, 5SPEED, 307 posi, 235/75R15 on ralleys =======16-17mpg around town AND up to 22mpg crusing on the interstate at 70mph===tach reads 2500rpm. Cost of gas here in this part of KY $1.22. Now if I could just find a nice short fleetside rust free bed --now that would be real cool!!
By the way, with the truck geared so high, pulling a heavy tandem trailer with load or favorite bass boat, requires me to downshift to 4th or 3rd on steep hills but that's OK with me.

Willy Prost · 06-11-2002, 10:07 AM

High milage, 250-6/3-speed, 71 short bed stepside. Only change from stock(for now) is Pertronix module replacing points.

14-16 in in town traffic and communiting, 17-19 highway.

I once got 21 for a tankful by highway driving on rural highway traveling no faster than 50 mph.

okietruck · 06-11-2002, 10:58 AM

1972 LWB stepside. New GW350 with Holley Street Avenger 670, Holley Street Dominator manifold, headman hedders, Accel HEI dist., original 3-speed w/floor shift, 3.73 rear end. 10-11 mpg at 80 mph.

06-11-2002, 07:21 AM	#26
jku72 Registered User Join Date: Jan 2002 Location: cornville, maine Posts: 659	I am sorry if your trucks get bad gas mileage. If you spent as much energy going for good mileage, as you did for speed, you would see it is not only possible, but higher figures are also possible. Try running synthetic oil, and tuning the engine for maximum mileage. I run an accel HEI in both trucks, and opened the plug gaps to 55 thousanths. On the highway, keep the throttle position constant, and, if you go on long trips, advance the timing a hair more than you would for around town driving. And listen to Bush, keep the tires full, plus 5 pounds. It is possible, and not to hard to achieve. Headers, as you know, work great as well, along with an h pipe, and duals. I also have squeezed 19.8 mpg out of a 67 catalina, with a 400 cid and t-400, with 3.08 gears, but the true secret is compression ratio. __________________ jku Cornville, Maine 68 C10 burb 42 Willys MB 46 Dodge WF-32 1.5 ton 53 & 56 Olds' 60 Cadillac 22 Dodge Brothers

06-11-2002, 07:32 AM	#27
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	'69 short step that weighs 3700lbs with a stock 1974 350/350. Can't give exact mileage until I fix inaccurate speedometer but im guessing 15-17 or even higher in town which is great! It seems to get a bit better gas mileage than my '69 Chevelle and that one I have checked at 17 in town. (307 w/powerglide and 3.08 rear) My truck's gas mileage seems to suffer on big highways. The gears are somewhere around 355-373. Still trying to confirm that. My old '69 4X4 Blazer got a consistant 10 mpg in 2 wheel drive. That sucked! __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

06-11-2002, 08:20 AM	#28
Huck Senior Member Join Date: Jun 2001 Location: Shelbyville, KY Posts: 3,261	72 LWB 1/2 ton = GM crate 350, headers, HEI, Edelbrock 600cfm, 5SPEED, 307 posi, 235/75R15 on ralleys =======16-17mpg around town AND up to 22mpg crusing on the interstate at 70mph===tach reads 2500rpm. Cost of gas here in this part of KY $1.22. Now if I could just find a nice short fleetside rust free bed --now that would be real cool!! By the way, with the truck geared so high, pulling a heavy tandem trailer with load or favorite bass boat, requires me to downshift to 4th or 3rd on steep hills but that's OK with me.

06-11-2002, 10:07 AM	#29
Willy Prost Senior Member Join Date: Jan 2000 Location: Arlington, VA Posts: 398	High milage, 250-6/3-speed, 71 short bed stepside. Only change from stock(for now) is Pertronix module replacing points. 14-16 in in town traffic and communiting, 17-19 highway. I once got 21 for a tankful by highway driving on rural highway traveling no faster than 50 mph.

06-11-2002, 10:58 AM	#30
okietruck Registered User Join Date: Apr 2002 Location: Tulsa, OK, USA Posts: 117	1972 LWB stepside. New GW350 with Holley Street Avenger 670, Holley Street Dominator manifold, headman hedders, Accel HEI dist., original 3-speed w/floor shift, 3.73 rear end. 10-11 mpg at 80 mph.



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