MPG

[7echo]

My truck gets about 10.5 to 11.5 MPG in city driving.

Is that typical for these trucks?

Stock, '93 RCSB, 4L60e, 305, 188,000 miles.

 

[RichLo]

Unfortunatly yea, unless you do some work to improve it, but even still were only talking a few MPGs with a full tune-up, exhaust, e-fans, and some other odds and ends.

I just averaged just under 15 on a road trip with the cruise control at 60mph following a semi with the truck already at operating temperature when I filled up before (best case scenario). it averages around yours for normal driving. Mines a stock 1993, 305, 5-speed, 250k miles with a fresh tune-up around 5k miles ago.

 

[c1500deathtrap]

Really hilly out there or what ? I average 15 city 17-18 highway

 

[L31MaxExpress]

Seems low for a RCSB.

My guess is the timing chain has alot of slack in it retarding the cam timing and possibly ignition timing of it has not been checked. TBI base gaskets also fail, causing a vacuum leak which effects the MAP sensor and fuel delivery.

I drove an 87 G20 van with a 305 TBI and 3spd auto with 3.08 gears for a while. Had no problem getting 15 mpg out of it in mixed driving.

 

[7echo]

"My guess is the timing chain has alot of slack in it retarding the cam timing and possibly ignition timing of it has not been checked. TBI base gaskets also fail, causing a vacuum leak which effects the MAP sensor and fuel delivery."
I timed the motor when i did a tune up soon after i got it. But I don't doubt the timing chain is worn. I will ck the tbi gasket but it was replaced when I rebuilt the tbi.


"really hilly ou there or what ? i average 15 city 17-18 highway"
Flat here, on the Georgia coast.

 

[c1500deathtrap]

"My guess is the timing chain has alot of slack in it retarding the cam timing and possibly ignition timing of it has not been checked. TBI base gaskets also fail, causing a vacuum leak which effects the MAP sensor and fuel delivery."
I timed the motor when i did a tune up soon after i got it. But I don't doubt the timing chain is worn. I will ck the tbi gasket but it was replaced when I rebuilt the tbi.


"really hilly ou there or what ? i average 15 city 17-18 highway"
Flat here, on the Georgia coast.

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[tanman_2006]

My 95 K1500 305 w/ 3.42s got 16mpg city and 23 highway. I'd say you need a tune up, and clean up the tbi. I would plan on a full distributor and timing chain kit.

 

[7echo]

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Thanks! Much better.

My 95 K1500 305 w/ 3.42s got 16mpg city and 23 highway. I'd say you need a tune up, and clean up the tbi. I would plan on a full distributor and timing chain kit.

Is the timing chain replacement the same for all the SBCs? I see some videos for the 5.7 but not 5.0.

If someone could point out a video or write up for the process I would appreciate it!

Thanks.

 

[jkeaton]

I get that around town. Maybe 16-17 on a trip. I maintain mine well, it's just the nature of the beast to me. I hardly ever drive it, so it really does not bother me. I pity those that use these trucks as daily drivers...lol

 

[homesick]

I don't know what axle ratios y'all run, or what ratios were available, but that's a factor that needs to be considered.

My all-stock '95 2-door Tahoe 4X4, with a 350 and 3.73 gears, is getting about the same city mileage as OP.

FWIW, I don't drive it far, and I'm a life-long 'warm it up before you drive it' kind of guy.

joe